Einstein's Theory To Go Beta Testing 326
pinqkandi writes: "This article over at CNN looks into the relativity of Einstein's theory of relativity (pun intended) as equipment becomes more and more precise. Soon atomic clocks will be placed in the International Space Station to analyze the accuracy of Einstein's theories. One of the lead researchers says that if Einstein's theory is not right, it will only need minor adjustments to account for changes in space-time, due to its deadly accurate precision."
There are 2 theories of relativity (Score:4, Informative)
If you don't understand either one, take a look
here [bartleby.com]:
Kostelecky's page... (Score:5, Informative)
GPS Satelites know this ! (Score:5, Informative)
Re:What's wrong with the older proofs? (Score:3, Informative)
Re:What's wrong with the older proofs? (Score:5, Informative)
These tests have been performed on the ground recently by measuring the frequency of a clock as its direction relative to the stars changes due to the rotation of the earth. (For example, see Phillips, et al., Physical Review D 63, 111101 (2001) or Physical Review Letters 85, 5038 (2000)- showing off is always good.) In space, one could use the faster rotation of the space station as the atomic clocks in space which may substantially outperform ground based clocks.
Re:Zero gravity? (Score:5, Informative)
Technically, you're never going to get zero gravity. And yes, you're right, ISS isn't anywhere near that -- it's in orbit, and uses gravity to stay that way. ISS and the like are weightless (or near weightless) because they are effectually in a free fall; this state is termed "microgravity".
Re:There are 2 theories of relativity (Score:2, Informative)
Gravity Probe B - A Most Stringent Test (Score:3, Informative)
GPS measures relativity all the time (Score:4, Informative)
I doubt it (Score:1, Informative)
Re:Why do this again? (Score:2, Informative)
here [aip.org] if you want to read more regarding GPS birds and relativity
Gravity vs acceleration (Score:3, Informative)
whereas the general theory is concerned with bodys that are accelerating ( In general relativity acceleration and gravity are equivalent).
Common misconception. Acceleration and gravity are not equivalent in General Relativity. They are *locally* (that word is extremely significant here) indistinguishable. The fact of the matter is that Special Relativity can handle acceleration just fine by using calculus. General Relativity is only needed where spacetime is not flat (i.e. in the presence of gravity), since the two postulates of Special Relativity only hold in regions of flat spacetime.
Re:Relativity vs. Quantum Mechanics (Score:5, Informative)
_Special_ relativity and quantum mechanics have no trouble getting along. In fact, the so-called Standard Model of particle physics, based on relativistic quantum physics, is an enormously successful theory. The trouble lies in getting relativistic gravity (i.e., _general_ relativity) to play nice with quantum mechanics. This is where string theory comes in.
The good thing about string theory is that it allows gravity and quantum mechanics to get along. The bad thing about string theory is that there is absolutely _no_ experimental evidence for it, and there are almost no possible tests of it that could be conducted in the near future. Lorentz violation is a major exception:
The afore-mentioned Standard Model obeys a certain symmetry called ``Lorentz symmetry'', which lies at the heart of special relativity. However, string theory allows Lorentz symmetry to be broken. Thus, any experimental detection of Lorentz violation could be a great signature of string theory, and, maybe, quantum gravity. Moreover, there exist current experiments that are capable of detecting Lorentz violation to a very high precision.
To summarize: We are studying Lorentz violation because (1) It is a possible signature of quantum gravity, and (2) It can presently be studied to very high precision.
Chuck
Re:GPS measures relativity all the time (Score:2, Informative)
Chuck
GPS: been there, done that (Score:2, Informative)
Actually, GPS knows about this and takes advantage of it. It is the only consumer relativity application I know of.
The GPS SV's are going about 3900 m/s which is a sufficient percentage of the speed of light for relativity to come into play. If relativity weren't taken into account and Einstein obeyed, you'd be off by ~100 meters.
The correction could be done in the receiver or the signal could be biased in the SV. Following the Principle of Alice's Restaurant:
Factoring this correction into the SV, the onboard clocks use a frequency of 10.22999999543 MHz and your GPS receiver uses 10.23 MHz. This simplifies the GPS receiver software immensely.
GPS was designed during the 1970's by some really smart forward thinking guys.