From Science Alert: “Physicists just found a link between dark energy and the arrow of time”

Science Alert

20 MAY 2016
BRENDAN COLE

For years, physicists have attempted to explain dark energy – a mysterious influence that pushes space apart faster than gravity can pull the things in it together. But physics isn’t always about figuring out what things are. A lot of it is figuring out what things cause.

And in a recent paper*, a group of physicists asked this very question about dark energy, and found that in some cases, it might cause time to go forward.

When you throw a ball into the air, it starts with some initial speed-up, but then it slows as Earth’s gravity pulls it down.

Spacetime with Gravity Probe B. NASA

NASA/Gravity Probe B

If you throw it fast enough (about 11 km per second, for those who want to try), it’ll never slow down enough to turn around and start falling back towards you, but it’ll still move more slowly as it moves away from you, because of Earth’s gravity.

Physicists and astronomers in the 1990s expected something similar to have occured after the big bang – an event that threw matter out in all directions. The collective gravity from all that matter should have slowed it all down, just like the Earth slows down the ball. But that’s not what they found.

Instead, everything seems to have sped up. There’s something pervading the Universe that physically spreads space apart faster than gravity can pull things together. The effect is small – it’s only noticeable when you look at far-away galaxies – but it’s there. It’s become known as dark energy – “dark”, because no one knows what it is.

Dark energy depiction. Image: Volker Springle/Max Planck Institute for Astrophysics/SP)

Science is nothing if not the process of humans looking for things they can’t explain, so this isn’t the first time the Universe has stumped us. For centuries, one of those stumpers has been time itself: Why does time have an arrow pointing from the past to the present to the future?

It might seem like a silly question – I mean, if time didn’t go forward, then effects would precede causes, and that seems like it should be impossible – but it’s less of one than you might think.

The Universe, as far as we can tell, only operates according to laws of physics. And just about all of the laws of physics that we know are completely time-reversible, meaning that the things they cause look exactly the same whether time runs forward or backward.

One example is the path of a planet going around a star, which is governed by gravity. Whether time runs forward or backward, planetary orbits follow the exact same paths. The only difference is the direction of the orbit.

But one important piece of physics isn’t time-reversible, and that’s the second law of thermodynamics. It states that as time moves forward, the amount of disorder in the Universe will always increase. Just like dark energy, it’s something we’ve noticed about the Universe, and it’s something that we still don’t totally understand – though admittedly we have a better idea of it than we do of dark energy.

Physicists have, for this reason, reluctantly settled on the second law as the source of time’s arrow: disorder always has to increase after something happens, which requires that time can only move in one direction.

So physicists A. E. Allahverdyan from the Yerevan Physics Institute and V. G. Gurzadyan from Yerevan State University, both in Armenia, decided to see if – at least in a limited situation – dark energy and the second law might be related. To test it, they looked at the simple case of something like a planet orbiting a star with a changing mass.

They found that if dark energy either doesn’t exist or if it pulls space together, the planet just dully orbits the star without anything interesting happening. There’s no way to tell an orbit going forward in time from one going backward in time.

But if dark energy pushes space apart, like it does in our Universe, the planet eventually gets thrown away from the star on a path of no return. This gives us a distinction between the past and the future: run time one way, and the planet is flung off, run it the other way, and the planet comes in and gets captured by the star.

Dark energy naturally leads to an arrow of time.

The authors stress that this is a really limited situation, and they’re certainly not claiming dark energy is the reason time only ever moves forward. But they’ve shown a possible link between thermodynamics and dark energy that could help us to understand either – or maybe both – better than we ever have.

The research has been published in Physical Review E.

*Science paper:
Time arrow is influenced by the dark energy

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From Hopkins: “Space@Hopkins initiative launches with goal of bringing researchers together”

Johns Hopkins University

May 13, 2016
Katie Pearce

No caption. No image credit

Charles Bennett. No image credit.

Though Johns Hopkins University has a long history with space studies that dates to before the founding of NASA, Charles Bennett couldn’t help but notice how disconnected these research efforts have become across the institution.

“We’re a very major hub of space activity in this country, but the activities have been separate, and there’s never been anything that ties them together,” says Bennett, a professor of physics and astronomy and a Bloomberg Distinguished Professor at Hopkins.

Over the years, Bennett’s conversations with colleagues have revealed a shared interest in somehow uniting these disparate activities—which span dozens of Hopkins divisions, from the Applied Physics Laboratory’s space missions to physicists studying black holes.

The new Space@Hopkins initiative is an attempt to knit the threads together. The effort, which launched last month, includes a call for collaborative seed grant research proposals.

The initiative’s new website details Johns Hopkins’ rich history with space studies, from Professor Henry Rowlands’ 1883 invention of concave grating—which would become a basic tool for observations in space—to last year’s New Horizons mission to Pluto led by the Applied Physics Lab. In the 1920s, then-President Jonathan Ames served as a founder of the organization that would become NASA, which later honored his name through its Ames Research Center.

NASA/New Horizons spacecraft

Today, space research takes many forms across Johns Hopkins, Bennett says, whether that’s doctors focusing on astronaut health, engineers working on robotics that can be used in space, or undergraduates pursuing a minor in space science and engineering. Space-related work can also pop up in more unexpected places, Bennett says, noting a professor who recently used space imaging data to enhance an archaeological study.

Space@Hopkins names eight example research fields that fall under its umbrella, including astrophysics, planetary science, and spacecraft engineering. The work includes collaborations with affiliates like the Space Telescope Science Institute and NASA’s Goddard Space Flight Center.

Eight of the areas of research Space@Hopkins intends to unite. Image: Space@Hopkins

But it’s still a work in progress to pinpoint all the research and specialty areas that might fit within the initiative’s scope, Bennett says.

“I’m pleased with all the people who have come forward so far,” he says.

In addition to creating a centralized public hub for these varied efforts, Space@Hopkins strives to foster collaborative research between people who otherwise might not work together.

“We want to use our combination of knowledge to find that spark of extra creativity and collaboration,” Bennett says.

In the future, organizers are planning for social meet-ups and workshops to bring together different researchers. Assisting with research grants—whether publicizing opportunities or actually distributing seed funding—is also a big part of the mission.

The current round of annual seed grants of up to $25,000—with a May 20 deadline for proposals—is available for interdisciplinary projects involving undergraduates with prospects of leading to external research.

With Bennett as director, Space@Hopkins operates with an advisory board of professors and executives and two “space fellows”: PhD students Erini Lambrides and Kirsten Hall. Questions and comments should be directed to spacestudies@jhu.edu.

See the full article here .

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The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

From Ethan Siegel: “Which Elements Will Never Be Made By Our Sun?”

Starts with a Bang

May 11, 2016
Ethan Siegel

A high-resolution spectrum showing the elements in the Sun, by their visible-light absorption properties. Image credit: N.A.Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF.

Our Sun is the greatest source of heat and light in the entire Solar System, fusing hydrogen into helium in a nuclear chain reaction in its core. Because an atomic nucleus of helium is 0.7% lighter than the four hydrogen nuclei that it’s created from, that act of nuclear fusion releases a tremendously efficient amount of energy. Over the course of its 4.5 billion year lifetime (so far), the Sun had lost about the mass of Saturn due to the amount of hydrogen that’s fused into helium, through Einstein’s E = mc^2, which is the root source of all the sunlight we receive here on Earth. The Sun has a lot more going on inside of it than just fusing hydrogen (the lightest element) into helium (the second lightest), though, and is capable of making so many more elements than that. But the periodic table has a whole slew of elements the Sun can never make.

Periodic Table 2016

We’re pretty fortunate that our Sun wasn’t among the very first stars in the Universe. Shortly after the Big Bang, the Universe was made exclusively of hydrogen and helium: 99.999999% of the Universe was composed of these two elements alone. Yet the first massive stars didn’t just fuse hydrogen into helium, but eventually fused helium into carbon, carbon into oxygen, oxygen into silicon and sulfur, and then silicon and sulfur into iron, nickel and cobalt. When the inner core reached a large enough concentration of those heavy elements, a catastrophic supernova occurred, creating a rapid burst of neutrons that were scattered into the other nuclei. Very quickly, the types of elements present in the Universe climbed up and up the periodic table, creating everything we’ve ever found in nature and many elements even heavier than that. Even the very first core-collapse supernovae created elements that are beyond the limit of what we find on Earth: elements heavier than even uranium and plutonium.

