Thursday, September 29, 2011

Einstein continues to stand the test of time


In a week where there was a suggestion coming out of CERN that perhaps a Neutrino partial violated Einstein's E=MC2 equation by traveling faster than the speed of light; a new study of Galaxy Clusters Back Up Einstein’s Theory of Relativity.
Every time someone tells me that Evolution is "Just a theory" I'm tempted to suggest that since gravity is also"Just a theory" maybe they would like to step off the top of a 40 story building. Funny, but I have yet to find any takers, it seems that gravity in something we can all agree on. Yet while we can all nod our heads in agreement over the fact that gravity exists, actually explaining how it works becomes a bit trickier. Albert Einstein’s Theory of general relativity describes how the mass of an object warps the space and time that surrounds it around it, the greater the mass, the greater the gravitational pull and the more intense the effect on Time/Space.


In 1905 when Einstien first published his Theory of general relativity, physicists marveled at the beautiful simplicity of the final E=MC2, the math made sense (to the few at the time that were able to comprehend it's ramifications) but testing the equations proved to be allusive. We had not yet invented a Super particle accelerators, no Cern, no Hubble, no real way to test the validity of his theory. Over the years we have been able to confirm that General relativity works on the scale of the solar system, but proving it held true on cosmic scales, while logical, had not been proven - but now a group of astrophysicists in Denmark have done just that.


One of the basic tenets of General Relativity is that light is influenced by gravity and will loose energy as it escapes a gravitational field. The stronger the gravitational field, the greater the amount of energy will be lost as the light escapes. The same way that a rocket will need more power to reach escape velocity Earth than from the Moon. As you increase the gravity, you increase the power needed to escape it's influence. The work led by Radek Wojtak of the Niels Bohr Institute at the University of Copenhagen, was devised to test this central prediction of general relativity. Their method was to recognize that photons emitted from the center of a massive object containing thousands of galaxies, should reveal that they lost more energy than those photons that came from the edge of the galaxy cluster because gravity is strongest in the center.


So how do you test to see how much energy was lost by the proton's coming from various locations within a galaxy cluster, you measure the wavelength. The test is connected to the observations made by Hubble when he looked at the light spectrum of stars and recognized that their light was shifted towards the "Red" side of the spectrum. "Gravitational Redshifting demonstrates that light is moving away from the observer. It was this realization that lead to the knowledge that our universe is expanding. The team at the Niels Bohr Institute knew that the greater the energy loss, the greater the degree that the light waves should show a shift towards the red. What Radek Wojtak and his team found was a that the degree to which the light was redshifted was in direct proportion to the distance from the center of the cluster, just as the theory of general relativity predicted .


David Spergel, an astrophysicist at Princeton University, compliments Wojtak and his colleagues on “cleverly combining” a large cluster data set to detect a “subtle effect.” Spergel says, “This is another victory for Einstein. … This cluster test suggests that we do live in a strange universe with dark matter and dark energy, but one in which Einstein’s theory of gravity is valid on large scales.”


Well if I have to venture a guess, I would say that Cern most-likely miscalculated and that Einstein's E=MC2 equation will continue to stand the test of time.



Based on information in an article By Yudhijit Bhattacharjee, ScienceNOW