Why does light travel so fast

why does light travel so fast?
 
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Because we live so slow.
 
but why is it not instantanous because it is not actually matter so it does not have to overcome friction to move.
 

Pengwuino

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but why is it not instantanous because it is not actually matter so it does not have to overcome friction to move.
So? Even in a frictionless world, objects don't have to travel fast.
 
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This question is about philosophy, not physics.
 
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but why is it not instantanous because it is not actually matter so it does not have to overcome friction to move.
That's a better question. No one knows the answer, but one possibility is that the computational speed of the universe is limited (Wolfram), or even more simply, the universe may evolve in discrete finite time intervals.
 
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Because we live so slow.
No matter how fast we live, the speed of light is allways the same. And you, the observer, will allways move with zero speed relative to youself, so it allways would seem that the light moves at the speed of light and you are at rest.
 

epenguin

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but why is it not instantanous because it is not actually matter so it does not have to overcome friction to move.


Light is both a classical and quantum phenomenon and its classical aspect 'prevents' it from being instantaneous, as in the macro realm nothing is instantaneous(which is also forbidden by a postulate of special relativity). It's how nature is.
 
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I think it is about physics not philosophy and the solution is of the type of The_Duck's.
Asking that "why light travels at c instead of another speed or instantaneously" is a philosophical question and nothing to do with physics. It is a universal constant. Like pi for example..

If that's not philosophical, then I can ask you; why pi is 3,14... and not something else? Then is this mathematical?
 
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but why is it not instantanous because it is not actually matter so it does not have to overcome friction to move.
I'm just spouting stuff here, but it may have something to do with gravity. Light is confined to space-time, so there might be some relevance.
 

epenguin

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Asking that "why light travels at c instead of another speed or instantaneously" is a philosophical question and nothing to do with physics. It is a universal constant. Like pi for example...
I have given a very crude version of what would be a physical argument. When you say the speed of light is so many m/s like any other physical measurement it is a comparison. You can make it into a comparison with e.g. the size of atomic structures and the times of atomic events. As light is more fundamental than the atom the most meaningful comparison is the other way round. It is asking why atoms have the size and frequencies they do, more exactly try an explain why the size is such that light can get back and forth between two adjacent atoms in the time it takes for x flips of a Cs nucleus or something like that, thousands of things like that. Physical questions.


Like pi for example..

If that's not philosophical, then I can ask you; why pi is 3,14... and not something else? Then is this mathematical?
Not sure what your point is here but yes that is mathematical, once we define pi as twice the circumference of the unit circle. The mathematics answers of is the answer to any 'why' question.
 
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Pi is the ratio of the circumference of a circle to its diameter. It is 3,14... Asking "why it is 3,14... and not something else" is not a mathematical question. It is a philosophical question. There is no single living thing that can answer why pi is 3,14...
And this is the same case. Pi is a mathematical constant, c is a physical constant. Therefore, asking why speed of light is c is not physical question but philosophical.
Physics and mathematics (in fact any positive science) do not ask "why" questions.
 

epenguin

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Pi is the ratio of the circumference of a circle to its diameter. It is 3,14... Asking "why it is 3,14... and not something else" is not a mathematical question. It is a philosophical question. There is no single living thing that can answer why pi is 3,14...
And this is the same case. Pi is a mathematical constant, c is a physical constant. Therefore, asking why speed of light is c is not physical question but philosophical.
Physics and mathematics (in fact any positive science) do not ask "why" questions.
Puzzling and contradictory IMHO.

It was mathematically proved that pi when defined as you have is that decimal. So it was a mathematical question answered. The mathematical proof is the answer to the why. In ordinary parlance - maybe you can argue deeply that you cannot give a logical sense to the word 'why' that applies here.

Your 'therefore' is completely unwarranted since math and physics are of completely different status and nature - it is not like statements about physics carrying over to chemistry.

At first your use of the word 'philosophical' suggested to me you were one of those scientists who used 'philosophical' as equivalent to 'pointless, unworthy of an adult's attention'. But when I saw 'positive science' I thought you might come from a very definite philosophical position. Unless you just copied the expression.:smile: In any case just one position.

Would you say the Boltzmann constant is just what it is, asking why it has that value is a philosophical question?
 
why does light travel so fast?
It doesn't travel fast - it's appallingly slow.

If you are designing high speed computers it's annoyingly slow- and if you want to rule a galactic empire it's very frustrating.
 
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Puzzling and contradictory IMHO.

It was mathematically proved that pi when defined as you have is that decimal. So it was a mathematical question answered. The mathematical proof is the answer to the why. In ordinary parlance - maybe you can argue deeply that you cannot give a logical sense to the word 'why' that applies here.
I don't think it is contradictory and I don't think the mathematical proof is the answer to the why. "Why" has more deep meaning. Of course we know pi is 3,14... and not something else. But why it is? Can you answer? All you can say is that "Because for any circle circumference over diameter gives 3,14..". Then "Why for any circle circumference over diameter gives 3,14...?". You can ask these but you cannot find an answer. That's why there is a thing called philosophy :)

Your 'therefore' is completely unwarranted since math and physics are of completely different status and nature - it is not like statements about physics carrying over to chemistry.
I don't think math and physics have completely different status. Physics derived from mathematics. Physics can be considered as applied math. (I think)

At first your use of the word 'philosophical' suggested to me you were one of those scientists who used 'philosophical' as equivalent to 'pointless, unworthy of an adult's attention'. But when I saw 'positive science' I thought you might come from a very definite philosophical position. Unless you just copied the expression. In any case just one position.
No, I never use "philosophical" as pointless or unworthy. I know the boundaries of philosophy and science, so I am not saying that "Do not discuss why does travel so fast! It is pointless." , I am saying "Quantum Physics forum is not the right place to discuss this kind of why questions". Because it is philosophy.

