05-22-2016, 09:16 AM
(This post was last modified: 05-22-2016, 03:09 PM by John Duffield.)

All interesting stuff, Secur. We perhaps need a new thread on this. But for now, my point stands in that you can't refer to, or give a paraphrased version of, that clear intuitive understanding of the electron. Because it's missing from contemporary physics. I don't say this lightly, I say it after an awful lot of reading and discussion. I've spoken to Williamson and van der Mark and Qiu-Hong Hu and others too. It's like blind spot. People can't see the omission.

If I might make a few comments about your post:

Here are some of my reasons for thinking his intuition of the electron, though not "clear", was better than anyone else's. Obviously, the Dirac equation. In his book, he shows why the speed of any electron is precisely c!

If the electron is in front of you going nowhere, its speed is precisely zero. However I agree that there is a hidden motion witgh a speed of c.

Then he pointed out that prima facie his equation "proves" every particle must have spin 1/2 - and went on to explain why that's not the case. The clarity of his logic is always striking.

I find myself discussing the distinction between experimental evidence and mathematical proof. A mathematical proof in an equation does not prove that every particle must have spin ½.

For instance the offhand comment that a spherical wavefunction must have spin 0, and vice versa.

The electron has a spherical symmetry and spin ½.

He shows how symmetry leads to conservation of energy and momentum so lucidly you think it's sleight of hand

Symmetry is an abstract mathematical concept, energy is what matter is made of. It's the one thing you can neither create nor destroy. IMHO the former is not the cause of the latter.

His meticulous explanation of where the "i" comes from in Schroedinger's equation (he explains it three different ways; they're hard to notice). His casual invention of the multi-path approach, which 20 years later became QED (Feynman always credited him). And so on.

Ok, Dirac himself would agree his intuition of the electron wasn't clear.

This is my point. It's only when you look for this clear intuitive understanding of the electron, do you see that it isn't there.

But the question is: whose is clearer? I can't think of any theoretical physicist who qualifies. Can you say who that would be?

No. The people I talk to about this sort of thing tend to have physics qualilfications, and some have physics careers. But they're in electromagnetism and optics and teaching and experiment. They aren't what you'd call theoretical physicists.

If you say no theoretical physicist qualifies, but experimental physicists have a better intuitive understanding of the electron: I won't argue with that. It's a different kettle of fish. People like Carl Anderson do, in a way, have more intuition about sub-atomic particles than theoreticians do. You could mention chemists; even old-fashioned TV repairmen. And then there's Tesla! If that's what you mean, Ok, you have a point. But that objection applies to any theoretician.

I wouldn't say that experimental physicists have a better intuitive understanding of the electron. Or chemists, or TV repairmen, or Tesla. I'd say a few people have some understanding, and they don't fit into nice tidy category.

What do you say? If you want an appeal to authority, "finding anyone who agrees with that, try asking around for a reference" - I have none and am not going to look. OTOH if you have an "authority" who agrees with you, I'll be happy to check it out.

I refer to Einstein a lot, and others. But the only authority that I really care for, is the hard scientific evidence. Such as the Einstein-de Haas effect which "demonstrates that spin angular momentum is indeed of the same nature as the angular momentum of rotating bodies as conceived in classical mechanics".

But of course, to understand the electron, you have to understand the photon first.

If I might make a few comments about your post:

Here are some of my reasons for thinking his intuition of the electron, though not "clear", was better than anyone else's. Obviously, the Dirac equation. In his book, he shows why the speed of any electron is precisely c!

If the electron is in front of you going nowhere, its speed is precisely zero. However I agree that there is a hidden motion witgh a speed of c.

Then he pointed out that prima facie his equation "proves" every particle must have spin 1/2 - and went on to explain why that's not the case. The clarity of his logic is always striking.

I find myself discussing the distinction between experimental evidence and mathematical proof. A mathematical proof in an equation does not prove that every particle must have spin ½.

For instance the offhand comment that a spherical wavefunction must have spin 0, and vice versa.

The electron has a spherical symmetry and spin ½.

He shows how symmetry leads to conservation of energy and momentum so lucidly you think it's sleight of hand

Symmetry is an abstract mathematical concept, energy is what matter is made of. It's the one thing you can neither create nor destroy. IMHO the former is not the cause of the latter.

His meticulous explanation of where the "i" comes from in Schroedinger's equation (he explains it three different ways; they're hard to notice). His casual invention of the multi-path approach, which 20 years later became QED (Feynman always credited him). And so on.

Ok, Dirac himself would agree his intuition of the electron wasn't clear.

This is my point. It's only when you look for this clear intuitive understanding of the electron, do you see that it isn't there.

But the question is: whose is clearer? I can't think of any theoretical physicist who qualifies. Can you say who that would be?

No. The people I talk to about this sort of thing tend to have physics qualilfications, and some have physics careers. But they're in electromagnetism and optics and teaching and experiment. They aren't what you'd call theoretical physicists.

If you say no theoretical physicist qualifies, but experimental physicists have a better intuitive understanding of the electron: I won't argue with that. It's a different kettle of fish. People like Carl Anderson do, in a way, have more intuition about sub-atomic particles than theoreticians do. You could mention chemists; even old-fashioned TV repairmen. And then there's Tesla! If that's what you mean, Ok, you have a point. But that objection applies to any theoretician.

I wouldn't say that experimental physicists have a better intuitive understanding of the electron. Or chemists, or TV repairmen, or Tesla. I'd say a few people have some understanding, and they don't fit into nice tidy category.

What do you say? If you want an appeal to authority, "finding anyone who agrees with that, try asking around for a reference" - I have none and am not going to look. OTOH if you have an "authority" who agrees with you, I'll be happy to check it out.

I refer to Einstein a lot, and others. But the only authority that I really care for, is the hard scientific evidence. Such as the Einstein-de Haas effect which "demonstrates that spin angular momentum is indeed of the same nature as the angular momentum of rotating bodies as conceived in classical mechanics".

But of course, to understand the electron, you have to understand the photon first.