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Photons lost in space

CrossHair

Thinker
CrossHair
Joined
Mar 5, 2004
Messages
156
Just a quick dumb question for those Physics minds in-the-know.

All of the billions and billions of stars are emitting light, and other, energy constantly and continously (for the most part). Some of this we receive here on our nice planet earth. Obviously most of this tremendous amount of energy we never receive but is traveling to all of the other stars and planets in the Universe. What effect does all of this energy traveling or "photons lost in space" have on current theories of the Universe or does it not count much because it has no mass?
 
In an attempt to address your anything-but-dumb question, at the easy level, if massless photons hadn't done what they have done over the last 14 billion yrs +-, and continue to do today, we wouldn't be discussing things.

At the other level, someone conversant with, say, supersymmetry could help with the big picture; quantum electrodynamics math would assist in more mundane matters.

And I could be wrong ... :)
 
The first thought that comes to mind is a consideration of Richard Feynman's transactional interpretation of quantum mechanics. Specificaly the point that no photon can depart from an electron unless it knows that it will be 'caught' by another electron at the 'end' of it's journey. If there is no electron in to catch it in a particular direction -- no photon will every be emmited in that direction.

This makes the universe a closed system where no photons are 'lost'.
 
That's an interesting thought Molinaro, however I just can't accept that is true. Sounds as if electrons should apply for Randi's millions dollars if they always know that the photon will always be captured or else they will not emit them! ;)

If it is true then I ask if Richard defined any time limit from emition to reception? In the mean time, with all of those photons floating around the Universe looking for a place to land my original querry still stands.

I suppose my question may not be dumb but I am asking it in a dumb way because I just don't know a better way to ask. It just seems as if there is a tremendous amount of energy that we don't see when we look into space, but it is there nontheless. It has no mass but once it lands it will have an effect. Is it having any effect on the grand scheme of the Universe without landing on anything?
 
Molinaro said:
The first thought that comes to mind is a consideration of Richard Feynman's transactional interpretation of quantum mechanics. Specificaly the point that no photon can depart from an electron unless it knows that it will be 'caught' by another electron at the 'end' of it's journey. If there is no electron in to catch it in a particular direction -- no photon will every be emmited in that direction.

This makes the universe a closed system where no photons are 'lost'.
Click to expand...

I think that only applies to virtual photons, which are mediating the electric force. Other photons can be generated for all sorts of reasons, like when a particle/antiparticle collide.
 
Actualy it aplies to all photons. The mathematics that you get from this interpretation is identical to the Copenhagen interpretation and that governs all photons.

It goes like this...

When a photon is emited, it actualy radiates sphericaly through time AND space. That is to say, a portion of the photon travels forward in time while another portion travels backwards. The forward seeking portion of the photon is actualy 1/2 of the wave that an observer would see. This photon travels until it hits another electron. At that time, the 1/2 photon reflects backward -- in time -- along the same physical path back to the emiting electron. It also continues on forward.. but more on that in a moment.
Since the outgoing 1/2 wave follows the same path as the reflected 1/2 wave, and they are both going at C, an observer only sees their constructive interference that is seen to be traveling forward in time as a 1/2 + 1/2 = 1 wave of the photon.
When the backward traveling 1/2 wave reaches the emiting electron it continues back in time. This backward traveling 1/2 wave will then be creating destructive interference with the original backward traveling 1/2 wave from the emiter. A similar destructive interference occurs at the reciever. It consists of the original 1/2 forward traveling wave from the emiter, and the newly created 1/2 wave traveling forward from the receiver. As the receiver also creates a pair of 1/2 waves at the reflection event. One traveling back in time the other forward.
The net result is that the constructive interference only occurs between the emiter and the receiver and a whole wave is only ever observed traveling forward in time from emiter to receiver, at a speed of C.

Interestingly, from the point of view of the photon, it exists as a standing wave extending between the 2 electrons -- instantaneously -- since the journey takes 0 time when moving at a speed of C. This also leads to the view that it is the electrons reflecting back and forth, in time, off of the static photons.

I find this interpretation much more pleasing than the collapsing probability waves of the Copenhagen interpretation. It also has the pleasing effect of offering a much simpler interpretation of the Aspect experiment without requiring any paradox involving foreknowledge of the layout of the experiment by the photon. It also negates the need for an observer.

The photon, sends out a 'sphere' of 1/2 waves in all directions (forward and backward in time), and the one following the most probable path (path of lowest energy) is the only one that reflects back along that one path to re-enforce itself and instantiate that path as the true path followed by the photon.

Hence, a photon will only be emited if it 'knows' that it will be caught.


Now, as far as my own ideas go.. I think if this realy is what is going on, the momentary constructive and destructive interference of differing source photons that would momentarily occur throughout all of space could play a role in the source of the creation/destruction of virtual particles. But that's just a guess.
 
I probably misunderstand this topic, but that's not going to stop me from asking a question:

If only the photons that will get caught are ever emmitted, doesn't this affect the energy output of stars?

By this I mean, we calculate the amount of energy that a star generates and we assume it sends out this energy in a reasonably uniform sphere, but if only those paths that ends up in another particle the photon can be absorbed by, actually get a photon, this means that we observe a disproportionately large part of the photons emmitted by e.g. the Sun. The "sphere" of light emmitted isn't a sphere but rather a porcupine.

If this is correct, the stars emmit a lot less energy then previously thought, and this would make some drastic changes to some theories.


