Why is light limited to 299,792,458 meters per second, both in a vacuum and within our atmosphere?

Why does light have this defined terminal velocity, even in space, where there is no friction to slow the rays, photons or energy?


Due to my poor wording of the question, I am referring to the speed of light in a vacuum, space, as i understand the principle that the photons are absorbed in our atmosphere.

7 Answers

  • Fitz
    Lv 7
    9 years ago
    Favourite answer

    That is the defined speed of light in a VACUUM, meaning light traveling at it's fastest. Because light (a photon) has no mass; no matter how small the amount of energy you give it, it will run away as fast as possible.

    How do we know this? Math.

    We have found that time is not an independent factor in our universe; it is inextricably tied up with space. It can be loosely thought of as a direction of travel, like the three we are familiar with. The faster you go in the spatial directions, the slower you'll go in the time direction.

    What that basically means, is since speed = distance divided by time, once you're traveling fast enough that time reaches zero, there is simply no way of going any faster than that. It just violates light's mathematical relationship with time and distance.

    Light CAN be slowed down though, such as when it passes through water or glass as an example.

    So that should cover the answer of why it's LIMITED to that speed, but if you'd like to know why it's that speed in the first place ... no one really knows. We know that's the constant, all the math is consistant with it within the Special Theory Of Relativity ... but we don't know WHY that's the constant, just that it is.

  • 9 years ago

    Actually, it's a bit slower in the atmosphere, but light will travel through any media that can conduct it. In diamond, for example, it travels about 1/2 as fast as it does in vaccuum. In glass, it's slowed to about 3/4 it's speed in vaccuum, depending on the type of glass. It's not really a matter of friction, it's a matter of photons being absorbed and released by the molecules in what it's traveling through; in space, there *are* no molecules to travel through, so it can move at it's universal speed.

    As for the speed itself, that's simply a property of our universe. In another universe, maybe the speed of light would be set differently; but for whatever reason it moves as fast as it does, the universe will not allow it to move any faster.

  • Anonymous
    9 years ago

    If you are asking the question about what "gives" light this constant speed, scientists are not sure. This is part of what string theory tries to deliberate on. One idea that I know of is that the fundamental "strings" that make up our Universe but are too fundamental to detect actually act as light's "medium" and all energy (light is energy) that travels through the Universe is just a "ripple" so to speak in these strings, and the strings' frequency that allow for this fundamental energy flow just happen to "vibrate" at the speed that light travels. This only conjecture, however, and these terms I use such as vibrate and ripple are just terms to try to understand the phenomenon, not explain it scientifically.

    Source(s): Astrophysicist
  • 9 years ago

    Light travels slower in the atmosphere than it does in vacuum. The speed you quote is the speed light travels in a vacuum, not in the atmosphere.

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  • 9 years ago

    You could ask a million "why" questions and not receive an answer. Things are because they are and such things cannot be explained using answers of a material nature... This is like asking how did the universe originate with the Big Bang... The only possible and feasible answer will have to a metaphysical one, invoking a non-physical intelligence.

    I may suggest however that the velocity of light does actually vary in different parts of the universe, even within our own galaxy due the variations in the density of space-time.

    I discuss many of these subjects in my book... 'A NEW FORM OF ENERGY; ITS DESCRIPTION; ITS GENERATION; AND ITS APPL;ICATIONS'. (Amazon).

    Please also see my website... www.energyandphysicsatotalbreakthrough.com

    Source(s): 27 years research in physics, quantum physics, metaphysics, the paranormal
  • Ricky
    Lv 4
    9 years ago

    light always travels at that speed in a vacuum; its simply a physical constant in our universe just like the gravitational constant and planck's constant

    light actually travel slightly slower in our atmosphere due to matter-photon interactions with the gases in our atmosphere

  • Anonymous
    9 years ago

    The speed of light in the atmosphere is SLOWER than that. Why do the laws of physics exist?

    NO ONE can answer that question. Post your question in the Philosophy section instead wasting OUR TIME in Astronomy & Space with questions that don't have scientific answers



    Source(s): I HATE TROLLS.
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