2007-01-19 19:14:28 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Physics
who told you?
no its not... it depends on many factors.... medium is one of them...
2007-01-19 19:24:19 · answer #1 · answered by Sandeep K 3 · 0⤊ 0⤋
The speed of light is a constant, but that also depends on a "point of view", sort of.
Light speed can be slowed down or sped up, but the information conveyed by photons travels at a constant speed. For an interesting example of this phenomenon, go to:
http://www.rochester.edu/news/show.php?id=2544
Also, certain ideas in advanced theoretical physics suggest that light speed may be a constant of our 3-dimensional realm, but that there may be other dimensional realms in which the speed of light is different. Although this sounds pretty "out there", one example is Heim theory, which actually has some credibility because it's the only theory that's been able to successfully predict the masses of the quantum particles to within experimental error (even the standard model cannot do this).
2007-01-20 03:30:49 · answer #2 · answered by na n 3 · 0⤊ 0⤋
Yes. James Clerk Maxwell calculated that electromagnetic waves would propagate at a constant speed - the velocity we call c. Michaelson and Morley were able to measure this velocity in two directions and show that it was constant relative to the observer, even if the observer is moving. Einstein showed how it was possible that this result could hold true in all inertial frames of reference.
Keep in mind that the speed that light moves at is not necessarily the same as "the speed of light", which refers to c, the speed of light in vacuum.
2007-01-20 04:38:40 · answer #3 · answered by injanier 7 · 0⤊ 0⤋
Is The Speed of Light Constant?
There are a number of senses to the meaning of this question and so there are a number of different answers. Firstly . . .
Does the speed of light change in air or water?
Yes. Light is slowed down in transparent media such as air, water and glass. The ratio by which it is slowed is called the refractive index of the medium and is always greater than one.* This was discovered by Jean Foucault in 1850.
When people talk about "the speed of light" in a general context, they usually mean the speed of light in a vacuum. This quantity is also referred to as c.
Is c, the speed of light in vacuum, constant?
At the 1983 Conference Generale des Poids et Mesures, the following SI (Systeme International) definition of the metre was adopted:
The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
This defines the speed of light in vacuum to be exactly 299,792,458 m/s. This provides a very short answer to the question "Is c constant": Yes, c is constant by definition!
2007-01-20 03:24:58 · answer #4 · answered by Tulsen 2 · 0⤊ 0⤋
Have not really analysed this, but wouldn't strobe lights be a proof? They are used as calibration instruments for many things they have to be precisely timed.
2007-01-20 03:27:10 · answer #5 · answered by Anonymous · 0⤊ 0⤋
yes, it was proven by Einstein.
It is the highest speed attained by a moving object.
2007-01-20 03:26:31 · answer #6 · answered by Theta40 7 · 0⤊ 0⤋