On 10/30/2014 10:16 AM, John Clark wrote:
On Thu, Oct 30, 2014 at 4:01 AM, Peter Sas <[email protected] <mailto:[email protected]>> wrote:> The irony is that Kant thought his construction of the matter concept could not be proven wrong since it was a priori... And once again a philosopher has got it wrong. > it remains the case that the electromagnetic force causes positive charges to repel each other and to attract negative charges, which are repellent among themselves. Your description of how a magnetic field works just seems to offer another way of describing the same fact.A ELECTRIC field can only attract or repel a electron, but a MAGNETIC field can only apply a force at right angles to the direction the charged object is moving, and if it isn't moving the magnetic field has no effect on it. As for a ELECTROMAGNETIC field, a changing electric field causes a magnetic field at right angles to it, and a changing magnetic field causes a electric field at right angles to it.> can't we say that the electromagnetic force is completely described (on some general level) by noting the repulsive and attractive forces between charges? No.
Attractive/repulsive I would assume to refer to forces acting along the line between two bodies. The magnetic force between two moving charged particles is still along the line between them, even though it isn't along the direction of their motion. But that's in a non-relativistic picture where there's a frame independent meaning to "line between them". Relativistically you need to think of the "force" as local momentum exchange with the field. That takes place at a point and there is no "line between them".
> Also with respect to Russell's remark about Pauli's exclusion principle (PEP): It says that fermions of the same type cannot have the same quantum state. But how is that different from saying that those fermions repel each other?Nobody is saying nothing can be attractive or repulsive, we're just saying not everything is.> And what is the status of the PEP? It's the basis of chemistry which is the basis of biology. > It seems to be independent of the four basic forces.It's not. It explains how electrons and electromagnetism work at the atomic level (for larger things Maxwell's Equations work fine) and when things get even smaller it explains how the strong nuclear force works inside the nucleus.> Is it more of a logical principle?Yes. It explains why particles with half integer spin (1/2, 3/2, 5/2 etc) like electrons, protons and neutrons can't be in the same quantum state
I don't think the negation of Pauli's exclusion principle would entail a *logical* contradiction. The exclusion principle follows from Lorentz symmetry in quantum field theory applied to particles with half-integer spin.
Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
