Physics Colloquia Fall 2010

Twist and Shout! W.K. Clifford's Attempt to 'Solve the Universe'

Details: Created: Wednesday, December 02 2009 09:06; Last Updated: Wednesday, August 25 2010 11:27; Written by Carole Kiger; Hits: 3940

Jim Beichler, West Virginia University
August 31, 2010

William Kingdon Clifford is famous for statements that he made in 1870 to the effect that matter is nothing but ripples, hills and bumps of space curved in a higher dimension and the motion of matter is nothing more than variations in that curvature. For having said this Clifford has been both hailed and condemned for having anticipated Einstein’s general theory of relativity. The standard view of historians, scholars and scientists is that his ideas were not tenable at the time, he never developed or wrote down his theory (if he ever had one), and he had no followers or students to carry on his work. Nothing is further from the truth on all three counts. Modern scholars have failed to recognize Clifford’s theory because they have only been looking for Einstein’s gravity theory in the 1870s, which is based on tensors, while tensor calculus was not developed until decades after Clifford’s untimely and unfortunate early death from consumption in 1879. So they are wrong on both counts. Those scholars who have even bothered to look at the original literature on the subject have been unable to find Clifford’s published but incomplete theory because he was forced to develop his own mathematical system of biquaternions to model motion as it would appear in the higher-dimensional space. Nor was Clifford seeking a new theory of gravity, but rather a more coherent and intuitive portrayal of his friend Maxwell’s new electromagnetic theory. However, Clifford believed that dynamical forces in three-dimensional space reduced to kinematical motions in four-dimensional space and therefore planned to include a new theory of gravity after he polished off electromagnetism. In other words, Clifford was trying to develop a unified field theory that would more consistently look like modern day unifications rather than just an earlier version of general relativity.

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Colloquia are held Tuesdays in Room 1410 at 4:00 pm (preceded by light refreshments at 3:30). If you have additional questions, please call 301-405-5946.

Fundamental measurements of the proton's sub-structure using high-energy polarized proton-proton collisions

Details: Created: Wednesday, December 02 2009 09:06; Last Updated: Tuesday, August 31 2010 09:03; Written by Carole Kiger; Hits: 2792

Bernd Surrow, Massachusetts Institute of Technology
October 12, 2010

Understanding the structure of matter in terms of its underlying constituents has a long tradition in science. A key question is how we can understand the properties of the proton, such as its mass, charge, and spin (intrinsic angular momentum) in terms of its underlying constituents: nearly massless quarks (building blocks) and massless gluons (force carriers). The strong force that confines quarks inside the proton leads to the creation of abundant gluons and quark-antiquark pairs (QCD sea). These ‘silent partners’ make the dominant contribution to the mass of the proton. Various polarized deep-inelastic scattering measurements have shown that the spins of all quarks and antiquarks combined account for only 25% of the proton spin.

New experimental techniques are required to deepen our understanding on the role of gluons and the QCD sea to the proton spin. High energy polarized proton-proton (p + p) collisions at RHIC at Brookhaven National Laboratory provide a new and unique way to probe the proton spin structure using very well established processes in high-energy physics, both experimentally and theoretically. A major new tool has been established for the first time using parity-violating W boson production in polarized p + p collisions at ps = 500 GeV demonstrating directly the different polarization patterns of different quark flavors, paving the path to study the polarization of the QCD sea. Various results in polarized p + p collisions at ps = 200 GeV constrain the degree to which gluons are polarized suggesting that the contribution of the gluons to the spin of the proton is rather small, in striking contrast to their role in making up the mass of the proton.

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Colloquia are held Tuesdays in Room 1410 at 4:00 pm (preceded by light refreshments at 3:30). If you have additional questions, please call 301-405-5946.