Why does the light have a speed?

Let me put some "light" on that question ...

If "something" is thrown away, it starts to moves, and it's speed is proportional to the force we put in it. But for the light, it's not the same: if you put more energy in a source of light, you will produce more light... it's speed c remains the same... why?
More important why is it ~300 000km/sec?? I meam if the vacuum does slow down or block in some way the movement of the objet, why does the light have a (constant) speed???
My point of view on this is that the light is nothing else then "vibration" of the vacuum itself (as the sound in the air). Then it becomes more clear, the vibration propagate the energy(light) and the speed depends of the local "pressure"... the higher it is the higher the higher is light speed: the maximum is reach with the absence of matter.
So for my point of view, the vacuum is not "empty"... (ok, it sounds paradoxal, but maybe we shouldn't all it vacuum...).
What do you think? Does anyone have other explaination for the light speed?

The theory way back in the day, before Einstein, was that light propogated through space by means of something called the "ether". Basically, it was a kind of cosmic stuff that existed everywhere, and may have been the foundation of the universe. Light waves propogated through the ether.

However, if this were true, then if one were moving through the ether dependant on the light source, one would find the speed of light to be faster or slower depending on whether you were moving towards or away from the light source.

Some scientists did an experiment on this. Since the Earth doesn't travel in a perfect circle around the sun (but rather an oval, moving closer and then farther), they found when the earth was moving away from the sun, and when it moved towards the sun. They then did very precise experiments using the now famous Interferometre. They found that no matter where one was, the speed of light was always the same.

This is one of the reasons that light is such a perplexing subject - because it's not a normal kind of energy. In some respects its like a particle moving through space, and in other respects it's like a wave. They've found now that it's literally something "else" - something that's both a wave and a particle. Exactly how and why is unknown. I could venture a theory, but it'd almost certainly be wrong.

The theory way back in the day, before Einstein, was that light propogated through space by means of something called the "ether". Basically, it was a kind of cosmic stuff that existed everywhere, and may have been the foundation of the universe. Light waves propogated through the ether.

Ether Theory may be back, with a slight twist. Einstein came up with this one and then promptly rejected it due to Edwin Hubbles discovery that the Universe is expanding. It's called The Cosmological Constant and sounds quite a bit like the Ether that had Physists convinced of its existance.

[edit on 25-12-2005 by sardion2000]

Actually, the Cosmological Constant was a way for Einstein to try to make the universe "stable" - neither expanding or contracting - but rather at rest and unchanging. He rejected it, of course, calling it the biggest blunder of his life. However, the Cosmological Constant is now being looked at for it's possible implications in the so called "Vacuum Energy" theory (which is a terrible theory that, unfortunately, is recieving WAYY too much authority - it's basically "Hey, we can't account for missing energy or why the universe is expanding at an accelerating pace! Wait! I know! We'll invent Vacuum Energy - over huge distances everything pushes things away! It's like it works opposite to gravity! And look, if we do the numbers in a certain way, it kinda fills in the holes! Some duct-tape here and there... GREAT! I like it! Let's go!"

The theory way back in the day, before Einstein, was that light propogated through space by means of something called the "ether". Basically, it was a kind of cosmic stuff that existed everywhere, and may have been the foundation of the universe. Light waves propogated through the ether.

However, if this were true, then if one were moving through the ether dependant on the light source, one would find the speed of light to be faster or slower depending on whether you were moving towards or away from the light source.

Well, ancient were imagining a 3D world... Eisntein learned to all of us that space and time is the same thing: the 3 dimension of space can't be considered independetly of the time. This is a difficult exercise for the mind... but this is how he explain why the speed of the light is constant from any point of view.
So the "vacuum" is obviously not 3 dimensional but 4(or more)

Originally posted by Yarium
Actually, the Cosmological Constant was a way for Einstein to try to make the universe "stable" - neither expanding or contracting - but rather at rest and unchanging. He rejected it, of course, calling it the biggest blunder of his life. However, the Cosmological Constant is now being looked at for it's possible implications in the so called "Vacuum Energy" theory (which is a terrible theory that, unfortunately, is recieving WAYY too much authority - it's basically "Hey, we can't account for missing energy or why the universe is expanding at an accelerating pace! Wait! I know! We'll invent Vacuum Energy - over huge distances everything pushes things away! It's like it works opposite to gravity! And look, if we do the numbers in a certain way, it kinda fills in the holes! Some duct-tape here and there... GREAT! I like it! Let's go!"

