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  • richardmitnick 9:50 am on June 18, 2021 Permalink | Reply
    Tags: "Brookhaven Lab Intern Returns to Continue Theoretical Physics Pursuit", Co-design Center for Quantum Advantage (C2QA), DOE Science Undergraduate Laboratory Internships, National Quantum Information Science Research Centers, , , , , Theoretical Physics, Wenjie Gong recently received a Barry Goldwater Scholarship., Women in STEM-Wenjie Gong   

    From DOE’s Brookhaven National Laboratory (US) : Women in STEM-Wenjie Gong “Brookhaven Lab Intern Returns to Continue Theoretical Physics Pursuit” 

    From DOE’s Brookhaven National Laboratory (US)

    June 14, 2021
    Kelly Zegers

    Wenjie Gong virtually visits Brookhaven for an internship to perform theory research on quantum information science in nuclear physics.

    Wenjie Gong, who recently received a Barry Goldwater Scholarship. (Courtesy photo.)

    Internships often help students nail down the direction they’d like to take their scientific pursuits. For Wenjie Gong, who just completed her junior year at Harvard University (US), a first look into theoretical physics last summer as an intern with the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory made her want to dive further into the field.

    Gong returns to Brookhaven Lab this summer for her second experience as a virtual DOE Science Undergraduate Laboratory Internships (SULI) participant to continue collaborating with Raju Venugopalan, a senior physicist and Nuclear Theory Group leader. Together, they will explore the connections between nuclear physics theory—which explores the interactions of fundamental particles—and quantum computing.

    “I find theoretical physics fascinating as there are so many different avenues to explore and so many different angles from which to approach a problem,” Gong said. “Even though it can be difficult to parse through the technical underpinnings of different physical situations, any progress made is all the more exciting and rewarding.”

    Last year, Gong collaborated with Venugopalan on a project exploring possible ways to measure a quantum phenomenon known as “entanglement” in the matter produced at high-energy collisions.

    The physical properties of entangled particles are inextricably linked, even when the particles are separated by a great distance. Albert Einstein referred to entanglement as “spooky action at distance.”

    Studying this phenomenon is an important part of setting up long-distance quantum computing networks—the topic of many of the experiments at Co-design Center for Quantum Advantage (C2QA). The center led by Brookhaven Lab is one of five National Quantum Information Science Research Centers and applies quantum principles to materials, devices and software co-design efforts to lay the foundation for a new generation of quantum computers.

    “Usually, entanglement requires very precise measurements that are found in optics laboratories, but we wanted to look at how we could understand entanglement in high-energy particle collisions, which have much less of a controlled environment,” Gong said.

    Venugopalan said the motivation behind thinking of ways to detect entanglement in high-energy collisions is two-fold, first asking the question: “Can we think of experimental measures in collider experiments that have comparable ability to extract quantum action-at-a distance just as the carefully designed tabletop experiments?”

    “That would be interesting in itself because one might be inclined to think it unlikely,” he said.

    Venugopalan said scientists have identified sub-atomic particle correlations of so-called Lambda hyperons, which have particular properties that may allow such an experiment. Those experiments would open up the question of whether entanglement persists if scientists change the conditions of the collisions, he said.

    “If we made the collisions more violent, say, by increasing the number of particles produced, would the quantum action-at-a-distance correlation go away, just as you, and I, as macroscopic quantum states, don’t exhibit any spooky action-at-a-distance nonsense,” Venugopalan said. “When does such a quantum-to-classical transition take place?”

    In addition, can such measurements teach us about the nature of the interactions of the building blocks of matter–quarks and gluons?

    There may be more questions than answers at this stage, “but these questions force us to refine our experimental and computational tools,” Venugopalan said.

    Gong will continue collaborating with Venugopalan to develop the project on entanglement this summer. She may also start a new project exploring quirky features of soft particles in the quantum theory of electromagnetism that also apply to the strong force of nuclear physics, Venugopalan said. While her internship is virtual again this year, she said she learned last summer that collaborating remotely can be productive and rewarding.

    “Wenjie is the real deal,” Venugopalan said. “Even as a rising junior, she was functioning at the level of a postdoc. It’s a great joy to exchange ‘crazy’ ideas with her and work out the consequences. She shows great promise for an outstanding career in theoretical physics.”

    Others have noticed Gong’s scientific talent. She was recently honored with a Barry M. Goldwater Scholarship. The prestigious award supports impressive undergraduates who plan to pursue a PhD in the natural sciences, mathematics, and engineering.

    “I feel really honored and also very grateful to Raju, the Department of Energy (US) , and Brookhaven for providing me the opportunity to do this research—which I wrote about in my Goldwater essay,” Gong said.

    Gong said she’s looking forward to applying concepts from courses she took at Harvard over the past year, including quantum field theory, which she found challenging but also rewarding.

    Gong’s interest in physics started when she took Advanced Placement (AP) Physics in high school. The topic drew her in because it requires a way of thinking that’s different compared to other sciences because it explores the laws governing the motion of matter and existence, she said.

    In addition to further exploring high energy theoretical physics research, Gong said she hopes to one day teach as a university professor. She’s currently a peer tutor at Harvard.

    “I love teaching physics,” she said. “It’s really cool to see the ‘Ah-ha!’ moment when students go from not really understanding something to grasping a concept.”

    The SULI program at Brookhaven is managed by the Lab’s Office of Educational Programs and sponsored by DOE’s Office of Workforce Development for Teachers and Scientists (WDTS) within the Department’s Office of Science.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    One of ten national laboratories overseen and primarily funded by the DOE(US) Office of Science, DOE’s Brookhaven National Laboratory (US) conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University(US), the largest academic user of Laboratory facilities, and Battelle(US), a nonprofit, applied science and technology organization.

    Research at BNL specializes in nuclear and high energy physics, energy science and technology, environmental and bioscience, nanoscience and national security. The 5,300 acre campus contains several large research facilities, including the Relativistic Heavy Ion Collider [below] and National Synchrotron Light Source II [below]. Seven Nobel prizes have been awarded for work conducted at Brookhaven lab.

    BNL is staffed by approximately 2,750 scientists, engineers, technicians, and support personnel, and hosts 4,000 guest investigators every year. The laboratory has its own police station, fire department, and ZIP code (11973). In total, the lab spans a 5,265-acre (21 km^2) area that is mostly coterminous with the hamlet of Upton, New York. BNL is served by a rail spur operated as-needed by the New York and Atlantic Railway. Co-located with the laboratory is the Upton, New York, forecast office of the National Weather Service.

    Major programs

    Although originally conceived as a nuclear research facility, Brookhaven Lab’s mission has greatly expanded. Its foci are now:

    Nuclear and high-energy physics
    Physics and chemistry of materials
    Environmental and climate research
    Energy research
    Structural biology
    Accelerator physics


    Brookhaven National Lab was originally owned by the Atomic Energy Commission(US) and is now owned by that agency’s successor, the United States Department of Energy (DOE). DOE subcontracts the research and operation to universities and research organizations. It is currently operated by Brookhaven Science Associates LLC, which is an equal partnership of Stony Brook University(US) and Battelle Memorial Institute(US). From 1947 to 1998, it was operated by Associated Universities, Inc. (AUI) (US), but AUI lost its contract in the wake of two incidents: a 1994 fire at the facility’s high-beam flux reactor that exposed several workers to radiation and reports in 1997 of a tritium leak into the groundwater of the Long Island Central Pine Barrens on which the facility sits.


    Following World War II, the US Atomic Energy Commission was created to support government-sponsored peacetime research on atomic energy. The effort to build a nuclear reactor in the American northeast was fostered largely by physicists Isidor Isaac Rabi and Norman Foster Ramsey Jr., who during the war witnessed many of their colleagues at Columbia University leave for new remote research sites following the departure of the Manhattan Project from its campus. Their effort to house this reactor near New York City was rivalled by a similar effort at the Massachusetts Institute of Technology (US) to have a facility near Boston, Massachusettes(US). Involvement was quickly solicited from representatives of northeastern universities to the south and west of New York City such that this city would be at their geographic center. In March 1946 a nonprofit corporation was established that consisted of representatives from nine major research universities — Columbia University(US), Cornell University(US), Harvard University(US), Johns Hopkins University(US), Massachusetts Institute of Technology(US), Princeton University(US), University of Pennsylvania(US), University of Rochester(US), and Yale University(US).

    Out of 17 considered sites in the Boston-Washington corridor, Camp Upton on Long Island was eventually chosen as the most suitable in consideration of space, transportation, and availability. The camp had been a training center from the US Army during both World War I and World War II. After the latter war, Camp Upton was deemed no longer necessary and became available for reuse. A plan was conceived to convert the military camp into a research facility.

    On March 21, 1947, the Camp Upton site was officially transferred from the U.S. War Department to the new U.S. Atomic Energy Commission (AEC), predecessor to the U.S. Department of Energy (DOE).

    Research and facilities

    Reactor history

    In 1947 construction began on the first nuclear reactor at Brookhaven, the Brookhaven Graphite Research Reactor. This reactor, which opened in 1950, was the first reactor to be constructed in the United States after World War II. The High Flux Beam Reactor operated from 1965 to 1999. In 1959 Brookhaven built the first US reactor specifically tailored to medical research, the Brookhaven Medical Research Reactor, which operated until 2000.

    Accelerator history

    In 1952 Brookhaven began using its first particle accelerator, the Cosmotron. At the time the Cosmotron was the world’s highest energy accelerator, being the first to impart more than 1 GeV of energy to a particle.

    The Cosmotron was retired in 1966, after it was superseded in 1960 by the new Alternating Gradient Synchrotron (AGS).

    The AGS was used in research that resulted in 3 Nobel prizes, including the discovery of the muon neutrino, the charm quark, and CP violation.

    In 1970 in BNL started the ISABELLE project to develop and build two proton intersecting storage rings.