The various layers of a supernova-bound star. During the supernova itself, many trans-uranic elements are created, through rapid neutron capture. Image credit: Nicolle Rager Fuller of the NSF.

But our Sun won’t go supernova, and won’t ever make those elements. That rapid burst of neutrons that happens in supernova allows the creation of elements through the r-process, where elements rapidly absorb neutrons and climb the periodic table in great leaps and jumps. Instead, our Sun will burn through the hydrogen in its core, and then will contract and heat up until it can begin fusing helium in its core. This phase of life — where our Sun will become a red giant star — is something that happens to all stars that are at least 40% as massive as our own.

Red Giant, SSL UC Berkeley

Reaching the right temperatures and densities, simultaneously, for helium fusion, is what separates red dwarfs (which can’t get there) from all other stars (which can). Three helium atoms fuse together into carbon, and then through another hydrogen-fusion pathway — the CNO cycle — we can create nitrogen and oxygen, while we can continue to add helium to various nuclei to climb up the periodic table. Carbon and helium make oxygen; carbon and oxygen make neon; carbon and neon make magnesium. But two very particular reactions take place that will create the vast majority of elements we know:

carbon-13 will fuse with helium-4, creating oxygen-16 and a free neutron, and
neon-22 will fuse with helium-4, creating magnesium-25 and a free neutron.

Image credit: screenshot from the wikipedia article on the s-process.

Free neutrons aren’t created in great abundance, just in relatively scarce numbers, since such a small percentage of these atoms actually are carbon-13 or neon-22 at any given time. But these free neutrons can only stick around for about 15 minutes, on average, until they decay away.

The two types (radiative and non-radiative) of neutron beta decay. Image credit: Zina Deretsky, National Science Foundation.

Fortunately, the interior of the Sun is dense enough that 15 minutes is more than enough time for this free neutron to run into another atomic nucleus, and when it does, it inevitably gets absorbed, creating a nucleus that’s one atomic mass unit heavier than before the neutron was absorbed. There are a few nuclei this won’t work for: you can’t create a mass-5 nucleus (out of helium-4, for instance) or a mass-8 nucleus (out of lithium-7, for examples), since they’re all inherently too unstable. But everything else will either be stable on timescales of at least tens of thousands of years, or it will decay by emitting an electron (through β-decay), which causes it to move one element up the periodic table.

Image credit: E. Siegel, based on the original from the University of Oregon’s physics department, via http://zebu.uoregon.edu/2004/a321/lec10.html.

During any star’s red giant, helium-burning phase, this enabled you to build all the elements between carbon and iron through this process of slow neutron capture, and heavy elements from iron all the way up through lead through that very same process. This process, known as the s-process (because neutrons are produced-and-captured slowly), runs into a problem when it tries to build elements heavier than lead. The most common isotope of lead is Pb-208, with 82 protons and 126 neutrons. If you add a neutron to it, it beta decays to become bismuth-209, which can then capture a neutron and β-decay again to become polonium-210. But unlike the other isotopes, which live for years, Po-210 only lives for days before emitting an alpha particle — or a helium-4 nucleus — and returning back to lead in the form of Pb-206.

The chain reaction that’s at the end of the line for the s-process. Image credit: E. Siegel and the English Language Wikipedia.

This leads to a cycle: lead captures 3 neutrons, becomes bismuth, which captures one more and becomes polonium, which then decays back to lead. In our Sun and in all stars that won’t go supernova, that’s the end of the line. Combine that with the fact that there’s no good pathway to get the elements between helium and carbon (lithium, beryllium and boron are produced from cosmic rays, not inside of stars), and you’ll find that the Sun can make a total of 80 different elements: helium and then everything from carbon through polonium, but nothing heavier. For that, you need a supernova or a neutron star collision.

Two neutron stars colliding, which is the primary source of many of the heaviest periodic table elements in the Universe. Image credit: Dana Berry, SkyWorks Digital, Inc.

But think about that: of all the naturally occurring elements here on Earth, the Sun makes about 90% of them, all from a tiny, non-descript star of no particular cosmic significance. The ingredients for life are literally that easy to come by.

See the full article here .

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“Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

From The Globe and Mail via PI: “‘Brilliant’ physicist to hold $8-million research chair at Perimeter Institute”

Perimeter Institute

Apr. 28, 2016
IVAN SEMENIUK

Long before the February press conference where physicists reported the first detection of gravitational waves from space – a major scientific achievement that made headlines around the world – Asimina Arvanitaki had arrived at a way to do the same thing with a far smaller and cheaper experiment involving a microscopic disk suspended by powerful lasers.

The 36-year-old theorist, known to friends and colleagues as Mina, has become a specialist in thinking up novel approaches to some of of the deepest problems in fundamental physics. Her work is at the forefront of an emerging area of research that is sometimes called “the precision frontier” because it involves making exacting measurements of well-understood phenomena and looking for unexpected deviations from what theory predicts.

“Most of these ideas you can actually build on a table,” said Dr. Arvanitaki.

Now Dr. Arvanitaki will have more scope and resources to pursue her ideas as the latest recipient of an $8-million research chair at the Perimeter Institute for Theoretical Physics in Waterloo, Ont., where she has worked as a researcher since 2014.

The new chair is noteworthy for a few reasons. In addition to representing an area of research that thrives on working off the beaten track, Dr. Arvanitaki will become the first female chair holder at the high-profile institute and the first to be supported by a funding source from outside Canada.

The Stavros Niarchos Foundation, a philanthropic organization headquartered in Athens and associated with a shipping industry fortune, will cover half the cost of the chair with the remaining support coming from the Perimeter Institute.

Greek heritage is evident in the title of the new position, dubbed the Aristarchus Chair in Theoretical Physics after the ancient philosopher from the Greek island of Samos who famously suggested that the Earth revolves around the sun, some 18 centuries before Nicolaus Copernicus.

“His thinking implied the sun is exactly like the distant stars,” said Dr. Arvanitaki, who suggested the name for the inaugural chair.

She added that by foreseeing that our solar system many not be unique in the universe, Aristarchus was also setting the stage for a far more contentious theory in current physics, which holds that our entire universe is just one of many.

“It’s a very controversial idea. People hate it, but I find it fascinating,” Dr. Arvanitaki said.

Raised in a small village in southern Greece, Dr. Arvanitaki was the child of two teachers and grew up with an appetite for learning. She recalls that at a young age she correctly calculated the time it takes light to travel from Earth to the sun – about eight minutes – and was stunned to realize that “we cannot know the ‘now’ of the sun.”

Dr. Arvanitaki came to Perimeter after earning her PhD and doing postdoctoral work at Stanford University under Savas Dimopoulus, a widely respected theorist who also hails from Greece.

“She’s one of the most brilliant young people I’ve ever met,” Dr. Dimopoulos said of his former student and collaborator.

He added that intelligence alone was not enough for success in physics, and that one way Dr. Arvanitaki excels is in selecting problems to work on that lead to productive results.

“You have to have good taste,” he said. “Or in her case, even inventing new directions and new ways to see very well-motivated ideas.”

Dr. Arvanitaki said she was looking forward to bringing on more researchers and students to accelerate her efforts to explore new domains of physics, and was pleased at the prospect of doing it at the Perimeter Institute. “There’s something about this place – you feel it when you walk in the building – it’s intoxicating.”

The Institute was established in 1999 by BlackBerry co-founder Mike Lazaridis and has since drawn substantial government support, including a $50-million investment over five years announced in the latest federal budget.

Black holes merging Swinburne Astronomy Productions

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.

From Many Worlds: “Breaking Down Exoplanet Stovepipes”

NASA NExSS

Many Worlds

2016-04-25
Marc Kaufman

The search for life beyond our solar system requires unprecedented cooperation across scientific disciplines. NASA’s NExSS collaboration includes those who study Earth as a life-bearing planet (lower right), those researching the diversity of solar system planets (left), and those on the new frontier, discovering worlds orbiting other stars in the galaxy (upper right). (NASA)

That fields of science can benefit greatly from cross-fertilization with other disciplines is hardly a new idea. We have, after all, long-standing formal disciplines such as biogeochemistry — a mash-up of many fields that has the potential to tell us more about the natural environment than any single approach. Astrobiology in another field that inherently needs expertise and inputs from a myriad of disciplines, and the NASA Astrobiology Institute was founded (in 1998) to make sure that happened.

