Lawrence Krauss on Physics

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World-famous physicist Lawrence Krauss of Arizona State University joins Arizona Horizon monthly to talk about the latest science and physics news.

Ted Simons: Each month we check in with ASU theoretical physicist and author Lawrence Krauss to get his take on the latest scientific news, ideas, and theories. Among the topics on the table, why antimatter, matters.
Lawrence Krauss: It's great to be back.
Ted Simons: I've got all sorts of questions. Let's start with something easy. What is matter, what is antimatter, and how -- when do the Twain ever meet?
Lawrence Krauss: Antimatter really isn't as strange -- it sounds like a science fiction concept. And it is used in science fiction: Star Trek But it's really not that strange. It's strange in the sense that Belgians are strange. Do you to a room and ask how many Belgians there are, and you g to Belgium and they're pretty normal people. The reason antimatter seems so strange, we happen to live in a universe of matter. But antimatter is where every particle in nature, the laws of relativity and quanta mechanics tell us for every particle there should be a particle of equal mass but opposite electric charge, basically. So a proton has an antiproton. Same mass, opposite electric charge. Electron has an anti electron, we call it the positron. And with these -- when these were first proposed it was outlandish, but in fact, it was true. The thing about matter and antimatter that makes it exciting and exotic is that you put matter and antimatter together, the proton and the antiproton they can annihilate into pure radiation.
Ted Simons: Why does that happen? Why do they annihilate each other?
Lawrence Krauss: Because it's possible. Because they have opposite charges, and therefore in quantum mechanics anything that's possible happens, and mass can turn into energy. If you have a positive charge and a negative charge, the sum total charge is zero, so you can create pure energy, since you don't have any electric charge left. Quantum mechanics allows that to happen. You can't take two positively charged particles and annihilate them into pure radiation because you have charge. Similarly you can't take a proton and electron and annihilate them because they have different mass. You need exactly the same mass to annihilate.
Ted Simons: OK.
Lawrence Krauss: The big question, the thing you probably wake upper morning and ask yourself, why do we live in a universe full of matter and antimatter?
Ted Simons: You and me both.
Lawrence Krauss: And the answer -- you should, because it's really remarkable. If you were a sensible creator you'd create a universe with equal amounts of matter and antimatter because they have the same mass. And if you dump a lot of energy in the universe, heat it up you'll produce equal amounts of particles and antiparticles. And so, what's really weird, when we look at the galaxies, we only see matter and no antimatter. The antimatter we create in laboratories, we can do that by collisions. And so we think, and one of the great unheralded developments in theoretical physics is a way to understand how you might start out with a universe with equal amounts of matter and antimatter and end up with a universe we live in. If it wasn't the case, the universe would be boring. We wouldn't be having this conversation. If you had equal amounts, they'd all annihilate and you'd have nothing left in the universe. It turns out we think through processes we can sort of understand, for every billion particles of antimatter in the universe, a billion and one particles of matter were made. So the billion particles of matter and the billion parties of antimatter are annihilated and that actually produces the cosmic microwave background radiation that we see. There are a billion photons in the cosmic microwave background for each proton in the universe, but that one extra particle of matter didn't have any particles of antimatter to annihilate & with and it got left over. If you do that in every region of space you end up with enough matter to account for everything you see.
Ted Simon: Thus, that's what we have.
Lawrence Krauss: That's what we have. That's a theory. The neat thing would be to test that theory. And you would have to have some process that creates -- starts out with equal amounts of matter and antimatter and creates matter. Physics is a two-way street. If you can create matter where there was none before you should be able to destroy it. The prediction of this theory is that diamonds are not eternal. That if you take a proton, like the protons that make up particles in this table, if you wait long enough they'll decay. They'll decay and disappear. You have to wait a long time. About we think about 10 to 35 years, which is about a billion, billion, billion times the age of the universe almost. And you might say, how can you test that? Quantum mechanics, again. Because if you get 10 to 35 protons in a single place, on average one will decay each year. We have big big tanks of water underground, Japan and other places, 50,000 tons of water, instrumented with photo tubes sitting there in the dark to wait and see if any protons - again they haven't decay the yet --
Ted Simons: There's still time to wait.
