…does light have a speed?

Seems strange.  I’m sure Einstein or someone answered that, but I’m not sure I’ve ever heard the reason.

Update: The auto “related post” generator reminded me that I asked this question at least once before back in ’08.

9 thoughts on “Why…

    • Professor Landsburg: Thanks for the comment.

      Maybe. Do Maxwell’s equations explain why space has permittivity and permeability constants or just use those constants to model how em waves behave? I’m definitely not an expert there. There may be an obvious and known reason for these two constants. I’ll look into it. If you know, please share.

  1. did your kid ask you this? =]

    is it because we have chosen it as our frame of reference? “In the beginning God created the heavens and the earth, and the earth was welter and waste and darkness over the deep and the wind of God hovering over the waters, and God said, ‘Let there be light,’ and there was light;”

    entropy exists..maybe we’ve got it all wrong, and we are really moving toward oblivion rather than away from it.

    good question – perhaps the best. descartes may have answered it.

    have you read zelazny’s ‘chronicles of amber’?

    • dave – Thank you. I have not read (or heard of) Zelazny, but from the Wikipedia page it seems he offers an interesting basis for a story.

      I’d be interested if you have anything specific from Descartes that explains the speed of light. Didn’t he think it was infinite?

      And my kid didn’t ask it, though he has asked some doozy’s.

      The question occurred to me a few years ago after watching a pop science TV show on string theory.

      It seemed to me that if there were tiny energy strings that made up the fabric of space-time (I’m not sure if that’s exactly what string theory says), then having a photon represented a state that an energy string could be in and the speed of light could derive from the time it takes that state to propagate from one string to the next. Though, I’m not sure why it would take time to do that.

      But, it seems like that would have to hold true for gravity also. But, I don’t think there’s a speed of gravity.

      I know. Quack thoughts. But, I’m still interested to know if there’s a known reason for the speed of light.

      • doc mentioned maxwells equations – the wiki article on the wave/particle duality of light is a good one.

        i think the old ‘grand unified field theory’ is what they are going after to bring gravity into the fold.

        thanks for this question. it prompted me to do more research on a subject i thought i knew something about (electricity). i never thought of it as an em wave because ive always been used to its propagation in a medium. (circuits) my navy schooling on the subject was more practical than theoretical. tesla was such an incredible thinker. he had some great ideas for wireless that i feel havent fully been realized. (yet)
        ive got an idea for a circumpolar generator that i think would work in theory. transmission would be a hurdle, but with wireless, we could all have ‘free’ energy. now wouldnt that be something. the drawback is that we would be slowing our planets rotation by a fraction.

        i dont know what descartes thought about the speed of light, i only quoted him because i feel that your question tugs at the apron-strings of reality in a fundamental way.

        does anything in the universe move faster than the speed of light? it seems to me that everything is moving at exactly the speed of light. i like the ‘big-bang’ theory because it resonates with me. galaxies and solar systems can coalesce ‘later’. i imagine solar system formation works just like a specific gravity meter for a battery: density seperates lighter atoms from heavier atoms.

        im not sure on this, but i also think the universe will never ‘collapse’ – it just seems like it will someday wink out of existence. (the big-wink) ;]

    • Nice posts.

      I agree that it tugs at the ‘apron strings or reality’. I like that phrase.

      Maxwell’s equations – near as I can tell – tell us how electromagnetism behaves, not why it behaves that way. Similarly, we know how gravity behaves and approximate it with Newton’s law of universal gravitation. But, (and I could be wrong) these are abstractions. These aren’t the real thing.

      So they don’t answer why these things behave this way, just how they behave.

      Have you read about cellular automaton? Made me think the laws of physics may be a set of rules for an automaton.

      Also made me think that the speed of light is how fast the cells can change.

  2. Pingback: Does the speed of light change? and more crazy stuff | Our Dinner Table


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