Until fairly recently, the world of exoplanet study was not especially interdisciplinary. Astronomers and astrophysicists searched for distant planets and when they succeeded came away with some measures of planetary masses, their orbits, and sometimes their densities. It was only in recent years, with the advent of a serious search for exoplanets with the potential to support life, that it became apparent that chemists (astrochemists, that is), planetary and stellar scientists, cloud specialists, geoscientists and more were needed at the table.

Universities were the first to create more wide-ranging exoplanet centers and studies, and by now there are a number of active sites here and abroad. NASA formally weighed in one year ago with the creation of the Nexus for Exoplanet System Science (NExSS) — an initiative which brought together 17 university and research center teams with the goal of supercharging exoplanet studies, or at least to see if a formal, national network could produce otherwise unlikely collaborations and science.

That network is virtual, unpaid, and comes with no promises to the scientists. Still, NASA leaders point to it as an important experiment, and some interesting collabortions, proposals and workshops have come out of it.

“A year is a very short time to judge an effort like this,” said Douglas Hudgins, program scientist for NASA’s Exoplanet Exploration Program, and one of the NASA people who helped NExSS come into being.

“Our attitude was to pull together a group of people, do our best to give them tool to work well together, let them have some time to get to know each other, and see what happens. One year down the road, though, I think NExSS is developing and good ideas are coming out of it.”

Illustration of what a sunset might look like on a moon orbiting Kepler 47c and its two suns. (Softpedia)

One collaboration resulted in a “White Paper” on how laboratory work today can prepare researchers to better understand future exoplanet measurements coming from new generation missions. Led by NExSS member Jonathan Fortney of the University of Clalfornia, Santa Cruz, it was the result of discussions at the first NExSS meeting in Washington, and was expanded by others from the broader community.

Another NExSS collaboration between Steven Desch of Arizona State University and Jason Wright of Penn State led to a proposal to NASA to study a planet being pulled apart by the gravitational force a white dwarf star. The interior of the disintegrating planet could potentially be analyzed as its parts scatter.

Leaders of NExSS say that other collaborations and proposals are in the works but are not ready for public discussion yet.

In addition, NExSS — along with the NASA Astrobiology Institute (NAI) and the National Science Foundation (NSF) — sponsored an unusual workshop this winter at Arizona State University focused on a novel way to looking at whether an exoplanet might support life. Astrophysicists and geoscientists spent three days discussing and debating how the field might gather and use information about the formation, evolution and insides of exoplanets to determine whether they might be habitable.

One participant was Shawn Domogal-Goldman, a research space scientist at the Goddard Space Flight Center and a leader of the NExSS group. He’s an expert in ancient earth as well the astrophysics of exoplanets, and his view is that the Earth provides 4.5 billion years of physical, chemical, climatic and biological dynamics that need to be mined for useful insights about exoplanets.

When the workshop was over he said: “For me, and I think for others, we’ll look back at this meeting years from now and say to ourselves, ‘We were there at the beginning of something big.”

NExSS has two more workshops coming up, one on “Biosignatures” July 27 t0 29 in Seattle and another on stellar-exoplanet interactions in November. Reflecting the broad reach of NExSS, the biosignatures program has additional sponsors include the NASA Astrobiology Institute (NAI), NASA’s Exoplanet Exploration Program (ExEP), and international partners, including the European Astrobiology Network Association (EANA) and Japan’s Earth-Life Science Institute (ELSI).

By looking for signs of life, scientists focus on the potential presence of oxygen, ozone, water, carbon dioxide, methane and nitrous oxide, which could indicate plant or bacterial life. The figure above shows how complex Earth’s spectra is compared to Mars or Venus. This is a reflection of the intricate balance and control of elements needed to support life. The upcoming NExSS workshop will focus on what we know, and need to know, about what future missions and observations should be looking for in terms of exoplanet biosignatures. (ESA)

The initial idea for NExSS came from Mary Voytek, senior scientist for astrobiology in NASA’s Planetary Sciences Division. Interdisciplinary collaboration and solutions are baked into the DNA of astrobiology, so it is not surprising that an interdisciplinary approach to exoplanets would come from that direction. In addition, as the study of exoplanets increasingly becomes a search for possible life or biosignatures on those planets, it falls very much into the realm of astrobiology.

Hudgins said that while this dynamic is well understood at NASA headquarters, the structure of the agency does not necessarily reflect the convergence. Exoplanet studies are funded through the Division of Astrophysics while astrobiology is in the Planetary Sciences Division.

NExSS is a beginning effort to bring the overlapping fields closer together within the agency, and more may be on the way. Said Hudgins: “We could very well see some evolution in how NASA approaches the problem, with more bridges between astrobiology and exoplanets.”

NExSS is led by Natalie Batalha of NASA’s Ames Research Center in Moffett Field, California; Dawn Gelino with NExScI, the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena; and Anthony Del Genio of NASA’s Goddard Institute for Space Studies in New York City.

All three see NExSS as an experiment and work in progress, with some promising accomplishments already. And some clear challenges.

Del Genio, for instance, described the complex dynamics involved in having a team like his own — climate modelers who have spent years understanding the workings of our planet — determine how their expertise can be useful in better understanding exoplanets.

These are some of his thoughts:

“This sounds great, but in practice it is very difficult to do for a number of reasons. First, all the disciplines speak different languages. Jargon from one field has to be learned by people in another field, and unlike when I travel to Europe with a Berlitz phrase book, there is no Earth-to-Astrophysics translation guide to consult.

“Second, we don’t appreciate what the important questions are in each others’ fields, what the limitations of each field are, etc. We have been trying to address these roadblocks in the first year by having roughly monthly webinars where different people present research that their team is doing. But there are 17 teams, so this takes a while to do, and we are only part way through having all the teams present.

“Third, NExSS is a combination of teams that proposed to different NASA programs for funding, and we are a combination of big and small teams. We are also a combination of teams in areas whose science is more mature, and teams in areas whose science is not yet very mature (and maybe if you asked all of us you’d get 10 different opinions on whose science is mature and whose isn’t).

What’s more, he wrote, he sees an inevitable imbalance between the astrophysics teams — which have been thinking about exoplanets for a long time — and teams from other disciplines that have mature models and theories for their own work but are now applying those tools to think about exoplanets for the first time.

But he sees these issues as challenges rather than show-stoppers, and expects to see important — and unpredictable — progress during the three-year life of the initiative.

Natalie Batalie said that she became involved with NExSS because “I wanted to help expedite the search for life on exoplanets.”

“Reaching this goal requires interdisciplinary thinking that’s been difficult to achieve given the divisional boundaries within NASA’s science mission directorate. NExSS is an experiment to see if cooperation between the divisions can lead to cross-fertilization of ideas and a deeper understanding of planetary habitability.”

She said that in the last year, scientists working on planetary habitability both inside and outside of NExSS — and funded by different science divisions within NASA — have had numerous NExSS-sponsored opportunities to interact, learn from each other and begin collaborations.

The Fortney et al “White Paper” on experimental data gaps, for example, was conceived during one of these gatherings, as was the need for a biosignatures analysis group to support NASA’s Science & Technology Definition Teams studying the possible flagship missions of the future.

In full disclosure, Many Worlds is funded by NExSS but represents only the views of the writer.

See the full article here .

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About Many Worlds

There are many worlds out there waiting to fire your imagination.

Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

About NExSS

The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

From Quanta: “Physicists Hunt for the Big Bang’s Triangles”

Quanta Magazine

The story of the universe’s birth — and evidence for string theory — could be found in triangles and myriad other shapes in the sky.

Hannes Hummel and Olena Shmahalo/Quanta Magazine

April 19, 2016
Natalie Wolchover

Once upon a time, about 13.8 billion years ago, our universe sprang from a quantum speck, ballooning to one million trillion trillion trillion trillion trillion trillion times its initial volume (by some estimates) in less than a billionth of a trillionth of a trillionth of a second. It then continued to expand at a mellower rate, in accordance with the known laws of physics.

