My guest blogger today is Joe Bochenek, a Ph.D student at Florida State
University. He is working at CMS, one of the experiments at the Large Hadron Collider, located on the border between Switzerland and France.The LHC announced
observation of a new particle on July fourth.
Stephanie--Joe, what can you tell us about the amazing discovery that has taken place at the LHC?
 |
| Large Hadron Collider |
Joe--The exciting thing about the LHC is
that it is on the absolute boundary of human knowledge about nature.
There is a theory called the Standard Model of Particle Physics that
describes all of the matter that we know about, from stars to the particles
that make up a new born baby, to more exotic forms of matter. Everything
we have observed experimentally fits in to this eloquent mathematical framework,
and this framework can be used to make predictions to fantastic accuracy.
The only problem is that the framework, by itself, is incomplete - it has
a mathematical inconsistency. To fix this, some very smart theoretical
Physicists, including Peter Higgs, proposed an addition to the theory.
This addition is called the Higgs field (keep this distinct in your mind
from the Higgs boson, which is related but not the same). The Higgs field
"fixes" the standard mode so that the Standard Model gives us everything:
a theory that describes all that we have seen in experiments over the last 100
years or more, and complete mathematical consistency. But if we include
this modification to the theory we get some extra baggage, and that baggage is
called the Higgs boson.
The Higgs boson is a particle predicted by the
Standard Model if we include the Higgs field -- it MUST exist if the Higgs
field exists, so we should be able to see it in our experiments. No Higgs
particle, no Higgs field, no consistency, and thus our theory is wrong, and
there must be something else that we don't know about or haven't been clever
enough to think up.
Electromagnets at the LHC
However, on July 4th the world saw
evidence for a particle that is consistent with a Higgs boson. If, upon
further scrutiny, it turns out to be the Higgs field, then the theorists who
proposed it 50 years ago will be very happy.
Then again, it could be something else.
It could be something that is imitating the Higgs field, or it could be a
brand of Higgs boson a bit different from the one predicted. In either
case it would mean that there is more in nature than our theory tells us.
But this is actually a good thing because we can use this new particle,
whatever it is, to try to determine the real theory that explains everything.
That is, at least if we're wrong, we have a lead. When we have more
data we will be able to measure the properties of this new particle and better
determine if it is a Higgs boson, or if not, we can see more clearly what it
is.
Now I should mention that
Cosmological experiments tell us that normal matter -- quarks, electrons and
the other particles described by the standard model -- only make up 4% of the
universe. The rest of the universe is comprised of so-called "dark
matter" and "dark energy".
We don't know ANYTHING about
this stuff, but we can see that it is there by the way stars move around each
other. So even if the particle we observe is a Standard Model Higgs boson, and the
Standard Model is shown to be right, we still have a lot to learn about the
universe, and we hope that we can catch some hint of what is out there using
the LHC, in concert with other experiments.
Also, we know that even if we
have found the Higgs, that the standard model doesn't explain gravity. So
there are many problems left unsolved. But that is the nature of pure
science: you don't know what you will find until you look. You don't know
what will be the windfall a particular experiment, either technologically,
scientifically or just in terms of human edification, until you look over that
next mountain. Or maybe you won't find anything at all (of course, we're
pretty sure we would find something otherwise we wouldn't have built the
experiment and dedicated many sleepless nights to making it work). And so
the observation of this new particle at the LHC is very encouraging.
I think this is a good video
explaining the Higgs better than I could (and the artwork is cool):
Or for something less colorful, here
is the CERN press release from July 4th:
http://press.web.cern.ch/press/PressReleases/Releases2012/PR17.12E.htmlStephanie--Joe, thank you for your explanation. I think I understand a little more about this fascinating subject. Keep us up to date on any new discoveries.
Joe--Thank you.
