Colloquia are held on Mondays at 4:00pm (Refreshments at 3:30pm) in Barus & Holley 168. Past colloquia from the current and previous years, including many videos, can be found on the Past Physics Colloquia page.
January 26, 2015 -- Carlton Caves (University of New Mexico) - CANCELLED
February 2, 2015 -- Vidya Madhavan (University of Illinois at Urbana-Champaign) - CANCELLED
February 9, 2015 -- David Weitz (Harvard University) - CANCELLED
February 23, 2015 -- Jané Kondev (Brandeis University)
"The Physical Genome"
Every day there seems to be a story in the news about DNA and some gene that it encodes. While this abstraction of DNA as an information storage device is useful, in this talk I will consider the physical nature of DNA, namely the fact that it is a long, flexible, and charged molecule. This is important because the physical properties of DNA affect a number of critical functions that it performs in the cell. One such function is to turn on and off the production of proteins, which are the building blocks of the cell, in response to different physical and chemical ques. Another is to repair itself when breaks occur. In this talk I will describe how simple physics models combined with experiments on cells and single molecules are being used to develop a quantitative understanding of the physical genome.
March 2, 2015 -- Julio Navarro (University of Victoria)
"Dwarf Galaxies as Cosmological Probes"
A prime challenge to our understanding of galaxy formation concerns the scarcity of dwarf galaxies compared with the numerous low-mass halos expected in the current ΛCDM paradigm. This is usually accounted for by assuming that energetic feedback from evolving stars confines dwarf galaxy formation to relatively massive halos spanning a narrow mass range. I will highlight a number of observations that may be used to test this assumption and discuss the puzzles and challenges that arise from this analysis. I will also discuss a number of challenges that ΛCDM faces on the scale of dwarf galaxies and their possible resolutions.
March 9, 2015 -- Benjamin Wandelt (Sorbonne University)
“The Physics of the Cosmos: from the Big Bang to the Cosmic Web”
The cosmic microwave background (CMB) carries a cosmic message, preserved through time, written in its anisotropies. The Planck mission has just revealed a new chapter of this message using high-resolution nearly all-sky information of the polarization anisotropies for the first time, in addition to upgrading from the nominal mission to the full mission data set. These data provide new insights into several open questions related to the nature of the primordial fluctuations that seeded all structure; the global properties of the universe; neutrinos; dark matter; dark energy; atomic physics; and gravity. Beyond the CMB I will describe how new physics-based analysis methods of astronomical data sets allow us explore our cosmic past on and off the light cone and understand the origin and evolution of large scale structure of the Universe in unprecedented detail.
"Elementary ! Is this the right answer ?"
With the discovery of the Higgs Boson, Quantum field theory has established itself as the theoretical framework to address the fundamental questions and elementary particle physics the way to confirm it experimentally. Paradoxically this success of the Standard Model is also highlighting the fundamental questions which we have difficulty to answers: the problems in including gravitation in the Standard model framework, the issue of understanding the nature of the elusive Dark Matter or the failure to explain why there is only Baryons and not Anti-Baryons in our universe are clear evidence that our description of nature is incomplete. In this colloquium, after recollecting the recent successes of Elementary particle physics through the achievements of one of the large experiments at the LHC accelerator, CMS, I will show what can be expected from the future runs: in a few weeks the LHC will break a new energy frontier when it will restart with protons colliding at 13 TeV center of mass energy and this will allow a new exciting run with the potential to access new physics phenomena in the near future. The CERN council has also approved a long term plan which will be extending the operation of the LHC for the next 20 years providing a program which will increase the luminosity of the Accelerator by factor of 5 and creating the intensity frontier program of the future: I will also show examples of what can be achieved from this long term program.
March 30, 2015 -- Gary Horowitz (UC Santa Barbara)
"The Remarkable Power of General Relativity"
This is the 100th anniversary of Einstein's discovery of general relativity. This theory has been very successful in reproducing a wide range of gravitational phenomena. I will briefly review this success, and then explain how general relativity can describe other areas of physics as well, including aspects of particle physics and condensed matter physics. This is a result of the gauge/gravity duality that emerged from string theory. I will explain this remarkable development and show how general relativity reproduces properties of QCD and superconductivity.
April 6, 2015 -- William Irvine (University of Chicago)
"The life of a vortex knot: Linking coiling and twisting across scales"
Can you take a vortex loop - akin to a smoke ring in air - and tie it into a knot or a link? The possibility of such knottiness in a fluid has fascinated physicists and mathematicians ever since Kelvin¹s 'vortex atom' hypothesis, in which the atoms of the periodic table were hypothesized to correspond to closed vortex loops of different knot types. More recently, the knottiness (Helicity) of a fluid has re-emerged as a conserved quantity in many idealized situations (such as Euler fluids and ideal plasmas) offering the potential for new fundamental insights. In the real physical counterparts to these systems progress has however been hindered by lack of accessible experimental systems. I will tell of how to make a vortex knot and link in water, in the wave function of a superfluid (on a computer) and of what happens thence. In particular I will talk about how linking coiling and twisting interplay across scales.
April 13, 2015 -- Sumit Das (University of Kentucky)
"HOLOGRAPHY, QUANTUM QUENCH AND COSMOLOGY"
Over the last couple of decades it has become clear that in many situations gravity can be thought of as an emergent, "dual" description of non-gravitational gauge theories in lower number of dimensions. This realization is a key ingredient in our current understanding of the quantum physics of black holes in terms of the properties of the underlying gauge theory. In the other direction, this duality has been used to address difficult issues in strongly coupled field theories, by mapping them to classical problems in gravity. This talk will discuss the physical origins of this duality and its modern applications to the understanding of far from equilibrium properties of strongly coupled systems, and attempts to uncover the mysteries of big-bang like singularities.
Arthur O. Williams Lecture:
April 20, 2015 -- Rolf Heuer (Director-General, CERN)
“Breaking the wall of the hidden universe - what the discovery of the Higgs boson tells us about Physics, Mankind and the Universe “
With the start of the Large Hadron Collider (LHC) at CERN, particle physics entered a new era. The LHC will provide a deeper understanding of the universe and the insights gained could change our view of the world, and the talk will present some of the reasons for the excitement surrounding the LHC. The LHC is expected to yield insights into the origin of mass, the nature of dark matter and into many other key questions. This lecture will address the exciting physics prospects offered by the LHC, discuss in particular the recent discovery of the Higgs-Boson, and present a look forward.