Would you say the Boltzmann constant is just what it is, asking why it has that value is a philosophical question?
Every constant in science has a meaning. But "why it has that meaning" is something else.
 
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No one knows why the speed of light is what it is, nor even why it is fixed; nor why the charge of an electron is what it is, nor why gravity has it's particular value....
 

DevilsAvocado

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why does light travel so fast?
Yes, from "the human perspective" it is fast; 299,792,458 meters per second. But remember that meters and seconds are related to humans, living on the planet Earth.

One meter was originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole.

One second was originally intended to be 1⁄86,400 of the mean solar day (24 x 60 x 60).

Now imagine an alien civilization of terrible large giants visiting our solar system, where the Earth had the size of a head of a pin and the Moon the pin tip, form their perspective (impossible but just for fun). Imagine that these alien visitors saw a laser beam leaving Earth towards the Moon.

– What would that look like to them?

[URL]http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Speed_of_light_from_Earth_to_Moon.gif/400px-Speed_of_light_from_Earth_to_Moon.gif[/URL]
A beam of light is travelling between the Earth and the Moon in 1.255 seconds

As you can see, these giant aliens could most probably walk faster-than-light! :smile:

But this is not possible; it’s just science fiction to give you some "perspective". Absolutely nothing can move faster than the speed of light in space (the expansion of space itself is another story), and this has to do with causality. If you could travel faster than the speed of light (FTL), then you could do time travel, which in turn would cause unsolvable paradoxes with observers going back in time to erase the cause of their own "present" existence, etc.

In the theory of relativity, the speed of light (c) is invariant. If you had an extremely fast "science-fiction-car" doing 0.5 x the speed of light, at what speed would the light of your headlights leave the car? Well the natural answer is 0.5 x the speed of light, as the sum up speed would be 0.5 + 0.5 = 1 x the speed of light, which is maximum speed, right?

But this is wrong! The speed of the light leaving your headlights will always be 1 x the speed of light, no matter how fast you drive, when you measure that speed.

In special relativity, space and time is a unified structure known as spacetime, with c relating the units of space and time, and c = 1, i.e. the speed of light = 1.

but why is it not instantanous because it is not actually matter so it does not have to overcome friction to move.
There is no friction in outer space, whether you are a spaceship or a light beam. If the speed of light was instantaneous, there would not be any time = crazy mess... where everything happens at once...

"The only reason for time is so that everything doesn't happen at once." -- Albert Einstein
 
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The problem here is that some people are solving this by just saying " it just does" but imagine if Newton wondered "why did this apple fall?" and then just said " oh yeah, it just does" we have to to a crack at the question.
 
don't mind my last comment thanks for the explanation Devilsavacado
 

DevilsAvocado

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Are you talking to me!? :grumpy:

(:rofl:)


EDIT: Ahhh OK! :blushing: (:wink:)
 

epenguin

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Would you say the Boltzmann constant is just what it is, asking why it has that value is a philosophical question?
Every constant in science has a meaning. But "why it has that meaning" is something else.
Well the Boltzmann constant comes in a bit everywhere at least in bulk matter theory. So it can have the appearance of a fundamental constant. But if you analyse it it is nothing but a property of water, its solid/liquid/gas states. If you can predict the energy of its melting and boiling you have it. So a property of atoms in the end. I suggest the speed of light is a property of atoms in the same kind of way.
 
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The problem here is that some people are solving this by just saying " it just does" but imagine if Newton wondered "why did this apple fall?" and then just said " oh yeah, it just does" we have to to a crack at the question.
No he went much further, and said "oh yeah, it just does, because of gravity". And we're still at that point now + a few unexplained constants. :P
 

Drakkith

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The problem here is that some people are solving this by just saying " it just does" but imagine if Newton wondered "why did this apple fall?" and then just said " oh yeah, it just does" we have to to a crack at the question.
No, the problem is that we don't actually know WHY light travels so fast, only that it DOES. We can explain how light works to the best of our knowledge, but thats it. It's like the little kid that continually asks why when you explain something too them. Eventually, you HAVE to say "It just does" or "Thats just the way it works". Either because its far to complicated to explain, or because we just don't know.

We can follow up on this with a detailed explanation on an electromagnetic wave and other related subjects, but the first answer might have been enough for the poster.
 

Rap

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I think its a valid question. It could be restated as "why have earth life forms evolved to deal with only Newtonian physical situations?" (i.e. the speed of light is large compared to any velocities that are relevant to the survival of the organism). It probably has something to do with the fact that life forms cannot be (or have not been) "built" which have "circuits" (neurons) that can send signals at anywhere near the speed of light, nor can they generate forces which would accelerate any body part to anywhere near the speed of light. If they could, then organisms would have to respond relativistically in order to survive either as predator or prey, and the speed of light would not seem so fast.
 

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