    The groundbreaking for the project was in October 1978. In 1981, with the tunnel for the accelerator already excavated, problems with the superconducting magnets needed for the ISABELLE accelerator brought the project to a halt, and the project was eventually cancelled in 1983.

    The National Synchrotron Light Source (US) operated from 1982 to 2014 and was involved with two Nobel Prize-winning discoveries. It has since been replaced by the National Synchrotron Light Source II (US) [below].

    After ISABELLE’S cancellation, physicist at BNL proposed that the excavated tunnel and parts of the magnet assembly be used in another accelerator. In 1984 the first proposal for the accelerator now known as the Relativistic Heavy Ion Collider (RHIC)[below] was put forward. The construction got funded in 1991 and RHIC has been operational since 2000. One of the world’s only two operating heavy-ion colliders, RHIC is as of 2010 the second-highest-energy collider after the Large Hadron Collider(CH). RHIC is housed in a tunnel 2.4 miles (3.9 km) long and is visible from space.

    On January 9, 2020, It was announced by Paul Dabbar, undersecretary of the US Department of Energy Office of Science, that the BNL eRHIC design has been selected over the conceptual design put forward by DOE’s Thomas Jefferson National Accelerator Facility [Jlab] (US) as the future Electron–ion collider (EIC) in the United States.

    In addition to the site selection, it was announced that the BNL EIC had acquired CD-0 (mission need) from the Department of Energy. BNL’s eRHIC design proposes upgrading the existing Relativistic Heavy Ion Collider, which collides beams light to heavy ions including polarized protons, with a polarized electron facility, to be housed in the same tunnel.

    Other discoveries

    In 1958, Brookhaven scientists created one of the world’s first video games, Tennis for Two. In 1968 Brookhaven scientists patented Maglev, a transportation technology that utilizes magnetic levitation.

    Major facilities

    Relativistic Heavy Ion Collider (RHIC), which was designed to research quark–gluon plasma and the sources of proton spin. Until 2009 it was the world’s most powerful heavy ion collider. It is the only collider of spin-polarized protons.
    Center for Functional Nanomaterials (CFN), used for the study of nanoscale materials.
    BNL National Synchrotron Light Source II(US), Brookhaven’s newest user facility, opened in 2015 to replace the National Synchrotron Light Source (NSLS), which had operated for 30 years.[19] NSLS was involved in the work that won the 2003 and 2009 Nobel Prize in Chemistry.
    Alternating Gradient Synchrotron, a particle accelerator that was used in three of the lab’s Nobel prizes.
    Accelerator Test Facility, generates, accelerates and monitors particle beams.
    Tandem Van de Graaff, once the world’s largest electrostatic accelerator.
    Computational Science resources, including access to a massively parallel Blue Gene series supercomputer that is among the fastest in the world for scientific research, run jointly by Brookhaven National Laboratory and Stony Brook University.
    Interdisciplinary Science Building, with unique laboratories for studying high-temperature superconductors and other materials important for addressing energy challenges.
    NASA Space Radiation Laboratory, where scientists use beams of ions to simulate cosmic rays and assess the risks of space radiation to human space travelers and equipment.

    Off-site contributions

    It is a contributing partner to ATLAS experiment, one of the four detectors located at the Large Hadron Collider (LHC).

    It is currently operating at CERN near Geneva, Switzerland.

    Brookhaven was also responsible for the design of the SNS accumulator ring in partnership with Spallation Neutron Source at DOE’s Oak Ridge National Laboratory (US), Tennessee.

    Brookhaven plays a role in a range of neutrino research projects around the world, including the Daya Bay Neutrino Experiment (CN) nuclear power plant, approximately 52 kilometers northeast of Hong Kong and 45 kilometers east of Shenzhen, China.

  • richardmitnick 4:12 pm on June 2, 2021 Permalink | Reply
    Tags: , , Extending the idea of dark matter ‘talking’ to dark forces., , If two particles of dark matter are attracted to or repelled by each other then dark forces are operating., It is proposed that there may be a fourth dimension that only the dark forces know about., , , , The key feature of the extra-dimensional theory is that the force between dark matter particles is described by an infinite number of different particles with different masses called a continuum., The new research proposes the existence of an extra dimension in space-time., The team will explore a continuum version of the “dark photon” model., Theoretical Physics,   

    From UC Riverside (US) : “A new dimension in the quest to understand dark matter” 

    UC Riverside bloc

    From UC Riverside (US)

    Flip Tanedo.

    As its name suggests, Dark Matter — material which makes up about 85% of the mass in the universe — emits no light, eluding easy detection. Its properties, too, remain fairly obscure.


    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com.

    Coma cluster via NASA/ESA Hubble.

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science).

    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL).

    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu.


    Now, a theoretical particle physicist at the University of California, Riverside, and colleagues have published a research paper in the Journal of High Energy Physics that shows how theories positing the existence a new type of force could help explain dark matter’s properties.

    Photo shows Flip Tanedo (left), Sylvain Fichet (center), and Hai-Bo Yu. Credit: Flip Tanedo/UCR.

    “We live in an ocean of dark matter, yet we know very little about what it could be,” said Flip Tanedo, an assistant professor of physics and astronomy and the paper’s senior author. “It is one of the most vexing known unknowns in nature. We know it exists, but we do not know how to look for it or why it hasn’t shown up where we expected it.”

    Physicists have used telescopes, gigantic underground experiments, and colliders to learn more about dark matter for the last 30 years, though no positive evidence has materialized. The negative evidence, however, has forced theoretical physicists like Tanedo to think more creatively about what dark matter could be.

    The new research, which proposes the existence of an extra dimension in space-time to search for dark matter, is part of an ongoing research program at UC Riverside led by Tanedo. According to this theory, some of the dark matter particles don’t behave like particles. In effect, invisible particles interact with even more invisible particles in such a way that the latter cease to behave like particles.

    “The goal of my research program for the past two years is to extend the idea of dark matter ‘talking’ to dark forces,” Tanedo said. “Over the past decade, physicists have come to appreciate that, in addition to dark matter, hidden dark forces may govern dark matter’s interactions. These could completely rewrite the rules for how one ought to look for dark matter.”

    If two particles of dark matter are attracted to or repelled by each other then dark forces are operating. Tanedo explained that dark forces are described mathematically by a theory with extra dimensions and appear as a continuum of particles that could address puzzles seen in small galaxies.

    “Our ongoing research program at UCR is a further generalization of the dark force proposal,” he said. “Our observed universe has three dimensions of space. We propose that there may be a fourth dimension that only the dark forces know about. The extra dimension can explain why dark matter has hidden so well from our attempts to study it in a lab.”

    Tanedo explained that although extra dimensions may sound like an exotic idea, they are actually a mathematical trick to describe “conformal field theories” — ordinary three-dimensional theories that are highly quantum mechanical. These types of theories are mathematically rich, but do not contain conventional particles and so are typically not considered to be relevant for describing nature. The mathematical equivalence between these challenging three-dimensional theories and a more tractable extra dimensional theory is known as the holographic principle.

    “Since these conformal field theories were both intractable and unusual, they hadn’t really been systematically applied to dark matter,” Tanedo added. “Instead of using that language, we work with the holographic extra-dimensional theory.”

    The key feature of the extra-dimensional theory is that the force between dark matter particles is described by an infinite number of different particles with different masses called a continuum. In contrast, ordinary forces are described by a single type of particle with a fixed mass. This class of continuum-dark sectors is exciting to Tanedo because it does something “fresh and different.”

    According to Tanedo, past work on dark sectors focuses primarily on theories that mimic the behavior of visible particles. His research program is exploring the more extreme types of theories that most particle physicists found less interesting, perhaps because no analogs exist in the real world.

    In Tanedo’s theory, the force between dark matter particles is surprisingly different from the forces felt by ordinary matter.

    “For the gravitational force or electric force that I teach in my introductory physics course, when you double the distance between two particles you reduce the force by a factor of four. A continuum force, on the other hand, is reduced by a factor of up to eight.”

    What implications does this extra dimensional dark force have? Since ordinary matter may not interact with this dark force, Tanedo turned to the idea of self-interacting dark matter, an idea pioneered by Hai-Bo Yu, an associate professor of physics and astronomy at UCR who is not a coauthor on the paper. Yu showed that even in the absence of any interactions with normal matter, the effects of these dark forces could be observed indirectly in dwarf spheroidal galaxies. Tanedo’s team found the continuum force can reproduce the observed stellar motions.

    “Our model goes further and makes it easier than the self-interacting dark matter model to explain the cosmic origin of dark matter,” Tanedo said.

    Next, Tanedo’s team will explore a continuum version of the “dark photon” model.

    “It’s a more realistic picture for a dark force,” Tanedo said. “Dark photons have been studied in great detail, but our extra-dimensional framework has a few surprises. We will also look into the cosmology of dark forces and the physics of black holes.”

    Tanedo has been working diligently on identifying “blind spots” in his team’s search for dark matter.

    “My research program targets one of the assumptions we make about particle physics: that the interaction of particles is well-described by the exchange of more particles,” he said. “While that is true for ordinary matter, there’s no reason to assume that for dark matter. Their interactions could be described by a continuum of exchanged particles rather than just exchanging a single type of force particle.”

    Tanedo was joined in the research by Ian Chaffey, a postdoctoral researcher working with Tanedo; and Sylvain Fichet, a postdoctoral researcher at the International Center for Theoretical Physics – South American Institute for Fundamental Research in Brazil.

    The research was funded by the U.S. Department of Energy.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC Riverside Campus

    The University of California, Riverside (US) is a public land-grant research university in Riverside, California. It is one of the 10 campuses of the University of California (US) system. The main campus sits on 1,900 acres (769 ha) in a suburban district of Riverside with a branch campus of 20 acres (8 ha) in Palm Desert. In 1907, the predecessor to UC Riverside was founded as the UC Citrus Experiment Station, Riverside which pioneered research in biological pest control and the use of growth regulators responsible for extending the citrus growing season in California from four to nine months. Some of the world’s most important research collections on citrus diversity and entomology, as well as science fiction and photography, are located at Riverside.

