why does light have a finite speed

@Enzo,

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it is because of how meter and second is defined by us.

No, yes, sorry Enzo if you misunderstood. I was asking why it should go at that particular speed, not some other slower or faster

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and that is as pointless as asking why any of the other fundamental constants of the universe happen to be their values.

Not really, Bill. If for instance we knew the energy required to free the photon from the atom, then couldn't we calculate its mass

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@InfraBlue,

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Well, c is the net result after the interaction between massless particles/waves and the physical properties of a vacuum.

Thanks Blue but that bothers me as a sort of tautology. If it's massless then meeting no resistance shouldn't its speed be infinite

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@Enzo,

Why exactly does the units we measure it in matter?

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@Enzo,

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Oh boy, how can I be any clearer? Sure c is a constant in our given standard unit of measurement, however, the velocity measured, which is a numerical value, is directly dependent to the standard system of units used to measure

Come off it the number you get will depend on the units but they all stand for the same damn value so what is your point!!!!!

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@dalehileman,

I think Thomas described earlier the mechanic by witch light moves, the energy light has does not change its speed rather it changes its frequency and amplitude, so i realise now that the energy it has doesnt actually result in its movement meaning my original question is actually quite a stupid one- i need to read a book.

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@BillRM,

I agree who gives a damn about the units.

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@cheeser,

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i need to read a book.

Me too Che
However I'm still intensely curious about c, why it should assume that value and not some other

My theory is that the speed of light if massless is actually infinite, in a a purely relative way. That is, I envision that each observer at the center of his own set of concentric circles where each succeeding sphere represents a later time

Thus if you energize your flashlight at noon and the beam appears to arrive at Mars at 12:05 actually the trip was instantaneous. That is, at the instant it was 12:000 here it was 12:05 there

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@dalehileman,

Interesting but i dont think its energy to mass ratio actually effects its speed, i think its to do with the mechanic mentioned by thomas eralier which i know nothing about and obviously need to read about.

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@cheeser,

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Interesting but i dont think its energy to mass ratio actually effects its speed,

that's a new one on me but if my "relative relativity" proves fitting it doesn't matter. In my system a moving object doesn't shrink, gain mass, nor does its clock slow

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i think its to do with the mechanic mentioned by thomas earlier which i know nothing about and obviously need to read about.

Amen Che, I'll have to ruminate on that one[/quote]

But the title of the OP, "why does light have a finite speed" I have addressed. I say it doesn't, or at least you can look at it in that relative way, which easily explains those three apparent peculiarities of a moving object, eg, it looks shorter because the light from its head and tail arrive simultaneously

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@dalehileman,

Incidentally Che is it the photon itself which is reputed to have a frequency or the rate at which the packets arrive. always confused me

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@dalehileman,

Im pretty sure its rate that packets arrive though dont quote me on that maybe someone else more sure of them selves can answer.

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@cheeser,

Doubtless Che somebody will respond, we have a smart crew

The "scientific" reason light travels at a certain specific speed is that c fits into all the formulas; that is, it's the value it is because no other value will work. Extending the principle, it seems increasingly evidence from recent thinking that everything is the way it is because--notwithstanding my own weird theory-- it can't be any other way; everything depends on everything else, the speed of light is what it is to make everything else ok and that everything from the Big Bang onward is the natural product of evolution

Quite OT to this thread however, the mechanism whereby the humanoid turns out to play such an evidently important part is still a complete mystery; why everything seems to have been "adjusted" to permit the evolution of life, with us being the most complex objects in the entire panoply

Getting back to the speed of light however, "science" leaves Intuition unfulfilled. In terms the Average Clod (me) should comprehend, how else can we explain crazy relativistic phenomena like the moving object gaining mass and the limitation of c; it's still as mysterious as to why there should have to be life

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@cheeser,

cheeser wrote:

I think i can understand that, but could you possibly elaborate?

No.

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@cheeser,

cheeser wrote:

Interesting, the problem is there is just so much and its so daunting, what to read and what not. I am only in sixth form, ( between school and university) do you think its a good idea to start seriously reading now or to wait until im doing this stuff uni.

If you want to cut down on reading obligations, you may want to delay the relativistic stuff and the quantum stuff until later. Maxwell's equation and their application to light do not require an understanding of relativistic physics (although those, too, are interesting). While there is no truly easy way of understanding electricity and magnetism, I suppose the most layman-friendly introduction is The Feynman lectures, volume 2.

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We do not have a scientific explanation as to why light travels a 300,000,000 m/s. Science knows this from experiments done. One of the first experiments was Fizeau's toothed wheel experiment done around the 1850's. Maxwell's equations can be manipulated to solve for the speed of light based on two experimentally determined constants: the permittivity of free space ɛ ̻ and the permeability of free space µ ̻. The relationship is c = (µ ̻ɛ ̻ )^-½. Maxwell was the first to discover this relationship. No theory predicts that the speed of light should be c from some more fundamental science.

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@dalehileman,

The speed of light in a vacuum is hardly the only fundamental constant we have that is some value due to that just how the universe happen to be as far as we know.

G as in the gravity constant come to mind as another example of this.

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@BillRM,

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The speed of light in a vacuum is hardly the only…...

True. However it's one especially puzzling to the Intuition, hence this OP

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G as in the gravity constant come to mind as another example of this.

Not quite; Intuition can speculate, eg, that the local field represents a "crowded" area of space "pushed aside" by the presence of matter.Not very "scientific" of course; but the speed of light does remain more totally mysterious

Getting back to gravity however, Intuition is intrigued by the recent observation that we would be impossible were it half of one percent different in value, seeming to suggest there's something "special" to the Universe about life

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@cheeser,

Light has certain concept or frequencies which leads it in the finite speed

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@Toshith,

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Light has certain concept or frequencies which leads it in the finite speed

Thank you Tos for that insight but to save me the entire morning scrolling through Google, does the photon itself have a specific freq or is it the rate of arrival that determines it

I'd think the latter. Suppose for instance that a single photon passes by every second. Wouldn't the frequency be 1 pps and if not is this photon somehow different from one passing at 2 pps

And how or if does it explain why its velocity is c, not some other value, b or d

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@dalehileman,

actually i am going to pull a u-turn, can someone please verify this, i think that radio wave photons as a for instance, are intrinsically different from gamma ray photons so i think the photon must have a frequency associated to it.

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why does light have a finite speed

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