Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum mass of photon

we will not trouble ourself with a useless question... when we find it. thats kind of hard to do. this one certainly is not useless.

Thank you; Pasti.

I never noticed before that you were member number 5!

Your example is very good and that is the sort of mind game I play when dealing with things I think are as yet worth further consideration. You know something of my simplistic manners so I will try what some of my betters referred to as a mental experiment. I will try to be brief.

My first conjecture is that the statement ?nothing can exceed the speed of light in a true vacuum,? implies that unhindered light has a fixed speed.
The next conjecture is why would light be limited in its speed unless the vacuum was a cause or the substance of light itself, the photon, was the cause. We know that a vacuum is not without hindrance because there are invisible gravitation concerns and electromagnetic factors but for this mental experiment we must conceive a totally benign vacuum that provides no impediment against light to reach its maximum potential.

All we have left at this point is the light consisting contribution by the source and the means by which it gets from here to there. To my simple way this means that a light source, photon/wave/particle or whatever is not the controlling factor because science tells us all photons travel within the same speed limit, in general, without regard to the size or the energy of the source. IF there is a universal limit on the speed of light, and I know of no proven explanation for same, then that fact should be found within the makeup of light/photons themselves.

I suspect that your use of intensity equates to my use of density. We know that not all sources of light will carry on as far as the most ?intense? or to me, the densest. The last conjecture is that light blasted off from a powerful source should gain speed constantly as it escapes the gravitational restraints close the source. Why would anything in our unique vacuum stop it or slow it down? If we have pure energy on the loose some thing must be draining some of that energy away to keep the photon from going faster.

So, I say it is the expansion of the photon as it travels from there to here with the demands of the extra energy being devoted to filling up ever increasing volumes of space providing a limit on the speed. That is why I am interested in the natural expansion of light photons.
Probably not very scientific but at least verbose.

jjw

Note, based on my view light condensed into a stream without permiting expansion should have no limit to its speed. Lasers get close but not enough of a squeese.

jjw

How about I take a perfect box filled of a perfect reflective material, and shoot into it a beam of light. I then close the box. The box doesn't move , and thus the system is stationary with concern to momentum. Will the box not gain a very small amount of mass?

Good question!

I believe that the answer to your question could be as follows: The light will be reflected between the walls to form standing waves; each standing wave is formed by two wave components moving with speed c (relative to the box) into opposite directions. The light waves thus still have kinetic energy which can be equated to mass. This will cause the weight of the box to increase. It thus seems as if the light under these conditions has a rest mass which adds to the total mass; however, light on its own do not have rest mass. It seems that in order for light energy to add to the mass of another material (like the box), the light has to be confined (as it is within the box). I believe that this is also what happens when light (a "photon") is absorbed by an atomic "electron". The incoming light-wave coalesces (entangles) with the electron-wave (orbital), becomes confined, and thus adds to the mass. The electron orbital then has to "morph" into a higher enery orbital; i.e. one with more mass.

there is already something close to this. its called a black hole device. basically its a cylinder that is as close to perfectly reflective inside. a beam of light enters though a small hole near in such a way that it bounces around the cylinder always going in a circle. since it cant get a angle to hit the hole without hiting a mirror that would bounce it back in, it has to keep going. unfortuantly i dont know alot of the test that were done with it.

jjw, I will post the reply to your post later, I am working on it.

dehammer:"there is already something close to this. its called a black hole device. basically its a cylinder that is as close to perfectly reflective inside."

dehammer, let's keep the terminology correct. The device you mention is not a black-hole device it is caled a black-body radiation device. The difference between this device and a black-hole cannot be emphasized enough.

In my time, the device was not a cylinder, but a sphere (for the obvious reasons), and it was called the Ulbricht sphere. It was used to determine the thermal distribution of the spectral density of the radiation emitted by an optical black-body,you know,the ~T^4 dependence of the spectral density, and similar.

This makes much more sense, and I know understand where you were coming from in your earlier posts. Confinement of the wave is possible due to its size, but would you say that this confinement is an entaglement of two waves, or a change of phase, or something altogether unrelated to the typical ideas of wave interaction?

Ive heard it referred to as a black hole device, as it allowed light to enter but not escape. the sphere did as the light would refract a little in all directions and would eventually bounce. back out. the cylander did not allow that, as if the light went in to a direction no alined with the hole, it would hit a wall and then hit the cylander again.

perhaps that was not its official name.

Hi all,

Been a bit busy the last few days - lost track of this thread. On looking it over a few things occur to me.

MBroderick brought up the idea of a container with perfectly reflection walls. This idea was original thought of by Adolfo Bartoli in 1876. He was arguing, from Maxwell's relatively new theory of electromagnetism, that light should exert a pressure. He imagined light trapped in a cylinder, with a piston at one end, all with perfectly reflecting walls. He used the second law of thermodynamics to deduce that the trapped light would and in fact must make a pressure. This pressure is not very big and it was not until about 1905 when Nichols and Hull and independently by Lebedev actually measured it.

The Bartoli Cylinder was again used by Boltzmann to derive Stefan's radiation law. This is the law that Pasti is quoting. It says that the total radiated power of a body at temperature T is gigen by the Stefan-Boltzmann law

P = sigma T^4

where P is power, sigma is called - what else - the Stefan-Boltzman constant and T is the absolute temperature.