    UC Riverside’s undergraduate College of Letters and Science opened in 1954. The Regents of the University of California declared UC Riverside a general campus of the system in 1959, and graduate students were admitted in 1961. To accommodate an enrollment of 21,000 students by 2015, more than $730 million has been invested in new construction projects since 1999. Preliminary accreditation of the UC Riverside School of Medicine was granted in October 2012 and the first class of 50 students was enrolled in August 2013. It is the first new research-based public medical school in 40 years.

    UC Riverside is classified among “R1: Doctoral Universities – Very high research activity.” The 2019 U.S. News & World Report Best Colleges rankings places UC Riverside tied for 35th among top public universities and ranks 85th nationwide. Over 27 of UC Riverside’s academic programs, including the Graduate School of Education and the Bourns College of Engineering, are highly ranked nationally based on peer assessment, student selectivity, financial resources, and other factors. Washington Monthly ranked UC Riverside 2nd in the United States in terms of social mobility, research and community service, while U.S. News ranks UC Riverside as the fifth most ethnically diverse and, by the number of undergraduates receiving Pell Grants (42 percent), the 15th most economically diverse student body in the nation. Over 70% of all UC Riverside students graduate within six years without regard to economic disparity. UC Riverside’s extensive outreach and retention programs have contributed to its reputation as a “university of choice” for minority students. In 2005, UCR became the first public university campus in the nation to offer a gender-neutral housing option.UC Riverside’s sports teams are known as the Highlanders and play in the Big West Conference of the National Collegiate Athletic Association (NCAA) Division I. Their nickname was inspired by the high altitude of the campus, which lies on the foothills of Box Springs Mountain. The UC Riverside women’s basketball team won back-to-back Big West championships in 2006 and 2007. In 2007, the men’s baseball team won its first conference championship and advanced to the regionals for the second time since the university moved to Division I in 2001.


    At the turn of the 20th century, Southern California was a major producer of citrus, the region’s primary agricultural export. The industry developed from the country’s first navel orange trees, planted in Riverside in 1873. Lobbied by the citrus industry, the UC Regents established the UC Citrus Experiment Station (CES) on February 14, 1907, on 23 acres (9 ha) of land on the east slope of Mount Rubidoux in Riverside. The station conducted experiments in fertilization, irrigation and crop improvement. In 1917, the station was moved to a larger site, 475 acres (192 ha) near Box Springs Mountain.

    The 1944 passage of the GI Bill during World War II set in motion a rise in college enrollments that necessitated an expansion of the state university system in California. A local group of citrus growers and civic leaders, including many UC Berkeley(US) alumni, lobbied aggressively for a UC-administered liberal arts college next to the CES. State Senator Nelson S. Dilworth authored Senate Bill 512 (1949) which former Assemblyman Philip L. Boyd and Assemblyman John Babbage (both of Riverside) were instrumental in shepherding through the State Legislature. Governor Earl Warren signed the bill in 1949, allocating $2 million for initial campus construction.

    Gordon S. Watkins, dean of the College of Letters and Science at University of California at Los Angeles(US), became the first provost of the new college at Riverside. Initially conceived of as a small college devoted to the liberal arts, he ordered the campus built for a maximum of 1,500 students and recruited many young junior faculty to fill teaching positions. He presided at its opening with 65 faculty and 127 students on February 14, 1954, remarking, “Never have so few been taught by so many.”

    UC Riverside’s enrollment exceeded 1,000 students by the time Clark Kerr became president of the University of California(US) system in 1958. Anticipating a “tidal wave” in enrollment growth required by the baby boom generation, Kerr developed the California Master Plan for Higher Education and the Regents designated Riverside a general university campus in 1959. UC Riverside’s first chancellor, Herman Theodore Spieth, oversaw the beginnings of the school’s transition to a full university and its expansion to a capacity of 5,000 students. UC Riverside’s second chancellor, Ivan Hinderaker led the campus through the era of the free speech movement and kept student protests peaceful in Riverside. According to a 1998 interview with Hinderaker, the city of Riverside received negative press coverage for smog after the mayor asked Governor Ronald Reagan to declare the South Coast Air Basin a disaster area in 1971; subsequent student enrollment declined by up to 25% through 1979. Hinderaker’s development of innovative programs in business administration and biomedical sciences created incentive for enough students to enroll at Riverside to keep the campus open.

    In the 1990s, the UC Riverside experienced a new surge of enrollment applications, now known as “Tidal Wave II”. The Regents targeted UC Riverside for an annual growth rate of 6.3%, the fastest in the UC system, and anticipated 19,900 students at UC Riverside by 2010. By 1995, African American, American Indian, and Latino student enrollments accounted for 30% of the UC Riverside student body, the highest proportion of any UC campus at the time. The 1997 implementation of Proposition 209—which banned the use of affirmative action by state agencies—reduced the ethnic diversity at the more selective UC campuses but further increased it at UC Riverside.

    With UC Riverside scheduled for dramatic population growth, efforts have been made to increase its popular and academic recognition. The students voted for a fee increase to move UC Riverside athletics into NCAA Division I standing in 1998. In the 1990s, proposals were made to establish a law school, a medical school, and a school of public policy at UC Riverside, with the UC Riverside School of Medicine and the School of Public Policy becoming reality in 2012. In June 2006, UC Riverside received its largest gift, 15.5 million from two local couples, in trust towards building its medical school. The Regents formally approved UC Riverside’s medical school proposal in 2006. Upon its completion in 2013, it was the first new medical school built in California in 40 years.


    As a campus of the University of California(US) system, UC Riverside is governed by a Board of Regents and administered by a president. The current president is Michael V. Drake, and the current chancellor of the university is Kim A. Wilcox. UC Riverside’s academic policies are set by its Academic Senate, a legislative body composed of all UC Riverside faculty members.

    UC Riverside is organized into three academic colleges, two professional schools, and two graduate schools. UC Riverside’s liberal arts college, the College of Humanities, Arts and Social Sciences, was founded in 1954, and began accepting graduate students in 1960. The College of Natural and Agricultural Sciences, founded in 1960, incorporated the CES as part of the first research-oriented institution at UC Riverside; it eventually also incorporated the natural science departments formerly associated with the liberal arts college to form its present structure in 1974. UC Riverside’s newest academic unit, the Bourns College of Engineering, was founded in 1989. Comprising the professional schools are the Graduate School of Education, founded in 1968, and the UCR School of Business, founded in 1970. These units collectively provide 81 majors and 52 minors, 48 master’s degree programs, and 42 Doctor of Philosophy (PhD) programs. UC Riverside is the only UC campus to offer undergraduate degrees in creative writing and public policy and one of three UCs (along with University of California-Berkeley (US) and University of California-Irvine (US)) to offer an undergraduate degree in business administration. Through its Division of Biomedical Sciences, founded in 1974, UC Riverside offers the Thomas Haider medical degree program in collaboration with University of California-Los Angeles(US). UC Riverside’s doctoral program in the emerging field of dance theory, founded in 1992, was the first program of its kind in the United States, and UC Riverside’s minor in lesbian, gay and bisexual studies, established in 1996, was the first undergraduate program of its kind in the UC system. A new BA program in bagpipes was inaugurated in 2007.

    Research and economic impact

    UC Riverside operated under a $727 million budget in fiscal year 2014–15. The state government provided $214 million, student fees accounted for $224 million and $100 million came from contracts and grants. Private support and other sources accounted for the remaining $189 million. Overall, monies spent at UC Riverside have an economic impact of nearly $1 billion in California. UC Riverside research expenditure in FY 2018 totaled $167.8 million. Total research expenditures at UC Riverside are significantly concentrated in agricultural science, accounting for 53% of total research expenditures spent by the university in 2002. Top research centers by expenditure, as measured in 2002, include the Agricultural Experiment Station; the Center for Environmental Research and Technology; the Center for Bibliographical Studies; the Air Pollution Research Center; and the Institute of Geophysics and Planetary Physics.

    Throughout UC Riverside’s history, researchers have developed more than 40 new citrus varieties and invented new techniques to help the $960 million-a-year California citrus industry fight pests and diseases. In 1927, entomologists at the CES introduced two wasps from Australia as natural enemies of a major citrus pest, the citrophilus mealybug, saving growers in Orange County $1 million in annual losses. This event was pivotal in establishing biological control as a practical means of reducing pest populations. In 1963, plant physiologist Charles Coggins proved that application of gibberellic acid allows fruit to remain on citrus trees for extended periods. The ultimate result of his work, which continued through the 1980s, was the extension of the citrus-growing season in California from four to nine months. In 1980, UC Riverside released the Oroblanco grapefruit, its first patented citrus variety. Since then, the citrus breeding program has released other varieties such as the Melogold grapefruit, the Gold Nugget mandarin (or tangerine), and others that have yet to be given trademark names.

    To assist entrepreneurs in developing new products, UC Riverside is a primary partner in the Riverside Regional Technology Park, which includes the City of Riverside and the County of Riverside. It also administers six reserves of the University of California Natural Reserve System. UC Riverside recently announced a partnership with China Agricultural University[中国农业大学](CN) to launch a new center in Beijing, which will study ways to respond to the country’s growing environmental issues. UC Riverside can also boast the birthplace of two name reactions in organic chemistry, the Castro-Stephens coupling and the Midland Alpine Borane Reduction.

