2006-09-12 18:08:39 · 15 answers · asked by Anonymous in Science & Mathematics ➔ Physics
For those of you who think I'm an idiot:
http://science.nasa.gov/headlines/y2002/27mar_stoplight.htm
2006-09-12 18:54:27 · update #1
As far as I can tell it is rubidium and sodium vapors used and not crystal.
2006-09-13 01:47:14 · update #2
Light speed is not a constant, it is slowed and bent by gravity, water, and other enviormental variables
2006-09-19 13:17:52 · answer #1 · answered by Anonymous · 1⤊ 1⤋
c is the speed of light in VACUUM. So passing it through matter will slow it down.
Reason: we need to look at light in this case as particles (photons). The photons are sent through the material, and are soon absorbed by the atoms' electrons. The atoms gain energy because of the event, stored in the atom itself and not as additional motion for the atom. Gas atoms, on average, move at around the speed of sound.
After a certain time, the atom is "commanded" to release the energy, and it is done so by the emission of a photon.
As I understand the explanation on the link, it is the reverse of creating laser light.
2006-09-20 10:20:33 · answer #2 · answered by dennis_d_wurm 4 · 0⤊ 0⤋
Actually, it's been discovered that the speed of light may have not been constant after all. It's believed that when the big bang happened, the speed of light was much faster but it has been in an exponential decay ever since. Good job at thinking about this. I had never considered this until I heard about it from my Physics teacher.
2006-09-13 01:20:39 · answer #3 · answered by meta_slime 2 · 1⤊ 1⤋
The speed of light is the constant 'c' IN A VACUUM. The speed of light is less than 'c' when it is traveling through a medium like water or glass. The ratio 'n', the index of refraction for a material, is 'c' divided by the speed of light in that material.
For example, 'n' for water is 1.33, so the speed of light traveling through water is only 3/4 c. Diamond has n = 2.4, so the speed of light in diamond is only 0.42 c, less than half the speed of light in a vacuum.
Scientists have created/discovered special crystals wherein the speed of light is very, very slow, by arranging the atoms in the crystal so that the light interacts strongly with them, slowing it down.
2006-09-13 01:17:24 · answer #4 · answered by Mark V 4 · 9⤊ 0⤋
As far as i know, the speed of the light is constant c in vacuum...
The speed of the light in vacuum cant be slowed down....
But, the speed of the light is less than c in a medium such as water or glass... and theoretically the speed of light can be slowed down below the speed of sound...
Just to note that the speed of sound is different in different mediums...
2006-09-13 01:28:15 · answer #5 · answered by fireashes 4 · 1⤊ 1⤋
Light consists of protons. Protons have a mass of 0. If E=MC2, then there is an inconsistency. How can you apply energy to an entity that has no mass? Remember basic math.. 0 x 0 = 0. Is it possible, that to accelerate to the speed of light is actually, Absoloute 0 in speed in relative speed to the universe? as it is with temperature. Maybe we are the ones that are moving and it is light that is standing still like a fog. Light speed or C is Einstein's "First Frame".
2006-09-13 01:52:48 · answer #6 · answered by digital_massage 1 · 1⤊ 3⤋
the spped of light c is constant at 2.998x10^8m/s in a vacuum, the spped of light varies depending on the medium (air, glass, water, etc). if u look into the deep end of a swinning pool, it does not appear to be as deep as it is, this is because the spped of light entering and exiting the water is slower than the speed of light in air. as regards to light been slown down to the speed of sound, its sounds like a huge decrease in velocity, down to about 343m/s.
2006-09-20 13:09:02 · answer #7 · answered by paddy.ryan 2 · 0⤊ 0⤋
Actually, under the right conditions, you can get the speed of light down to under 100 m/s. This can be made to happen in what's called a 'Böse-Einstein condensate'.
Doug
2006-09-13 01:30:59 · answer #8 · answered by doug_donaghue 7 · 2⤊ 0⤋
I think it is because matter is causing the light to travel further before it can reach the what the observer considers the same amount of distance.
2006-09-13 01:21:16 · answer #9 · answered by jeff.sadowski 2 · 1⤊ 1⤋
They don´t! Not below the speed of sound.
2006-09-13 01:19:11 · answer #10 · answered by Vovó (Grandma) 7 · 0⤊ 2⤋