Re: Just what is a particle?

[Hugh Haskell <hhaskell@MINDSPRING.COM>]

All points here well taken. I was not trying to make any definitive
statement about particles, just trying to differentiate them from
maxwellian waves, without letting them get mixed up with the
"ordinary" particles of everyday life. I have some of the same
questions that Cliff has, although I guess I am not bothered by the
mass-momentum thing as much as he is. Whatever it is that we
attribute to the photons and call "momentum," it *behaves* like
momentum, I guess in the same sense that whatever it is that we
attribute to electrons, and call "spin" it *behaves* like angular
momentum. I don't know if it is reasonable to attribute an "effective
mass" to a photon, that is, an inertial content of the "thing" that
happens to be equal to h*nu/c^2, but that seems to get me past most
of the stumbling blocks that are bothering Cliff. I will leave it to
the more philosophically-oriented on this list to sort this all out.

Hugh

> Thank you for picking up on this.  I have asked the same question a number
> of times, usually when people talk about wave-particle duality.  I have no
> idea what "paricle" means in this context.  And please dont tell me that
> particle beams don't show interference pattern.  All beams show
> interference patterns to the extent that one can make the beams coherent.
>                                 Regards,
>                                         Jack
>
> Adam was by constitution and proclivity a scientist; I was the same, and
> we loved to call ourselves by that great name...Our first memorable
> scientific discovery was the law that water and like fluids run downhill,
> not up.
>                           Mark Twain, <Extract from Eve's Autobiography>
>
> On Thu, 17 Feb 2000, Cliff Parker wrote:
>
>  > Hugh Haskell wrote in an earlier post --  Photons are particles (not like
>  > electrons or protons, but particles nevertheless)
>  >
>  > I would like some discussion on this point as I try to clarify my thinking.
>  > What characteristics are necessarily present in order to call something a
>  > particle?  I have listed a few characteristics particles often
> seem to have and
>  > thoughts about how each may apply to photons.  Comments, clarifications,
>  > disagreements, and instructions are hereby solicited.
>  >
>  > 1)  Charge -  No.  Photons like neutrons and many other "particles" have no
>  > charge.
>  >
>  > 2)  Mass -  No.  I guess photons are massless since they travel
> at the speed of
>  > light.  I don't really understand what this means however especially when
>  > momentum and energy are considered.
>  >
>  > 3)  Momentum - Yes.  I understand that photons do have momentum.
> Exactly what
>  > this means however is unclear to me.  It must not mean p = mv
> since photons have
>  > no mass.
>  >
>  > 4) Inertia - I am really baffled on this one.  No mass means no inertia but
>  > photons obey Newton's First Law.  How can that be?
>  >
>  > 5) Energy - Yes, they can cause change I suppose.  I used to be
> more sure of
>  > this, but that was when I thought I understood what energy was.  After
>  > considering Leigh's thoughts and those of others I'm not so sure anymore.
>  >
>  > 6) Something that is quantized - Perhaps a particle can be
> considered anything
>  > that is quantized.
>  >
>  > 7) Others ----
>  >
>  >
>  > Cliff Parker
>  >


Hugh Haskell
<mailto://hhaskell@mindspring.com>

Let's face it. People use a Mac because they want to, Windows because they
have to..
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