  • richardmitnick 5:14 pm on February 1, 2021 Permalink | Reply
    Tags: "Searching for dark matter through the fifth dimension", , Even the abundance of dark matter in the cosmos as observed in astrophysical experiments can be explained by their theory., , , The 5-dimensional field equations predicted the existence of a new heavy particle with similar properties as the famous Higgs boson but a much heavier mass., The embedding of the Standard Model of particle physics in a 5-dimensional spacetime could explain the so far mysterious patterns seen in the masses of elementary particles., The existence of a fifth dimension could resolve some of the profound open questions of particle physics., The mechanism discovered would make dark matter accessible to forthcoming experiments because the properties of the new interaction between ordinary matter and dark matter., The proposed particle would necessarily mediate a new force between the known elementary particles of our visible universe and the mysterious dark matter-the dark sector., Theoretical Physics   

    From Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE): “Searching for dark matter through the fifth dimension” 

    From Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE)

    1 February 2021

    Professor Dr. Matthias Neubert
    Theoretical High Energy Physics (THEP)
    Institute of Physics
    Johannes Gutenberg University Mainz
    55099 Mainz (DE)

    A discovery in theoretical physics could help to unravel the mysteries of dark matter.

    Credit: CC0 Public Domain.

    Theoretical physicists of the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) are working on a theory that goes beyond the Standard Model of particle physics and can answer questions where the Standard Model has to pass – for example, with respect to the hierarchies of the masses of elementary particles or the existence of dark matter.

    Standard Model of Particle Physics (LATHAM BOYLE AND MARDUS OF WIKIMEDIA COMMONS).

    The central element of the theory is an extra dimension in spacetime. Until now, scientists have faced the problem that the predictions of their theory could not be tested experimentally. They have now overcome this problem in a publication in the current issue of the European Physical Journal C.

    Already in the 1920s, in an attempt to unify the forces of gravity and electromagnetism, Theodor Kaluza and Oskar Klein speculated about the existence of an extra dimension beyond the familiar three space dimensions and time – which in physics are combined into 4-dimensional spacetime. If it exists, such a new dimension would have to be incredible tiny and unnoticeable to the human eye. In the late 1990s, this idea has seen a remarkable renaissance when it was realized that the existence of a fifth dimension could resolve some of the profound open questions of particle physics. In particular, Yuval Grossman of Stanford University and Matthias Neubert, then a professor at Cornell University in the US, showed in a highly cited publication that the embedding of the Standard Model of particle physics in a 5-dimensional spacetime could explain the so far mysterious patterns seen in the masses of elementary particles.

    Another 20 years later, the group of Professor Matthias Neubert – since 2006 on the faculty of Johannes Gutenberg University Mainz and spokesperson of the PRISMA+ Cluster of Excellence – made another unexpected discovery: they found that the 5-dimensional field equations predicted the existence of a new heavy particle with similar properties as the famous Higgs boson but a much heavier mass – so heavy, in fact, that it cannot be produced even at the highest-energy particle collider in the world, the Large Hadron Collider (LHC) at the European Center for Nuclear Research CERN near Geneva in Switzerland. “It was a nightmare,” recalled Javier Castellano Ruiz, a PhD student involved in the research. “We were excited by the idea that our theory predicts a new particle, but it appeared to be impossible to confirm this prediction in any foreseeable experiment.”

    The detour through the fifth dimension

    In a recent paper published in the European Physical Journal C, the researchers found a spectacular resolution to this dilemma. They discovered that their proposed particle would necessarily mediate a new force between the known elementary particles of our visible universe and the mysterious dark matter, the dark sector. Even the abundance of dark matter in the cosmos, as observed in astrophysical experiments, can be explained by their theory. This offers exciting new ways to search for the constituents of the dark matter – literally via a detour through the extra dimension – and obtain clues about the physics at a very early stage in the history of our universe, when dark matter was produced. “After years of searching for possible confirmations of our theoretical predictions, we are now confident that the mechanism we have discovered would make dark matter accessible to forthcoming experiments, because the properties of the new interaction between ordinary matter and dark matter – which is mediated by our proposed particle – can be calculated accurately within our theory,” said Professor Matthias Neubert, head of the research team. “In the end – so our hope – the new particle may be discovered first through its interactions with the dark sector.” This example nicely illustrates the fruitful interplay between experimental and theoretical basic science – a hallmark of the PRISMA+ Cluster of Excellence.

    See the full article here.


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    Stem Education Coalition

    The Johannes Gutenberg University Mainz [Johannes Gutenberg-Universität Mainz] (DE) is a public research university in Mainz, Rhineland Palatinate, Germany, named after the printer Johannes Gutenberg since 1946. With approximately 32,000 students (2018) in about 100 schools and clinics, it is among the largest universities in Germany. Starting on 1 January 2005 the university was reorganized into 11 faculties of study.

    The university is a member of the German U15, a coalition of fifteen major research-intensive and leading medical universities in Germany. The Johannes Gutenberg University is considered one of the most prestigious universities in Germany.

    The university is part of the IT-Cluster Rhine-Main-Neckar. The Johannes Gutenberg University Mainz, the Goethe University Frankfurt and the Technische Universität Darmstadt together form the Rhine-Main-Universities (RMU).

    The first University of Mainz goes back to the Archbishop of Mainz, Prince-elector and Reichserzkanzler Adolf II von Nassau. At the time, establishing a university required papal approval and Adolf II initiated the approval process during his time in office. The university, however, was first opened in 1477 by Adolf’s successor to the bishopric, Diether von Isenburg. In 1784 the University was opened up for Protestants and Jews (curator Anselm Franz von Betzel). It fastly became one of the largest Catholic universities in Europe with ten chairs in theology alone. In the confusion after the establishment of the Mainz Republic of 1792 and its subsequent recapture by the Prussians, academic activity came to a gradual standstill. In 1798 the university became active again under French governance, and lectures in the department of medicine took place until 1823. Only the faculty of theology continued teaching during the 19th century, albeit as a theological Seminary (since 1877 “College of Philosophy and Theology”).
    Statue of Johannes Gutenberg at the University of Mainz.

    The current Johannes Gutenberg University Mainz was founded in 1946 by the French occupying power. In a decree on 1 March the French military government implied that the University of Mainz would continue to exist: the University shall be “enabled to resume its function”. The remains of anti-aircraft warfare barracks erected in 1938 after the remilitarization of the Rhineland during the Third Reich served as the university’s first buildings and are still in use today.

    The continuation of academic activity between the old university and Johannes Gutenberg University Mainz, in spite of an interruption spanning over 100 years, is contested. During the time up to its reopening only a seminary and midwifery college survived.

    In 1972, the effect of the 1968 student protests began to take a toll on the University’s structure. The departments (Fakultäten) were dismantled and the University was organized into broad fields of study (Fachbereiche). Finally in 1974 Peter Schneider was elected as the first president of what was now a “constituted group-university” institute of higher education. In 1990 Jürgen Zöllner became University President yet spent only a year in the position after he was appointed Minister for “Science and Advanced Education” for the State of Rhineland-Palatinate. As the coordinator for the SPD’s higher education policy, this furloughed professor from the Institute for Physiological Chemistry played a decisive role in the SPD’s higher education policy and in the development of Study Accounts.

  • richardmitnick 11:02 pm on December 9, 2020 Permalink | Reply
    Tags: "Physics professor advances research on black hole paradox", , , It turns out that a powerful way to learn about one black hole is to study two black holes., Late physicist Stephen Hawking showed that when quantum effects are included black holes do have a temperature., Theoretical Physics   

    From Cornell Chronicle: “Physics professor advances research on black hole paradox” 

    From Cornell Chronicle

    December 9, 2020
    Kate Blackwood

    Thomas Hartman, right, associate professor of physics, and Amirhossein Tajdini, Ph.D. ’20, diagram in 2019 a replica wormhole, a concept associated with quantum gravity. They were two authors of “Replica Wormholes and the Entropy of Hawking Radiation,” a paper important to recent progress on the black hole paradox. Credit: Dave Burbank/Cornell University.

    Do black holes emit information?

    For decades, physicists have theorized on this high-stakes question. At the heart of the so-called “black hole information paradox” is a fundamental incompatibility between the two pillar theories of theoretical physics: general relativity and quantum mechanics.

    But in the past two years, a series of breakthrough calculations by researchers – including Tom Hartman, associate professor of physics in the College of Arts and Sciences – have led to proclamations in the field of theoretical physics that “the most famous paradox in physics,” according to Quanta Magazine, is nearing its end.

    “It’s fair to say that these calculations have given us a new way to think about black hole information and given us hints about how to make sense of quantum gravity,” Hartman said, confirming the progress and his significant contribution. “It solves some corner of the paradox.”

    Hartman researches quantum gravity, a theory to reconcile quantum mechanics and general relativity. His paper published in May in the Journal of High Energy Physics, reports a mathematical technique for calculating the physics of a black hole. Collaborators on the paper included former Cornell postdoctoral researcher Edgar Shaghoulian, now a postdoc at the University of Pennsylvania; and Amir Tajdini, Ph.D. ’20, now a postdoc at the University of California, Santa Barbara.

    “Black holes are a place where both quantum mechanics and gravity can be important at the same time,” Hartman said. “If you’re thinking about quantum gravity and how to put the two theories together, black holes are a great way to study that problem.”

    Although we think of black holes as having nothing coming out from them, Hartman said, late physicist Stephen Hawking showed that when quantum effects are included, black holes do have a temperature.

    This leads to the paradox: The fact that black holes have a temperature, Hartman said, means that particles are escaping the black hole. Hawking found that these particles are “pure thermal radiation,” or radiation that is completely random and does not carry any information, Hartman said. If this is true, then when a black hole evaporates away and disappears, the information that was originally contained in the black hole has been destroyed, he said.

    “It is a fundamental principle of quantum mechanics that information cannot be destroyed,” Hartman said. “So the paradox is a contradiction between quantum mechanics and Hawking’s calculation showing that black holes radiate randomly.”

    In the paper, Hartman and collaborators used a mathematical trick involving extra copies of the black hole called “replicas” to calculate the physics of a single black hole.

    “It turns out that a powerful way to learn about one black hole is to study two black holes,” he said. “The reason is that there are statistical properties of radiation that are hard to understand if you look at one black hole but easier to understand if you look at two at once.”

    Using this technique, they found evidence that the particles emitted in Hawking radiation are not random, after all.

