Re: Anti-matter questions (fwd)

[Leigh Palmer <palmer@sfu.ca>]

> > > Also is there still postulated an "anti-universe" someplace since there
> > > is always antimatter produced when energy is converted to matter? If not,
> > > where did the anti-matter go?

I said:

> > There is no reason to believe in the existence of an anti-universe.
> > There may be large isolates of antimatter in our observable universe.
> > Many physicists feel there are not, but there might be no observable
> > consequences if they do exist.

Paul Camp replied with the traditional view accepted by most cosmologists:

> There are some observable consequences. If both matter and antimatter
> galaxies existed in the same cluster, there should be strong gamma
> emissions which are not observed. So if there is a significant amount
> of antimatter in the universe, it must be segregated from the matter
> on scales at least as large as 10^12 solar masses which would be
> difficult to account for cosmologically.

It is difficult to account for the observed universe cosmologically,
let alone hypothetical unobserved universes. Over the age of the
known universe there is no reason to expect that superclusters of
galaxies should survive given the velocities of galaxies and the
amount of gravitational binding present due to observable mass (one
of several dark matter problems).

Of course there are not mixtures of galaxies and antigalaxies in the
same cluster. The only scale which is at all relevant is the largest
scale, that of the superclusters.

One of the original arguments against the existence of sizable
quantities of antimatter in the universe was the absence of
unexplained gamma rays. Well, now that unexplained gamma rays are
seen daily that argument has simply been dropped. Arguments for
absence are difficult to make, of course, but it is my opinion that
this argument has not been sufficiently well made that it should be
enshrined as it has been. Time was when the absence of antimatter
was justified by cosmologists by saying "The astronomers say that it
is not there." That's not true, and it never was true.

Paul's further arguments, very well put, are ones I acknowledge, but
I do not find them persuasive. It is merely a matter of taste at this
point. Neither of us can point to a critical observation.

I don't believe in inflation, either, on aesthetic (Platonic) grounds.
My position is a minority one, but on the latter position I'd put my
money. I feel more strongly about inflation than I do about baryon
asymmetry.

Leigh