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2Physics Quote:
"Perfect transparency has never been realized in natural transparent solid materials such as glass because of the impedance mismatch with free space or air. As a consequence, there generally exist unwanted reflected waves at the surface of a glass slab. It is well known that non-reflection only occurs at a particular incident angle for a specific polarization, which is known as the Brewster angle effect. Our question is: is it possible to extend the Brewster angle from a particular angle to a wide range of or all angles, so that there is no reflection for any incident angle."
-- Jie Luo, Yuting Yang, Zhongqi Yao, Weixin Lu, Bo Hou, Zhi Hong Hang, Che Ting Chan, Yun Lai

(Read Full Article: "Ultratransparent Media: Towards the Ultimate Transparency"

Saturday, February 28, 2009

5 Most Important Breakthroughs That My Field of Research Needs -- Nathan Seiberg

Nathan Seiberg [photo courtesy: Institute for Advanced Study, Princeton]

[Our guest today in the feature ‘5-Breakthroughs’ is Nathan Seiberg, Professor at the Institute for Advanced Study in Princeton, NJ. Prof. Seiberg’s work has spanned a wide spectrum of research revolving around particle physics phenomenology, field theory, gauge theory, Matrix theory, string theory, and supersymmetry.

In early 1990s, he formulated the application of holomorphy to calculations in gauge theories with supersymmetry. In his famous 1994 article “Electric-Magnetic Duality in Supersymmetric Non-Abelian Gauge Theories” (Abstract link) he conjectured a new kind of Strong-Weak duality or S-duality relating two different supersymmetric QCDs which are not identical, but agree at low energies. This is now well-known as Seiberg duality.

Working with Edward Witten, he also devised a series of partial differential equations that simplified the classification of 4-dimensional manifolds. The invariants of such compact smooth 4-manifolds are now known as Seiberg–Witten invariants. Later, they analyzed the appearance of non-commutative geometry in theories containing open strings, and identified a low energy limit of open string dynamics as a noncommutative quantum field theory.

Prof. Seiberg also made pioneering contribution in Matrix Theory, M Theory and various subfields of particle physics. Here is link to his list of publications: Google Scholar.

He received his Ph.D from the Weizmann Institute of Science in Israel in 1982. Before joining the Institute for Advanced Study, he had been a Professor of Physics at the Weizmann Institute for Science and at Rutgers University.

Prof. Seiberg is a member of National Academy of Sciences and Fellow of American Academy of Arts and Sciences. He received The John D. and Catherine T. MacArthur Fellowship (Genius Grant) in 1996. In 1998, American Physical Society awarded Dannie Heineman Prize for Mathematical Physics to Nathan Seiberg and Ed Witten "for their decisive advances in elucidating the dynamics of strongly coupled supersymmetric field and string theories. The deep physical and mathematical consequences of the electric-magnetic duality they exploited have broadened the scope of Mathematical Physics (quote from the citation)."

It’s an honor and privilege on our part to present 5 most important breakthroughs that Prof. Seiberg would like to see in his fields of research.
— 2Physics.com ]

1. Origin of electroweak symmetry breaking. This will shed light on the origin of mass of elementary particles. An effective description of this phenomenon in terms of the Higgs mechanism is known. The Large Hadron Collider (LHC) will explore it in detail and perhaps will point to a deeper structure. One possibility is that the LHC will discover supersymmetry – a new kind of symmetry which extends our understanding of space and time. Alternatively, it will find new particles which might have a description in terms of new space dimensions. If only the Higgs particle is discovered, its mass might be set anthropically. Is this true?

2. Origin of the elementary particles. What determines the properties of the quarks and the leptons (their quantum numbers)? Why do they appear in 3 generations? Most of the parameters of the Standard Model of particle physics are associated with the quark and lepton masses. It is possible that the underlying structure which controls them exists at very high energies which will not be explored soon. One possible explanation of the properties of the quarks, the leptons, and their interactions is the idea of grand unification. Is this idea correct?

3. Dark matter and dark energy of the Universe. Is the dark matter weakly interacting massive particles? This question could be settled soon either by detecting these particles, or the product of their interactions, or by creating them at the LHC. Is the dark energy a cosmological constant? What sets the value of the cosmological constant today? Is it anthropic?

4. Inflation. It seems that in the past the Universe had a period of rapid expansion known as inflation, during which the cosmological constant was large. What is the detailed description of this phenomenon? The study of inflation naturally leads to the idea of a multiverse – the Universe is a lot larger than what we observe and different parts of the Universe have different physics. How should we think about physics in such a setup? What are the correct observables? What is the precise role of anthropic ideas in this context?

5. Theory of quantum gravity. The correct theory of quantum gravity appears to be string theory. At the moment we do not have a clear conceptual formulation of the theory, nor do we have clear experimentally verifiable predictions of string theory. Can we solve these problems? Presumably, a deeper understanding of string theory will show that space and time are emergent concepts which are not present in the fundamental formulation of the theory. This could have important implications for the mysteries of the Big Bang.

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At 12:10 AM, Anonymous Spenta Wadia said...

This is an accurate and accessible formulation of some of the fundamental questions of modern science from a renowned physicist. It would be great to be able to read a short summary of exciting questions in others areas of science too.

At 12:29 PM, Anonymous Rick Martin said...

Very useful overview. Thanks to Prof. Seiberg and also 2physics.com for bringing it to us.


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