    In November, Hartman published further research in the Journal of High Energy Physics. In the paper, he and Shaghoulian, along with Yikun Jiang, a Ph.D. student in the field of physics, explore the possibility that the new theory of Hawking radiation could also apply to the early universe.

    Hartman co-organized a virtual workshop on this and related topics in November with researchers from Stanford and the University of California, San Diego, joined by 40 participants from around the world.

    Far from being near an end, the information paradox is a problem that multiplies as physicists look into it, Hartman said. What started as one paradox has grown into a whole field of study.

    “There are many aspects of it,” he said. “It’s something thousands of people will work on for decades.”

    See the full article here .


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    Stem Education Coalition

    Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

    Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

    On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

  • richardmitnick 1:40 pm on November 20, 2020 Permalink | Reply
    Tags: "The gravity of dreams", , , , Lavinia Heisenberg, , Theoretical Physics, Why is gravity the most mysterious force of nature?   

    From ETH Zürich (CH): “The gravity of dreams” Lavinia Heisenberg 

    From ETH Zürich (CH)

    Florian Meyer

    Why is gravity the most mysterious force of nature? Lavinia Heisenberg studies how the universe was formed, and how it is changing. She has now been awarded the ETH Zürich Latsis Prize for her outstanding achievements in the field of theoretical physics.

    The gravity of dreams – Portrait Lavinia Heisenberg.

    Lavinia Heisenberg

    Anyone who observes the sky at night may have an idea of what Lavinia Heisenberg does for a living. She is a cosmologist. Her field of research is space and what is to be found there, whether visible or dark matter, light or energy, particles or waves, bodies or forces. Her interest lies not in individual planets, a solar system or a galaxy, such as our Milky Way. Her research drive is oriented much more towards entire galactic clusters and the forces of nature that tell us something about the origin of the universe.

    Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

    There are times when Heisenberg finds herself overwhelmed when looking at the billions of galaxies in the sky. “Curiosity was always the driving force for me,” she says on the Hönggerberg campus. “There is so much unknown out there. And we should just keep exploring.”

    Exciting times, mysterious forces

    For a physicist such as Heisenberg, who investigates the interaction between particle physics and cosmology, these are most certainly exciting times, with two major discoveries having significantly expanded the possibilities for research. A new particle, the Higgs boson, was discovered at CERN in July 2012.

    CERN CMS Higgs Event May 27, 2012.

    CERN ATLAS Higgs Event
    June 12, 2012.

    CERN map

    The first direct observation of gravitational waves was made in September 2015.

    Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo (IT) came online in August 2018.

    MIT /Caltech Advanced aLigo .

    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA.

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    Heisenberg is convinced that gravitational waves will open up further potential for discovery: “All the information so far that we have about the universe has only come through photons, through light. And now we also have this new channel of gravitational wave observations. You can compare it with a situation where we were completely blind, and now suddenly we can actually see all these beautiful colours.”

    Gravity is a key element in her research. “When you think of cosmological scales, of large scales, the gravitational force is the dominant one. So if you want to describe the nature or the physics behind the universe, you need to know what the fundamental law of gravity is,” she explains. “If you now combine precision measurements coming from gravitational waves with all the observations that we already had through light, at the end of the day we will come closer to what really is the true nature of gravity.” To date, a conclusive explanation has not been found. Approaches that describe the world on a large scale – i.e. in space – explain gravity differently than those approaches that describe the world on a small scale, i.e. in the innermost part of the atomic nucleus.

    These explanatory differences are based on the two great theoretical achievements of physics in the 20th century – the theory of relativity and quantum mechanics. The fact that it can still not be explained in a uniform way with a single theory makes gravitation the most mysterious of the four fundamental forces of physics. These basic forces determine the behaviour of bodies, fields, particles and systems; the other three are the weak interaction, the strong interaction and electromagnetism.

    Many perspectives, stable solutions

    Heisenberg’s approach is characterised by the way in which she studies gravity from a range of perspectives: like a telescope, each theory opens up another outlook on reality. She uses these perspectives to obtain new insights into the essential and fundamental properties of gravity. “We combine the various interpretations of gravity in order to find stable solutions to the problems of general relativity,” she adds. Heisenberg has now won the ETH Zurich Latsis Prize for her detailed analysis of gravity in the light of classical and quantum physics and the corresponding conclusions drawn from astrophysical, cosmological and particle physics experiments. The prize will be awarded at ETH Day 2020.

    Heisenberg’s multidisciplinary approach combines gravitational physics, cosmology, particle physics and computational astrophysics. As a theoretical physicist, she does not perform experiments in the lab or particle accelerators – she works with a pen and notebook, and carries out computer calculations. Mathematics is her most important tool. The quality of her theories is measured by the extent to which the mathematical equations can explain the data from particle physics experiments or from cosmological and astrophysical observations.

    Beethoven, bouldering and a bow and arrow

    Her multidisciplinary approach is reflected in the composition of her team and in her teaching. Heisenberg is a team player, and it is important to her to see open questions discussed: “I really enjoy interacting with my team and my students.” For her, enjoyment is the best compensation for disappointment and stress.

    Heisenberg also finds balance in running, climbing, fitness training and archery, and in activities that require a high level of concentration: “In archery I have to focus very closely on my position if I want to hit the target. In moments like these, I’m completely present in the here and now – not thinking about the past or worrying about the future.” She also experiences such inspiring moments of complete immersion in her research, moments when she is fully absorbed in what she is doing. In difficult times she finds stability in music, in the symphonies of Beethoven.

    Heisenberg’s career path is as diverse as her research: she has lived in various countries since childhood, “and in every country, I have learned the language.” Today she can speak six languages, including German. She originally arrived at ETH as a fellow of the Institute for Theoretical Studies. In 2018, she received an ERC Starting Grant, which is awarded only to the best researchers, and was appointed assistant professor in the Department of Physics. Her future is literally written in the stars – ever since she was a child, Heisenberg has dreamed of becoming an astronaut. And this goal continues to drive her: “To see Earth from such a perspective – it must be an amazing feeling to see how fragile our Earth is.”


    Heisenberg L: A systematic approach to generalisations of General Relativity and their cosmological implications. [Physics Reports]

    Jiménez JB, Heisenberg L, Koivisto TS: [The Geometrical Trinity of Gravity].
    Heisenberg L: Generalization of the Proca Action. [Journal of Cosmology and Astroparticle Physics].

    See the full article here .


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    ETH Zurich campus
    ETH Zürich (CH) is one of the leading international universities for technology and the natural sciences. It is well known for its excellent education, ground-breaking fundamental research and for implementing its results directly into practice.

    Founded in 1855, ETH Zürich (CH) today has more than 18,500 students from over 110 countries, including 4,000 doctoral students. To researchers, it offers an inspiring working environment, to students, a comprehensive education.

    Twenty-one Nobel Laureates have studied, taught or conducted research at ETH Zürich (CH), underlining the excellent reputation of the university.

  • richardmitnick 1:05 pm on July 23, 2020 Permalink | Reply
    Tags: , Computational Quantum Physics, , , Flatiron Institute, In the quantum mechanical world electrical resistance is a byproduct of electrons bumping into things., Links to astrophysics, , , Quantum Monte Carlo algorithm, , , Strange metals are related to high-temperature superconductors and have surprising connections to the properties of black holes., Theoretical Physics   

    From Simons Foundation: “Quantum physicists crack mystery of ‘strange metals,’ a new state of matter” 

    From Simons Foundation

    July 23, 2020
    Thomas Sumner

    Strange metals have surprising connections to high-temperature superconductors and black holes.

    A diagram showing different states of matter as a function of temperature, T, and interaction strength, U (normalized to the amplitude, t, of electrons hopping between sites). Strange metals emerge in a regime separating a metallic spin glass and a Fermi liquid. P. Cha et al./Proceedings of the National Academy of Sciences 2020.

    Even by the standards of quantum physicists, strange metals are just plain odd. The materials are related to high-temperature superconductors and have surprising connections to the properties of black holes. Electrons in strange metals dissipate energy as fast as they’re allowed to under the laws of quantum mechanics, and the electrical resistivity of a strange metal, unlike that of ordinary metals, is proportional to the temperature.

    Generating a theoretical understanding of strange metals is one of the biggest challenges in condensed matter physics. Now, using cutting-edge computational techniques, researchers from the Flatiron Institute in New York City and Cornell University have solved the first robust theoretical model of strange metals. The work reveals that strange metals are a new state of matter, the researchers report July 22 in the Proceedings of the National Academy of Sciences.

    “The fact that we call them strange metals should tell you how well we understand them,” says study co-author Olivier Parcollet, a senior research scientist at the Flatiron Institute’s Center for Computational Quantum Physics (CCQ). “Strange metals share remarkable properties with black holes, opening exciting new directions for theoretical physics.”

    In addition to Parcollet, the research team consisted of Cornell doctoral student Peter Cha, CCQ associate data scientist Nils Wentzell, CCQ director Antoine Georges, and Cornell physics professor Eun-Ah Kim.

    In the quantum mechanical world, electrical resistance is a byproduct of electrons bumping into things. As electrons flow through a metal, they bounce off other electrons or impurities in the metal. The more time there is between these collisions, the lower the material’s electrical resistance.

    For typical metals, electrical resistance increases with temperature, following a complex equation. But in unusual cases, such as when a high-temperature superconductor is heated just above the point where it stops superconducting, the equation becomes much more straightforward. In a strange metal, electrical conductivity is linked directly to temperature and to two fundamental constants of the universe: Planck’s constant and Boltzmann’s constant. Consequently, strange metals are also known as Planckian metals.

    Models of strange metals have existed for decades, but accurately solving such models proved out of reach with existing methods. Quantum entanglements between electrons mean that physicists can’t treat the electrons individually, and the sheer number of particles in a material makes the calculations even more daunting.

