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Author Topic: How The Photon Direction Is Determined When Its Born?  (Read 9996 times)

Offline sciconoclast

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #25 on: 26/03/2013 20:06:16 »
Glad to hear it.
                          I also do not accept non-locality and quantum filed collapse.  Some time ago when I posted experiments that challenged non-locality they were sent to the new theory dungeon. The video I just listed in new theory contains some of these that anybody can perform.

I think the dots are connected but not by anything that is in our conceptual experience.  My thought is that the same phenomena is responsible for the illusions that we perceive as matter, energy, space, time, etc..  Presently math is the only language with which we describe this process.

I feel obligated to correct people when they think that Bohr was describing real waves.  Otherwise they will not understand why some very prominent physicist refer to it as voodoo physics.

I am getting off the original topic.  If anyone is willing to accept the orthodox, or Bohr, view of light they cannot have photons with directional propagation through space.
 

Offline yor_on

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #26 on: 27/03/2013 15:45:19 »
To me it goes back to a duality. And I think it is a 'real' duality. I do not expect it to be waves giving us excitations, although you gave me a very competent description. Neither do I expect it to be ping pong balls, although I still would like that concept better :) And I agree JP, it's not intuitive. But it should be, if we find the right description.
 

Offline yor_on

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #27 on: 27/03/2013 15:50:44 »
My point, if I now have one :) is that if one accept a duality then it's high time to find out from what that would come. If one stops at one of the descriptions, then?
=

One reason why Lightarrows description was interesting to me is just that, it's a duality. But a photon do not have a momentum in his description, although you can refer to it as a idealized fock state in where a presumption is just that directionality.

But if you allow a 'photon' to exist, as it comes to be measured, then you don't need directions. Instead you need relations, and that's also why I wondered about if the amount might be what gives a direction. The other case is our 'ping pong ball' bouncing, which can't be correct if the direction is unspecified experimentally.

So, is it?
« Last Edit: 27/03/2013 15:57:01 by yor_on »
 

Offline Pincho

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #28 on: 27/03/2013 20:00:42 »
I would go with the Spin Spin...

http://www.sciencemag.org/content/339/6122/928.abstract

Using spacetime as a spin locator, and the photon with it own spin sitting in a spin locator, so that's just like pointing an invisible gun of Dark Matter. Spin Spin. It would use the area of least resistance per C cycle. Sort of like Dandelion seeds. I always go with the simplest idea, because the Universe is always supposed to go with the simplest idea.
« Last Edit: 27/03/2013 20:02:56 by Pincho »
 

Offline Pmb

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #29 on: 27/03/2013 21:30:22 »
Nicely put Pete.

What about a atom getting hit by a photon annihilating in the collision, emitting a new one. Will that one also have a unspecified direction until measured? (Btw, not directed to Pete but to you all)
No. The photon must be in the same direction and have the same energy, and hence the same momentum, in order to conserve momentum. That's how laser works.
« Last Edit: 27/03/2013 21:32:13 by Pmb »
 

Offline lightarrow

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #30 on: 28/03/2013 12:48:36 »

No. The photon must be in the same direction and have the same energy, and hence the same momentum, in order to conserve momentum.
Don't understand why: after having absorbed the photon, the atom recoils, taking the photon's momentum and this conserves it. Then the atom can emit a subsequent photon in any other direction or in all of them simultaneously (as a spherical wave) and as a consequence it will recoil again accordingly.
« Last Edit: 28/03/2013 12:50:24 by lightarrow »
 

Offline JP

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #31 on: 28/03/2013 14:29:42 »
Nicely put Pete.

What about a atom getting hit by a photon annihilating in the collision, emitting a new one. Will that one also have a unspecified direction until measured? (Btw, not directed to Pete but to you all)
No. The photon must be in the same direction and have the same energy, and hence the same momentum, in order to conserve momentum. That's how laser works.

No, Pmb, a laser works because of one particular type of emission of photons called stimulated emission.  This requires that a background EM field is present when the atom emits a photon, and that background field causes the atom to emit photons identical to those making up the background field. 

More commonly, atoms emit through spontaneous emission, which is random in direction, and is what Lightarrow described. 
 

Offline Pmb

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #32 on: 28/03/2013 16:34:34 »
Quote from: JP
No, Pmb, a laser works because of one particular type of emission of photons called stimulated emission.  This requires that a background EM field is present when the atom emits a photon, and that background field causes the atom to emit photons identical to those making up the background field. 
What you and Lightarrow spoke of is spontaneous emission where the incident photon does not match one of the excited states of the atom. I was referring to stimulated emission. The background EM field you speak of is in the form of photons. I just looked it up to be sure. From Modern Physics - Fourth Edition by Paul A. Tipler and Ralph A. Llewellyn, page 419
Quote
Called stimulated emission, its probability of stimulated emission per atom pr unit time (transition rate) can be written B21u(f), where B21 is called Einstein's coefficient of emission. In this process the electric field of an incident photon with energy hf equal to the energy difference E2 - E1 ... stimulates the atom or molecule in state 2 to emit a photon with energy E2 - E1 = hf which is propagated in the same drection and with the same phase as the incident photon. Such photons (or radiation) is called coherent.
« Last Edit: 28/03/2013 16:58:01 by Pmb »
 

