Hi guys first post here so bare with me if I sound stupid...

Why are photons limited to light speed?

From my limited understanding the maximum speed of anything in the verse is the speed on which photons are measured at, I also understand anything with mass cannot be propelled up to this speed as it would need an infinite amount of energy as it reaches near to this speed. As photons have no mass they do not suffer from this setback.

I have read that it is possible to slow down photons by using heated caesium gas ?? Or other types, but upon leaving the gas chamber the photons are instantly moving at light speed again.

I have a theory but i'd like your input as it could sound a bit odd

Hi, Fubaruk!

There is a frequent poster here who I hope will see your post and provide
you with a set of links to other threads which have discussed your main
question at length.

Light traveling through any medium slows down, but what is happening
on an atomic and photon scale is quite likely that the photons travel from
one electrically-charged particle to the next at the speed of light, then
are momentarily absorbed by the particle and emitted again a short time
later. The delays are the result of the time the energy is tied up in the
charged particles. Some very strange materials have been developed in
recent years which allow photons to keep on traveling from one particle
to the next for a very long time without getting permanently absorbed
or scattered in all directions.

Others can give you more complete descriptions.

-- Jeff, in Minneapolis

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Because they have no (rest) mass. Anything with mass can (will) slow.

As Jeff Root says, photons never slow but propagation of photons does slow as a function of refractive index. It is a peeve of mine that Harvard's own web site avoids this fact to promote sensationalism in their Bose-Einstein condensate studies.

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I mean why is lightspeed (in a vacum) 300,000 kps and not 400,000 kps or faster.

Because then you would ask why the speed limit was 400,000los

I thought the answer to "why" is "because". Science creates models to explain actions, not to answer "why". There are a whole list of parameters that we do not know "why". My favorite is the Fine Structure constant; 1/137 + a little bit; "why",we do not know.

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(By the way, I hate it that so many papers in the areas of planetary science and geology are not easily available to the dreaded "non-subscribers". It is like they are screaming at me: "YOU CAN'T HANDLE THE TRUTH". Good, I feel better now.)

"Quaerendo inventis"

ok well my theory is that, quarks are, not nessicaryly fundamental particles but a fundamental canvass on which the universe is based on, what I think is quarks are everwhere but unless any information is at the same point. Then nothing is displayed, and by information I mean protons, neutron, electrons and photons.

I believe photons are infinite is space and time are are only limited or visible because of the restriction of information transition between quarks. Has this been disproofen already, or which I really doubt, has no-one thought of this, or is it so stupid that I should just be quiet

from what we know,
quarks make up baryons. (a baryon is a neutron or proton) leptons are pretty much everything else like electrons and mesons.

a photon is an electromagnetic wave. electromagnetic waves and particles like quarks and leptons are interchangable. you can make quarks out of gamma rays and gamma rays out of quarks.

no body really knows what a quark really is.
they have never ever been observed by them selves, only in groups. some speculate that that a quark is just a twisted electromagnetic field that has two or more ends.


but that is beside the point. you asked why the speed of light is what it is.

but first, I have to disagree with jlhredshift on the subject that because it seems to me that the very basis of science is to answer "why" based on observable actions.

but, as for "why?", current research and proposed "theories" as to why there is a limit to the speed of propagation of light is still in contention. meaning, researchers are still trying to figure it out.

but so far the limit seems to be directly related to the very structure of spacetime itself

maybe someday

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Jeff Root is right in that photons never travel bellow c. Any delay on their path when traversing a medium is due to a series of absorption-emission by particles in the way.

And I agree with jlhredshift in that science is more suited to explain the 'hows', 'wheres', 'whens', and not the 'whys'. Why is the speed of light c?

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You are asking why the speed of light is the speed of light.

It's like trying to define time; an exercise in futility.

Well, why it takes on the value we know? I think that´s what I meant: a futility exercise.

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What brings us together is stronger than what pulls us apart

if you know the "how", then wouldn't you also know the "why"?

I have always equated "how" to "why"
(this is why this works = this is how this works)

or is the usage of the word "why" in this paticular sense more of a description of intent?


the OP did ask "why"
do we need to define "why"?

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it seems to me that if we can figure out exactly how/why the speed of light is what it is then we will have a much better understanding of the physical universe.

is this wrong?

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Is this so called speed specific to light?

I'm thinking it's broader. It's also the speed of gravity.

it seems to me that if we ever figure out the actual structure of the universe then the question as to how and why gravity and 'c' propagate at the speed they do will be self evident.

like knowing why the speed of sound is what it is. we fully understand that a mechanical wave propagation speed is a function of the density of the material through which the wave radiates. by understanding the component in the system that allows the wave to traverse through the medium, we have a much deeper understanding of the nature of the material in question and can even extrapolate and build models that predict the structure of an object. all this because we understand how/why a wave travels through a material.

i would further postulate that if we understand how/why the speed of light is what it is then we would have a deeper understanding of the physical universe for which we live in.

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Not really a good example. There is no absolute speed of sound, like there is an absolute speed of light. This little fact gives us plenty of other information that we can go on to determine the whys, hows, and therefores.

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Numbers are not case sensitive. (me)

well, there is an absolute speed of sound in a medium with uniform density.

furthermore, sound energy and acoustic wave propagation can be described using Maxwell's equations for electromagnetic wave propagation:
http://www.physicsofsound.com/
one reason that electromagnetic and gravitational wave may travel at the speed they do may be a function of the properties of spacetime itself, just as the speed of sound is a function of the property of the medium it travels through.

maybe one could test this by determining if light had a faster speed in an earlier, denser universe.

physicist João Magueijo suggests that in the very early days of the universe light traveled faster than it does today.
http://en.wikipedia.org/wiki/Jo%C3%A3o_Magueijo
http://en.wikipedia.org/wiki/Varying_speed_of_light
http://arxiv.org/abs/astro-ph/9811018v2


i mean do we "really" understand the nature of the structure of spacetime?

would it not be in our best interest to try and fully understand the very structure of the universe that we live in?

