Re: diameter of proton, neutron wrt electron

From: FrediFizzx (fredifizzx_at_hotmail.com)
Date: 01/20/05 

Date: Thu, 20 Jan 2005 15:06:13 -0800

"Franz Heymann" <notfranz.heymann@btopenworld.com> wrote in message
news:cspc79$klr$12@hercules.btinternet.com...
|
| "FrediFizzx" <fredifizzx@hotmail.com> wrote in message
| news:350olpF4coc5hU1@individual.net...
| > "Gregory L. Hansen" <glhansen@steel.ucs.indiana.edu> wrote in
| message
| > news:csdrss$tdv$2@rainier.uits.indiana.edu...
| > | In article
| <1105861899.406604.265370@z14g2000cwz.googlegroups.com>,
| > | Ken S. Tucker <dynamics@vianet.on.ca> wrote:
| > | >To Mr. Porat, Landle et al...
| > | >Any particle that can have spin can't be point-like,
| > | >because a point cannot spin, so a neutron must
| > | >possess structure and so should an electron.
| > | >Ken
| > | >
| > |
| > | If it were a rotating extended object it would have angular
| momentum of
| > | n*hbar, n an integer. You cannot get a half-integral unit of
| angular
| > | momentum by rotating something.
| >
| >
| > Well, not by rotating a quantum object directly. But consider this:
| Take a
| > right circular cylinder. Have a point-like object start at a point
| on the
| > circumference of one end. Then it travels around the surface of the
| > cylinder to a point on the circumference of the other end of the
| cylinder
| > that is at the 0 degree starting mark from the other end where the
| particle
| > started. IOW, it has gone around the surface of the cylinder 360
| degrees.
| > Now have it go back to its starting point in the same manner. The
| particle
| > has gone around 720 degrees to get back to its starting position.
| >
| > It is doubtful to me that a point-like quantum object would have
| "internal"
| > spin. I think spin is an external effect.
|
| You think wrong. Go and study Dirac. He showed that a point particle
| has to have spin 1/2 if it is to obey the Dirac equation. That the
| electron obeys that equation has been very strongly supported by all
| the relevant experiments performed over the last eighty years or so.
| The quantisation of angular momentum demands that a body which
| performs an actual rotary motion has to have an angular momentum whose
| z-component is an integral multiple of hbar.

I am not dis-agreeing that an elementary fermion has spin 1/2. For sure
it does. Can we really tell if spin is external or "internal"? If we
make it an external effect due to the quantum vacuum and relativistic
effects, then we have no problem with point-like particles having no
"internal" stucture.

FrediFizzx

Relevant Pages

  • Re: Nobel Prize for David Thomson?!
    ... That isn't a spin operator. ... the angular momentum you had to add to get J in the first place. ... spin of a particle does not come from any mechanical rotation. ... singlet and triplet radiation is well known. ...
    (sci.physics.particle)
  • Re: Nobel Prize for David Thomson?!
    ... That isn't a spin operator. ... the angular momentum you had to add to get J in the first place. ... spin of a particle does not come from any mechanical rotation. ... singlet and triplet radiation is well known. ...
    (sci.physics)
  • Re: Nobel Prize for David Thomson?!
    ... That isn't a spin operator. ... the angular momentum you had to add to get J in the first place. ... spin of a particle does not come from any mechanical rotation. ... singlet and triplet radiation is well known. ...
    (sci.physics.relativity)
  • Re: diameter of proton, neutron wrt electron
    ... |>Any particle that can have spin can't be point-like, ... not by rotating a quantum object directly. ... right circular cylinder. ... that is at the 0 degree starting mark from the other end where the particle ...
    (sci.physics)
  • Re: Electron Spin Concept Artificial
    ... But electron is a point particle. ... > a point spin? ... It's not known that the electron really rotates in a classical way. ... It may be that classical angular momentum is a gross approximation ...
    (sci.physics)