Let There Be Light

[hazelm]

from the heavens.  It must be great fun to play with things like this.  Imagine the feeling of power to squeeze light from empty space.  Or is it a feeling of humility?  Probably depends on the person doing it.

 

https://www.sciencemag.org/news/2019/03/physicists-predict-way-squeeze-light-vacuum-empty-space?utm_campaign=news_daily_2019-03-29&et_rid=432455128&et_cid=2741682

[exchemist]

To save readers a bit of time, what this is about is the idea that under an extremely strong magnetic field the virtual particles that have transient existence in vacuum fluctuations can be polarised, generating a polarisation of empty space that can act like a medium and slow down the phase velocity of light.

 

The prediction is that one could theoretically produce Cerenkov radiation from very fast charged particles travelling through this "medium".  The first problem is that, as any physicist will realise, a charged particle in a magnetic field is forced into a curved path, i.e. accelerating, and will emit synchrotron radiation anyway. So any Cerenkov radiation would have to be distinguished from that. The second problem is that (of course) the predicted effect is tiny, slowing the phase velocity by a millionth of a %. So the particles will have to be travelling amazingly close to c before Cerenkov radiation is induced. 

 

There does not seem to be any firm plan to conduct such experiments. However this work predicts that perhaps they could be done.   

[hazelm]

To save readers a bit of time, what this is about is the idea that under an extremely strong magnetic field the virtual particles that have transient existence in vacuum fluctuations can be polarised, generating a polarisation of empty space that can act like a medium and slow down the phase velocity of light.

 

The prediction is that one could theoretically produce Cerenkov radiation from very fast charged particles travelling through this "medium".  The first problem is that, as any physicist will realise, a charged particle in a magnetic field is forced into a curved path, i.e. accelerating, and will emit synchrotron radiation anyway. So any Cerenkov radiation would have to be distinguished from that. The second problem is that (of course) the predicted effect is tiny, slowing the phase velocity by a millionth of a %. So the particles will have to be travelling amazingly close to c before Cerenkov radiation is induced. 

 

There does not seem to be any firm plan to conduct such experiments. However this work predicts that perhaps they could be done.   

Thank you, Exchemist.  I would not have dared try to say it that way.  You saved everybody a  lot of reading.  My question is what use will it serve?  They did admit that it has a long way to go before anyone can get too specific.  I am still agog at people being able to maneuver in outer space while sitting in their comfortable chairs. 

[exchemist]

I did not sleep last night, and I was letting my mind wander. I wondered could wave particle duality be caused by Unruh effect, and something like Cherenkov radiation. I got up and read a book in the end, on black holes and Hawking radiation.

 

What is a photon? If it is regarded as a packet of energy accelerating and colliding with virtual particles, which might momentarily appear real to an accelerating packet of energy according to the Unruh effect. The speed of the photon might be restricted by collisions with virtual particles similar to Cherenkov radiation. ie the sonic boom if you like that causes Cherenkov radiation might be the same thing that causes the double slit experiment wave effect. Wave particle duality ? Should I think about my garden instead? E=hf  the apparent frequency is dependent on the packet of energy released from its source.

Hmm, sounds as if you may have not woken up yet from your dream. :)  The Unruh effect (which has yet to be observed, by the way) is a prediction of QFT, so it relies on quantum theory. It seems to me you won't have much luck trying to explain wave-particle duality by relying on a quantum phenomenon that already implicitly assumes it! 

 

 

Also, you can't have a "packet of energy". It is a common misconception to think of energy as if it were "stuff". But it isn't. You can't have a jug of "energy". Energy is not an entity but merely a property of a physical system  (even if the "system" in question only comprises fluctuating EM fields, as in the case of the photon).

[exchemist]

I will sleep tonight as I am now a trifle tired. Yes the Unruh effect has not been observed and likely wont be, similar to Hawking radiation, the effects of which wont be seen unless a black hole decides to explode via evaporation. I am not so sure you are 100% correct however, I still toying with the ideas :)

 

Hawking radiation and Unruh radiation are basically the same thing, many astrophysicists are scanning the skies in the hope of detecting a black hole explode due to it evaporating enough of its mass away. Smaller black holes are warmer than super massive blackholes for a reason. Hawking might have nailed it, and since Unruh radiation is effectively the same thing from a different angle ??  

 

A photon has an implied frequency E=hf and an inertia E = pv. v being c. The inertia of the photon is in lumps ie is quantised, it represents the particle properties of the electromagnetic wave. Quantum theory comes from individual quanta which are the representation of the smallest quantities of electromagnetic waves that can exist. The HUP predicts free space is full of virtual particles. Virtual particles can become real due to absorbing gravitational energy according to Hawking. They can also become real momentarily borrowing energy from some where else then releasing it. 

 

The speed of light in free space is c, the speed of light due to passing through a fluid or glass is reduced due to collisions. The way the light passes through the liquid might I mused last night have a correlation taking into account something like the unruh effect which if something is accelerating will cause virtual particles to become real especially accelerating to c. 

