Isn't it true that in some experiments, people have actually sped up & slowed the speed of light?

The speed of light varies depending on the medium it is passing through. The optical density of the material it is passing through is used to find the speed of light through the material.





Where c is a constant is in a vacuum. If that is what you are referring to, I have no idea.Isn't it true that in some experiments, people have actually sped up %26amp; slowed the speed of light?
When I was a physics major in college, I heard of some experiments in quantum mechanics where light seems to travel at a speed faster than c. We're talking microscopic distances, though. Unfortunately I don't remember what the experiment was. That's the closest thing I can think of to what you're asking. There are no other ways to change the speed of light in a vacuum, to my knowledge.Isn't it true that in some experiments, people have actually sped up %26amp; slowed the speed of light?
CoveEnt is correct that the speed of light depends on the medium it is passing through. Scientists call the ratio of the speed of light in a vaccum (3x10^8 m/s) divided by the speed of light in a given material the *index of refraction* (usually abbreviated as ';n';) of that material. As far as has been discovered to my knowledge, the maximum speed of light is that in a *vaccum*, or 3x10^8 m/s, about 186,000 miles/second. This is the constant ';c';. However, scientists have recently produced a Boise-Einstein condensate (the fifth state of matter, besides gas, solid, liquid, and plasma), and light projected through it is slowed down to 36 miles/hour or some such ';super-slow'; speed.
close to the speed of light relativity starts to kick in and it changes depending on the observer but the speed of light has never exceeded its constant..
it all depends on the density of the medium or if there is one
it's easier to slow it down, light goes at c just in vacuum space, any other media should slow it down, the amount of that is given by the indice of refraction of the material.


speeding it up has not been possible yet ( I think is more a theoretical barrier more than a practical one..something to do with relativity) I heard also about that experiment of QM at microscopical level with cesium atoms..the guy had a chinesse last name ( don't remember :/)..but it was some other effect , he corrected himself and apologize for giving hope to people :) ( going faster than c would imply crazy changings in physics and humankind)
Slowing down the speed of light is no big deal since, as mentioned, EM radiation travels at different speeds in different media (the velocity factor). However, there have been recent experiments where ';the group velocity'; has been increased above the speed of light. There is a Wikipedia article below that describes this pretty throughly.





However, as far as I know, all of these ';faster than light'; phenonemnon will not allow the transmission of information faster than the speed of light.