Mosquito - waiting for the "lies to children" that will confuse me into comfort on this subject.
 
If the undetected photon (probability wave?) radiates spherically, then it will inevitably be intercepted eventually.

No?
 
When I talked about the spherical spread I was not refering to a collection of photons, but rather an individual photon -- or better yet -- each individual photon.

The photons, who appear as both particle and wave to us, are actualy the moving region of intersection of the 2 wavefronts. One is moving forward in time, the other backwards. From both the emmission and absorption points the 2 waves emminate, and their points of intersection along the path of least energy is that which we see as a photon moving forward in time at C. Everywhere else off that path the waves combine destructively and nothing is measured -- within the limits of the uncertainty principle.
 
What if there are two points in the sphere that are equidistant from the photon? Does it split into two and each electron gets half the energy? Is another photon spontaneously converted in the same spot to go off to the alternate destination?
 
I don't mean to say anything more than that if a photon is observed, that photon is part of a triplet consisting of emmision, travel, and absorption. I am not saying anything about why it left. For those emiting and absorbing electrons, the path of least energy between them is the one the photon will have been observed to travel.

The single event of the emission of a single photon involves the shere expanding out from the electron -- in space and in time. When that intersects an electron who will absorbe it, at some point in the future, another is then emmited from that second electron. The backwards traveling portion of it's emission reinforces the orginal event's forward traveling wave along the path of least energy. Elsewhere they cancel. Because elsewhere they cancel at every point in time as well, there is no oportunity available for any other 3rd party electron to have absorbed it instead.
 
Molinaro said:
The first thought that comes to mind is a consideration of Richard Feynman's transactional interpretation of quantum mechanics. Specificaly the point that no photon can depart from an electron unless it knows that it will be 'caught' by another electron at the 'end' of it's journey. If there is no electron in to catch it in a particular direction -- no photon will every be emmited in that direction.

This makes the universe a closed system where no photons are 'lost'.
Click to expand...

That was John C. Cramer, not Feynman. Look here for the entire paper:
www.npl.washington.edu/tiqm/TI_toc.html

Basically, it's a time thingy. A photon is not emitted from an electron until it receives a "handshake" from it's future ineraction partner. Good reading.
 
OK, so from a this QM perspective of photons, there are no such things as "photons lost in space" because if they are not ultimately captured then they are not emitted. It still sounds as if the emitting electrons should apply for the million dollar prize as the description of the process involves time travel backwards ;)
 
The idea that they should not be emitted unless known to be absorbed sounds absolutely absurd (but so do other things in QM). But how does an electron "know" anything? An electron is an electron is an electron. How can an electron contain information if it is supposed to be identical to all other electrons (down, Kumar, down!)?

Now, this may be a stupid answer, but isn't it that those photons that have been emitted and have not been absorbed are simply still out there someplace? They are just racing on into the infinite. And since there is matter distributed in the universe, and it is infinite, then they will hit matter, sooner or later.

Hans
 
John Bentley said:
That was John C. Cramer, not Feynman. Look here for the entire paper:

[EDIT)
**URL removed since I can't post them yet**
[/EDIT]

Basically, it's a time thingy. A photon is not emitted from an electron until it receives a "handshake" from it's future ineraction partner. Good reading.
Click to expand...


From your link:

"The basic element of TI is the transaction describing a quantum event as an exchange of advanced and retarded waves, as implied by the work of Wheeler and Feynman, Dirac, and others."

Feynman is the one who started it all, others expanded on it. Cramer is the guy given credit for the theory as it stands under the name Transactional Interpretation.

I always think of it as Feynman's... personal prejudice I guess.. since he's my favorite!
 
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CrossHair said:
OK, so from a this QM perspective of photons, there are no such things as "photons lost in space" because if they are not ultimately captured then they are not emitted. It still sounds as if the emitting electrons should apply for the million dollar prize as the description of the process involves time travel backwards ;)
Click to expand...


The math in all other interpretations of QM have already suggested negative energy and negative momentum solutions to the equations that have up to now simply been discarded and ignored as being not part of reality. In their place, for example in the Copenhagen interpretation, it is said that a probability wave expands out from the emmiting electron. That probability wave is said to have no physical substance or energy to it. That is not exactly a more realistic view.

Instead, in the Transactional interpretation, the emmiting electron sends out 2 'real' fields of energy.. one forward and one backward in time. The forward seeking field upon interacting with a receiving electron will cause it to emit it's own pair of forward and backwards seeking fields.

There is no advance knowledge needed by the emitting electron because the backward traveling field from the receiver arrives at the EXACT MOMENT of emmission! It is that receipt of a 'handshake' that allows that moment of emmission to take place in the 1st place.
 
Molinaro said:
From your link:

"The basic element of TI is the transaction describing a quantum event as an exchange of advanced and retarded waves, as implied by the work of Wheeler and Feynman, Dirac, and others."

Feynman is the one who started it all, others expanded on it. Cramer is the guy given credit for the theory as it stands under the name Transactional Interpretation.

I always think of it as Feynman's... personal prejudice I guess.. since he's my favorite!
Click to expand...

Well, of course! Isn't he everyones? But IIRC Feynman's work showed that retarded waves (hard to even write that without smiling) were accounted for and predicted by the math, but Feynman didn't pursue that aspect precisely because it would mean that waves were travelling backward in time. I could be wrong about that, it has been a long time since I read about it.
 
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