He slimed me !
Posted on 01/15/2004 12:57:06 AM PST by neverdem
OAKLAND, Calif., Jan. 13 — At least three advanced diagnostic tests suggest that an experiment at the Brookhaven National Laboratory has cracked open protons and neutrons like subatomic eggs to create a primordial form of matter that last existed when the universe was roughly one-millionth of a second old, scientists said here on Tuesday.
The hot, dense substance, called a quark-gluon plasma, has managed to generate intense disputes in the 15 years or so in which scientists have pursued it. In 2000, a major European laboratory claimed that it had, for the first time, liberated particles called quarks from where they are normally trapped in protons and neutrons, a big step on the way to creating the plasma.
Possibly seeking to avoid the outpouring of criticism that followed, Brookhaven scientists at the meeting here recited a series of striking new measurements from their particle accelerator in Upton on Long Island, but refused to say that they had actually produced the plasma.
Creating such a plasma would fulfill some of scientists' biggest dreams, because it would enable them to study the earliest moments of the Big Bang, the colossal explosion that is believed to have been the birth of the entire universe.
"I think the most economical explanation of what we're seeing is a quark-gluon plasma," said Dr. William Zajz, a Columbia University physicist who is the spokesman for an experiment, Phenix. "But we're holding ourselves to rigorous, very scientific standards, precisely to distinguish it from previous claims."
Other scientists here said it was clear that the Brookhaven Relativistic Heavy Ion Collider had achieved a milestone.
"The evidence for the quark-gluon plasma is overwhelming," said Miklos Gyulassy, a theorist at Columbia.
Each of the 197 protons and neutrons that make up a gold nucleus has three quarks and a handful of other particles called gluons that transmit the strong force that holds the quarks together. By the strange rules of subatomic physics, swarms of other quarks and gluons flit into and out of existence in each nucleus.
Physicists would like to study the quarks individually, but the force carried by the gluons is something like a rubber band that never loses its elasticity. So a given quark can never escape the embrace of another quark and roam free. The lone exception — theoretically, at least — should occur when a collection of ordinary particles becomes so hot and dense that their innards can spill out and form a kind of quark soup, the quark-gluon plasma.
That is the state that the universe is thought to have been in a few millionths of a second after the start of the Big Bang, before the zoo of ordinary particles like protons and neutrons and pions and kaons had coalesced from the primordial soup. A speck of that soup is what the Brookhaven collider seeks to generate, by smashing together gold nuclei at close to the speed of light.
Previous measurements have shown that the lump of material at the center of that collision is from 10 to 100 times as dense as normal nuclear matter. Its temperature is more than a trillion degrees.
The new data, from particle detectors known by their acronyms — Brahms, Star, Phenix and Phobos — showed that this searing goo had a remarkable number of properties expected from the plasma.
One finding focused on the almond-shape region, possibly filled with plasma, created when two spherical gold nuclei strike each other, but not quite head on. Theory predicts that fast particles trying to escape the region should become hung up in the gooey plasma and sometimes stopped completely.
That general effect, called jet quenching, had been seen before. But observations by Star have shown for the first time that particles escaping down the long dimension of the almond are more likely to be stopped than those escaping along the short dimension, where there is less plasma to travel through.
"This is demonstrating, if you will, that our understanding is correct about the jet quenching," said Timothy Hallman, a Brookhaven physicist on the Star experiment. "But it's not proof positive of the quark-gluon plasma."
Another finding indicates that two kinds of particles — mesons, containing two quarks each, and baryons, containing three — speed from the collision point in ways suggesting that they were formed in the hot brew of quarks and gluons.
Still another measurement shows the narrow part of the almond-shaped region, the most tightly compressed part, expanding faster than the rest, in just the way expected of a plasma expanding because of its own pressure.
"The fact that the particles march in lockstep, with the pressure that's expected from the quark-gluon plasma, is sufficient for me," Dr. Gyulassy said. "That's my definition of the quark-gluon plasma."
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Oh jeez, I need to read these posts first...
Just take an ultraviolet light into any hotel room and you'll find it everywhere.
Who is G*d?
I prefer to use that term for the Creator. There's a trucking company that uses the initials GOD for Guaranteed Overnight Delivery that I think is most disrespectful. BTW, I don't post at FR to get involved in Biblical discourses. I know some here enjoy science.
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