    Cha and his colleagues employed two different methods to crack the problem. First, they used a quantum embedding method based on ideas developed by Georges in the early ’90s. With this method, instead of performing detailed computations across the whole quantum system, physicists perform detailed calculations on only a few atoms and treat the rest of the system more simply. They then used a quantum Monte Carlo algorithm (named for the Mediterranean casino), which uses random sampling to compute the answer to a problem. The researchers solved the model of strange metals down to absolute zero (minus 273.15 degrees Celsius), the unreachable lower limit for temperatures in the universe.

    The resulting theoretical model reveals the existence of strange metals as a new state of matter bordering two previously known phases of matter: Mott insulating spin glasses and Fermi liquids. “We found there is a whole region in the phase space that is exhibiting a Planckian behavior that belongs to neither of the two phases that we’re transitioning between,” Kim says. “This quantum spin liquid state is not so locked down, but it’s also not completely free. It is a sluggish, soupy, slushy state. It is metallic but reluctantly metallic, and it’s pushing the degree of chaos to the limit of quantum mechanics.”

    The new work could help physicists better understand the physics of higher-temperature superconductors. Perhaps surprisingly, the work has links to astrophysics. Like strange metals, black holes exhibit properties that depend only on temperature and the Planck and Boltzmann constants, such as the amount of time a black hole ‘rings’ after merging with another black hole. “The fact that you find this same scaling across all these different systems, from Planckian metals to black holes, is fascinating,” Parcollet says.

    For more information, please contact Stacey Greenebaum at press@simonsfoundation.org.

    See the full article here.


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    Mission and Model

    The Simons Foundation’s mission is to advance the frontiers of research in mathematics and the basic sciences.

    Co-founded in New York City by Jim and Marilyn Simons, the foundation exists to support basic — or discovery-driven — scientific research undertaken in the pursuit of understanding the phenomena of our world.

    The Simons Foundation’s support of science takes two forms: We support research by making grants to individual investigators and their projects through academic institutions, and, with the launch of the Flatiron Institute in 2016, we now conduct scientific research in-house, supporting teams of top computational scientists.

  • richardmitnick 5:29 pm on June 26, 2016 Permalink | Reply
    Tags: , , , Theoretical Physics   

    From Science Alert: “What’s the point of theoretical physics?” 


    Science Alert

    24 JUN 2016

    Ahuli Labutin/Shutterstock.com

    You don’t have to be a scientist to get excited about breakthroughs in theoretical physics. Discoveries such as gravitational waves and the Higgs boson can inspire wonder at the complex beauty of the Universe no matter how little you really understand them.

    But some people will always question why they should care about scientific advances that have no apparent impact on their daily life – and why we spend millions funding them. Sure, it’s amazing that we can study black holes thousands of light-years away and that Einstein really was as much of a genius as we thought, but that won’t change the way most people live or work.

    Yet the reality is that purely theoretical studies in physics can sometimes lead to amazing changes in our society. In fact, several key pillars on which our modern society rests, from satellite communication to computers, were made possible by investigations that had no obvious application at the time.

    Around 100 years ago, quantum mechanics was a purely theoretical topic, only developed to understand certain properties of atoms. Its founding fathers such as Werner Heisenberg and Erwin Schrödinger had no applications in mind at all. They were simply driven by the quest to understand what our world is made of.

    Quantum mechanics states that you cannot observe a system without changing it fundamentally by your observation, and initially its effects to society were of a philosophical and not a practical nature.

    But today, quantum mechanics is the basis of our use of all semiconductors in computers and mobile phones. To build a modern semiconductor for use in a computer, you have to understand concepts such as the way electrons behave when atoms are held together in a solid material, something only described accurately by quantum mechanics.

    Without it, we would have been stuck using computers based on vacuum tubes.

    At a similar time as the key developments in quantum mechanics, Albert Einstein was attempting to better understand gravity, the dominating force of the universe.

    Rather than viewing gravity as a force between two bodies, he described it as a curving of space-time around each body, similar to how a rubber sheet will stretch if a heavy ball is placed on top of it. This was Einstein’s general theory of relativity.

    Today the most common application of this theory is in GPS. To use signals from satellites to pinpoint your location you need to know the precise time the signal leaves the satellite and when it arrives on Earth.

    Einstein’s theory of general relativity means that the distance of a clock from Earth’s centre of gravity affects how fast it ticks. And his theory of special relativity means that the speed a clock is moving at also affects its ticking speed.

    Without knowing how to adjust the clocks to take account of these effects, we wouldn’t be able to accurately use the satellite signals to determine our position on the ground. Despite his amazing brain, Einstein probably could not have imagined this application a century ago.

    Scientific culture

    Aside from the potential, eventual applications of doing fundamental research, there are also direct financial benefits. Most of the students and post-docs working on big research projects like the Large Hadron Collider will not stay in academia but move into industry.

    During their time in fundamental physics, they are educated at the highest existing technical level and then take their expertise into working companies. This is like educating car mechanics in Formula One racing teams.

    Despite these direct and indirect benefits, most theoretical physicists have a very different motive for their work. They simply want to improve humanity’s understanding of the Universe.

    While this might not immediately impact everyone’s lives, I believe it is just as important a reason for pursuing fundamental research.

    GPS: a relative success. Shutterstock

    This motivation may well have begun when humans first looked up at the night-sky in ancient times. They wanted to understand the world they lived in and so spent time watching nature and creating theories about it, many of them involving gods or supernatural beings.

    Today we have made huge progress in our understanding of both stars and galaxies and, at the other end of the scale, of the tiny fundamental particles from which matter is built.

    It somehow seems that every new level of understanding we achieve comes in tandem with new, more fundamental questions. It is never enough to know what we now know. We always want to continue looking behind newly arising curtains. In that respect, I consider fundamental physics a basic part of human culture.

    Now we can wait curiously to find out what unforeseen spin-offs that discoveries such as the Higgs boson or gravitational waves might lead to in the long-term future. But we can also look forward to the new insights into the building blocks of nature that they will bring us, and the new questions they will raise.

    See the full article here .

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  • richardmitnick 4:31 pm on June 17, 2016 Permalink | Reply
    Tags: Institute for Quantum Computing U Waterloo, Noncontextuality, , , Theoretical Physics, What does it mean to say the world is quantum?   

    From PI: “New Experiment Clarifies How The Universe Is Not Classical” 

    Perimeter Institute
    Perimeter Institute

    June 17, 2016
    Erin Bow

    “This is a great example of what’s possible when Perimeter and IQC work together. We can start with these exciting, abstract ideas and convert them to things we can actually do in our labs.”
    – Kevin Resch, Faculty member, Institute for Quantum Computing

    From left to right: Matthew Pusey (Perimeter postdoctoral researcher), Kevin Resch (IQC and University of Waterloo faculty member), Robert Spekkens (Perimeter faculty member), and Michael Mazurek (University of Waterloo and IQC PhD student) interact in a quantum optics lab at the Institute for Quantum Computing. No image credit.

    Theorists from Perimeter and experimentalists from the Institute for Quantum Computing have found a new way to test whether the universe is quantum, a test that will have widespread applicability: they’ve proven the failure of noncontextuality in the lab.

    What does it mean to say the world is quantum? It’s a surprisingly difficult question to answer, and most casual discussions on the point are heavy on the hand-waving, with references to cats in boxes.

    If we are going to turn the quantum-ness of the universe to our advantage through technologies like quantum computing, our definition of what it means to be quantum – or, more broadly, what it means to be non-classical – needs to be more rigorous. That’s one of the aims of the field of quantum foundations, and the point of new joint research carried out by theorists at Perimeter and experimentalists at the University of Waterloo’s Institute for Quantum Computing (IQC).

    “We need to make precise the notion of non-classicality,” says Robert Spekkens, a faculty member at Perimeter, who led the work from the theoretical side. “We need to find phenomena that defy classical explanation, and then subject those phenomena to direct experimental tests.”

    One candidate for something that defies classical explanation is the failure of noncontextuality.

    “You can think of noncontextuality as the ‘if it walks like a duck’ principle,” says Matthew Pusey, a postdoctoral researcher at Perimeter who also worked on the project.

    As the saying has it, if something walks like a duck and quacks like a duck, it’s probably a duck. The principle of noncontextuality pushes that further, and says that if something walks like a duck and quacks like a duck and you can’t tell it apart from a duck in any experiment, not even in principle, then it must be a duck.

    Though noncontextuality is not something we often think about, it is a feature one would expect to hold in experiments. Indeed, it’s so intuitive that it seems silly to say it aloud: if you can’t tell two things apart, even in principle, then they’re the same. Makes sense, right?

    But in the quantum universe, it’s not quite true.

    Under quantum theory, two preparations of a system can return identical results in every conceivable test. But researchers run into trouble when they try to define exactly what those systems are doing. It turns out that in quantum mechanics, any model that assigns the systems well-defined properties requires them to be different. That’s a violation of the principle of noncontextuality.

    To understand what’s happening, imagine a yellow box that spits out a mix of polarized photons – half polarized horizontally and half polarized vertically. A different box – imagine it to be orange – spits out a different mix of photons, half polarized diagonally and half polarized anti-diagonally.

    Now measure the polarization of the photons from the yellow box and of the photons from the orange box. You can measure any polarization property you like, as much as you like. Because of the way the probabilities add up, the statistics of any measurement performed on photons from the yellow box are going to be identical to the statistics of the same measurement performed on photons from the orange box. In each case, the average polarization is always zero.

    “Those two kinds of boxes, according to quantum theory, cannot be distinguished,” says Spekkens. “All the measurements are going to see exactly the same thing.”

    You might think, following the principle of noncontextuality, that since the yellow and orange boxes produce indistinguishable mixes of photons, they can be described by the same probability distributions. They walk like ducks, so you can describe them both as ducks. But as it turns out, that doesn’t work.

    In a noncontextual world, the fact that the yellow-box photons and orange-box photons are indistinguishable would be explained in the natural way: by the fact that the probability distribution over properties are the same. But the quantum universe resists such explanations – it can be proven mathematically that those two mixtures of photons cannot be described by the same distribution of properties.

