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Why does light travel at 299,792,458 meters per second


Lightmeow
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The fact that you brought up a tangential point means it's not obvious that you knew it.

 

Anyone with the very basic understanding of physics , knows that light photons do not "accelerate" and by this time you should be aware of the fact, that the level of my understanding of physics goes beyond that of primary school children.

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Alan... Might wanna bring it down a notch or two. Plenty of people outside of "primary school children" may have areas of interest outside of the physics of light.

 

Besides, while I agree with your intent, that photons don't really "accelerate" in that they're massless and can not experience G-forces and that they're traveling at the speed of light upon emission... They can still be considered to accelerate in some senses of the word. Think of a coordinate system sth light teaveling directly along the Y axis. That light goes through a gravitational field and the direction changes to a few degrees into the x axis. While the photon is moving at the same speed, it's progress along the Y axis has slowed and it's progress along the X axis has increased. It has experienced both acceleration and deceleration... Relatively.

 

A person holding a viewpoint different than your own should not immediately be assumed to be ignorant.

 

 

As for Swanson: yes. Measurement is important. The calculations for a certain theory (such as relativity) MAY be spot-on... While the variables are still attributed improperly. For example, muons extended lifespan being predictable by relativity. I completely agree that they can be observed places they shouldn't be and the math for relativity explains the relationbetween their speed and their extended life. However, the fact that we observe them CAN mean that muons invariably only live a certain amount of time, and that their motion changes how they experience time, so what looks like more time has past to us seems like the same period of time to them... I.e. they tell time more accurately than time exists.... It's invariably fixed to a completely alterable state.

 

OR, we can take the simple explanation that the high speeds physically change the rate of decay. And they live longer at high speeds because the physical object is affected by its motion rather than the matter being unaffected while some intangible, subjective concept of "time" is affected instead.

 

I agree on the numbers. The explanation is observably bass-ackwards. The fact that equasions match make no difference. The equasions are fine. The explanation for those equasions are flawed.

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As for Swanson: yes. Measurement is important. The calculations for a certain theory (such as relativity) MAY be spot-on... While the variables are still attributed improperly. For example, muons extended lifespan being predictable by relativity. I completely agree that they can be observed places they shouldn't be and the math for relativity explains the relationbetween their speed and their extended life. However, the fact that we observe them CAN mean that muons invariably only live a certain amount of time, and that their motion changes how they experience time, so what looks like more time has past to us seems like the same period of time to them... I.e. they tell time more accurately than time exists.... It's invariably fixed to a completely alterable state.

 

OR, we can take the simple explanation that the high speeds physically change the rate of decay. And they live longer at high speeds because the physical object is affected by its motion rather than the matter being unaffected while some intangible, subjective concept of "time" is affected instead.

 

I agree on the numbers. The explanation is observably bass-ackwards. The fact that equasions match make no difference. The equasions are fine. The explanation for those equasions are flawed.

Yes, we could decide to abandon science, but it's worked pretty well thus far, so is there a legitimate reason to do so?

 

If you want to abandon relativity as an explanation for what we see with regard to muons — which matches relativity quite well — then you need to come up with an alternative to it. Similarly for Maxwell's equations. Otherwise, you simply have to accept that the data matches the model, and in doing so represents support for the model. Not liking that it matches doesn't suffice.

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Change the subject all you want. Fact is, the speed of light being constant relative to anything other than its source has never been measured. To skew so much of science to protect a theory that has never been adequitely supported... Yet is so obviously falsified (by the Doppler effect) is not science. That's religon. Don't try to shift blame as though we are the ones "abandoning science" by requesting direct evidence before we put faith in a thing that defies logic.

 

Swans, math is a language that quantifies what we observe. If you observe a thing, completely misrepresent it, but quantify that misrepresentation with accurate numbers.... We're left with nothing more than a very well articulated bit of foolishness. Numbers are right, but you're looking at it entirely upside down.

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The original question asked in this thread was "Why does light travel at 299,792.458 kilometers per second in a vacuum. The best answer I can think of is that any object that has mass, even a fundamental particle would need an infinite amount of energy to reach C It is simply a reality of our universe,such as phi.

 

This barrier would apply equally to a colossal mountain of a trillion tonnes, as well as that of a single proton, it is all about diminishing returns. At first a huge amount more energy is needed to accelerate the huge mountain, and almost nothing to accelerate the proton. Assuming the energy is available to continue acceleration both said object closer and closer to C the energy needed to get closer to C would begin to equalize until at say?

 

0,9999999999999999999999999999999999999999999999999999999999999999991 C the energy to drive both object towards C would begin to equalize. Hypothetically speaking at exactly C the exact same amount of energy would be needed to get the colossal trillion tonne mountain or the single proton to C (Impossible infinite)

 

The energy increases exponentially the closer to C you get, and your input will exhaust eventually no matter how large it is. Lets assume you get to the last infinitesimal tiny faction of speed needed before actual C say as I indicate below!