So goes the story of cosmic inflation, the modern version of the Big Bang theory.

Inflationary Universe. NASA/WMAP

Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

SDSS Telescope at Apache Point, NM, USA

That single short, outrageous growth spurt fits all existing cosmological data well and accounts for the universe’s largeness, smoothness, flatness and lack of preferred direction.

Cosmic Microwave Background per ESA/Planck

ESA/Planck

But as an explanation of how and why the universe began, inflation falls short. The questions it raises — why the growth spurt happened, how it happened, what (if anything) occurred beforehand — have confounded cosmologists since the theory emerged in the 1980s. “We have very strong evidence that there was this period of inflation,” said Matthew Kleban, a cosmologist at New York University. “But we have no idea — or we have many, many ideas — too many ideas — what inflation was, fundamentally.”

To understand the origin of the universe, today’s cosmologists seek to identify the unknown driver of inflation, dubbed the “inflaton.” Often envisioned as a field of energy permeating space and driving it apart, the inflaton worked, experts say, like a clock. With each tick, it doubled the size of the universe, keeping nearly perfect time — until it stopped. Theorists like Kleban, then, are the clocksmiths, devising altogether hundreds of different models that might replicate the clockwork of the Big Bang.

Like many cosmological clocksmiths, Kleban is an expert in string theory — the dominant candidate for a “theory of everything” that attempts to describe nature across all distances, times and energies. The known equations of physics falter when applied to the tiny, fleeting and frenzied environment of the Big Bang, in which they struggle to cram an enormous amount of energy into infinitesimal space and time. But string theory flourishes in this milieu, positing extra spatial dimensions that diffuse the energy. Familiar point particles become, at this highest energy and zoom level, one-dimensional “strings” and higher-dimensional, membranous “branes,” all of which traverse a 10-dimensional landscape. These vibrating, undulating gears may have powered the Big Bang’s clock.

At his office on a recent afternoon, Kleban sketched his latest inflaton design on the blackboard. First, he drew a skinny cylinder to depict the string landscape. Its length represented the three spatial dimensions of macroscopic reality, and its circumference signified the six other spatial dimensions that string theory says exist, but which are too small to see. On the side of the cylinder, he drew a circle. This is Kleban’s timepiece: a membrane that bubbles into being and naturally expands. As its inflating interior forms a new universe, its energy incrementally ticks down in clocklike fashion each time the expanding circle winds around the cylinder’s circumference and overlaps itself. When the energy of the “brane” dilutes, the clock stops ticking, and inflation ends. It’s a scheme that some string cosmologists have hailed for its economy. “I think it’s pretty plausible that some version of this happens,” he said.

A sketch by the string theorist and cosmologist Matthew Kleban of his Big Bang model known as unwinding inflation. Olena Shmahalo/Quanta Magazine

Though Kleban acknowledges that it’s too soon to tell whether he or anyone else is on to something, plans are under way to find out.

The record of the inflaton’s breakneck ticking can be read in the distribution of galaxies, galaxy clusters and superclusters that span the cosmos. These structures (and everything in them, including you) are artifacts of “mistakes in the clock,” as Matias Zaldarriaga, a cosmologist at the Institute for Advanced Study (IAS) in Princeton, N.J., put it. That is, time is intrinsically uncertain, and so the universe inflated at slightly different rates in different places and moments, producing density variations throughout. The jitter in time can also be thought of as a jitter in energy that occurred as pairs of particles spontaneously surfaced all over an “inflaton field” and stretched apart like two points on an inflating balloon. These particles were the seeds that gravity grew into galactic structures over the course of eons. The pairs of structures spanning the largest distances in the sky today came from the earliest quantum fluctuations during inflation, while structures that are closer together were produced later. This nested distribution across all cosmic distance scales “is telling you in detail that the clock was ticking,” said Nima Arkani-Hamed, a theoretical physicist at IAS. “But it doesn’t tell you anything about what it was made of.”

To reverse-engineer the clockwork, cosmologists are seeking a new kind of data. Their calculations indicate that galaxies and other structures are not merely randomly spread out in pairs across the sky; instead, they have a slight tendency to be arranged in more complex configurations: triangles, rectangles, pentagons and all manner of other shapes, which trace back not just to quantum jitter in the Big Bang’s clock, but to a much more meaningful turning of the gears.

Teasing out the cosmological triangles and other shapes — which have been named “non-Gaussianities” to contrast them with the Gaussian bell curve of randomly distributed pairs of structures — will require more precise observations of the cosmos than have been made to date. And so plans are being laid for a timeline of increasingly sensitive experiments. “We’re going to have far more information than we have now, and sensitivity to far subtler effects than we can probe now,” said Marc Kamionkowski, a cosmologist at Johns Hopkins University. In the meantime, theorists are making significant progress in determining what shapes to look for and how to look for them. “There’s been a great renaissance of understanding,” said Eva Silverstein, a string cosmologist at Stanford University who devised the dimensional-winding mechanism used by Kleban, as well as many clock designs of her own.

The rigorous study of non-Gaussianities took off in 2002, when Juan Maldacena, a revered, monklike theorist at IAS, calculated what’s known as the “gravitational floor”: the minimum number of triangles and other shapes that are guaranteed to exist in the sky, due to the unavoidable effect of gravity during cosmic inflation. Cosmologists had been struggling to calculate the gravitational floor for more than a decade, since it would provide a concrete goal for experimenters. If the floor is reached, and still no triangles are detected, Maldacena explained, “then inflation is wrong.”

When Maldacena first calculated the gravitational floor, actually detecting it seemed a distant goal indeed. At the time, all precise knowledge of the universe’s birth came from observations of the “cosmic microwave background” — the oldest light in the sky, which illuminates a two-dimensional slice of the infant universe as it appeared 380,000 years after the Big Bang. Based on the limited number of nascent structures that appear in this 2-D snapshot, it seemed impossible that their slight propensity to be configured in triangles and other shapes could ever be detected with statistical certainty. But Maldacena’s work gave theorists the tools to calculate other, more pronounced forms of non-Gaussianity that might exist in the sky, due to stronger effects than gravity. And it motivated researchers to devise better ways to search for the signals.

A year after Maldacena made his calculation, Zaldarriaga and collaborators showed that measuring the distribution of galaxies and groupings of galaxies that make up the universe’s “large-scale structure” would yield many more shapes than observing the cosmic microwave background. “It’s a 3-D versus 2-D argument,” said Olivier Doré, a cosmologist at NASA’s Jet Propulsion Laboratory who is working on a proposed search for non-Gaussianities in the large-scale structure. “If you start counting triangles in 3-D like you can do with galaxy surveys, there are really many more you can count.”

The notion that counting more shapes in the sky will reveal more details of the Big Bang is implied in a central principle of quantum physics known as “unitarity.” Unitarity dictates that the probabilities of all possible quantum states of the universe must add up to one, now and forever; thus, information, which is stored in quantum states, can never be lost — only scrambled. This means that all information about the birth of the cosmos remains encoded in its present state, and the more precisely cosmologists know the latter, the more they can learn about the former.

But how did details of the Big Bang get encoded in triangles and other shapes? According to Zaldarriaga, Maldacena’s calculation “opened up the understanding of how it comes about.” In a universe governed by quantum mechanics, all of nature’s constituents are cross-wired, morphing into and interacting with one another with varying degrees of probability. This includes the inflaton field, the gravitational field, and whatever else existed in the primordial universe: Particles arising in these fields would have morphed into and scattered with each other to produce triangles and other geometric configurations, like billiard balls scattering on a table.

Lucy Reading-Ikkanda for Quanta Magazine

These dynamical events would be mixed in with the more mundane quantum jitter from those particle pairs that popped up in the inflaton field and engendered so-called “two-point correlations” throughout the sky. A pair of particles might, for instance, have surfaced in some other primordial field, and one member of this pair might then have decayed into two inflaton particles while the other decayed into just a single inflaton particle, yielding a three-point correlation, or triangle, in the sky. Or, two mystery particles might have collided and split into four inflaton particles, producing a four-point correlation. Rarer events would have yielded five-point, six-point and even higher-point correlations, with their numbers, sizes and interior angles encoding the types and relationships of the particles that produced them. The unitarity principle promises that by tallying the shapes ever more precisely, cosmologists will achieve an increasingly detailed account of the primordial universe, just as physicists at the Large Hadron Collider in Europe hone their theory of the known particles and look for evidence of new ones by collecting statistics on how particles morph and scatter during collisions.