I dont like the idea of vaccuum energy either. Do you know if scientists have found what accounts for all the missing mass? Last I heard many were just calling 'dark matter' and leaving it at that.

Light has speed because measurement of the frequency of the wave and the length of the wave are taken and multiplied to give the speed. This is how wave speeds are measured, I'm fairly sure. Usually appears as a lambda times v equals h formula.

Originally posted by TJ11240
I dont like the idea of vaccuum energy either. Do you know if scientists have found what accounts for all the missing mass? Last I heard many were just calling 'dark matter' and leaving it at that.

Well, it's good to have a supporter out there!

As for the missing mass, no scientists haven't quite filled it all in yet. Basically chopping most of it up to MACHOs and WIMPs - and the remainder to Vacuum Energy. I think that the calculations have failed to intigrate time as a variable, since area of the universe which have little mass would seem to expand faster since time in that area proceeds faster than in an area with mass. This might have a sense of "fooling" the calculations into thinking there's more energy than there actually is.

Originally posted by Frosty
Light has speed because measurement of the frequency of the wave and the length of the wave are taken and multiplied to give the speed. This is how wave speeds are measured, I'm fairly sure. Usually appears as a lambda times v equals h formula.

c=λ.f or in general v=λ.f: this is how we mesure the speed of a wave... it doesn't explain why it has that speed.
By the way, the wave nature of the light doesn't suppose that it needs a "support"? (Sound doesn't move in vacuum)

Originally posted by Lillo

Originally posted by Frosty
Light has speed because measurement of the frequency of the wave and the length of the wave are taken and multiplied to give the speed. This is how wave speeds are measured, I'm fairly sure. Usually appears as a lambda times v equals h formula.

c=λ.f or in general v=λ.f: this is how we mesure the speed of a wave... it doesn't explain why it has that speed.
By the way, the wave nature of the light doesn't suppose that it needs a "support"? (Sound doesn't move in vacuum)

Sound is the tranfers of Kenetic energy through the air.
Their is no air in vacuum. Thus there is no "sound" in a vacuum.
The idea of the Ether was that light needed a medium in which to travel.

If "something" is thrown away, it starts to moves, and it's speed is proportional to the force we put in it. But for the light, it's not the same: if you put more energy in a source of light, you will produce more light... it's speed c remains the same... why?

I think you just answered your own question, instead of speeding up the light the object produces more of it.

More important why is it ~300 000km/sec?? I meam if the vacuum does slow down or block in some way the movement of the objet, why does the light have a (constant) speed???

Light DOES NOT actually have a constant speed.
LIght move throuh vacuum at a constant speed because vacuum doesn't slow things down. So YOU would move through it at a cosntant speed as well, but becaue you are bigger than a photon you would eventually hit things like dust particles and so forth that would slow you down.)

Light moves slower through the air than it does through vacuum and slower through water than it does through air.

Recently they've even slowed it down to a few mile per hour in labs.

Light get's it's rather constant innitial velocity/speed from how it is produced.

Linky to site that explains how it is produced.

Originally posted by I_AM_that_I_AM

If "something" is thrown away, it starts to moves, and it's speed is proportional to the force we put in it. But for the light, it's not the same: if you put more energy in a source of light, you will produce more light... it's speed c remains the same... why?

I think you just answered your own question, instead of speeding up the light the object produces more of it.

In fact, this is a wave behavior...

Originally posted by I_AM_that_I_AM

More important why is it ~300 000km/sec?? I meam if the vacuum does slow down or block in some way the movement of the objet, why does the light have a (constant) speed???

Light DOES NOT actually have a constant speed.
LIght move throuh vacuum at a constant speed because vacuum doesn't slow things down.

In fact, since the vacuum doesn't slow things down, I would expect the light speed to be infinite! Do you get my point? Why 300.000Km/sec? Why not 10 times less or more? Since the vacuum has not effect on the things(if it is refered as empty), it shouldn't limit or better "regulate" the speed of the light in any way


[edit on 26/12/2005 by Lillo]

The answer to the question posed in this thread is answered through Maxwell's equations. Google it, look it up, read about it, whatever...take a closer look at the equations and ponder their meanings towards relativity. It's a thought process posed to physics students in upper level courses, such as physical mechanics.