 

0,00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001 of the speed of light the energy needed to bridge this final last gap to reach C is still infinite no matter what was the original mass of the object.

Edited by Alan McDougall
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Change the subject all you want. Fact is, the speed of light being constant relative to anything other than its source has never been measured. To skew so much of science to protect a theory that has never been adequitely supported... Yet is so obviously falsified (by the Doppler effect) is not science. That's religon. Don't try to shift blame as though we are the ones "abandoning science" by requesting direct evidence before we put faith in a thing that defies logic.

 

Swans, math is a language that quantifies what we observe. If you observe a thing, completely misrepresent it, but quantify that misrepresentation with accurate numbers.... We're left with nothing more than a very well articulated bit of foolishness. Numbers are right, but you're looking at it entirely upside down.

 

You are making a mountain out of a molehill - much of science is based on indirect measurement, best-fit scenarios, and presumptions; the measure of a scientific theory is not whether it explains the why, nor if it is appealing, and not that it fits our preconceptions - it is whether it fits known observations and if it makes predictions which turn out to be correct.

 

Your obvious falslification is anything but - no experimental evidence (within the realms of application) has shown relativity to be flawed; and until something does (other than an ill-conceived gedanken) then we will continue to use it to understand our observations, make predictions for the future, and as a base for other theories.

 

You seem to be labouring under the misapprehension that physics and science in general is a search for the "ultimate why" - it is not. We make theories that explain empirical observations, make valid predictions, and are self consistent - these models are the be all and end all; there is no search for explanations of why, agreement with things we cannot measure, or rightness / fitness with our preconceptions.

 

To conclude - which observations do you believe relativity does not explain, and which observations contradict relativity; Observations - not thought experiments.

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Change the subject all you want. Fact is, the speed of light being constant relative to anything other than its source has never been measured. To skew so much of science to protect a theory that has never been adequitely supported... Yet is so obviously falsified (by the Doppler effect) is not science. That's religon. Don't try to shift blame as though we are the ones "abandoning science" by requesting direct evidence before we put faith in a thing that defies logic.

 

Swans, math is a language that quantifies what we observe. If you observe a thing, completely misrepresent it, but quantify that misrepresentation with accurate numbers.... We're left with nothing more than a very well articulated bit of foolishness. Numbers are right, but you're looking at it entirely upside down.

 

Baloney. The Doppler shift affects both wavelength and frequency. It falsifies nothing.

 

As I said, come up with an alternative. Science picks the best model, i.e. one which matches observation. Refusing to accept it because you don't personally understand it, or it somehow offends your sensibilities is not on the menu.

 

My mistake, my point is that any object that has mass cannot be accelerated up to C!

 

Which doesn't explain why c has the value it does, which was what the OP was asking.

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I have a horrid feeling that the value of c as 299,792,458 m/s is just one of those things. We can either view the permeability and permittivity of the vacuum as fixed and say that the speed of light must be one over the square root of their product, or view the speed of light as sacrosanct and that the permeability&permittivity vary - but we have no reason for privileging one explanation over the other. We can measure the permeability and permittivity without reference to the speed of light and get a good answer - but we can measure the speed of light without reference to the p&p and get a good answer. There will always be numbers that just are - with no more basic explanation; in time we may find a reason for this in terms of more fundamental constant; but at present we have not.

 

In our universe the speed of light is 299,792,458m/s - if you change that all bets are off.

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I have a horrid feeling that the value of c as 299,792,458 m/s is just one of those things. We can either view the permeability and permittivity of the vacuum as fixed and say that the speed of light must be one over the square root of their product, or view the speed of light as sacrosanct and that the permeability&permittivity vary - but we have no reason for privileging one explanation over the other. We can measure the permeability and permittivity without reference to the speed of light and get a good answer - but we can measure the speed of light without reference to the p&p and get a good answer. There will always be numbers that just are - with no more basic explanation; in time we may find a reason for this in terms of more fundamental constant; but at present we have not.

 

In our universe the speed of light is 299,792,458m/s - if you change that all bets are off.

 

The same, of course, can be said of the fundamental charge, or Planck's constant, etc.

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Baloney. The Doppler shift affects both wavelength and frequency. It falsifies nothing.

 

As I said, come up with an alternative. Science picks the best model, i.e. one which matches observation. Refusing to accept it because you don't personally understand it, or it somehow offends your sensibilities is not on the menu.

 

Which doesn't explain why c has the value it does, which was what the OP was asking.

 

c is what it is because that is a "reality of our universe", you cant change it in the same manner you cant change the value of phi, the diminishing returns in energy needed to get an object to c, becomes infinite, the total energy of the entire universe, is insufficient to drive an object to c , thus it is an impossibility for any object with mass to reach c , mass-less particles like photons are always at c.

 

Would you like me to suggest some cosmic traffic official set the limit of c in our particular universe? Must I answer an impossible question, if I could I would outrank Einstein as a theoretical physicist?

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It's a little more subtle than that. The propagation speed of photons is always c, but it takes time to interact (absorption/emission in virtual states). The result is not because of a zig-zag path.

