2015 Fall Graduate Colloquium Series: Lesley Vestal/Brooks McMaster

DateSeptember 18, 2015
Time3:35 - 5:00 pm
LocationBaylor Sciences Building, Room E.125
Lesley Vestal

203K Superconductivity

This paper is a step toward the dream of room-temperature superconductors. Believed to be a good candidate material, sulfur hydride has a predicted transition temperature of 80K. In this experiment, a 90 gigapascal pressure was applied, transforming the substance into a metal, and it was then observed to be possibly superconductive after being cooled to only 203K. This is much warmer than previous experiments were able to
observe the characteristic drop of resistivity to zero. An electron-photon mechanism is suspected, implying that this might be an example of Bardeen-Cooper-Schrieffer (BCS) theory. This theory suggests a way for superconductors to exist at any temperature. The current highest temperature superconductors were observed at 133K at ambient
pressure and 164K under high pressure.

Reference: http://dx.doi.org/10.1038/nature14964

Brooks McMaster

Why Galaxy EGSY8p7 Challenges Modern
Cosmological Consensus

As modern cosmology grows, bigger and better tools and data become available to the
scientists who study it. This new information can both confirm and contradict modern
cosmological models and practices, and Galaxy EGSY8p7 is a strong candidate for the latter. Distant galaxies are frequently observed and analysed by the red shift of their
electromagnetic spectra, using signposts like Lyman-Alpha (H n=2->n=1) emission. These same methods put recently catalogued galaxy EGSY8p7 at a redshift of Z=8.683, which corresponds to an age 200 million years before current cosmological models say galaxies should have begun to form. The observation of what appears to be an energetic
star-forming galaxy deep into the so-called "Dark Age" of the universe calls into question both modern galactic dating techniques and the currently accepted timeline for the birth of our universe.

Reference: http://dx.doi.org/10.1088/2041-8205/810/1/L12

For more information, please contact: Dr. Kenichi Hatakeyama 254-710-2286
PublisherDepartment of Physics
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