Quark Gluon Plasma

<<Music>> So if I were to ask you what was the hottest thing in the universe, what would you pick? I know, I know- you'd pick me, right? No, no, I understand, I get that a lot… (Cut!) What? (Don, we talked about this…) If we want to talk about hot things, perhaps the best place to start is with the familiar. Perhaps the first thing you thought of was fire, which is, without a doubt, hot. However, an ordinary fire, which has a temperature of one or two thousand degrees Fahrenheit, isn't even competitive in a hot contest. So what's hotter than a familiar fire? Well, there's the blowtorch, which is about twice as hot as a campfire, But even a torch isn't competitive in a contest for the hottest thing in the universe. For instance, the surface of the sun is twice as hot as a typical torch and the center of the sun is three thousand times hotter than that, weighing in at sixteen million degrees centigrade. And even that incredible temperature is eclipsed by technologies employed by my colleagues and me to study the laws of nature. Using huge particle accelerators, we can smash beams of subatomic particles together at near the speed of light and generate temperatures a million times hotter than the center of the sun. We particle physicists do have the coolest toys. Well… hottest… but you know what I mean. A really interesting thing to think about is what happens to ordinary matter when it encounters temperatures like these. To understand that, we can remember some familiar phenomena and then learn about some more exotic things that you might not have heard about before. To begin with, we know about the states of matter that we learned about in school- specifically solid, liquid and gas. Of course, things are solid when they are cold, gaseous when they're hot, and liquid when they're in between. So how does temperature affect the structure of matter? To understand that, we need to think both molecularly and atomically. In solids, molecules are moving very slowly, slow enough that the forces between molecules are strong enough to hold them in place. In liquids, the molecules have much more energy and the interactions between molecules remain, but dominate less. This leads to phenomena like viscosity. When matter is heated even more, the interaction between molecules becomes negligible and matter turns into a gas, with molecules bouncing around randomly. So, until now, I have described things that you learned about in school, but it turns out that there are states of matter beyond the familiar three. So what happens if we take a gas and turn the heat up even more? To understand this, we can zoom in on a single molecule and see what happens. At a certain temperature, the energy is enough to rip molecules apart into their constituent atoms. If one raises the temperature even more, the nucleus of an atom can no longer hold onto the electrons and the result is that you have electrons running around willy-nilly, unbound to an atom. The nuclei might initially hold onto some of its electrons, but eventually the temperature will be so high that what you have are electrons and bare atomic nuclei running around. The temperature at which these stages occur depends on the molecule and atoms under consideration, but what I've described here is generally true of all matter. When matter is heated enough that electrons are being pulled off the atoms, this is a new state of matter called a plasma. You have seen plasma in fluorescent lightbulbs, lightning bolts and in those cool plasma balls. The temperature of the plasma in lightning bolts can be ten times higher than what occurs in a blowtorch. Creating an entirely different new state of matter is pretty amazing, but we're not done. Let's raise the temperature even more. To see what happens then, we need to turn our attention to the atomic nucleus. As the temperature increases, the nuclei have so much energy they can no longer reliably hold the protons and neutrons together. But even that amazing achievement isn't the final word. In order to simplify the language, we use the word nucleon to describe both protons and neutrons. This is because they are both inside the nucleus of an atom. Nucleons are each made of three particles called quarks and the quarks are held very strongly indeed. In fact, under ordinary conditions, one cannot pull a quark out of a nucleon. However, the temperatures we can achieve in particle accelerators are anything but ordinary. If we heat matter enough, we can literally melt the nucleons and have quarks and a particle of force called the gluon run around no longer bound together. This outrageous state of affairs is a new form of matter, called a quark-gluon plasma. I'll say that again, a quark-gluon plasma occurs when the temperature is so high that individual protons and neutrons literally melt. So you may be wondering if a quark-gluon plasma is a real thing, or just an idea. It turns out that scientists can create quark-gluon plasmas at specialized particle accelerators. At the Relativistic Heavy Ion Collider on Long Island, also called RHIC, and the Large Hadron Collider in Europe, also called the LHC, physicists shoot bare atomic nuclei at one another, like shooting two bullets together. The temperature in these impacts was last common in the universe a millionth of a second after the Big Bang. We see here a simulation of a collision at the LHC, in which two nuclei of lead are slammed together and a quark gluon plasm is formed. Physicists generate collisions like these about one month each year. The study of quark gluon plasmas is still a relatively new science, but scientists at RHIC and the LHC are studying their data and it is guaranteed that the next few years will teach us something very interesting about this hottest state of matter. And that… is totally cool.

Channel: Fermilab

Views: 199,924

Rating: 4.9495139 out of 5

Keywords: explained, discovery, proof, scientist, Large Hadron Collider, learn, metaphor, quark gluon plasma, science, fermilab, CERN, plasma, example, particle, gluon, LHC, physics, quark, physicist, educational, Ancient, funny, Physics, Don Lincoln, Ian Krass, ATLAS, Fermilab, QGP, CMS, ALICE, hottest, hot, qgp, fire, blowtorch, sun, accelerators, subatomic, temperature, heat, solid, liquid, gas, molecules, moving, energy, interaction, states, of, matter, atom, graphic, lightning, melt, nucleon, RHIC, big bang

Id: Rk9KZLaVItI

Length: 6min 35sec (395 seconds)

Published: Thu May 07 2015