 

The slower propagation is also perfectly consistent with the classical wave nature of light. The wavelength decreases by a factor of 1/n, and propagation speed depends on the wavelength.

 

So using the example of a prism, it appears as if light enters one side of the prism, is absorbed/emitted many times, and exits the other side of the prism. When a photon is emitted, is it essentially emitted traveling in the same direction as the photon that was previously absorbed? Or is it emitted in some random direction, and what I interpret as light entering one side of the prism and exiting the other, is in reality simply some of the photons making it all the way through, while others head off in other directions?

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c is what it is because that is a "reality of our universe", you cant change it in the same manner you cant change the value of phi, the diminishing returns in energy needed to get an object to c, becomes infinite, the total energy of the entire universe, is insufficient to drive an object to c , thus it is an impossibility for any object with mass to reach c , mass-less particles like photons are always at c.

 

Would you like me to suggest some cosmic traffic official set the limit of c in our particular universe? Must I answer an impossible question, if I could I would outrank Einstein as a theoretical physicist?

It only becomes impossible if you define it as such. Note that with an expanding universe, objects are moving apart faster and faster. This inherently means that when the universe reaches a certain size, objects on the edge will be traveling beyond the speed of light relative to other objects.

 

Of course, certain people will redefine time to give the illusion of this not being the case via time dilation. No matter what evidence a person presents, reality is simply redefined by altering the definition of time and space in order to protect the omnipotence of C.

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Of course, certain people will redefine time to give the illusion of this not being the case via time dilation.

I don't think anyone will do that. There are very clearly objects, sufficiently far apart, that are separating faster than the speed of light. So what. The speed of light limit is a purely local thing.

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So using the example of a prism, it appears as if light enters one side of the prism, is absorbed/emitted many times, and exits the other side of the prism. When a photon is emitted, is it essentially emitted traveling in the same direction as the photon that was previously absorbed? Or is it emitted in some random direction, and what I interpret as light entering one side of the prism and exiting the other, is in reality simply some of the photons making it all the way through, while others head off in other directions?

 

The absorption/emission must conserve energy and momentum, and since the state is virtual. the photon is re-emitted in the same direction and with the same energy as long as you are in the bulk medium. At the interface there is a change in direction.

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It only becomes impossible if you define it as such. Note that with an expanding universe, objects are moving apart faster and faster. This inherently means that when the universe reaches a certain size, objects on the edge will be traveling beyond the speed of light relative to other objects.

 

Of course, certain people will redefine time to give the illusion of this not being the case via time dilation. No matter what evidence a person presents, reality is simply redefined by altering the definition of time and space in order to protect the omnipotence of C.

 

Yes even massive objects like colossal galaxies, that are imbedded in space can separate from each other faster than c , by the overall expansion of the universe, but that does not alter the fact that no object that has mass can travel "through" space at c.

 

c is immutable sorry!

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Could you say that we call "light" what is travelling at C?

 

Hmm - gluons are also massless and whilst they are a lot harder (than the photon) to understand and rationalize QCD is an incredibly successful and useful way of looking at things. Gravitons will also be massless when pinned down.

 

How much either of these two can be said to be travelling (I don't think gluons really get out of the hadron let alone out of the nucleus) like we imagine we know the photon travels is another question

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Perhaps light must go at 299,792,458 metres per second, because if went at any other speed, it would make the physical Universe unable to sustain a prolonged existence.

 

The Universe would somehow either blow up almost instantaneously, or be so slow moving that structures like stars and planets couldn't form. And without planets, life mightn't have a chance to evolve, so humans wouldn't exist, and there'd be nobody to ask these questions.

 

This is classic "anthropic principle", of course, and might supply an easy answer. But is it satisfactory. Doesn't there seem something odd about the speed of light as a constant.

 

I mean if other constants, such as the Strong Force, were changed, then atoms and stars might become impossible. Either imploding, or dissipating into the vacuum.

 

But suppose the speed of of light were changed to have a value of say, 400,000,000 mps. Would that make a practical difference to the Universe that we see and experience?

Edited by Dekan
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Perhaps light must go at 299,792,458 metres per second, because if went at any other speed, it would make the physical Universe unable to sustain a prolonged existence.

 

The Universe would somehow either blow up almost instantaneously, or be so slow moving that structures like stars and planets couldn't form. And without planets, life mightn't have a chance to evolve, so humans wouldn't exist, and there'd be nobody to ask these questions.

 

This is classic "anthropic principle", of course, and might supply an easy answer. But is it satisfactory. Doesn't there seem something odd about the speed of light as a constant.

 

I mean if other constants, such as the Strong Force, were changed, then atoms and stars might become impossible. Either imploding, or dissipating into the vacuum.

 

But suppose the speed of of light were changed to have a value of say, 400,000,000 mps. Would that make a practical difference to the Universe that we see and experience?

 

I don't think if c were different it would make alter the physical universe in the huge way you suggest, however, if the "force of gravity" were different then what you suggest would be true.

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