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That's my point. We have nothing to compare it to. From our point of view there is only one speed and it is not dependent on any other variable.

Did anybody say we do really understand it?

Are you saying nobody is trying to understand it?

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Numbers are not case sensitive. (me)

It's not quite the same because the speed of light is the same regardless of your inertial frame of reference (e.g., two observers moving at 0.5c with respect to each other will measure the same speed of light from any given source), whereas the speed of sound is not.

As to the OP, the question can be generalized: why do the fundamental constants of nature have the values they do? This is actually a profound question, and one that we do not yet have an answer for.

Nick

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Nick Theodorakis

Hey there!


above, you had mentioned ‘a’, the Sommerfeld fine-structure constant, haven’t physics been studying this to see if it is indeed variable to address questions and solve for cosmological problems? String theory calls for a variable in ‘a’ and didn’t John Webb from the University of New South Wales in 1999 detect a variation in ‘a’ using Keck?

Webb, John K.; et al (1999). "Search for Time Variation of the Fine Structure Constant". Physical Review Letters 82 (5): 884–887. American Physictal Society.
doi:10.1103/PhysRevLett.82.884. Retrieved on 2006-08-12.
M. T. Murphy et al, Mon. Not. Roy. Astron. Soc. 327, 1208 (2001)
Webb, John K.; et al (2001). "Further Evidence for Cosmological Evolution of the Fine Structure Constant". Physical Review Letters 87 (9): 091301. American Physictal Society. doi:10.1103/PhysRevLett.87.091301. Retrieved on 2006-08-12.
M.T. Murphy, J.K. Webb and V.V. Flambaum, Mon. Not R. astron. Soc. 345, 609 (2003)

While there is contention as to the results of the observations in the above cite, on going investigation work is taking place to confirm or dispel the reported observations.


I took this statement below to suggested that just by the information we have, we can understand the mechanism fully.

I can take these statements from above suggest that there is no real reason to try to understand it.

Is that ok?

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Whoa, what? Stop... I did not mention that. I don't even know what it is.

Whoa, what? Stop... I suggested nothing of the sort. I was refering to the speed of sound, and if you had quoted the ENTIRE SENTENCE . You would notice that I said I was referring to the speed of sound and it's variables.

What?
Are you putting words in my mouth or are you taking some away (again).

I questioned this statement....
I am questioning why you are asking this. If the answer were yes, then it means that somebody really does understand it. So; to ask the question, implies that you have some idea that somebody does understand it. Where do you get the idea that somebody does understand it?

Likewise you said...
By asking the question, you are implying that nobody is studying it, or implying that somebody says it's not worth studying.
Again; where do you get the idea that nobody is interested in studying it?

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Numbers are not case sensitive. (me)

c=1/sqrt(epsilon0*mu0)

c is dependent on the electromagnetic properties of free space.

It really isnt all that hard people.

Yes, because we´re saying the same thing. Alainprince is just nitpicking, and you, apparently, too.

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yikes
You are correct, jlhredshift talked about it in post #6
Sorry about that

here is exactly what you said
I guess this statement is ambiguous to me because apparently I did not understand what you were talking about I took it as we know that the speed of light is absolute therefore that fact is all the information we need to “determine the whys, hows, and therefores”

Sorry if I took this out of context.

As for the rest, they were most likely rhetorical.

however, as you asked,
Again because two posts above seemingly shrugged off the premise that there is a need to understand why and how the speed of light is what it is, an exercise in futility means to me that something is pointless. How could trying to understand why and how the speed of light is what it is be pointless?


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Hey neowatcher,
if you are interested, here is a very basic article on the The fine-structure constant.

http://physics.nist.gov/cuu/Constants/alpha.html

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-work in progress--

yes, we all nitpick.

apparently we have no life

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-work in progress--

It´s not pointless. You could try this way:

Why is the speed of light ~300,000 km/s? Because the permeability of the vaccum determines that.

But why does the vaccum permit only that, and not, say, 400,000 km/s?

Those are fundamental questions of qualitative nature, and scientific knowledge is about quantifications. And here´s the Mother of all qualitative questions: Why did the universe come to be?

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What brings us together is stronger than what pulls us apart

So you put other peoples words in my mouth...
I thought I tasted something funny.

Hmmm... It seems like we talked about that elsewhere.

In many ways, Yes;

I guess if I need to summarize my part in this whole thread.
- I don't think anybody knows the true nature of why light behaves as it does, although we have models to be able to work with it. And we have evidence of it's constant nature.
- We don't have or foresee that we can get evidence from other universes.
- As long as we know we don't understand, we should look for clues to help solve the problem, and, there are people (much smarter than I) looking into this.

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Numbers are not case sensitive. (me)

what do you mean by "permeability" in this context?

as for the how the universe came to be, well I have my personal belief and it makes total sense to me while at the same time letting me understand what happened/ is happening now and before this universe began. and it involves no "god" what so ever.

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Well, this is not a rigorous definition. I wrote it so for illustrative purpose. here´s what I´m hinting at.

Note I said why, which is really different in the context of this discussion.

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What brings us together is stronger than what pulls us apart