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Nov 19 2010

Antihydrogen: tiny atom, HUGE F’N DEAL

CERN physicists have done something heretofore outside the grasp of humankind — creating and trapping antimatter. This is a big deal, because catching antimatter and keeping it without it annihilating whatever you’re trapping it with is hard as hell. It’s also a big deal because antimatter is one of physics’ largest mysteries, way out on the very fuzziest of fuzzy boundaries of human knowledge. It’s such a big deal in my estimation, in fact, that when I found out that humankind had managed to leap this hurdle, the most eloquent and comprehensible words out of my mouth for the next half hour were — and I quote — “HOLY FUCKING SHIT.” I’m still buzzing over the news — because this IS huge. It means we might be able to figure out why there’s something rather than nothing in this anthropic universe.

Too late, Ackbar. We have the rebel scum in our clutches.

You see, in the beginning, this universe was seeded from a set of initial conditions that resulted in a good deal of both matter and antimatter. However, the balance was not perfect — some fundamental aspect of the physics of quarks tipped the scales ever so slightly toward matter — and while well over 99% of the matter that was generated from the Big Bang self-annihilated, the remnants became the universe we see today.

Our understanding of the process of the Big Bang — though we know it probably happened, given all the evidence pointing that way — is fairly limited. Since nobody was around to see it (and really, nobody COULD, as time and space mean nothing outside the context of the event itself), we have only the evidence we see today with which to extrapolate how the quantum soup turned into matter, or why matter won the showdown. That is, except we managed to replicate some of the conditions of the initial spark via the LHC and its “little bang”, and we’ve only just now figured out a way to even begin investigating why matter won out over antimatter in this iteration of the universe.

The really amazing thing about this experiment is not that it created some small quantity of antihydrogen. We’ve actually created a good deal of antimatter in the past, but it tends to explode when it touches… well, anything. This quantity of antihydrogen, however, was successfully suspended in an electric field such that we can theoretically study it in the same manner that we study hydrogen. Hydrogen is the smallest, simplest element, and is the most well-studied and well-understood. Antihydrogen is therefore the perfect candidate for study, not only because it’s the simplest to create, but because we can more easily compare its physical properties to its counterpart.

Not that the creation process is at all simple. From The Economist:

Coaxing hot and bothered antiprotons and positrons to couple is quite a task. The magnetic traps employed to hold the antihydrogen are only strong enough to confine it if it is colder than around half a degree above absolute zero. The antiprotons themselves, which are produced by smashing regular protons into a piece of iridium, are around 100 billion times more energetic than this. Several stages of cooling are needed to slow them down before they can be trapped, forming a matchstick-sized cloud of around 30,000 particles. The positrons, produced by the decay of radioactive sodium, are cooled into a similarly sized cloud of around 1m particles and held in a neighbouring trap.

The antiprotons are then pushed into the same trap as the positrons and left to mingle for a second or so. In that time some of the particles get together and form antihydrogen. Next, an electrical field is used to kick out any remaining positrons and antiprotons. The electrically neutral antihydrogen atoms are left behind.

To test whether any antihydrogen was actually formed and captured in their trap, the ALPHA team turned off its trapping magnet. The antihydrogen was then free to wander towards the walls, and thus annihilation. The detectors duly observed 38 bursts of energy which the team concluded came from antihydrogen atoms hitting the wall of the trap.

We are investigating the fundamental nature of our universe, and we are meeting with great success at every turn. To put this leap into perspective, Homo sapiens has existed on this planet for, at absolute most, 200,000 years. Compared to the age of the Earth, or, say, the age of the universe itself, we practically climbed down out of the trees yesterday. Humans have existed for, at best, 0.0000015% of the lifespan of this universe. Our sun will continue to burn in a life-sustaining manner for another five billion years — or 25,000 times as long as we’ve existed in our present, sapient state. Life will be sustainable in this universe for, at worst, another 25 billion years thereafter.

Can you imagine what else we can achieve, if we can manage to stay alive long enough?

Original paper available here.

1 comment

1 ping

  1. 1
    Dan J

    In fewer than forty-eight hours, I will willingly be injected with fludeoxyglucose (18F). This is a glucose analog, with the positron-emitting radioactive isotope fluorine-18 substituted for the normal hydroxyl group at the 2′ position in the glucose molecule.

    Yes! There will be a substance in my body emitting positrons! Antimatter for the win!

    This is all part of a standard PET (Positron Emission Tomography) scan (combined with CT scan). The sugar analog binds most easily to cells with a high metabolic rate (i.e. cancer). The emitted positron meets with an electron, producing a pair of annihilation (gamma) photons moving in approximately opposite directions. The pair of gamma photons are then recorded by a detector.

    How cool is that!?!?

    Science!!

  1. 2
    Our first tentative steps onto the shore of the ocean of space « Lousy Canuck

    [...] thing is for sure, though — we humans are definitely making up for lost time. We recently managed to create and trap antihydrogen, which was a big enough deal. Now we’ve evidently discovered a way to directly detect black [...]

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