Re: Matter/anti-matter asymmetry


Ian Parker wrote:
There's even a possibility that there is no asymmetry. That is,
distant parts of the universe are made of antimatter. They
would have to be remote enough that we wouldn't see the
characteristic annihilation signature at the interface between
the regions, but other than that the physics would be the
same. There is an experiment known as the AMS experiment,
http://cyclo.mit.edu/~bmonreal/

Surely there would be some sort of gamma ray background produced as
annilation took place.

That sets a lower limit to how far away the antimatter would have to
be.
There is some disagreement about what those limits are, but
certainly on the scale of galactic superclusters. The issue
is discussed in detail in the background literature for the experiment.

Also the asymmetry has been observed with
particle accelerators here on earth, so if there is no asymmetry it
will mean that the asymmetry observed is caused by matter itself.


Not sure what you're trying to say there. As I said, the observed
matter/antimatter asymmetry (CP violation) in paricle accelerators
is not nearly enough to explain the matter dominance in the
universe.

BTW - The experiment would be done far better on a dedicated unmanned
satellite. Please do not try and justify the Molloch that is destroying
all space science. See sci.space.policy.

A few years ago, NASA was desperate to find some "science" to do
on the ISS, and some clever scientists took advantage of that to
fast track the AMS experiment by designing it around the ISS.
It seemed like very saavy politicking at the time, but they didn't
forsee
the shuttle blowing up or NASA abandoning science entirely, and
now the whole thing is many years behind the original schedule.

For a number of reasons, it would be extremely difficult at this point
to redesign the experiment to fly independently. They've made their
bed; now they have to lie in it.

IIRC, the AMS was supposed to fly before (W)MAP. There's
probably a moral lesson to be learned there.

-jc

.

Relevant Pages