tians

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Among physicists around the world, the Theory of Relativity by Albert Einstein is being questioned in terms of its credibility. To me, it is as credible today as the day it was established, it has solved many of the unanswered questions which would have been almost unfeasible without the help of the theories of relativity.

The famous equation attributed to Einstein, E=mc2, describes the relationship between energy and the rest mass of a body.
 * A bit of Background:**[[image:http://farm1.static.flickr.com/90/230142842_86c13caabf.jpg width="208" height="154" align="left"]]


 * Special Relativity**--(1) The speed of light is constant for all (inertial) observers, regardless of their velocities relative to each other. (2) The laws of physics are identical in all inertial reference frames.


 * General Relativity**--General Relativity is a theory of gravity that is compatible with Special Relativity. The theory was inspired by a thought experiment developed by Einstein involving two elevators. The first elevator is stationary on the Earth, while the other is being pulled through space at a constant acceleration of g. Einstein realized that any physical experiment carried out in the elevators would give the same result. This realization is known as the equivalence principle and it states that accelerating frames of reference and gravitational fields are indistinguishable. General Relativity is the theory of gravity that incorporates Special Relativity and the equivalence principle.

There are of course two sides to this conflict of opinions, some physicists believe that the Theory of Relativity the correct theory to follow while others believe in different theories. According to conservapedia, two of the more commonly studied attempts are string theory and loop quantum gravity, but they have failed to produce any evidence that science mandates a science must have, and both typically take large amounts of work to even conform to what scientists believe. Critics increasingly point out that string theory and loop quantum gravity are largely untestable and unfalsifiable, and thus potentially unscientific under the principles of science advanced by Karl Popper.

To test the theory, scientists in 1972, sent very accurate clocks around the world in both directions on commercial airlines, the scientists then made predictions on the time differences which observable on the clocks, at the end of the experiment, the eastbound clock gained 273 nanoseconds, while the westbound clock lost 59 nanoseconds, meeting the predictions of general relativity in excepted experimental accuracy.
 * The evidence of Relativity:**[[image:GPS.jpg width="124" height="124" align="right"]]

Some internet articles claim that GPS timing differences confirm the Theory of Relativity. GPS clocks run slower in the weaker gravitation field of the satellites than on ground stations on Earth, with the effects predicted by general relativity far outweighing the effects predicted by special relativity. However, the articles claiming that the slower GPS satellite clocks confirm relativity do not address the effect, if any, of the weaker gravitational force under Newton's theory on the GPS satellite clocks.

The effects of relativity have been observed with the frequency shift of the signal being sent back to earth several times as various spacecraft have dipped into the gravity wells around massive objects such as the sun or Saturn. A satellite called Gravity Probe B was put in orbit about the Earth to examine the effects of frame dragging and geodetic warping of space, but the results were inconclusive. However, that Newtonian mechanics also predicts deflection of light by gravity, and in the initial theory of relativity it predicted the same amount of deflection. Adjustments to the theory of relativity resulted in a prediction of a greater deflection of light than that predicated by Newtonian mechanics, though it is debatable how much deflection Newtonian mechanics should predict (NASA).  General relativity predicts twice as much bending in light as it passes near massive objects than Newton's theory predicts, a phenomenon known as gravitational lensing. A large number of instances of gravitational lensing have been observed, and it is now a standard astronomical tool.  **Potential discrepancies:**  Although both sides of the argument present very convincing claims, I feel that the Theory of Relativity is still very credible and accurate. To explain the possible discrepancies, I think those are the consequences of human error, both point to only one study and I believe that is not enough to renounce the Theories of Relativity especially when it is the rendering of a brilliant man named Einstein.
 * The Theory of Relativity implies that physical constants like the speed of light have remained constant. But at least one study suggests that physical constants, and possibly even the speed of light, have changed as the universe has aged. "For the first time, scientists have experimentally demonstrated that sound pulses can travel at velocities faster than the speed of light, c. William Robertson's team from Middle Tennessee State University also showed that the group velocity of sound waves can become infinite, and even negative. ... Although such results may at first appear to violate special relativity (Einstein's law that no material object can exceed the speed of light), the actual significance of these experiments is a little different. These types of superluminal phenomena, Robertson et al. explain, violate neither causality nor special relativity, nor do they enable information to travel faster than c. In fact, theoretical work had predicted that the superluminal speed of the group velocity of sound waves should exist. 'The key to understanding this seeming paradox is that no wave energy exceeded the speed of light,' said Robertson." "A team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light – both slowing it down and speeding it up – in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions. Their results, to be published in the August 22 issue of Applied Physics Letters, could have implications that range from optical computing to the fiber-optic telecommunications industry." Both slowing down and speeding up of light within a substance other than a vacuum is made possible, because the light travels through the material, and that material affects the speed of light, i.e. a photon hits an electron, which then exits and emits a slightly lower energy photon out in the direction that the original photon was traveling, thus maintaining conservation of momentum. No matter how transparent an object may appear, it radically impacts the speed of the light traveling through it, as demonstrated by the refractive production of a rainbow by a crystal, which Newton himself discovered. "A pair of German physicists claim to have broken the speed of light - an achievement that would undermine our entire understanding of space and time. ... Dr Nimtz told New Scientist magazine: 'For the time being, this is the only violation of special relativity that I know of" (Conservapedia).
 * The Theory of Relativity enjoys a disproportionate share of federal funding of physics research today. In at least one case that research has been unsuccessful. The $365 million dollar LIGO project has failed to detect the gravity waves predicted by relativity.
 * Conclusion:**

"NOVA | Einstein's Big Idea | Relativity (Lightman Essay) | PBS." __PBS__. 29 Jan. 2009 . This article was a tremendous help in my research. Although I did not use any of its information in my wiki, it was very helpful for me to obtain information and better my understanding of the Theory of Relativity.
 * Bibliography:**

"Relativity for dummies | Education | The Guardian ." __Latest news, sport, business, comment and reviews from the Guardian | guardian.co.uk__. 30 Jan. 2009 . This was one of the first sites that I looked at. When I did not have any idea what the Theory of Relativity was, this site was the one that gave me valuable background information what was easy to understand, it was quick and easy.

"Theory of relativity - Conservapedia." __Main Page - Conservapedia__. 1 Feb. 2009 . From this site is where I got the idea that I was going to talk about its status and not the impacts on society. Most of my information came from this particular site.

"NASA - Relativity ." __NASA - Home__. 28 Jan. 2009 . This site was very useful, some of my information came from here. It was nice to know that nasa had a site for things like this, it ensured credibility I didn't have to worry about whether it was trustworthy or not.