Following Maldacena’s calculation of the gravitational floor, other researchers demonstrated that even many simple inflationary models generate much more pronounced non-Gaussianity than the bare minimum. Clocksmiths like Silverstein and Kleban have since been busy working out the distinct set of triangles that their models would produce — predictions that will become increasingly testable in the coming years. Progress accelerated in 2014, when a small experiment based at the South Pole appeared to make a momentous discovery about the universe’s birth. The announcement drummed up interest in cosmological triangles, even though the supposed discovery ultimately proved a grave disappointment.

As news began to spread on March 17, 2014, that the “smoking gun” of cosmic inflation had been detected, Stanford University’s press office posted a celebratory video on YouTube. In the footage, the cosmologist Andrei Linde, one of the decorated pioneers of inflationary cosmology, and his wife, the string and supergravity theorist and cosmologist Renata Kallosh, answer their door to find their Stanford colleague Chao-Lin Kuo on the doorstep, accompanied by a camera crew.

“It’s five sigma, at point two,” Kuo says in the video.

“Discovery?” Kallosh asks, after a beat. She hugs Kuo, almost melting, as Linde exclaims, “What?”

Viewers learn that BICEP2, an experiment co-led by Kuo, has detected a swirl pattern in the cosmic microwave background that would have been imprinted by ripples in space-time known as “primordial gravitational waves.”

BICEP 2

And these could only have arisen during cosmic inflation, as corkscrew-like particles popped up in the gravitational field and then became stretched and permanently frozen into the shape of the universe.

In the next scene, Linde sips champagne with his wife and their guest. In the early 1980s, Linde, Alexei Starobinsky, Alan Guth and other young cosmologists devised the theory of cosmic inflation as a patch for the broken 1930s-era Big Bang theory, which described the universe as expanding outward from a “singularity” — a nonsensical point of infinite density — and couldn’t explain why the universe hadn’t become mottled and contorted as it grew. Cosmic inflation provided a clever fix for these problems, and BICEP2’s finding suggested that the theory was conclusively proved.

Gravitational Wave Background [?] from BICEP2

“If this is true,” Linde says to the camera, “this is a moment of understanding of nature of such a magnitude that it just overwhelms. Let’s see. Let’s just hope that this is not a trick.”

To many researchers, the most exciting thing about the alleged discovery was the strength of the swirl signal, measured as r = 0.2. The measurement indicated that inflation occurred at an extremely high energy scale and at the earliest moments in time, near the time-energy domain where gravity, as well as the effects of strings, branes or other exotica, would have been strong. The higher the energy scale of inflation, the more cross-wiring there would be between the inflaton and these other primordial ingredients. The result would be pronounced triangles and other non-Gaussianities in the sky.

“After BICEP, we all stopped what we were doing and started thinking about inflation,” Arkani-Hamed said. “Inflation is like having a gigantic particle accelerator at much higher energy scales than you can get to on Earth.” The question became how such an accelerator would operate, he said, “and if there really was exotic stuff up there [near the inflation scale], how you could go about looking for it.”

As these investigations took off, more details of BICEP2’s analysis emerged. It became clear that the discovery was indeed a trick of nature: The team’s telescope at the South Pole had picked up the swirly glow of galactic dust rather than the effect of primordial gravitational waves. A mix of anguish and anger swept through the field. Two years on, primordial gravitational waves still haven’t been detected. In January, BICEP2’s predecessor, the BICEP/Keck Array, reported that the value of r can be no more than 0.07, which lowers the ceiling on the energy scale of inflation and moves it further below the scale of strings or other exotic physics.

Keck Array

Nonetheless, many researchers were now aware of the potential gold mine of information contained in triangles and other non-Gaussianities. It had become apparent that these fossils from inflation were worth digging for, even if they were buried deeper than BICEP2 had briefly promised. “Yeah, r went down a little bit,” Maldacena said. But it’s not so bad, in his opinion: A relatively high scale is still possible.

In a paper last spring that drew on previous work by other researchers, Maldacena and Arkani-Hamed used symmetry arguments to show that a key feature of string theory could manifest itself in triangles. String theory predicts an infinite tower of “higher-spin states” — essentially, strings vibrating at an infinitely rising sequence of pitches. So far, no fundamental particles with a “spin” value greater than two have been discovered. Maldacena and Arkani-Hamed showed that the existence of such a higher-spin state would result in alternating peaks and troughs in the strength of the signal produced by triangles in the sky as they grow more elongated. For string theorists, this is exciting. “You can’t build a consistent interacting theory of such a particle except if you have an infinite tower of them” like the tower in string theory, explained Daniel Baumann, a theoretical cosmologist at the University of Amsterdam. Finding the oscillatory pattern in the triangles in the sky would confirm that this tower exists. “Just seeing one particle of spin greater than two would be indicative of string theory being present.”

Other researchers are pursuing similarly general predictions. In February, Kamionkowski and collaborators reported detailed information about primordial particles that is encoded in the geometry of four-point correlations, which “get interesting,” he said, because four points can lie flat or sweep into the third dimension. Observing the signals predicted by Arkani-Hamed, Maldacena and Kamionkowski would be like striking gold, but the gold is buried deep: Their strength is probably near the gravitational floor and will require at least 1,000 times the sensitivity of current equipment to detect. Other researchers prefer to tinker with bespoke string models that predict more pronounced triangles and other shapes. “So far we’ve explored only, I think, a very small fraction of the possibilities for non-Gaussianity,” Kamionkowski said.

Meanwhile, Linde and Kallosh are pushing in a totally different direction. Over the past three years, they’ve become enamored with a class of models called “cosmological alpha-attractors” that do not predict any non-Gaussianities above the gravitational floor at all. According to these models, cosmic inflation was completely pure, driven by a solitary inflaton field. The field is described by a Kähler manifold, which maps onto the geometric disk seen in Escher’s drawing of angels and devils. The Escherian geometry provides a continuum of possible values for the energy scale of inflation, including values so low that the inflaton’s cross-wiring to the gravitational field and other primordial fields would be extremely weak. If such a model does describe the universe, then swirls, triangles and other shapes might never be detected.

Linde isn’t bothered by this. In supporting the alpha-attractor models, he and Kallosh are staking a position in favor of simplicity and theoretical beauty, at the expense of ever knowing for sure whether their cosmological origin story is correct. An alpha-attractor universe, Linde said, is like one of the happy families in the famous opening line of Anna Karenina. As he paraphrased Tolstoy: “Any happy family, well, they look in a sense alike. But all unhappy families — they’re unhappy for different reasons.”

Will our universe turn out to be “happy” and completely free of distinguishing features? Baumann, who co-authored a book last year on string cosmology, argues that models like Linde’s and Kallosh’s are too simple to be plausible. “They are building these models from the bottom up,” he said. “Introducing a single field, trying to be very minimal — it would have been a beautiful model of the world.” But, he said, when you try to embed inflation into a fundamental theory of nature, it’s very hard to engineer a single field acting by itself, immune to the effects of everything else. “String theory has many of these effects; you can’t ignore them.”

And so the search for triangles and other non-Gaussianities is under way. Between 2009 and 2013, the Planck space telescope mapped the cosmic microwave background at the highest resolution yet, and scientists have since been scouring the map for statistical excesses of triangles and other shapes. As of their most recent analysis, they haven’t found any; given the sensitivity of their instruments and their 2-D searching ground, they only ever had an outside chance of doing so. But the scientists are continuing to parse the data in new ways, with another non-Gaussianity analysis expected this year.

Hiranya Peiris, an astrophysicist at University College London who searches for non-Gaussianities in the Planck data, said that she and her collaborators are taking cues from string cosmologists in determining which signals to look for. Peiris is keen to test a string-inflationary mechanism called axion monodromy, including variants recently developed by Silverstein and collaborators Raphael Flauger, Mehrdad Mibabayi, and Leonardo Senatore that generate an oscillatory pattern in triangles as a function of their size that can be much more pronounced than the pattern studied by Arkani-Hamed and Maldacena. To find such a signal, Peiris and her team must construct templates of the pattern and match them with the data “in a very numerically intensive and demanding analysis,” she said. “Then we have to do careful statistical tests to make sure we are not being fooled by random fluctuations in the data.”