    “So that’s the theoretical result,” says Spekkens. “If quantum theory is right, then we can’t have a noncontextual model.”

    But can such a theoretical result be tested? Theorists from Perimeter and experimentalists from IQC set out to discover that very thing.

    Kevin Resch, a faculty member at IQC and the Department of Physics and Astronomy at the University of Waterloo, as well as a Perimeter Affiliate, worked on the project from the experimental end in his lab.

    “The original method of testing noncontextuality required two or more preparation procedures that give exactly the same statistics,” he says. “I would argue that that’s basically not possible, because no experiments are perfect. The method described in our paper allows contextuality tests to deal with these imperfections.”

    While previous attempts to test for the predicted failure of noncontextuality have had to resort to assuming things like noiseless measurements that are not achievable in practice, the Perimeter and IQC teams wanted to avoid such unrealistic assumptions. They knew they couldn’t eliminate all error, so they designed an experiment that could make meaningful tests of noncontextuality even in the presence of error.

    Pusey hit on a clever idea to fight statistical error with statistical inference. Ravi Kunjwal, a doctoral student at the Institute for Mathematical Sciences in Chennai, India, who was visiting at the time, helped define what a test of noncontextuality should look like operationally. Michael Mazurek, a doctoral student with Waterloo’s Department of Physics and Astronomy and IQC, built the experimental apparatus – single photon emitters and detectors, just as in the yellow-and-orange box example above – and ran the tests.

    “The interesting part of the experiment is that it looks really simple on paper,” says Mazurek. “But it wasn’t simple in practice. The analysis that we did and the standards that we held ourselves to required us to really get on top of the small systematic errors that are present in every experiment. Characterizing those errors and compensating for them was quite challenging.”

    At one point, Mazurek used half a roll of masking tape to keep optical fibres from moving around in response to tiny shifts in temperature. Nothing about this experiment was easy, and much of it can only be described with statistics and diagrams. But in the end, the team made it work.

    The result: an experiment that definitively shows the failure of noncontextuality. Like the pioneering work on Bell’s theorem, this research clarifies what it means for the world to be non-classical, and confirms that non-classicality experimentally.

    Importantly, and in contrast to previous tests of contextuality, this experiment renders its verdict without assuming any idealizations, such as noiseless measurements or statistics being exactly the same. This opens a new range of possibilities.

    Researchers in several fields are working to find “quantum advantages” – that is, things we can do if we harness the quantum-ness of the world that would not be possible in the classical world. Examples include quantum cryptography and quantum computation. Such advantages are the beams and girders of any future quantum technology we might be able to build. Noncontextuality can help researchers understand these quantum advantages.

    “We now know, for example, that for certain kinds of cryptographic tasks and computational tasks, the failure of noncontextuality is the resource,” says Spekkens.

    In other words, contextuality is the steel out of which the beams and girders are made.

    “This is a great example of what’s possible when Perimeter and IQC work together,” says Resch, Canada Research Chair in Optical Quantum Technologies. “We can start with these exciting, abstract ideas and convert them to things we can actually do in our labs.”

    See the full article here .

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    About Perimeter

    Perimeter Institute is a leading centre for scientific research, training and educational outreach in foundational theoretical physics. Founded in 1999 in Waterloo, Ontario, Canada, its mission is to advance our understanding of the universe at the most fundamental level, stimulating the breakthroughs that could transform our future. Perimeter also trains the next generation of physicists through innovative programs, and shares the excitement and wonder of science with students, teachers and the general public.

  • richardmitnick 6:39 am on May 20, 2016 Permalink | Reply
    Tags: , , Theoretical Physics   

    From CERN: “In Theory: Is theoretical physics in crisis?” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead


    20 May 2016
    Harriet Jarlett

    “The way physics develops is often a lot less logical than the theories it leads to — you cannot plan discoveries. Especially in theoretical physics.” Gian Giudice, Head of CERN’s Theory Department (Image: Sophia Bennett/ CERN)

    Over the past decade physicists have explored new corners of our world, and in doing so have answered some of the biggest questions of the past century.

    When researchers discovered the Higgs boson in 2012, it was a huge moment of achievement.

    CERN CMS Higgs Event
    CERN CMS Higgs Event

    It showed theorists had been right to look towards the Standard Model for answers about our Universe.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    But then the particle acted just like the theorist’s said it would, it obeyed every rule they predicted. If it had acted just slightly differently it would have raised many questions about the theory, and our universe. Instead, it raised few questions and gave no new clues about to where to look next.

    In other words, the theorists had done too good a job.

    “We are struggling to find clear indications that can point us in the right direction. Some people see in this state of crisis a source of frustration. I see a source of excitement because new ideas have always thrived in moments of crisis.” – Gian Giudice, head of the Theory Department at CERN.

    Before these discoveries, physicists were standing on the edge of a metaphorical flat Earth, suspecting it was round but not knowing for sure. Finding both the Higgs boson, and evidence of gravitational waves has brought scientists closer than ever to understanding two of the great theories of our time – the Standard Model and the theory of relativity.

    Now the future of theoretical physics is at a critical point – they proved their own theories, so what is there to do now?

    So what next?

    “Taking unexplained data, trying to fit it to the ideas of the universe […] – that’s the spirit of theoretical physics” – Gian Giudice

    In an earlier article in this series [link to series is below], we spoke about how experimental physicists and theoretical physicists must work together. Their symbiotic relationship – with theorists telling experimentalists where to look, and experimentalists asking theorists for explanations of unusual findings – is necessary, if we are to keep making discoveries.

    Just four years ago, in 2012, physicists still held a genuine uncertainty about whether the lynchpin of the Standard Model, the Higgs boson existed at all. Now, there’s much less uncertainty.

    “We are still in an uncertain period, previously we were uncertain as to how the Standard Model could be completed. Now we know it is pretty much complete so we can focus on the questions beyond it, dark matter, the future of the universe, the beginning of the universe, little things like that,” says John Ellis, a theoretical physicist from Kings College, London who began working at CERN since 1973.

    Michelangelo Mangano moved to the US to work at Princeton just as String Theory was made popular. “After the first big explosion of interest, there’s always a period of slowing down, because all the easier stuff has been done. And you’re struggling with more complex issues,” he explains. “This is something that today’s young theorists are finding as they struggle to make waves in fields like the Standard Model. Unexpected findings from the LHC could reignite their enthusiasm and help younger researchers to feel like they can have an impact.” (Image: Maximillien Brice/CERN)

    With the discovery of the Higgs, there’s been a shift in this relationship, with theoreticians not necessarily leading the way. Instead, experiments look for data to try and give more evidence to the already proposed theories, and if something new is thrown up theorists scramble to explain and make sense of it.

    “It’s like when you go mushroom hunting,” says Michelangelo Mangano, a theoretical physicist who works closely with experimental physicists. “You spend all your energy looking, and at the end of the day you may not find anything. Here it’s the same, there is a lots of wasted energy because it doesn’t lead to much, but by exploring all corners of the field occasionally you find a little gold nugget, a perfect mushroom.”

    At the end of last year, both the ATLAS and CMS experiments at CERN found their mushroom, an intriguing, albeit very small, bump in the data.

    This little, unexpected bump could be the door to a whole host of new physics, because it could be a new particle. After the discovery of the Higgs most of the holes in the Standard Model had been sewn up, but many physicists were optimistic about finding new anomalies.

    “What happens in the future largely depends on what the LHC finds in its second run,” Ellis explains. “So if it turns out that there’s no other new physics and we’re focusing on understanding the Higgs boson better, that’s a different possible future for physics than if LHC Run 2 finds a new particle we need to understand.”

    While the bump is too small for physicists to announce it conclusively, there’s been hundreds of papers published by theoretical physicists as they leap to say what it might be.

    “Taking unexplained data, trying to fit it to your ideas about the universe, revising your ideas once you get more data, and on and on until you have unravelled the story of the universe – that’s the spirit of theoretical physics,” expresses Giudice.

    John Ellis classifies himself as a ‘scientific optimist’, who is happy to pick up whatever tools are available to him to help solve the problems that he has thought up. ‘By nature I’m an optimist so anything can happen, yes, we might not see anything beyond the Higgs boson, but lets just wait and see.’ Here he is interviewed by Harriet Jarlett (left) in his office at CERN. (Image: Sophia Bennett/CERN)

    But we’ll only know whether it’s something worthwhile with the start of the LHC this month, May 2016, when experimental physicists can start to take even more data and conclude what it is.

    Next generation of theory

    This unusual period of quiet in the world of theoretical physics means students studying physics might be more likely to go into experimental physics, where the major discoveries are seen as happening more often, and where young physicists have a chance to be the first to a discovery.

    Speaking to the Summer Students at CERN, some of whom hope to become theoretical physicists, there is the feeling that this period of uncertainty makes following theory a luxury, one that young physicists, who need to have original ideas and publish lots of papers to get ahead, can’t afford.

    Camille Bonvin is working as a fellow in the Theory Department on cosmology to try and understand why the universe is accelerating. If gravity is described by Einstein’s theory of general relativity the expansion should be slowing, not accelerating, which means there’s something we don’t understand. Bonvin is trying to find out what that is. Bonvin thinks the best theories are simple, consistent and make sense, like general relativity. “Einstein is completely logical, and his theory makes sense. Sometimes you have the impression of taking a theory which already exists and adding one element, then another, then another, to try and make the data fit it better, but its not a fundamental theory, so for me its not extremely beautiful.” (Image: Sophia Bennett/CERN)

    Camille Bonvin, a young theoretical physicist at CERN hopes that the data bump is the key to new physics, because without new discoveries it’s hard to keep a younger generation interested: “If both the LHC and the upcoming cosmological surveys find no new physics, it will be difficult to motivate new theorists. If you don’t know where to go or what to look for, it’s hard to see in which direction your research should go and which ideas you should explore.”