Enjoy yourself

(I don't necessarily subscribe or not to the theories) but the key question about light velocity is usually said to be whether it's possible to travel faster than the nearly-300,000 MPS found experimentally in space, and not whether it can slow down in other media. Einseinian relativity requires constant light speed and impossibility of travelling faster than that, due to special relativity's basic postulate that all "frames" in space are inertially equivalent. Einstein came up with this in 1905, and proposed it as a model for the universe based on the comparatively new idea that an aetheric conducting medium doesn't exist, which had been the result of the way the famous Michelson-Morley experiment a decade and a half earlier had come out. So you can't exceed light speed because all the media traveled through behave the same relative to each other. Lorentzian relativity, proposed in 1904, is based on lorentz's retention of the concept of an aetheric conducting medium and ties that in with the concept that light speed varies according to gravitation, which of course varies according to where you are located, so Lorentzian relativity would theoretically allow for faster-than-observed-from-earth light-speed. It is presently claimed that the latest experimental evidence favors Lorentzian Relativity (LR) over Einsteinian Relativity (ER).

Originally posted by LilloIn fact, since the vacuum doesn't slow things down, I would expect the light speed to be infinite!

Except that would have to be producing an infinite amount of energy to get to infinite speed.
This would make solar power the only source of energy/fuel we ever needed.

From the Maxwell equation (Thanks Jesus ):
hyperphysics.phy-astr.gsu.edu...
I forgot about this... so the light speed is defined by the electrical property (permittivity and permeabilty) of the vacuum...
Then I would like to redefine my question, (guess how) but ok ok, I won't

No problem buddy. I am a physicist - if you want to redefine your question you can ask it here or U2U me...I'll see if I can answer your question.

Well ok... let's make a little comparison:
- the sound moves into the air at 340m/s, and into the water at a little less than 1500m/s. The speed of sound is determined by the density (ρ) and compressibility (β) of the medium which give v = (βρ)^-1/2
- these are measurable parameters given a specific medium.
- now the Maxwell equation states the same thing: with ε0 and μ0, which are the vacuum permitivity and the permeability of free space, we get c= (ε0.μ0)^-1/2
So, as the sound moves because of the physical characteristics of the medium, the light also moves because of the physical characteristics of the medium.
The question becomes: If the vacuum is "the absence of thing", how come that we give phisycal characteristics to this "nothing"?

ps:I guess this is what we mesured, we've been from mesurment to the theory, not from theorised values than confirmed by experiences....

Light is always created the same way with the same amount of energy. Therefore when light is created it is always moving at that speed.

Light is small enough that most any other considerations do not affect it.

I still beleive its possible to travel faster then light without warp drives etc. ( If we could ever tap that much energy)

We have observed several things moving faster then light already. That fact is normally brushed aside, but its still there. All I ask is that each person think through this issue and all issue's for themselves. Do not beleive someone or anyone because of who they are/were or what they have done.

Time after time even the most brilliant minds among humanity have been proven wrong. It is not because they were stupid or even because they overlooked something. Its simply because they didnt have all of the information. Once new information arrives which tells you what you beleive cannot be true you must abandon what you beleive. That goes for all things in life.

because we measured it.


300000km/s, is that because of the frequency? the higher the frequency the faster it spreads, not? me not knowing of, answer would be nice.


and is there any higher light? like one that can't be measured, one that is limitless, one that is everywhere at all times? the unmeasured!

The speed of light doesn't depend of its frequency: it is constant for all the frequency in given medium(the fastest is in vacuum).

For things traveling faster than light, the theory says it impossible. But somehow, there are experiments that seem to break this law.
For instance, if you send a single photo (required for the validity of the experience) on a semi-mirror, you get in output 2 twin photon going in different direction. The strange thing comes when we stop one of the two photon: the other one disapear also instantaneously! This should be impossible, so we are creating new theories to explain this (if you are insterested, look for "the elegant univers" or holografic univers)
Another similar experiment: we are able to "teleport" (startrek) the spin orientation of the particules also instantaneously...

ps: does anyone read my previous post?