Some string models have already been ruled out by this data analysis. Regarding the public debate about whether string theory is too divorced from empirical testing to count as science, Silverstein said, “I find it surreal, because we are currently doing some traditional science with string theory.”

LSST camera, built at SLAC, LSST telescope, currently under construction in Chile.

Moving forward, cosmologists plan to scour ever larger volumes of the universe’s large-scale structure. Starting in 2020, the proposed SPHEREx mission could measure non-Gaussianity sensitively enough in the distribution of 300 million galaxies to determine whether inflation was driven by one clock or two cross-wired clocks (according to models of the theory known as single- and multi-field inflation, respectively).

“Just to reach this level would dramatically reduce the number of possible inflation theories,” said Doré, who is working on the SPHEREx project. A few years further out, the Large Synoptic Survey Telescope will map 20 billion cosmological structures. If the statistical presence of triangles is not detected in the universe’s large-scale structure, there is yet another, perhaps final, approach. By mapping an ultra-faint radio signal called the 21-centimeter line, which is emitted by hydrogen atoms and traces back to the creation of the first stars, cosmologists would be able to measure even more “modes,” or arrangements of structures. “It’s going to have information about the whole volume of the universe,” Maldacena said.

If or when triangles show up, they will, one by one, reveal the nature of the inflaton clock and why it ticked. But will enough clues be gathered before we run out of sky in which to gather them?

The promise of unitarity — that information can be scrambled but never lost — comes with a caveat.

“If we assume we can make perfect measurements and we have an infinite sky and so on,” Maldacena said, “then in principle all the interactions and information about particles during inflation is contained in these correlators” — that is, three-point correlations, four-point correlations and so on. But perfect measurements are impossible. And worse, the sky is finite. There is a cosmic horizon: the farthest distance from which light has had time to reach us, and thus, beyond which we cannot see. During inflation, and over the entire history of the accelerating expansion of the universe since then, swirls, triangles, quadrilaterals and other shapes have been flying past this horizon and out of sight. And with them, the subtlest of signals, associated with the rarest, highest-energy processes during inflation, are lost: Cosmologists will never be able to gather enough statistics in our finite patch of sky to tease them out, precluding a complete accounting of nature’s fundamental constituents.

In his paper with Maldacena, Arkani-Hamed initially included a discussion of this issue, but he removed most of it. He finds the possibility of a limit to knowledge “tremendously disturbing” and sees it as evidence that quantum mechanics must be extended. One possible way to do this is suggested by his work on the amplituhedron, which casts quantum mechanical probabilities (and with them, unitarity) as emergent consequences of an underlying geometry. He plans to discuss this possibility in a forthcoming paper that will relate an analogue of the amplituhedron to non-Gaussianities in the sky.

People vary in the extent to which they are bothered by a limit to knowledge. “I’m more practical,” Zaldarriaga said. “There are, like, tens or many tens or orders of magnitude more modes that in principle we could see, that we have not been able to measure just because of technological or theoretical inability. So, these ‘in principle’ questions are interesting, but we are way before this point.”

Kleban also feels hopeful. “Yeah, it’s a finite amount of information,” he said. “But you could say the same thing about evolution, right? There’s a limited number of fossils, and yet we have a pretty good idea of what happened, and it’s getting better and better.”

If all goes well, enough fossils will turn up in the sky to tell a more complete story. A vast searching ground awaits.

See the full article here .

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Stem Education Coalition

Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

From ND: ” Unearthing the Secrets of a Star”

Notre Dame University

Scientists are using space in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, to work on a project called the Compact Accelerator System for Performing Astrophysical Research (CASPAR).

CASPAR’s accelerator is expected to be operational by 2015

CASPAR uses a low-energy particle accelerator that will allow researchers to mimic nuclear fusion reactions in stars. If successful, their findings could help complete our picture of how the elements in our universe are built. “Nuclear astrophysics is about what goes on inside the star, not outside of it,” said Dan Robertson, a Notre Dame assistant research professor of astrophysics working on CASPAR. “It is not observational, but experimental. The idea is to reproduce the stellar environment, to reproduce the reactions within a star.”

SURF is located in the former Homestake Gold Mine, which operated for more than a century extracting ore from hundreds of miles of tunnels, thousands of feet below the earth’s surface.

That depth is key to projects like CASPAR. With a keen sense of the irony at play, Robertson explains that researchers must “reproduce the stellar environment” by getting as far away from that environment as possible to reduce the cosmic radiation that constantly bombards the earth and creates “noise” which interferes with sensitive physics experiments.

“When we go underground, there’s a lot of rock above us that’s a mild shielding from cosmic rays,” Robertson said. “Once you get underground, cosmic ray background almost completely disappears.”

It’s a fairly direct rationale for a project that took a winding path to fruition.

Finding a Site

Notre Dame’s involvement with SURF has its origins in a facility called the Deep Underground Science and Engineering Laboratory (DUSEL), planned by the National Science Foundation (NSF) as a complex of laboratories for research in multiple fields: biology, chemistry, geology, as well as physics.

Notre Dame researchers were especially interested in one aspect of the DUSEL concept called DIANA (Dual Ion Accelerators for Nuclear Astrophysics). And with good reason, according to Robert J. Bernhard, the University’s vice president for research. “The nuclear astrophysics community identified DIANA as a priority, and identified Michael Wiescher to lead that facility,” Bernhard said.

Wiescher, the Freimann Professor of Nuclear Physics at Notre Dame, led the planning for the DIANA portion of the NSF proposal. That is, right up until sequestration of federal spending made funding of the project impossible. The NSF would eventually ask Wiescher and Notre Dame to withdraw the DIANA proposal, with hopes of one day revisiting it.

“So the question was, do we just drop it, or do we move ahead?” Wiescher recalls. “And we decided to move ahead, with a smaller scale version.”

Moving ahead with a smaller project allowed the NSF to still be involved, while a coalition of other partners was formed, including the South Dakota School of Mines and Technology, and Colorado School of Mines. The collaborative nature of CASPAR is indicative of a trend in scientific research at large, and especially at Notre Dame, according to Bernhard. For its part, Notre Dame is strategically investing in labs and equipment that serve multiple researchers and collaborative programs.

”Instead of buying equipment for individual labs, we’re directing funding in high performance, shared facilities such as the integrated imaging facility, the center for nano research and technology, the genomics and bioinformatics facility, the mass spectrometry and proteomics facility,” Bernhard said.

That same philosophy is at work at SURF, which, like CASPAR, has its own indirect path to realization. The Homestake Mine was founded after an expedition led by George Armstrong Custer discovered gold in South Dakota’s Black Hills in 1874. Five years later, the Homestake Mining Company began operations, eventually carving out 370 miles of tunnels as deep as 8,000 feet, creating one of the deepest mines in the country. The gold vein was eventually exhausted after producing 1.25 million kilograms of gold in its lifetime (roughly $80 billion at today’s rates), and Homestake shut down in 2001.

The closing of Homestake resulted in an economic and identity crisis for Lead and the surrounding area. However, in addition to its gold mining past, Homestake had a unique astrophysics connection.

In 1965, Ray Davis, a nuclear chemist from Brookhaven National Laboratory, began building an experiment deep in the Homestake mine with the goal of counting neutrinos, subatomic particles produced in fusion reactions inside stars. In 2002, Davis was awarded a share of the Nobel Prize for Physics for his neutrino work at Homestake.

When Homestake announced it would close the mine, physicists, aware of Davis’ neutrino success, proposed converting it into a deep underground laboratory. In 2004, the South Dakota Legislature created the South Dakota Science and Technology Authority (SDSTA) to work with the scientists proposing the lab. In 2006, Homestake Mining Co. donated the underground mine to the SDSTA. Also in 2006, the SDSTA accepted a $70 million gift from South Dakota philanthropist T. Denny Sanford, who stipulated that $20 million of the donation be used for a Sanford Science Education Center.

Then the real work began, according to Ani Aprahamian, Notre Dame’s Freimann Professor of Experimental Nuclear Physics and a member of SDSTA’s board.

