| I have been curious for many years how all of the
anti-matter in the universe disappeared. I just
read another article that indicates this is an
active area of research. I often read descriptions
of the early universe that follow a common
progression: universe begins as a dense 1” wide
point, space is created, inflation occurs,
elements occur as universe expands and cools. So
my questions are: 1. Why is there no mention of
anti-matter in these early steps? 2. Wouldn’t we
expect it to exist as soon as elements condensed?
3. If it did exist, and if it was annihilated
through a succession of reactions, wouldn’t that
process deserve a footnote in the description of
the process? 4. How long would it take to convert
all of the matter/anti-matter into matter? 5. How
many reactions would be required to perform the
conversion? It seems we are missing an important
step in the process the early universe followed. I
understand that scientists don’t like to
speculate, but this seems like a good time to. I
have asked my friend Joel about this, but he said
we don't know. Can’t we at least acknowledge the
elephant in the room? Thanks. |
Answer 1:
This is one of the great unanswered questions in
physics - I guarantee you whoever answers this one
is going to get the Nobel prize. We know of no
process that can create matter without also
creating equal amounts of antimatter, and
vice-versa. Likewise we know of no way to
destroy matter that do not require the destruction
of an equal amount of antimatter, or vice-versa.
The problem is that, while physicists
acknowledge that this problem exists, none of the
hypotheses that have been proposed to explain it
make any predictions that we can test, and as a
result we have no way of knowing which, of any, of
these explanations are even partially correct. In
science, problems like this get ignored not
because they aren't there, but because they're
unanswerable with our given capabilities, so
we scientists instead focus our efforts on those
questions that we can answer. Also, while this is
a big problem in physics, I can think of other
elephants in the room that are even bigger than
this one (the natures of dark matter and energy
leap to mind).
From what I can tell, there are two leading
possibilities for why the matter-antimatter
asymmetry might exist. These are (1) there is some
process that we have never observed that creates
matter but not antimatter or that destroys
antimatter but not matter, and (2) there are
regions of the universe that are dominated by
antimatter instead of matter, and some force that
separated the matter and antimatter into these
respective domains. Both of these must involve
processes that are unlike anything we have ever
seen before, either in the laboratory or in
nature, so it is difficult to imagine what kind of
observation or experiment would be needed to test
them.
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