Saturday, February 18, 2012

Antimatter and Dark Matter

I came across an article on the National Geographic website describing a new theory that replaces dark matter with gravitationally repulsive antimatter. The new theory was proposed by Dr. Hajdukovic. An experiment to determine whether antimatter is gravitationally attracted or repelled by normal matter was proposed and at least partially completed by Dr. William Fairbank Sr.’s team at Stanford. While the results were published for electrons in the apparatus, no results were published for positrons,the antimatter counterpart of the elecctron. The experiment is described in an article from the Review of Scientific Instruments. Another paper by Dr. Fairbank regarding what I assume is a similar experiment is mentioned on the NASA abstract site. There is currently an experiment at CERN that proposes to measure the acceleration of gravity on anti-hydrogen. By using neutral anti-hydrogen, they hope to avoid some of the issues that have cropped up around trying to measure the affect of gravity on charged anti-particles such as the positron. The need for an experiment like the one at CERN is explained by Dr. Phillips of Duke University. For a very complete review of the experiments performed to determine how antimatter is effected by gravity up until 1992 see the Reviews of Modern Physics article by Darling,Rossi, et. al. If you’d like to read Dr. Hajdukovic’s paper regarding antimatter, dark matter, and gravity, it can be found on arxiv at http://arxiv.org/ftp/arxiv/papers/1106/1106.0847.pdf.

References:
Hajdukovic, arxiv, (2007),Black holes, neutrinos and gravitational proprieties of antimatter

Hajdukovic, arxiv, (2008), Dark matter, dark energy and gravitational proprieties of antimatter

Darling, Rossi, et. al., Reviews of Modern Physics, 64, (1992), 237

Witteborn, Fairbank, Physical Review Letters, 19, (1967), 1049

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