“When you have a mine, it’s just people going under to dig at the rock. It’s dirty, filthy,” Aprahamian said. “This is a laboratory that requires a high level of cleanliness, underground. It’s a little bit more than just building a scientific lab, like you would above ground. So the transformation was quite astounding.”

The first step in that transformation was to pump millions of gallons of water out of the tunnels of the old mine. That task took months. Then came the installation of the power and technology infrastructure required in the roughly 4,400 square feet occupied by CASPAR. Meanwhile, the group of Notre Dame astrophysicists had to devise a way to disassemble and move an accelerator that had been on campus for 10 years to its new underground home.

“We worked in conjunction with the team at SURF so that everything we designed and built at Notre Dame was modular,” said Robertson. “The idea was that we could dismantle every section and bring it down in much smaller pieces and rebuild it from scratch. We packed it all up into two U-Haul vans and dragged it all the way from campus to SURF.”

When it arrived, the equipment was brought down the mine shaft via infrastructure originally designed to move men and minerals, not highly sensitive scientific equipment. Robertson recalls the series of roughly two-mile trips from the surface to the underground lab taking upwards of 45 minutes because of the pace at which the conveyances had to travel with accelerator parts on board.

The Unique Journey to a Unique Lab

It’s just one of the ways the space’s mining past is meeting its scientific present. Indeed, a visit to CASPAR is unlike a visit to any other laboratory environment. It starts with a comprehensive safety briefing and signing of a series of waivers. Before descending into the mine, one dons overalls, steel-tipped boots, safety goggles and a hard hat and attaches a carbon monoxide detector around the waist. Next, you pick up a gold medallion with a number inscribed on it and enter your name and number on a clipboard. If the medallion is missing at the end of the day, it becomes clear that someone is still underground in the mine. While certainly effective, it’s a fascinating juxtaposition in the highly technical work of exploring the origins of the universe.

The descent into the mine takes place in a cage that, at most, holds 15 people. The approximately mile-long trip takes 10 minutes without lab equipment, which requires a slower pace and more time. Yet even those 10 minutes can seem longer. The only light in the cage is from a headlamp on the cage operator’s hard hat, which briefly illuminates the wood supports and rock pilings framing the shaft.

After the descent, you arrive at what is familiarly called the 4850 Level of SURF. You exit into a surprisingly well-lit area with tunnels, or “drifts” in mining parlance, running right and left. CASPAR is located through the left, mile-long tunnel. It’s a startling experience to emerge through the dark tunnel and enter the pristine, high-tech environs of CASPAR. There, Notre Dame researchers and doctoral students have nearly completed reassembly of the accelerator that was shipped in parts from Notre Dame, like an incredibly complex jigsaw puzzle. Experiments are expected to begin in the summer of 2016.

The groundbreaking scientific breakthroughs the CASPAR researchers are seeking cannot be achieved without the invaluable technical expertise of the former Homestake miners, who were brought back to operate and maintain the mine equipment still being used. The miners and astrophysicists have formed a close working relationship, and Wiescher indicates there is a bond between the two groups that extends beyond just the common workspace.

“Our goal in CASPAR is to measure the evolution of the elements in the stars,” he said. “There are a number of questions that need to be answered, one being the ratio of carbon to oxygen in our universe. That will be determined by one of the reactions we want to measure. But also, we want to understand the buildup of heavy elements. When you look at old stars – those that came to be around the time of the Big Bang – there are very few elements. You can see in younger stars the elements slowly build up, including heavy elements, such as gold.”

In other words, Notre Dame researchers are using a retired gold mine in a town called Lead, to determine what reactions lead to the formation of gold in stars, among other things.

CASPAR is on schedule to be the first such project of its kind to yield results. When it does, Wiescher said the knowledge will have implications across multiple fields of study, most obvious astronomy and the material sciences. Robertson adds that sometimes these kinds of experiments yield other technologies that have broad public familiarity. Nuclear physics experiments have been instrumental in developing MRI and PET scans, for example. While those kinds of outcomes are not an intended goal of projects like CASPAR, Bernhard believes in today’s world they’re nonetheless critical.

“Nationally, there is an increasing expectation that universities will be a vehicle of discovery that will continue to provide the basic foundation that will drive better understanding of our world and our future economy,” Bernhard said. “The CASPAR project is an excellent example of this type of research.”

For now, the precious gold researchers seek is a deeper understanding of our universe. It happens that the best way to do so is to build a deeper lab, where the cosmos can be shut out in hopes of revealing its secrets.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The University of Notre Dame du Lac (or simply Notre Dame /ˌnoʊtərˈdeɪm/ NOH-tər-DAYM) is a Catholic research university located near South Bend, Indiana, in the United States. In French, Notre Dame du Lac means “Our Lady of the Lake” and refers to the university’s patron saint, the Virgin Mary.

The school was founded by Father Edward Sorin, CSC, who was also its first president. Today, many Holy Cross priests continue to work for the university, including as its president. It was established as an all-male institution on November 26, 1842, on land donated by the Bishop of Vincennes. The university first enrolled women undergraduates in 1972. As of 2013 about 48 percent of the student body was female.[6] Notre Dame’s Catholic character is reflected in its explicit commitment to the Catholic faith, numerous ministries funded by the school, and the architecture around campus. The university is consistently ranked one of the top universities in the United States and as a major global university.

The university today is organized into five colleges and one professional school, and its graduate program has 15 master’s and 26 doctoral degree programs.[7][8] Over 80% of the university’s 8,000 undergraduates live on campus in one of 29 single-sex residence halls, each of which fields teams for more than a dozen intramural sports, and the university counts approximately 120,000 alumni.[9]

The university is globally recognized for its Notre Dame School of Architecture, a faculty that teaches (pre-modernist) traditional and classical architecture and urban planning (e.g. following the principles of New Urbanism and New Classical Architecture).[10] It also awards the renowned annual Driehaus Architecture Prize.

From Astronomy Now: “A research milestone in helping predict solar flares”

Astronomy Now

17 November 2015

Left: An image of our Sun taken by NASA’s Solar Dynamics Observatory, showing million-degree plasma being channelled into loop-like shapes by the immense magnetic fields. Right: A zoom-in of the highly magnetic region of the Sun’s corona studied by Dr. David Jess and colleagues from Queen’s University Belfast, Northern Ireland. Image credit: Queen’s University Belfast.

Solar flares are massive explosions of energy in the Sun’s atmosphere. Experts have warned that even a single ‘monster’ solar flare could cause up to $2 trillion worth of damage on Earth, including the loss of satellites and electricity grids, as well the potential knock-on dangers to human life and health. A key goal of the $300 million Daniel K Inouye Solar Telescope (DKIST), which will be the largest solar telescope in the world when construction is finished in 2019 on the Pacific island of Maui, is the measurement of magnetic fields in the outer regions of the Sun’s atmosphere.

DKIST

The technique pioneered by the Queen’s-led team, just published in the journal Nature Physics, will feed into the DKIST project, as well as allowing greater advance warning of potentially devastating space storms. The new technique allows changes in the Sun’s magnetic fields, which drive the initiation of solar flares, to be monitored up to ten times faster than previous methods.

The Queen’s-led team, which spans academics from universities in Europe, the Asia-Pacific and the USA, harnessed data from both NASA’s premier space-based telescope (the Solar Dynamics Observatory), and the ROSA multi-camera system, which was designed at Queen’s University Belfast, using detectors made by Northern Ireland company Andor Technology.

Lead researcher Dr David Jess from Queen’s Astrophysics Research Centre said: “Continual outbursts from our Sun, in the form of solar flares and associated space weather, represent the potentially destructive nature of our nearest star. Our new techniques demonstrate a novel way of probing the Sun’s outermost magnetic fields, providing scientists worldwide with a new approach to examine, and ultimately understand, the precursors responsible for destructive space weather.

“Queen’s is increasingly becoming a major player on the astrophysics global stage. This work highlights the strong international links we have with other leading academic institutes from around the world, and provides yet another example of how Queen’s research is at the forefront of scientific discovery.”

See the full article here .

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From MIT: “Small thunderstorms may add up to massive cyclones on Saturn”

MIT News

June 15, 2015
Jennifer Chu | MIT News Office

Saturn’s north polar vortex.m Image courtesy of Caltech/Space Science Institute

New model may predict cyclone activity on other planets.

