THE SPEED OF LIGHT CAN BE EXCEEDED! Fuckn' hell!

[FBM]

Everything I need to know about physics...I haven't learned yet.

Photon numbers aren't conserved, so what XC is saying seems right on target. A molecule doesn't require stimulation in order to give off photons, IIRC. It's kinda like the way the numbers of sound or water waves aren't conserved. Having more or less of them doesn't change the total energy of the system.

[Xamonas Chegwé]

Everything I need to know about physics...I haven't learned yet.

Photon numbers aren't conserved, so what XC is saying seems right on target. A molecule doesn't require stimulation in order to give off photons, IIRC. It's kinda like the way the numbers of sound or water waves aren't conserved. Having more or less of them doesn't change the total energy of the system.

A molecule doesn't require stimulation to give off a photon but it does lose energy when it does so. Just as it gains energy when it absorbs one. But really, matter and energy are two forms of the same stuff, so all that is happening is that stuff is squidging into different thingies - sorta!

[laklak]

so all that is happening is that stuff is squidging into different thingies - sorta!

You should consider a career as a uni lecturer XC, you have such a way of explaining complex ideas in a clear and concise manner.

[Xamonas Chegwé]

so all that is happening is that stuff is squidging into different thingies - sorta!

You should consider a career as a uni lecturer XC, you have such a way of explaining complex ideas in a clear and concise manner.

Reading more on this, it appears that the phenomenon has been noticed before but was written off as an experimental error! There are talks of extra dimensions and string theory creeping in. The implication being that neutrinos still travel at c but they have found a shortcut through dimensions that we don't normally experience!

Expect more brains to be boggled by this for quite some time!

[Seth]

Nah, God's just fucking with CERN for fucking with the universe and threatening to create a black hole that will eat up His Creation(s).

[Seth]

Confusing. I'm sure I heard or read one of these 'factoids' somewhere that a bout 4 Kg of light falls on the earth each year. Maybe I dreamed it or something.

(in fact they cannot do anything BUT travel at the speed of light!......)

I believe light has been measured (presumably through a medium) at speeds as low as 30-something mph. Weird.


Edit:- Just realised that we've kinda been here before...
http://rationalia.com/forum/viewtopic.p ... it=+photon

Light travels slower through different media - but not really!

In a vacuum, light travels at c and only at c. However, through air, photons hop from molecule to molecule - A photon travels through the vacuum between molecules until it collides and is absorbed - after that, the most likely event (although not the only possible event) is that the energy of the photon is released as another photon, travelling in the same direction as the first. Molecules are pretty sparsely spaced in air, so there is not a great deal of absorption and re-emitting going on, but there is enough to slow down the speed of light in air. In water, the molecules are much more closely packed, so light travels much slower. In glass, they are more closely packed still. BUT, the speed that the photon travels through the vacuum between the molecules is ALWAYS c - the extra time is taken up by the photon's energy being transformed into a higher electron state within matter and then retransformed back into a photon.

I am not sure about the "weight" of light falling upon Earth. i think this may have something to do with conservation of momentum but I need to go look at some books!

Thanks for that very cogent description. So how does that explain the different colors (frequencies) of light we see when light is refracted through a prism?

[Pensioner]

Confusing. I'm sure I heard or read one of these 'factoids' somewhere that a bout 4 Kg of light falls on the earth each year. Maybe I dreamed it or something.

(in fact they cannot do anything BUT travel at the speed of light!......)

I believe light has been measured (presumably through a medium) at speeds as low as 30-something mph. Weird.


Edit:- Just realised that we've kinda been here before...
http://rationalia.com/forum/viewtopic.p ... it=+photon

Light travels slower through different media - but not really!

In a vacuum, light travels at c and only at c. However, through air, photons hop from molecule to molecule - A photon travels through the vacuum between molecules until it collides and is absorbed - after that, the most likely event (although not the only possible event) is that the energy of the photon is released as another photon, travelling in the same direction as the first. Molecules are pretty sparsely spaced in air, so there is not a great deal of absorption and re-emitting going on, but there is enough to slow down the speed of light in air. In water, the molecules are much more closely packed, so light travels much slower. In glass, they are more closely packed still. BUT, the speed that the photon travels through the vacuum between the molecules is ALWAYS c - the extra time is taken up by the photon's energy being transformed into a higher electron state within matter and then retransformed back into a photon.

I am not sure about the "weight" of light falling upon Earth. i think this may have something to do with conservation of momentum but I need to go look at some books!

Thanks for that very cogent description. So how does that explain the different colors (frequencies) of light we see when light is refracted through a prism?

Something to do with different wave lengths

[MiM]

Confusing. I'm sure I heard or read one of these 'factoids' somewhere that a bout 4 Kg of light falls on the earth each year. Maybe I dreamed it or something.

Could that have been 2kg/s? Then it would be the mass equivalence of the energy that reaches the Earth from the Sun in one second (174 PJ), as calculated by E=mc2

And the equation that shows (in layman terms) that nothing that has a rest mass can reach the speed of light has a slightly more complicated form. It is the formula for the mass of a particle in motion:
E=gmc2, where g (or gamma or the Lorenz factor) is given by
g = 1 / sqrt(1-(v/c)2)

In this formula we find the factor (1- (v/c)2), in the denominator, which reaches 0 when v reaches c. And when this reaches 0, g reaches infinity, and then also the energy reaches infinity. Photons are not influenced by this problem, because, as XC pointed out, their rest mass (m) is 0, so g*m becomes 0/0, which is undefined, and this formula is then not applicable.

