LANL probes lives of nuclear particles
Related
Advertisement
Numerous, mainly unnoticed neutrinos may have been forces behind formation of today's universe
1/2/2009 - 1/3/09
Neutrinos may seem like lazy particles that hang out and do nothing all day, but shoot them through a big copper tube at near the speed of light and you could explain some of the deepest mysteries of the universe.Neutrinos are some of the smallest, lightest and most common nuclear particles in the universe.
And most of the time, they float around unnoticed — in fact, hold out your hand and a trillion of them will pass through every three seconds or so.
But at a hotter time, back when the universe first started forming, neutrinos may have exerted a huge amount of influence, and that could have changed how everything works today, from suns to solar systems to galaxies.
Understanding that influence, and how the properties of neutrinos have changed since the beginning of time, could help scientists understand some of the biggest puzzles about how the universe works.
As part of that, at Los Alamos National Laboratory, physicists are working with Fermilab in Illinois to try to figure out if the weak, humble little neutrino could explain why there is a huge imbalance between matter and antimatter in the universe.
And by spinning, smashing and tormenting the little guys in particle accelerators at Fermilab and Los Alamos, they might have found a hint that could explain some of that mystery, said Geoffrey Mills and Bill Louis, two LANL physicists.
"By looking at neutrinos, you can understand what's going on in the core of the sun," Mills said. "In other areas, you can understand how the distribution of elements we see today appear in the abundance they do. And they may play a big role in how heavier elements are produced in exploding supernova."
Physicists have long been trying to figure out why there's more matter in the universe than antimatter. If you start at the big bang, and move forward through time, you should have both in equal parts — but you don't, Mills said.
"All the interactions we see, that we know about, when we produce matter, like a baryon, you also produce antimatter, like an antibaryon," Mills said. "We know this from experiments and studying microscopic behavior. But symmetries in the universe between particles and antiparticles appear to be different."
That difference, Mills explained, is sort of like looking in a mirror. What stares back should be a symmetric version of the universe.
"But the universe doesn't behave that way — it's sort of like it parts its hair on one side," Mills said.
The neutrino, which actually comes in three types, could explain why that's happening.
"The neutrino has been a notoriously hard object to study, but it's ubiquitous in the universe," Mills said. "They're everywhere, but they don't really interact with anything."
Neutrinos interact with things through the weak force, but back during the big bang, when things were hotter, that force might have done a lot more than it does now.
And if neutrinos were interacting in strange ways way back then, it could explain some of the matter-antimatter asymmetry today.
The way to prove that is to make streams of them, both normal neutrinos and antineutrinos, by using particle accelerators and watch how they behave.
And what the scientists found in recent tests with neutrinos and antineutrinos at Fermilab and Los Alamos was that some of them changed type, sometimes — which could explain some of the weirdness in the universe, the scientists said.
"That could mean neutrinos are oscillating," Louis said. "And that could explain some of these violations we're seeing."
In essence, finding that antineutrinos are shifting types could give scientists a hint at what was happening way back in the big bang that would have caused all the imbalance problems, they said.
"The hope is that we may actually be on to something," Mills said.
Still, the experiments will have to continue for some time before the scientists collect enough data to understand what's going on, he said.
In coming months, though, the information could knock at least a few theories about the universe out of the running, he said.
"It's very exciting for us, and it holds out the possibility that there might be an effect here causing broad implications," Mills said.
Contact Sue Vorenberg at svorenberg@sfnewmexican.com.