For the last decade, astronomers have observed curious “hotspots” on Saturn’s poles. In 2008, NASA’s Cassini spacecraft beamed back close-up images of these hotspots, revealing them to be immense cyclones, each as wide as the Earth.

Cassini

Scientists estimate that Saturn’s cyclones may whip up 300 mph winds, and likely have been churning for years.

While cyclones on Earth are fueled by the heat and moisture of the oceans, no such bodies of water exist on Saturn. What, then, could be causing such powerful, long-lasting storms?

In a paper published today in the journal Nature Geoscience, atmospheric scientists at MIT propose a possible mechanism for Saturn’s polar cyclones: Over time, small, short-lived thunderstorms across the planet may build up angular momentum, or spin, within the atmosphere — ultimately stirring up a massive and long-lasting vortex at the poles.

The researchers developed a simple model of Saturn’s atmosphere, and simulated the effect of multiple small thunderstorms forming across the planet over time. Eventually, they observed that each thunderstorm essentially pulls air towards the poles — and together, these many small, isolated thunderstorms can accumulate enough atmospheric energy at the poles to generate a much larger and long-lived cyclone.

The team found that whether a cyclone develops depends on two parameters: the size of the planet relative to the size of an average thunderstorm on it, and how much storm-induced energy is in its atmosphere. Given these two parameters, the researchers predicted that Neptune, which bears similar polar hotspots, should generate transient polar cyclones that come and go, while Jupiter should have none.

Morgan O’Neill, the paper’s lead author and a former PhD student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), says the team’s model may eventually be used to gauge atmospheric conditions on planets outside the solar system. For instance, if scientists detect a cyclone-like hotspot on a far-off exoplanet, they may be able to estimate storm activity and general atmospheric conditions across the entire planet.

“Before it was observed, we never considered the possibility of a cyclone on a pole,” says O’Neill, who is now a postdoc at the Weizmann Institute of Science in Israel.

“Only recently did Cassini give us this huge wealth of observations that made it possible, and only recently have we had to think about why [polar cyclones] occur.”

O’Neill’s co-authors are Kerry Emanuel, the Cecil and Ida Green Professor of Earth, Atmospheric and Planetary Sciences, and Glenn Flierl, a professor of oceanography in EAPS.

Beta-drifting toward a cyclone

Polar cyclones on Saturn are a puzzling phenomenon, since the planet, known as a gas giant, lacks an essential ingredient for brewing up such storms: water on its surface.

“There’s no surface at all — it just gets denser as you get deeper,” O’Neill says. “If you lack choppy waters or a frictional surface that allows wind to converge, which is how hurricanes form on Earth, how can you possibly get something that looks similar on a gas giant?”

The answer, she found, may be something called “beta drift” — a phenomenon by which a planet’s spin causes small thunderstorms to drift toward the poles. Beta drift drives the motion of hurricanes on Earth, without requiring the presence of water. When a storm forms, it spins in one direction at the surface, and the opposite direction toward the upper atmosphere, creating a “dipole of vorticity.” (In fact, videos of hurricanes taken from space actually depict the storm’s spin as opposite to what’s observed on the ground.)

“The whole atmosphere is kind of being dragged by the planet as the planet rotates, so all this air has some ambient angular momentum,” O’Neill explains. “If you converge a bunch of that air at the base of a thunderstorm, you’re going to get a small cyclone.”

The combination of a planet’s rotation and a circulating storm generates secondary features called beta gyres that wrap around a storm and essentially split its dipole in half, tugging the top half toward the equator, and the bottom half toward the pole.

The team developed a model of Saturn’s atmosphere and ran hundreds of simulations for hundreds of days each, allowing small thunderstorms to pop up across the planet. The researchers observed that multiple thunderstorms experienced beta drift over time, and eventually accumulated enough atmospheric circulation to create a much larger cyclone at the poles.

“Each of these storms is beta-drifting a little bit before they sputter out and die,” O’Neill says. “This mechanism means that little thunderstorms — fast, abundant, but not very strong thunderstorms — over a long period of time can actually accumulate so much angular momentum right on the pole, that you get a permanent, wildly strong cyclone.”

Next stop: Jupiter

The team also explored conditions in which planets would not form polar cyclones, even though they may experience thunderstorms. The researchers found that whether a polar cyclone forms depends on two parameters: the energy within a planet’s atmosphere, or the total intensity of its thunderstorms; and the average size of its thunderstorms, relative to the size of the planet itself. Specifically, the larger an average thunderstorm compared to a planet’s size, the more likely a polar cyclone is to develop.

O’Neill applied this relationship to Saturn, Jupiter, and Neptune. In the case of Saturn, the planet’s atmospheric conditions and storm activity are within the range that would generate a large polar cyclone. In contrast, Jupiter is unlikely to host any polar cyclones, as the ratio of any storm to its overall size would be extremely small. The dimensions of Neptune suggest that polar cyclones may exist there, albeit on a fleeting basis.

“Saturn has an intense cyclone at each pole,” says Andrew Ingersoll, professor of planetary science at Caltech, who was not involved in the study. “The model successfully accounts for that. Jupiter doesn’t seem to have polar cyclones like Saturn’s, but Jupiter isn’t tipped over as much as Saturn, so we don’t get a good view of the poles. Thus the apparent absence of polar cyclones on Jupiter is still a mystery.”

The researchers are eager to see whether their predictions, particularly for Jupiter, bear out. Next summer, NASA’s Juno spacecraft is scheduled to enter into an orbit around Jupiter, kicking off a one-year mission to map and explore Jupiter’s atmosphere.

“If what we know about Jupiter currently is correct, we predict that we won’t see these wildly strong cyclones,” O’Neill says. “We’ll find out next year if our predictions are true.”

This research was funded in part by the National Science Foundation.

See the full article here.

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From New Scientist: “Looking into the voids could help explain dark energy”

New Scientist

10 April 2015
Anil Ananthaswamy

A complex web (Image: Volker Springle/Max Planck Institute for Astrophysics/SP)

HOLES in the universe could help explain why it’s ripping apart. The number and size of cosmic voids could shed light on the mysterious dark energy that is causing the universe to grow at an ever-increasing pace.

In the late 1990s, astronomers realised that the expansion of the universe was accelerating and attributed this to the inherent “dark energy” of space-time.

But we understand little about dark energy. Each unit of space-time contains some, but if this energy density changes with time, it implies different fates for our universe. If it is constant, as current observations suggest, then the universe will expand forever. But if it changes, we could be heading for a more dramatic end, like a big rip or a big crunch.

One way to understand whether dark energy changes with time is to observe its effect on the large-scale structure of the universe. Just instants after the big bang, quantum fluctuations in the fabric of space-time led to regions that had more matter than their neighbours. As the universe expanded, the denser regions evolved to form clusters of galaxies. The less dense regions became voids – regions of space-time almost empty of matter, which can stretch from 30 million to 150 million light years across.

While most efforts at deciphering dark energy involve studying its effect on clusters of galaxies, Alice Pisani and colleagues at the Paris Institute of Astrophysics decided to see if dark energy influenced the number of voids in the universe. “Voids are just an unavoidable part of the distribution of matter in the universe,” says team member Benjamin Wandelt.

It turns out that there was a time in the evolution of the universe when the effects of dark energy kicked in and stopped the formation of new large-scale structures, whether clusters or voids. The properties of dark energy influenced when this happened and therefore the distribution of these structures.

Pisani and colleagues considered three scenarios, all of which can explain the observed rate of expansion today. One was that dark energy is a cosmological constant [Λ]; in the other scenarios, dark energy changed with time. The second caused the expansion to accelerate later but faster than the cosmological constant would have, and in the third, it was earlier but slower.

“Depending exactly on when the universe started accelerating, you have more or less voids of various sizes,” says Wandelt. The team’s analysis shows that with later but faster acceleration, there should be more big voids but fewer smaller ones compared with the cosmological constant. The opposite would be the case for acceleration that began earlier but was slower (arxiv.org/abs/1503.07690).

Observations are not yet good enough to differentiate between the three scenarios but the European Space Agency’s Euclid mission, due for launch in 2020, will study more voids than ever before. The Paris team says its analysis could be applied to the Euclid data to elucidate dark energy, alongside studies investigating clusters.

ESA/Euclid

See the full article here.

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