# Magnetic corkscrews?

Usaf Moji
I found this website by a guy named David Sligar: http://www.geocities.com/Area51/Shire/3075/mfield.html

He says:

Roger Penrose explains in his book, The Emperor's New Mind that the momentum state wave function of a photon is a corkscrew or helix. He also explains that all emitted photons must carry some mass because E=mc2. Think of energy as a highly diluted form of mass or think of mass as a highly concentrated form of energy.

Thus one can visualize magnetic attraction and repulsion as streams of photons with their corkscrew shaped wave functions screwing into (attraction) or screwing out of (repulsion) each other.

Is there any merit to the second paragraph? How does he know that "screwing into" corresponds to attraction and "screwing out of" corresponds to repulsion? Does anyone know where I can get more info on this corkscrew model of magnetic attraction? (I e-mailed him and he never responded.)

Thanks.

## Answers and Replies

neu
He also explains that all emitted photons must carry some mass because E=mc2.

I don't think I'm being a pedant in pointing out that this is obviously wrong. Maybe I'm missing something?

Jakell
Yeah; photons do not have mass, but they do contain the energy associated with a mass. The author bases all the rest of the paper off this flawed idea, and most of it can be discounted.

The only reason one would view photons as having a "corkscrew momentum state" is because it has a spin of one. As photons travel, they have a certain helicity. This does not mean that they screw into or out of things as they travel. Instead, it is a way of conserving angular momentum.

if they did screw into or out of things, how would you deal with spin 1/2 or 3/2 or 2 or even 0 particles? Wineclasses will not do it for you.

The whole page is not very sound; lots of holes and bad arguments abound. If you want me to tear into the paper, PM or Email me and I might be able to give you a step by step list... it would be a long one.

Gold Member
Yeah; photons do not have mass
Photons definitely do have mass, what they do not have is rest mass.

Does anyone know where I can get more info on this corkscrew model of magnetic attraction?
I would say that visual model of magnetic field without complementary model of electric field won't be very interesting.

Staff Emeritus
Photons definitely do have mass, what they do not have is rest mass.

Photons have a relativistic mass, but to simply say that "photons have mass" is misleading at best.

Gold Member
Photons have a relativistic mass, but to simply say that "photons have mass" is misleading at best.
Interestingly enough but it is no more misleading than to say that "photons do not have mass".

neu
Interestingly enough but it is no more misleading than to say that "photons do not have mass".

I disagree. Everyone is aware of mass energy equivalence, to say photons have energy is equivalent to saying they have relativistic mass. To insist in saying photons have mass simply confuses the common terminology and serves no illustrative purpose; in my opinion it's pedantic.

Gold Member
I disagree. Everyone is aware of mass energy equivalence, to say photons have energy is equivalent to saying they have relativistic mass. To insist in saying photons have mass simply confuses the common terminology and serves no illustrative purpose; in my opinion it's pedantic.
I agree that saying "photons have mass" confuses the common terminology.
But at the same time I insist that to say "photons do not have mass" is misleading at best.

I don't think I'm being a pedant in pointing out that this is obviously wrong. Maybe I'm missing something?
Would it be right to say that photons can transfer mass from emitter to receiver?

Staff Emeritus
If this thread is going to meander into "photons have mass", etc. for the gazillionth time, then it will be locked. There's no confusion here. Read our FAQ.

Zz.

Usaf Moji
Jee wiz, I don't care about the whole photon-mass thing! And I don't think the author was suggesting that photons really do move in corkscrew paths - he was just using that as a model to account for their intrinsic angular momentum.

All I care about is the relative angular momenta and polarization of the exchanged photons in magnetic (or electric for that matter) attraction and how this is different in the case of repulsion.

In other words, is it true that attraction results from a virtual photon going one way with spin +1 and another photon going the other way with spin -1? And is it true that repulsion is the same, but with the spins reversed?

gendou2