2007-09-16 03:26:26 · 16 answers · asked by Neill 3 in Science & Mathematics ➔ Physics
The speed of light could never be slowed down.
2007-09-16 07:07:01 · answer #1 · answered by lil1 2 · 0⤊ 0⤋
In a vacuum, the speed of light is constant. Not only that, the Relativity Principle implies that, even if you are moving at great speed towards or away from the source of light, its speed relative to you is still the same (instead the light becomes bluer if you are moving towards the source and redder if you are moving away - galaxies are mostly moving away from the Earth and this phenomenon is known as "Red Shift").
You can slow light down by passing it through any transparent substance, - air, water, glass, diamond - how much it slows down is determined by the Refractive Index of the substance.
Using physics that I do not care to understand, modern researchers have found ways to slow light down to almost a walking pace from its vacuum speed of 186,000 miles per second.
2007-09-16 03:44:07 · answer #2 · answered by David E 2 · 1⤊ 0⤋
The speed of light is always the same. However, it's speed changes when traveling through a medium like our atmosphere, glass, crystal, water, etc. I am sure if you considered a very very small section of medium the speed of light is to that ina vacum.
The current value of the speed of light is exact. The theory of electrodynamics require this speed to stay the same for the theory to hold. E&M is one of the most solid theroies in physics by the way.
It also gave the basis for Enstein to develope his theroies of relativity.
Also, there is a flaw in the above answer. He is talking about group velocity of an E&M wave not the speed of the wave. Those are two different things. When you throw something in water, how fast the rings travel is group velocity whereas the individual ripples are a waves speed.
2007-09-16 03:50:20 · answer #3 · answered by Anonymous · 0⤊ 0⤋
It can be slowed waaaaaayyyyyyy down. The ratio of the speed of light in a material (other than a vacuum) to the speed of light in a vacuum is called the materials 'index of refraction' and, if weren't for that, we couldn't do things like lenses.
As far as how slow...... There was a team in Norway (IIRC) that recently created a 'Bose-Einstein Condensate' of sodium atoms at a couple tenths of a Kelvin which slowed light down to a few meters per second as it passed through.
Doug
2007-09-16 03:39:19 · answer #4 · answered by doug_donaghue 7 · 3⤊ 0⤋
I think, (therefore, I am), another equation versus the speed of light, or the possibility of slowing light down. Our thoughts, through our brains, travel much quicker than the speed of light. These same thoughts can also be slowed down in relation to the speed of light. Thank goodness for brains and quantum theory eh? And of course, lest we forget, relativity.
2007-09-16 16:03:24 · answer #5 · answered by smiley 2 · 0⤊ 0⤋
I found the answer of doug_donaghue (answerer #6) interesting. I looked up in the internet for the reference : http://www.seas.harvard.edu/haulab/ It's at Harvard University. The lead scientist http://www.seas.harvard.edu/haulab/lene_vestergaard_hau/lene_vestergaard_hau.htm is Danish.
However, the question can be raised "Can we still call it light?" Clearly in some of their experiments, and perhaps to a lesser degree in all of them, it's not so much that light is slowed down, but more that it gets transferred without loss of information into the medium. In the medium, it's not light anymore, but some other form of energy that is traveling.
2007-09-16 04:04:57 · answer #6 · answered by My account has been compromised 2 · 0⤊ 0⤋
Always the same, if it were slowed down it would no longer be the speed of light. Keep in mind that the speed of light is a unit of measurement, so it must be accurate. One example would be astronomers & NASA uses it all the time on distant stars and planets with the phrase "planet whatever is 100 light years away".
2007-09-16 03:38:09 · answer #7 · answered by Ricky H 4 · 1⤊ 2⤋
The speed of light is assumed to be constant (299,792,458 ms^-1) in a vacuum.
However, when it's passing through a medium, e.g. Air, or Water, it is slowed down slightly.
2007-09-16 20:50:31 · answer #8 · answered by tinned_tuna 3 · 0⤊ 0⤋
A number of factors alter the velocity of light, including gravity.
Light from the sun ( or any other star) accelerates as it climbs out of the Sun's own gravity well, albeit not by very much but it is measurable with sensitive instruments.
2007-09-16 12:41:03 · answer #9 · answered by Azalian 5 · 0⤊ 0⤋
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is slower than its speed in a vacuum.
2007-09-16 03:29:14 · answer #10 · answered by Anonymous · 6⤊ 0⤋