On Tue, 7 Jun 2011, de Bivort Lawrence wrote:
Greetings, everyone,
This is an exciting moment for physicists!
I imagine that one of the very big questions that the researchers will
probe is whether the antimatter follows the same laws of physics as
does 'matter.' Any speculations on this, Pete?
Umm, what I expect is that things will look very much like an exact
mirror, but, in order to explain why anything is able to exist at all,
there will be some little quirk which is different, and I don't know if
we have the skill to find it yet; that is, even if we were to do every
test we can now do on matter, it may not show up, because it may lie in
a region we haven't found yet in normal matter.
For instance, things we don't know about with neutrinos: we've only just
found out they're not massless, which we deduce from the fact that they
can change their "flavour" while in flight, so therefore they aren't
travelling at c, because there is no local time for objects travelling
at c, so they couldn't change. And something which doesn't travel at c
must have mass or it can't exist. The fact that neutrinos are changing
flavour means that their Lepton number isn't conserved, which is a big
surprise, and messes up the Standard Model, so that to account for
all the new untidyness a whole slew (Wikipedia says 7 or 8) new free
parameters will have to be added to the 19 already required by the
Standard Model, which represent 19 times more arbitrary deus ex machinae
than seekers after fundamental principles would prefer. But what's
really interesting lately is that not only do the three flavours of
lepton-linked neutrinos - the electron, muon and tau varieties, seem
to be vascillating over their identities, but there now seem that
there may be gaps in the data where none of these flavours are
available in a neutrino beam for reactions, suggesting that there may
be some number of unlinked ("sterile") neutrinos adding into the
identity mix, which can dominate for some periods of the oscillations.
Well this gets really abstruse, because that means that during these
periods of the oscillation there would be particles which, as far
as can be currently understood, are simply completely out of
communication with the rest of the matter in the universe, except
(maybe) via gravity. And who knows what mischief they might be
getting up to during these intervals.
Is the term "Antimatter" the best way to describe the phenomenon of
reversed poles, though? After all, we are still seeing nuclei and
electrons, albeit unfamiliar ones. Thoughts?
I'm not sure what you mean by "reversed pole". Anti particles have
"negative" values for some quantum numbers (I put that in quotes
because it is somewhat arbitrary. We give normal. ie common, matter
positive values, for instance the electron gets a Lepton number of +1
and a Lepton/electron number of +1, because it is the normal
condition, while the positron (anti-electron) gets -1 for both.
But the math works either way up, so it's just status quo chauvinism
that assigns us the positive, along with its value connotations.
You can think of matter and anti matter as just two different
aspects of material objects, like halves of something that unfolds.)
I envy your being on-site! Kudos are in order. As must be an eventual
Nobel.
Well, this is an interesting subject, actually. There is surprisingly
little funding for this project, and while Makoto's lecture this
afternoon was well attended, there haven't been a lot of people
jumping into this project. On the whole it seems that there has been
little expectation that new physics will come out of this in the
near term - to the extent that anti matter behaves as the exact mirror
of normal matter it will be within the bounds of the Standard Model
and thus not new physics. Similarly, it is doubtful that a Nobel
will come out of this unless something unexpected turns up. Say if
the spectrum of Hbar is completely unlike H, or if it falls up.
Otherwise, it seems a lot of folks will just regard this as an
excercise in further confirmation of stuff thought to be already
well understood; a pretty challenging technical achievement, with
a lot of cutting edge plasma engineering innovation, but not
yielding unexpected results.
But, that may be just a peculiarity of the particle physics community.
Folks a little farther away from the field, including the Nobel
committees, may see things differently. I wouldn't want to have to try
to choose recipients for a prize though; this is a small collaboration
by particle physics standards, but it is across a broad range of
expertise. To make this hardware work required a lot of crucial input
from a fair number of the main collaborators, and though I'm not
familiar with the process in detail, I suspect it would be hard to
whittle the key contributors down below about half a dozen.
-Pete
Cheers,
Lawry
On Jun 7, 2011, at 4:51 PM, pete wrote:
I like this link:
http://www.cbc.ca/news/technology/story/2011/06/06/science-antimatter-atoms-fujiwara-antihydrogen.html
That's our lab, where Makoto is talking, from 0:45 to 1:06, and I
walked through yesterday to find them filming there. In fact I'm
typing this from directly upstairs.
Anyway, alas I can't take any credit for contributions to the latest
work. The mark II version of the apparatus removed the detectors which
we whipped together for them in desperate last minute flurry a few
years ago, replacing them with fancy high resolution solid state
(silicon) detectors. And with my work in Japan, and now with the
new electron beamline, I haven't been available to do anything for
them, but at the same time, they currently have no need for our
detectors. So I've been somewhat out of touch, but I'm going to
catch up in about half an hour, as Makoto is going to give a talk
about the new paper.
A few points, though, on the current paper. Although the trap is
able to hold the atoms for up to 15 minutes, they are still creating
many more which they lose immediately. The numbers are better, but
still very small: they now create about 6000 H-bar per sequence,
and lose essentially all of them to anihilation immediately
(with an energy release of around 1.8 µJoules). The trap then
holds no more than 2 or 3 atoms, and those tend to be lost over
the next few minutes, so that not many trials show any remaining
after 15 minutes. There's lots of work to go yet before there's
enough there long enough to do some of the more interesting tests.
One advantage of the anihilation energy, though, is that there
are some things that can be done with these tiny quantities, and
even one atom will give a nice robust signal when it anihilates,
so you can see where and when that happens. I'll know more about
there plans in an hour or two.
-Pete
On Mon, 6 Jun 2011, D and N wrote:
Congratulations to Pete and his team, again!
Hope you approve of this link.
Natalia
http://genevalunch.com/blog/2011/06/06/cern-loves-1000-new-lhc-record-and-antimatter-caught-for-1000-seconds/
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