    The future’s bright

    Richard Feynman

    Richard Feynman, one of the most famous theoretical physicists once joked, “Physics is like sex. Sure, it may give some practical results, but that’s not why we do it.”

    And Gian Giudice agrees –while the field’s current uncertainty makes it more difficult for young people to make breakthroughs, it’s not the promise of glory that encourages people to follow the theory path, but just a simple passion in why our universe is the way it is.

    “It must be difficult for the new generations of young researchers to enter theoretical physics now when it is not clear where different directions are leading to,” he says. “But it’s much more interesting to play when you don’t know what’s going to happen, rather than when the rules of the game have already been settled.”

    “It’s much more interesting to play when you don’t know what’s going to happen, rather than when the rules of the game have already been settled,” says Giudice, who took on the role of leading the department in 2016 (Image: Sophia Bennett/ CERN) (Image: Sophia Bennett/CERN)

    Giudice, who took on the role of leading the theory department in January 2016 is optimistic that the turbulence the field currently faces makes it one of the most exciting times to become a theoretical physicist.

    “It has often been said that it is difficult to make predictions; especially about the future. It couldn’t be more true today in particle physics. This is what makes the present so exciting. Looking back in the history of physics you’ll see that moments of crisis and confusion were invariably followed by great revolutionary ideas. I hope it’s about to happen again,” smiles Giudice.

    See the full article here.

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    STEM Icon

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    Meet CERN in a variety of places:

    Cern Courier




    CERN CMS New

    CERN LHCb New II


    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

  • richardmitnick 1:52 pm on May 13, 2016 Permalink | Reply
    Tags: , , , , , , Theoretical Physics   

    From FNAL: “What do theorists do?” 

    FNAL II photo

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    May 13, 2016
    Leah Hesla
    Rashmi Shivni

    Pilar Coloma (left) and Seyda Ipek write calculations from floor to ceiling as they try to find solutions to lingering questions about our current models of the universe. Photo: Rashmi Shivni, OC

    Some of the ideas you’ve probably had about theoretical physicists are true.

    They toil away at complicated equations. The amount of time they spend on their computers rivals that of millennials on their hand-held devices. And almost nothing of what they turn up will ever be understood by most of us.

    The statements are true, but as you might expect, the resulting portrait of ivory tower isolation misses the mark.

    The theorist’s task is to explain why we see what we see and predict what we might expect to see, and such pronouncements can’t be made from the proverbial armchair. Theorists work with experimentalists, their counterparts in the proverbial field, as a vital part of the feedback loop of scientific investigation.

    “Sometimes I bounce ideas off experimentalists and learn from what they have seen in their results,” said Fermilab theorist Pilar Coloma, who studies neutrino physics. “Or they may find something profound in theory models that they want to test. My job is all about pushing the knowledge forward so other people can use it.”

    Predictive power

    Theorists in particle physics — the Higgses and Hawkings of the world — push knowledge by making predictions about particle interactions. Starting from the framework known as the Standard Model, they calculate, say, the likelihood of numerous outcomes from the interaction of two electrons, like a blackjack player scanning through the possibilities for the dealer’s next draw.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Experimentalists can then seek out the predicted phenomena, rooting around in the data for a never-before-seen phenomenon.

    Theorists’ predictions keep experimentalists from having to shoot in the dark. Like an experienced paleontologist, the theorist can tell the experimentalist where to dig to find something new.

    “We simulate many fake events,” Coloma said. “The simulated data determines the prospects for an experiment or puts a bound on a new physics model.”

    The Higgs boson provides one example.

    CERN ATLAS Higgs Event
    CERN ATLAS Higgs Event

    By 2011, a year before CERN’s ATLAS and CMS experiments announced they’d discovered the Higgs boson, theorists had put forth nearly 100 different proposals by as many different methods for the particle’s mass. Many of the predictions were indeed in the neighborhood of the mass as measured by the two experiments.

    CERN/LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN


    CERN/CMS Detector
    CERN/CMS Detector

    And like the paleontologist presented with a new artifact, the theorist also offers explanations for unexplained sightings in experimentalists’ data. She might compare the particle signatures in the detector against her many fake events. Or given an intriguing measurement, she might fold it into the next iteration of calculations. If experimentalists see a particle made of a quark combination not yet on the books, theorists would respond by explaining the underlying mechanism or, if there isn’t one yet, work it out.

    “Experimentalists give you information. ‘We think this particle is of this type. Do you know of any Standard Model particle that fits?’” said Seyda Ipek, a theorist studying the matter-antimatter imbalance in the universe. “At first it might not be obvious, because when you add something new, you change the other observations you know are in the Standard Model, and that puts a constraint on your models.”

    And since the grand aim of particle physics theory is to be able to explain all of nature, the calculation developed to explain a new phenomenon must be extendible to a general principle.

    “Unless you have a very good prediction from theory, you can’t convert that experimental measurement into a parameter that appears in the underlying theory of the Standard Model,” said Fermilab theorist John Campbell, who works on precision theoretical predictions for the ATLAS and CMS experiments at the Large Hadron Collider.

    Calculating moves

    The theorist’s calculation starts with the prospect of a new measurement or a hole in a theory.

    “You look at the interesting things that an experiment is going to measure or that you have a chance of measuring,” Campbell said. “If the data agrees with theory everywhere, there’s not much room for new physics. So you look for small deviations that might be a sign of something. You’re really trying to dream up a new set of interactions that might explain why the data doesn’t agree somewhere.”

    In its raw form, particle physics data is the amount and location of the energy a particle deposits in a particle detector. The more sensitive the detector, the more accurate the experimentalists’ measurement, and the more precise the corresponding calculation needs to be.

    Fermilab theorists John Campbell (left) and Ye Li work on a calculation that describes the interactions you might expect to see in the complicated environment of the LHC. Photo: Rashmi Shivni

    The CMS detector at the Large Hadron Collider, for example, allows scientists to measure some probabilities of particle interactions to within a few percent. And that’s after taking into account that it takes one million or even one billion proton-proton collisions to produce just one interesting interaction that CMS would like to measure.

    “When you’re making the measurement that accurately, it demands a prediction at a very high level,” Campbell said. “If you’re looking for something unexpected, then you need to know the expected part in quite a lot of detail.”

    A paleontologist recognizes the vertebra of a brachiosaurus, and the theoretical particle physicist knows what the production of a pair of top quarks looks like in the detector. A departure from the known picture triggers him to take action.

    “So then you embark on this calculation,” Campbell said.

    Embark, indeed. These calculations are not pencil-and-paper assignments. A single calculation predicting the details of a particle interaction, for example, can be a prodigious effort that takes months or years.

    So-called loop corrections are one example: Theorists home in on what happens during a particle event by adding detail — a correction — to an approximate picture.

    Consider two electrons that approach each other, exchange a photon and diverge. Zooming in further, you predict that the photon emits and reabsorbs yet another pair of particles before it itself is reabsorbed by the electron pair. And perhaps you predict that, at the same time, one of the electrons emits and reabsorbs another photon all on its own.

    Each additional quantum-scale effect, or loop, in the big-picture interaction is like pennies on the dollar, changing the accounting of the total transaction — the precision of a particle mass calculation or of the interaction strength between two particles.

    With each additional loop, the task of performing the calculation becomes that much more formidable. (“Loop” reflects how the effects are represented pictorially in Feynman diagrams — details in the approximate picture of the interaction.) Theorists were computing one-loop corrections for the production of a Higgs boson arising from two protons until 1991. It took another 10 years to complete the two-loop corrections for the process. And it wasn’t until this year, 2016, that they finished computing the three-loop corrections. Precise measurements at the Large Hadron Collider would (and do) require precise predictions to determine the kind of Higgs boson that scientists would see, demanding the decades-long investment.

    “Doing these calculations is not straightforward, or we would have done them a long time ago,” Campbell said.

    Once the theorist completes a calculation, they might publish a paper or otherwise make their code broadly available. From there, experimentalists can use the code to simulate how it will look in the detector. Farms of computers map out millions of fake events that take into account the new predictions provided courtesy of the theorist.

    “Without a network of computers available, our studies can’t be done in a reasonable time,” Coloma said. “A single computer can not analyze millions of data points, just as a human being could never take on such a task.”

    If the simulation shows that, for example, a particle might decay in more ways than what the experiment has seen, the theorist could suggest that experimentalists expand their search.

    “We’ve pushed experiments to look in different channels,” Ipek said. “They could look into decays of particles into two-body states, but why not also 10-body states?”

    Theorists also work with an experiment, or multiple experiments, to put their calculations to best use. Armed with code, experimentalists can change a parameter or two to guide them in their search for new physics. What happens, for example, if the Higgs boson interacts a little more strongly with the top quark than we expect? How would that change what we see in our detectors?

    “That’s a question they can ask and then answer,” Campbell said. “Anyone can come up with a new theory. It is best to try to provide a concrete plan that they can follow.”

    Outlandish theories and concrete plans

    Concrete plans ensure a fruitful relationship between experiment and theory. The wilder, unconventional theories scientists dream up take the field into exciting, uncharted territory, but that isn’t to say that they don’t also have their utility.

    Theorists who specialize in physics beyond the Standard Model, for example, generate thousands of theories worldwide for new physics – new phenomena seen as new energy deposits in the detector where you don’t expect to see them.

    “Even if things don’t end up existing, it encourages the experiment to look at its data in different ways,” Campbell said. An experiment could take so much data that you might worry that some fun effect is hiding, never to be seen. Having truckloads of theories helps mitigate against that. “You’re trying to come up with as many outlandish ideas as you can in the hope that you cover as many of those possibilities as you can.”

    Theorists bridge the gap between the pure mathematics that describes nature and the data through which nature manifests.

    “The field itself is challenging, but theory takes us to new places and helps us imagine new phenomena,” Ipek said.” We collectively work toward understanding every detail of our universe and that’s what ultimately matters most.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

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