Re: Is Intel exceptionally unsuccessful as an architecture designer?

On 28/09/2024 19:36, Tim Rentsch wrote:

Lawrence D'Oliveiro <ldo@nz.invalid> writes:
 

On Tue, 24 Sep 2024 20:33:58 +0000, MitchAlsup1 wrote:
>

Neutron stars are are collapsed forms of matter where gravity is
stronger than the electro-magnetic fields holding the electrons away
from each other and the protons.

>
Gravity here is stronger even than the Pauli exclusion principle, which
says that two matter particles (e.g. electrons, protons, neutrons) cannot
occupy the same space at the same time.

 This statement of the Pauli exclusion principle is wrong.  An
example is the two electrons of a helium atom, which occupy the same
"space" (the lowest orbital shell of the atom) as long as the helium
atom persists.
 

It was certainly over-simplifying the Pauli exclusion principle.  The principle applies only to fermions (particles with half-integer spin), and says they cannot occupy the same quantum state, rather than the "same space".  The two electrons in the innermost orbit of a helium atom must have opposite spins - then they are in different quantum states. If their spins were the same, they would in effect be pushed apart to different positions.

The Pauli exclusion principle doesn't apply to some matter particles
(meaning particles that have non-zero rest mass).  An example is
carrier particles of the weak force, W (and I believe there are
several kinds of W but I haven't bothered to verify that).

Those are bosons (Z, W+ and W-), with integer spin and so the Pauli exclusion principle does not apply.

 Also, in some situations the Pauli exclusion principle doesn't apply
to the kinds of particles it normally does apply to.  An example is
a pair of electrons in a Cooper pair, which since the electrons are
paired they act as a boson rather than a fermion and thus are not
subject to the Pauli exclusion principle (which is that two fermions
cannot occupy the same quantum state).

Yes.

 Note by the way that the Pauli exclusion principle is not an
independent principle but simply a consequence of the laws of
quantum mechanics as they apply to fermions.
 

Yes.

Finally, the original statement about gravity in a neutron star
being stronger than the Pauli exclusion principle is wrong.  It is
precisely because of Pauli exclusion operating between the neutrons
that make up the neutron star that stops it from collapsing into a
black hole.  The "pressure" of Pauli exclusion is not infinite,
which means there is an upper bound on how much mass a neutron star
can have before it collapses into a black hole.  This bound, called
the Tolman-Oppenheimer-Volkoff limit, is somewhere between 2 and 3
solar masses.
 

If all you wrote above is just from memory, then that's pretty good for a non-physicist.  But if you managed to remember and spell "Tolman-Oppenheimer-Volkoff limit" from memory, then I am /really/ impressed!

(Disclaimer:  all the above is to the best of my understanding;  I
am not a physicist.)

Me too.