[JacksSmirkingRevenge]

Could that have been 2kg/s?

Quite possibly, yes.

I'll have to come back to the rest of this. - I have yet to read through and take in any more of Schneibster's epic post a while ago.

[JimC]

Seth wrote:

Thanks for that very cogent description. So how does that explain the different colors (frequencies) of light we see when light is refracted through a prism?

The different frequencies of light are slowed by slightly different amounts as they go from air into glass, for example. The higher the frequency, the more light is slowed. When a photon of light passes through a surface at any other angle than perpendicular, its path is also bent, to a precise angle depending on how much it vas slowed. A photon of violet light slows more, and therefore bends more than a photon of red light. A prism bends light twice, in the same direction; once entering, and once again as it leaves. Hence the effect called dispersion, the seperation of white light into a "rainbow" as it passes through a glass prism.

I suspect that the deeper reason for the differential slowing effect is that higher frequencies have a greater interaction with the electric fields around the atoms of a material such as glass.

[Seth]

Seth wrote:

Thanks for that very cogent description. So how does that explain the different colors (frequencies) of light we see when light is refracted through a prism?

The different frequencies of light are slowed by slightly different amounts as they go from air into glass, for example. The higher the frequency, the more light is slowed. When a photon of light passes through a surface at any other angle than perpendicular, its path is also bent, to a precise angle depending on how much it vas slowed. A photon of violet light slows more, and therefore bends more than a photon of red light. A prism bends light twice, in the same direction; once entering, and once again as it leaves. Hence the effect called dispersion, the seperation of white light into a "rainbow" as it passes through a glass prism.

I suspect that the deeper reason for the differential slowing effect is that higher frequencies have a greater interaction with the electric fields around the atoms of a material such as glass.

Okay, so this conflicts with what MiM wrote, that photons do not "slow down" at all, they still travel at C between atoms in the glass, and are absorbed and reemitted at each atom.

I'd always heard that light "slowed" in different media, which is why we get refraction and why lenses work, but I've always wondered why, if light can "slow down" why C is a universal constant?

If light can be slowed down, in theory then, we should be able to slow a photon down to zero velocity and observe it. Has this ever been accomplished? Or is there something else going on? Does a photon have a vibrational frequency (color) in addition to a velocity perhaps? It would make sense that a photon traveling always at C, when it's absorbed by an atom in glass and then reemitted, would lose some energy in the transaction, and thus be vibrating at a different (slower) rate. Is this correct?

[Thinking Aloud]

The constant c refers to the speed of light in a vacuum. That's all there is to it. The speed light travels at in other materials is not c.

[Seth]

The constant c refers to the speed of light in a vacuum. That's all there is to it. The speed light travels at in other materials is not c.

Thanks. That clears it up.

[MiM]

Okay, so this conflicts with what MiM wrote, that photons do not "slow down" at all, they still travel at C between atoms in the glass, and are absorbed and reemitted at each atom.

I think it was XC who wrote that. I believe that there is quite a lot of inexactness in what XC has written here about why the speed of light in a medium is slower than c.

The constant c refers to the speed of light in a vacuum. That's all there is to it. The speed light travels at in other materials is not c.

And furthermore particles can move faster in a medium than light moves in the same medium. This is actually quite common, and lies behind phenomena like the Cherenkov radiation, the blue light that can be seen around nuclear fuel in water.

[JimC]

Seth wrote:

Thanks for that very cogent description. So how does that explain the different colors (frequencies) of light we see when light is refracted through a prism?

The different frequencies of light are slowed by slightly different amounts as they go from air into glass, for example. The higher the frequency, the more light is slowed. When a photon of light passes through a surface at any other angle than perpendicular, its path is also bent, to a precise angle depending on how much it vas slowed. A photon of violet light slows more, and therefore bends more than a photon of red light. A prism bends light twice, in the same direction; once entering, and once again as it leaves. Hence the effect called dispersion, the seperation of white light into a "rainbow" as it passes through a glass prism.

I suspect that the deeper reason for the differential slowing effect is that higher frequencies have a greater interaction with the electric fields around the atoms of a material such as glass.

Okay, so this conflicts with what MiM wrote, that photons do not "slow down" at all, they still travel at C between atoms in the glass, and are absorbed and reemitted at each atom.

I'd always heard that light "slowed" in different media, which is why we get refraction and why lenses work, but I've always wondered why, if light can "slow down" why C is a universal constant?

If light can be slowed down, in theory then, we should be able to slow a photon down to zero velocity and observe it. Has this ever been accomplished? Or is there something else going on? Does a photon have a vibrational frequency (color) in addition to a velocity perhaps? It would make sense that a photon traveling always at C, when it's absorbed by an atom in glass and then reemitted, would lose some energy in the transaction, and thus be vibrating at a different (slower) rate. Is this correct?

1. I think it was Xamonas... However, even if that picture is accurate (and I'm not completely sure it is) it still represents a considerable overall reduction in average speed, which is all that is required to generate a bending, by a well known principle in Physics called least effort.

2. The material which slows down light the most (to about 40% c) is diamond. As far as I'm aware this is as slow as it gets.

3. c is a universal constant because it represents the maximum speed that light can attain, which happens to occur in a vacuum. Until these recent results raised questions, it was regarded as an unapproachable asymmptotic limit of speed for anything...