 

Putting this idea to one side and looking at Feynmans ideas to add amusement/confusion, particles exist in both real and virtual states borrowing energy then repaying it. A photon with inertia passing through free space will interact with virtual particles, which momentarily might become real absorbing the photon, stopping it and reemiting it again. The picture last night seemed to give me a wave effect, as the virtual particles in the path of the photon would not be lined up in a straight line, so when the double slit is encountered the photons inertia might go through either slit. Feynmans picture of photons is not so clear cut as your own, If you wish to waste 3 minutes of your life here is a chat by Feynman

 

Photons could be corpuscles of energy, which I think is a packet, unless I am misinterpreting him.

 

Via analogy light is absorbed by atoms forcing electrons to a higher energy level, the electrons emit a photon as they decay to a lower energy level.

 

The speed of light is constant, is there anything that states it cant be being absorbed and emitted by virtual particles as it passes through space. The speed would appear to be constant, could the jittery movement of a photon be detected, would it appear like a wave in the double slit experiment. :) I am easily amused.

I have to say I don't think the Unruh effect and Hawking radiation are the same at all. The first is an effect on an accelerating charge, due to vacuum fluctuations, while Hawking radiation is due to pair production at the event horizon followed by capture of one member of the pair before they recombine again.

 

It also seems to me you are making rather heavy weather of wave-particle duality. The maths of QM describes this very well, i.e. it accords with experiment, so there is no mystery to be solved. The issue with wave-particle duality is that we are used to waves and particles being different things, which at the macro scale (where quantities are >>h) they are, but not at the atomic scale. To speak of "waves" and "particles" is to use mechanical models from everyday life which do not fully represent how nature works at the atomic scale. However the maths of QM describes it, reconciling the two aspects into one.

 

 

 

As for "corpuscles of energy", you need to be clear about what system this energy is a property of. As I say, energy is not "stuff": it is a property of a physical system. A photon is a wavepacket of EM radiation that has energy, according to E=hν, and momentum p=E/c = h/λ.  

Edited April 1, 2019 by exchemist

[exchemist]

 

 

 

 

 

 

Yes but the concept of a photon passing through space colliding with and being absorbed by and remitted by virtual particles is interesting. 

 This is not what happens when the phase velocity of light is slowed in a medium. If it were absorbed and re-emitted it would scatter or fluoresce. The electric vector polarises the medium as it passes, causing a coupling to the medium that alters the phase velocity. Absorption only occurs at frequencies that permit an electron to be promoted to a different orbital.

[Dubbelosix]

Actually, models do exist in which a photon can travel a zig zag path through space through an interaction with the vacuum. Various models of zitterbewegung exist and it was believed by Dirac and possibly Schrodinger that it was possible an electron was composed of a photon and only appeared to move below lightspeed, because it follows a non-linear motion through space.

[exchemist]

I was using electrons as an analogy, because I know they can absorb and re emit photons, as you correctly point out only if they have the correct energy levels to promote an electron to a different orbital.

 

What I am suspecting is the most relevant equation when thinking of photons is e=pv, not e=hf which is slightly misleading when trying to visualize their motion through space, in that they may not have a frequency. In the past when thinking of photons I have had in mind things like soliton waves which I do not think is helpful. Interestingly and ZPE interactions according to SED might be responsible for inertia p. 

I am puzzled by you saying that photons "may not have a frequency". Surely they always must, mustn't they? Although, per the Uncertainty Principle, it will be a bundle of frequencies, rather than a single one, if the position of the photon is well-defined. More here: https://en.wikipedia.org/wiki/Wave_packet

Edited April 2, 2019 by exchemist

[exchemist]

I am aware you can bundle frequencies to make wave shapes. (via fourier analysis) 

 

I was not being clear (again), the photon frequency I think is an ambiguous description, as it can infer a repeating frequency like an ac waveform for any given photon. I do not think this is the case. E=hf implies a frequency not a wave packet or pulse. 

 

The word frequency of course can be used to describe a half wave with a wavelength superimposed on a wire or travelling through space. ie a pulse or wave packet. A single wave packet or pulse does not need an ac component, but it does have a shape? . The shape of which is a little none descript.

 

To say a photon has spin is also a often misunderstood description of a photon, for some this implies it is rotating as it goes through space. It does not it refers to inertia, but not the inertia in E=pv Which gives the photons energy. 

https://en.wikipedia.org/wiki/Spin_(physics)

The spin of a charged particle is associated with a magnetic dipole moment with a g-factor differing from 1. This could only occur classically if the internal charge of the particle were distributed differently from its mass.

 

Whilst the math does give a partial picture, it is not good for visualising how the wave moves through space, and why on the small scale it does not appear to go in a straight line. ie double slit experiment. Interesting factoid, one can perform identical double slit experiments in a 100 different locations just firing a single photon. When the results are brought together you still get the wave effect. 

 

One could view the photon as being a blob of energy moving through space, ploughing a rough path through all the virtual particles. Viewing it as being absorbed and reemitted by the virtual particles as it makes a rough straight line through space may not be the best representation, but I don't think it is much different to the blob description above :)

I can't follow this, I'm afraid. I'll leave you to your speculations.