I disagree. In the lab where I work,we have failures day in and day out. There are lots of theories as to why the failures occured. However until the failure can be turned on and off, you have not found the root cause of the issue. Once you can turn it on and off, by finding the circumstances and proving that these are the cause through testing, your theory is just that. Evidence is the manupulation of the circumstance with repeatable forcastable results. Then and only then is it a fact. Tell me Ned- for years the constant speed of light was supposed as fact-yet Harvard has been able to speed it up, slow it, stop it, then release it. Is the speed of light still a constant? Was the theory of it's constant speed through space and time True? Now that it is known that the speed of light is indeed able to be manipulated it brings every quotient using the speed of light as a constant back into question. Can I turn gravity on and off? No I don't know how- but that in no way translates that it cannot be done. Just that I am unaware of how to do it. Maybe it can, maybe it can't, but no one here can anwser that. Blackholes appear have intense gravity, but no one knows why-they have theories. If Gravity is constant-why is the moon escaping earths gravitational pull a few inches every year? If everything is in decay as is believed, they should be getting closer because of the gravitational pull, right?
[This message has been edited by James J, 09-23-2003]
I believe that the speed of light IS constant...in a vacuum. The operative word here is "vacuum." If i am not mistaken they were able to slow down light in some kind of condensate (bose-einstien? (sp?))?
Light slows down when it passes through things. That's how refraction works, for instance. We've known this since Newton. The speed of light in a vacumn is constant to all observers, and no experiement has shown otherwise. The speed of light through various objects is not the same, but again, it's constant to all observers.
Not to mention, if the speed of light wasn't constant between given regions of spacetime, all of spatial relativity should break down in those regions, since motion is relative to the speed of light, and you'd have asymmetrical relative velocities. Correct? I always hate having to work out problems like this, it strains the mind.
I'll need to check my physics book, but I was under the impression that light moving through a prism or atmosphere doesn't "slow-down" but loses energy and changes frequency?
(edited because of my error )
I did some armchair research and I see that my thinking above was mostly wrong. While the light wave propogates at c, the phase velocity of the wave is either faster or slower than light due to interference from atoms in the material. It is this apparant speed that we treat as a slowing down of light.