Offline Pmb

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #33 on: 28/03/2013 17:06:43 »

No. The photon must be in the same direction and have the same energy, and hence the same momentum, in order to conserve momentum.
Don't understand why: after having absorbed the photon, the atom recoils, taking the photon's momentum and this conserves it. Then the atom can emit a subsequent photon in any other direction or in all of them simultaneously (as a spherical wave) and as a consequence it will recoil again accordingly.

What I said was incomplete. See above.
 

Offline yor_on

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #34 on: 29/03/2013 09:36:26 »
So, can you have a setting in where something gets its direction by the amount around it? Not referring to photons, just trying to see in what way such a thing could be possible? On the other tentacle, in my mind it seems to either have to with waves interacting, quenching and reinforcing, or with momentum(s), if we now assume that a wave have a momentum?

Because there is a momentum, as shown by Pete's idea about a laser?
And yes, I'm slightly bicycling.
 

Offline JP

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #35 on: 29/03/2013 11:45:31 »
Both photons and waves have momentum.  A monochromatic plane wave has a precise momentum and is made up of photons which each have precise momenta.

In other words, a classical plane wave and the photons making it up have fixed frequencies and are moving in a precise direction, giving them a precise momentum.
« Last Edit: 29/03/2013 11:51:29 by JP »
 

Offline acsinuk

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #36 on: 31/03/2013 18:57:46 »
Yes, JP the spontaneous emission of a photon follows the background EM direction. Agreed; but what if that EM direction is created in a star where the magnetization is backwards because the stars environment have positron shells instead of the normal  negative electron shells?
So I think that a stars photons look identical BUT are exact opposites magnetically and electrically thus can annihilate each other. If we fire a earth formed photon into the sun it will annihilate the stars photon and only the momentum energy will remain.
Happy Easter
CliveS
 

Offline Pincho

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #37 on: 31/03/2013 19:19:32 »
Yes, JP the spontaneous emission of a photon follows the background EM direction. Agreed; but what if that EM direction is created in a star where the magnetization is backwards because the stars environment have positron shells instead of the normal  negative electron shells?
So I think that a stars photons look identical BUT are exact opposites magnetically and electrically thus can annihilate each other. If we fire a earth formed photon into the sun it will annihilate the stars photon and only the momentum energy will remain.
Happy Easter
CliveS

You need to picture what you are calling a shell. The sun has photons that hit us all of the time. I do actually feel that you have thought it through, and got confused by the electron mainly.
 

Offline imatfaal

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #38 on: 31/03/2013 20:58:40 »
Clive - please keep on topic and leave the speculations to the New Theories board
 

Offline yor_on

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #39 on: 09/04/2013 03:15:30 »
But then we have this.

"it's interference between the different atoms that a photon is absorbed by then re-emitted that makes photons keep going the same direction in glass. It's not that an individual atom absorbs a photon and them re-emits it in the same direction; you can see this because only the interference between different atoms would lead to Snell's law of refraction. I believe Feynman has an excellent explanation of this in his book QED, which I highly recommend as an elementary presentation of quantum mechanics. Peter Shor "

Which is exactly what I was thinking of.
=

although, rethinking it :) It's a wave picture he presents here, calling it photons. But if it is possible to define it such from waves, then there should be some equivalent explanation treating it as 'particles', or maybe not? It is after all a 'duality'.
« Last Edit: 09/04/2013 03:18:30 by yor_on »
 

Offline evan_au

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #40 on: 09/04/2013 11:35:51 »
Quote
stars [with] positron shells instead of the normal  negative electron shells?
Recent experiments with antiHydrogen suggest that it produces photons with the same spectrum as normal hydrogen.
If the Sun were made of antiHydrogen = positron circling an antiproton, the solar wind would be made of antiHydrogen, and Earth's Aurora would be far more spectacular, as positrons and antiprotons annihilate in the upper atmosphere.
The same would occur for other stars whose antimatter solar wind was interacting with the matter-based galactic medium, bathing the galaxy in a glow of gamma rays - which is not seen.
It is a long-term mystery why the universe we live in seems to be made mostly of matter, but astronomers are convinced that antimatter is not common in our galaxy.

Quote
So I think that a stars photons look identical BUT are exact opposites magnetically and electrically thus can annihilate each other.

The photon is its own antiparticle, so photons produced by normal matter can annihilate each other if they have sufficient energy. They don't need to originate in atoms and anti-atoms.
 

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Re: How The Photon Direction Is Determined When Its Born?
« Reply #40 on: 09/04/2013 11:35:51 »

 

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