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New Theory of Gravity Decouples Space & Time
eldavojohn writes "Petr Horava, a physicist at the University of California in Berkeley, has a new theory about gravity and spacetime. At high energies, it actually snips any ties between space and time, yet at low energies devolves to equivalence with the theory of General Relativity, which binds them together. The theory is gaining popularity with physicists because it fits some observations better than Einstein's or Newton's solutions. It better predicts the movement of the planets (in an idealized case) and has a potential to create the illusion of dark matter. Another physicist calculated that under Horava Gravity, our universe would experience not a Big Bang but a Big Bounce — and the new theory reproduces the ripples from such an event in a way that matches measurements of the cosmic microwave background."
Wrong.
Special relativity is built on two principles:
(actually, if you take Maxwell's equation into account, the first is just a special case of the second). Especially it does not postulate that there's nothing faster than light. Rather,
However, you can describe hypothetical faster-than-light particles in SRT (so-called tachyons; those cannot be decelerated to below the speed of light), and AFAIK there have been experiments to look for them. Note however that as soon as you add quantum mechanics to the picture, even with tachyons no information can be transmitted faster than light (local disturbances in he quantum tachyon field only propagate with light speed).
General relativity adds the equivalence principle (locally you cannot distinguish between gravitation and acceleration) and the demand of general covariance (the equations must look the same regardless of choice of coordinates, even if those don't correspond to an inertial system).
The Tao of math: The numbers you can count are not the real numbers.
Then we need a new theory.
Well, "the same in all systems" in the post above didn't refer to "at different places in the universe", but "as seen/described by different observers in the same part of the universe".
That doesn't mean we don't also assume that the laws of nature are always and everywhere the same. Indeed, that's basically always assumed.
By applying the laws we found locally to observations of distant objects, and seeing if they fit. For example, we can look at the spectra of distant stars and look if we get the same atomic spectral lines as on earth. This works great; so we know that atomic physics obviously works the same in distant stars. Also we can observe the 21cm hydrogen line everywhere in space, so atomic physics seems to apply also in between the stars.
Where we do have some problems is with large scale gravitation (what we describe with dark matter and dark energy). However, the local effects of those deviations are small enough that we couldn't measure them directly anyway, so it's also no evidence that the local laws of physics are different than the distant ones, even if those effects are to be described with modified theories.
No, it's much too small for that. To be an indication for different physics "outside" it would have to be such a large deviation that we would have to have detected the difference if it applied to Earth.
The Tao of math: The numbers you can count are not the real numbers.