At what rate does light slow down at?

Question

Ok, so we know that when light travels through different mediums from a vacuum it will slow down. But at what rate does it slow down. Also if it goes from a medium to a vacuum will it speed back up?

Answer 1

The amount it "slows down" depends on the index of refraction of the material. (look up index of refraction on the web for more details). This index depends on a few more fundamental electromagnetic properties of the material and the wavelength of light.

When it goes back to vacuum it will speed back up.

Now here is the intellectual part that you won't find easily outside of a quantum optics class. Light in and of itself ALWAYS travels at the speed of light. In a medium you can think of it in the aggregrate as being constantly absorbed and re-radiated. (It's actually a bit more complicated and you can't full understand it without throwing ideas from quantum mecahnics in there) The rate at which this happens depends on the properties of the material.

Answer 2

Good questions! I don't know the rate of acceleration, but a photon does speed back up to c in a vacuum.

Answer 3

Sorry, you're off. Time fairly strikes on the comparable fee, fairly. What I recommend is that in case you have been with the clock that became into shifting close to easy velocity(if it fairly moved at easy velocity it would convert to uncooked capacity and be misplaced.. as a clock) it would seem as though in basic terms 10 seconds had surpassed ( you will in basic terms age 10 seconds ), yet in the international your twin would age fairly so lots extra. that's certainly annoying to entice close the "why" of this, yet while the neatest talkin monkey that ever lived believed it(Einstein) we small brainers are in basic terms gonna would desire to settle for it. the unusual area is that in case you went for a journey at close to easy velocity for say a 300 and sixty 5 days, the human race would probably destroy itself on your absence( it would be like a pair thousand years later or so....).all human beings you recognize could have perished of previous age, although if we controlled to stay alive as a race.

Answer 4

No clue. But I did stay at a Holiday Inn Express last night. Nah, not really. But check this out: http://en.wikinews.org/wiki/Light_stopped_for_over_a_second