Tagged: Dr. Steven Weinberg Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 6:17 pm on December 7, 2014 Permalink | Reply
    Tags: , Dr. Steven Weinberg, , ,   

    From Harvard: “The ever-smaller future of physics” 

    Harvard University

    Harvard University

    December 5, 2014
    Alvin Powell

    If physicists want to find their long-sought “theory of everything,” they have to get small. And Nobel Prize-winning theoretical physicist Steven Weinberg thinks he knows roughly how small.

    sw
    Nobel winner Steven Weinberg brought his thoughts on a “theory of everything” to the Physics Department’s Lee Historical Lecture. Jon Chase/Harvard Staff Photographer

    Weinberg, who spoke at a packed Geological Lecture Hall Monday evening, said there are hints that the answers to fundamental questions will reveal themselves at around a million billionths — between 10­-17 and 10-19 — of the radius of the typical atomic nucleus.

    “It is in that range that we expect to find really new physics,” said Weinberg, a onetime Harvard professor now on the faculty at the University of Texas at Austin.

    Physicists understand that there are four fundamental forces of nature. Two are familiar in our everyday lives: those of gravity and electromagnetism. The two less-familiar forces operate at the atomic level. The strong force holds the nucleus together while the weak force is responsible for the radioactive decay that changes one type of particle to another and the nuclear fusion that powers the sun.

    For decades, physicists have toiled to create a single theory that explains how all four of these forces work, but without success, instead settling on one theory that explains how gravity acts on a macro scale and another to describe the other three forces and their interactions at the atomic level.

    Weinberg, who won the 1979 Nobel Prize in Physics, with Sheldon Glashow and Abdus Salam, for electroweak theory explaining how the weak force and electromagnetism are related, returned to Harvard to deliver the Physics Department’s annual David M. Lee Historical Lecture. He was introduced by department chair Masahiro Morii and by Andrew Strominger, the Gwill E. York Professor of Physics, who recalled taking Weinberg’s class on general relativity as a Harvard undergrad.

    “I wish I could say I remembered you in Physics 210,” Weinberg said to laughs as he took the podium.

    The event also recognized the outstanding work of four graduate students — two in experimental physics, Dennis Huang and Siyuan Sun, and two in theoretical physics, Shu-Heng Shao and Bo Liu — with the Gertrude and Maurice Goldhaber Prize.

    Weinberg pointed to several hints of something significant going on at the far extremes of tininess. One hint is that the strong force, which weakens at shorter scales, and the weak and electromagnetic forces, which get stronger across shorter distances, appear to converge at that scale.

    Gravity is so weak that it isn’t felt at the atomic scale, overpowered by the other forces that operate there. However, Weinberg said, if you calculate how much mass two protons or two electrons would need for gravity to balance their repulsive electrical force, it would have to not just be enormous, but on a similar scale as the other measurements, the equivalent of 1.04 x 1018 gigaelectron volts.

    “There is a strong suggestion that gravity is somehow unified with those other forces at these scales,” Weinberg said.

    Weinberg also said there are experimental hints in the extremely small masses of neutrinos and in possible proton decay that the tiniest scales are significant in ways that are fundamental to physics.

    “This is a very crude estimate, but the mass of neutrinos which are being observed are in the same ballpark that you would expect from new physics associated with a fundamental length,” Weinberg said. “It all seems to hang together.”

    A major challenge for physicists is that the energy needed to probe what is actually going on at the smallest levels is far beyond current technology, something like 10 trillion times the highest energy we can harness now. And new technology to explore the problem experimentally is not on the horizon. Even with all the wealth in the world, scientists wouldn’t know where to begin, Weinberg said.

    But the experiment may have already been done, by nature, and there may be a way to look back at it, Weinberg said. During the inflationary period immediately after the Big Bang there was that kind of energy, he said, and it would be evident as gravitation waves in the cosmic microwave background, an echo of the Big Bang that astronomers study for hints of the early universe. In fact, astronomers announced they had found such waves earlier this year, though they are waiting for confirmation of the results.

    Gravitational Wave Background
    gravitational waves

    Cosmic Background Radiation Planck
    CMB per ESA/Planck

    ESA Planck
    ESA/Planck

    “The big question that we face … is, can we find a truly fundamental theory uniting all the forces, including gravitation … characterized by tiny lengths like 10-17 to 10-19 nuclear radii?” Weinberg said. “Is it a string theory? That seems like the most beautiful candidate, but we don’t have any direct evidence that it is a string theory. The only handle we have … on this to do further experiments is in cosmology.”

    See the full article here.

    Harvard is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s best known landmark.

    Harvard University has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 6:43 pm on April 21, 2012 Permalink | Reply
    Tags: , Dr. Steven Weinberg, , The New York Review of Books   

    From The New York Review of Books: Steven Weinberg “The Crisis of Big Science” 

    nyrb

    In The New York Review of Books, May 10, 2012 Dr. Weinberg writes, as beautifully as ever, about some of the past and future of what is essentially Basic Scientific Research, in the field of Physics. This article is copyright protected, so I will not even quote from it, out of respect for Dr. Weinberg. I will just suggest that you go to the link provided below and read the article.

    sw
    Dr. Steven Weinberg

    Suffice it for me to say that in this article he is concerned with the future of the U.S. budget for basic research, specifically in Physics and Astronomy. But he does spend some time describing where we have been before talking about where we are or are not going. I have read him before in NYRB, and he never fails to properly set a context for his major thesis. But, while this is one of the most eminent people in our scientific community, still, in his description of our history of support and the lack of it for basic research, Dr Weinberg seems to make the defining point of his interest the 1993 cancellation by the U.S. Congress of the Superconducting Super Collider, to have been built in Texas. I have seen it in his previous articles, I have seen him speak about it in videos of his lectures. On the one hand, he is not wrong. On the other hand, let it go. This failure to proceed in a program in the State of Texas, where he has been at the University of Texas, is in no way any sort of defining moment in his incredible and Nobel winning career.

    If Dr Weinberg can be criticized for anything at all in his writing, it is his too quick mentions of various sub-atomic particles and forces which are the elements of the Standard Model. While it might be reasonable for him to expect that his readers would already be familiar with these terms, still he is writing in a journal of popular press, no matter how erudite the journal or its readership. He might just keep some quickie descriptions of quarks, leptons, muons, and bosons, etc., in his word processing files and dump them in for his less learned readership.


    The “Standard Model” with the hypothetical Higgs boson

    The U.S. D.O.E. Office of Science funds about seventeen major research laboratories, such as Berkeley Lab, Brookhaven, Argonne, and Fermilab. There is a lot of concern about the future of many projects in these labs. At Fermilab, the Long Baseline Neutrino Experiment (LBNE) has been pushed back to economic re-design. That is a biggie. Dr. Weinberg comments that things are not rosy in Europe. But the European Southern Observatory, an incredible organization in Astronomy, seems to be pushing ahead with its long range telescope building program. Also, in a previous post here, we saw that Director Oddone of Fermilab had recently returned from meetings in which he was quite impressed with the planning he saw in both Europe and Asia.

    I highly recommend that you read Dr. Weinberg’s article. I always recommend that you read Dr Weinberg. The article can be found here.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
Follow

Get every new post delivered to your Inbox.

Join 378 other followers

%d bloggers like this: