Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Is Light speed really the limit?

Sparky: "This is an interesting forum, many people not familiar with GR and SR (general relativity and special relativity)..."

Are you sure?

Sparky: "... Experiments were set up to measure the speed of light in different directions, and by using diffraction, try to cause the slower moving light to lap the faster moving light and cause a diffraction pattern. It didn't work and ether was finally given up on. Light moved at the same velocity regardless of direction."

You mean Michelson and Morley used interference. And in the case of their interferometer, there is nothing whatsoever to suggest diffraction.

Sparky: "But it didn't always move at the same speed! Change the medium to air, or water or a prism and the light slowed down."

If you treat light like a wave. But then explain the phenomenology that causes the light to slow down, and more importantly, what causes light to regain its speed when it comes out of a material medium.

Sparky: "If anyone would like to win a Nobel and contribute to the understanding of light, please come up with a provable theory on the interaction of light as it passes though matter at slower speeds than in a vacuum."

The theory exists, why don't you look it up?

Sparky: "BTW that dose mean that light inside the sun is moving slower than in a vacuum as the sun is also matter."

Sparky, the light that the Sun radiates is emitted at the surface, or more accurately in the corona, which is mainly plasma, and as such, it has a density smaller than the air. The picture of the Sun as a ball of fire is not exactly an accurate one.


Sparky: "Depending on the new theory of the interaction of photons with matter, the flux of material outside of the sun may not be a perfect vacuum and therefore show some slowing of photons, but that would be very slight. and hopefully, that is not the explanation of the einsteinium effect that bends light around stars."

It definitely is not the cause of the redshift. A rather simple calculation would tell you that if the redshift of a star were due to intergalactic matter, the density of the latter would be quite high, which is contradicting observation.

Sparky: "Of course matter has traveled faster than light. Put the light in a heavy oil to slow it way down and compare it with some partials in a vacuum in an accelerator, but that doesn't disprove Einstein, it is just a special case."

Sparky, usually when one talks about speed of light in a general context, this means the speed of light in vacuum. And your above argument fails to prove that "light can travel faster than light".

Sparky: "As to measuring the size of a photon, it is the Heisenberg uncertainty principle, not quantum mechanics that we have to deal with."

And the Heisenberg uncertainty principle is derived in what context? What is the name of that theory? This is a good one.

Sparky: "So we can put some upper limits on the size of a photon. It gets smaller and therefore more penetrating (less likely to react with matter) as it's energy (frequency) increases."

That would be the day. Based on what? What is your criterion? And if your answer is based on Heisenberg inequalities, think about the precision to measure frequency/wavelenght. A photon cannot be described by a D-Delta function, not even (semi)classically.


Sparky: "But no it is not solid, and it is not matter. It is energy and it carries information in that energy."

Sparky, you already don't know what you are talking about.
If you represent light as a wave of frequency \nu (I am using latex syntax) then it will be a sine or a cosine. You cannot transmit/encode information in something like that.
If you are talking about a photon, a single photon, once again, you cannot encode anything in a photon. You need more photons than one to encode information, and as for a wave, you need modulation.


Sparky: "... we use Einstein?s SR rule set which is the same as Newton's rule set with just a tiny exception at very high velocities and gravities."

OK, now you are making a fool of yourself. SR deals only with (flat) Minkowski space, and as such, gravity plays no role.And at low speeds, newtonian dynamics is recovered as an approximation of SR.

GR deals with curved spacetimes, at any velocities. Since locally any metric with lorentzian signature can be approximated by a minkovskian metric, this means that for spacetimes with small curvature, Newtonian gravity can be recoveres as an approximation of GR. This is "slightly" different than your claim.

Sparky: "Time travel still belongs to SiFi because we still have no evidence that reverse travel in time is possible."

Observationally, no. theoretically, see wormholes, or the Kruskal extension for black-holes.

Sparky: "Everything we know says it is impossible."

Not quite. See above.

Sparky: "Time is not a normal dimension like length, width or height. Please understand, you can create a set of equations that seems to fit reality, but still have discontinuities that don't work."

You do, huh? Would you be so kind as to give me an example of metric with a temporal discontinuity (besides the Big Bang or the Big Crunch solutions)?

Sparky: "Likewise some extrapolations from rule sets are nonsense. We acknowledge that all our rule sets simply have nothing to say about what happens inside a singularity (black hole)."

You are slightly off again. You can extend the theory beyond the horizon or the ergosphere of a black-hole (see again the Kruskal extension, causal structure of a black hole, etc). Wheteher these extensions are off or not,that's another story. Be mor careful in your statements.