The Bartoli cylinder was transformed into a sphere by Wilhelm Wien. He was studying the adiabatic compression of radiation with an eye toward finding a good radiation law. He was using a mostly thermodynamic arguement.

Now all these ideas were mere thought experiments. Richard Ulbricht (1849-1923) actually made what is called a spherical integrator that is a rigid version of a Wien sphere. This is normally used as a kind of radiation calorimeter or to provide a homogeneous isotropic light for test purposes.

By the way light does have inertia. In fact this is equivalent to E = mc^2. To see the derivation look at Max Born's book entitled "Atomic Physics". It is a Dover book so so it is easy to get. I would quote it here - because the derivation is easy and visilizable - but I have to runn off right at this moment.

Dr. R.

P.S. Made some small mods here.

I have come to the conclusion that waves can superpose to occupy the same region in space in two different ways: (i) normal superposition where the waves retain their identities and move through each other thus generating an interference pattern. I have termed this "enmeshment" of waves. The standing waves in the box you have proposed are enmeshed; i.e. they move through eacch other and generate a standing wave interference pattern. (ii) the second mechanism is what I will call "entanglement": in this case the two waves coalesce and totally lose their separate identies in order to form a wave with a new "single" identity; for example when two electrons form a covalent bond. I have extended this concept to the absorption of EM radiation by an atomic electron. The light wave entangles with the ground state orbital, thus increasing its mass energy to, in this way, force it to "morph" into a higher energy electron orbital. The result in this case is not just a superposition of the two waves, but the formation of a single (holistic) electron orbital with a higher energy. The original two wave identities disappear completely.

In the case of the box one can probably argue that the light also entangles with the box in order to generate another box with a higher energy. Nonetheless, inside the box the light waves do not entangle with each other, but enmesh to form standing waves. A thought just struck me: can one not copnsider the ground state electron orbital as a "box" within which the absorbed light forms standing waves after the orbital has morphed into a higher energy orbital?

Another aspect of differentiating between "enmeshment" and "entanglement" is a new possible explanation for the EPR experiment. When two electrons entangle, they form a single holistic wave eintity with spin zero. When a spin measurement is subsequently made, the wave has to decompose into two entities, each being an electron wave: this has to occur so that the spins are opposite; however, after disentanglement the holistic wave with spin zero does not exist anymore, so that the two electrons cannot communicate with each other faster than light speed anymore. So I believe Einstein was correct: two "particles" cannot communicate faster than light speed; but a single holistic wave can be in immediate contact with itself over the whole region of space that it occupies.

On June 6 I made a reply to Pasti and I want to follow up on that poinr here. My view is simply a conjecture on my part arrived at a long time ago but voiced only recently. I search the Web a little to see what some others may have said about a cause for a limit on the speed of light and I was surpized at complex it can get.

http://users.bestweb.net/~jond4u/slolight.htm

This gentlemen covers the Universe when he might have said simply that the expansion of the photon filling up volumns of space may account for the limit on the sped of light. That does not mean either one of us are correct but it is interesting to me to see different approaches.
jjw

Frankly Sir I do not wish to elaborate right now but to me it appears that there is no limit on max Speed...and information can be carried at any speed but nature and form of the information spread changes.

Frankly to you dkv!

Did you mean speed instead of "spread".

Any way we, right now, do not know if some distant Galaxy is sending light to us that is traveling on its way faster than the speed of light we measure in this locale. We do know that Einstein and about all academics contend that there is a limit to the speed of light and use the measure we make here as a likely limit.

You appear to be talking about something else as if the "information form" or their "nature" is a factor and you lost me there. Any way it is nice to hear from you again.
jjw

dkv, can you back this statement up with some research results? I'm sure many people would like to know how to go faster than light speed.

No Sir.

Let us understand the nature of Information itself...
Please note every information can not be transmitted...
Let me give you an example...
We know that we humans are composed of Conscious and Unconscious thoughts....
Concious thoughts read what is being read ....
Unconscious thought reads what is not being read..
When visit a beautiful place we see large mountains ,flowers , good air , rivers ..etc and we say it feels good ...
somehow we feel beyond our conscious mind can observe...
Similary the same feeling comes when we a vast sea.. or look at the vast sky... or see a village wihout any obstructions...
Similarly as you read what I write .. you read more than what I read.. it is very personal..
This information came to you even before I posted anything...
Thats how speed barrier gets broken.
Now let me ask you the same question I asked in Evolution of Physics Debate..
Does the Information depends on the number of Observers Invovled...?
Greater the number observers greater is the instability of truth..
This is my principle of Uncertainity of Consciousness...
Now please do not delete it...
Trust me .. it wont hurt..
Thank you so much.

Thank you dvk for this wonderful treatise on the value of psychotherapy.

Please seek support from a competent psychiatrist.

One more time, please stick to Science and Science related topics. Your attempts to derail this discussion have been noted. If you persist in posting this sort of metaphysical crap I will start deleting your posts. You have been warned.

Amaranth
Moderator

Mass of the photon as predicted by QED is zero.
Current experimental measurements on the mass of the photon put an upper limit to 6*10^-17 eV.
Only massless particles can travel at c.
No massive particle (m>0) can travel at c.
Hope that this settles it.

The correct relationship is:

E^2=(mc^2)^2+(pc)^2

For photon m=0, therefore E=pc.

Do not use E=mc^2, it is an incomplete relationship.