Lawrence Krauss: If we understand that, we'll understand why we're here. We'll understand the process that led to a universe full of matter. Otherwise it would be a beautiful universe, there would be nothing in it, it would be quite elegant.
Ted Simons: Obviously quantum mechanics is involved, there. There's something called quantum teleportation, where a recent experiment, some sort of deal in the Canary Islands somewhere, 143 kilometers, a new record for, for what?
Lawrence Krauss: The point is if you say teleportation takings, you immediately get it in the newspapers. But quantum teleportation is in principle, just like the transporter on "Star Trek." Again, I keep mentioning "Star Trek" maybe I'm obliged. But in "Star Trek," remember, you have Spock or Kirk or whoever, and they get destroyed right here, and suddenly they reappear on the planet. Now, it would be wonderful, I travel a tremendous amount on the weekend, I would love a transporter. But we can't. But you can do it for atoms or quantum mechanical objects. You and I aren't quantum mechanical, we're very classical. But it turns out, it is possible if you very carefully prepare some quantum mechanical states, like photons, the particles in that experiment, very carefully prepare them in the laboratory, and let them travel off in different directions, they are intimately connected in a way that's completely impossible to imagine classically. If I measure this particle here, I make a measurement on it, it instantaneously affects the state of that particle over there. Even fits on the other side of the galaxy. Einstein hated it, he called it spooky action at a distance. He didn't like it. It's a property of quantum mechanics and it's true. And we can test it. And one of the ways we can test it is by very carefully preparing these states, making sure they don't interact with anything on the way. And then if you do things just right in the laboratory, you can literally destroy this particle, and instantaneously recreate the quantum mechanical state of that particle over here. Instantaneously, no time difference, and that's what they were able to do. Over 143 kilometers. It's not the other side of the galaxy but demonstrates this spooky action and at a distance really works. It's fascinating. It would be very useful in principle if we could do it. It turns out you can send information from one place to the other faster than light. It's a little too long to describe here. Even though it sounds like information is traveling faster than light, it turns out there's no message you can create here that would end up over here faster than light.
Ted Simons- It would be faster than what we have. Could you talk about quantum computers?
Lawrence Krauss: If you use that weird property of quantum mechanics and made a computer using that weird property, then using some complimentary properties of quantum mechanics you could make extremely fast computers. Quantum computers that could operate almost infinitely faster than classical computers. The nice thing you could also do, if you could do this, if you could prepare these states, even though you couldn't transfer information faster than light, if you could keep them entangled, then you could have secure messaging. Because it turns out in looking at the property of this particle, you would know if the other particle had been tampered with. So you can make completely secure communication and so if usual worried about being intercepted by spies or whatever, you can be completely secure. That's the good news. The good news is quantum teleportation, it could lead to completely secure messaging. The bad news is, if you can make quantum computers, which isn't so bad, you can probably do a lot of things you can't do now it turns out decode all of the information in your credit cards and the bank uses to store your information and to find out -- so all our credit cards would be insecure.
Ted Simons: It's a hacker's paradise.
Lawrence Krauss: It's a hacker's paradise. Like all things in technology, there's good and bad sides. You got to be prepared for.
Ted Simons: You mentioned, a little split here, they are -- there's a symbiotic relationship, if I may be so bold, between these two particular particles.
Lawrence Krauss: They're intimately connected. Even though, they are far away.
Ted Simons: But they're far away, but it sound like you said as long as the space between them is, what, smooth, free, noninteractive -- ?
Lawrence Krauss: as long as they don't interact with the air and other people and other particles, so they're quantum mechanical state is destroyed, as long as they're pristine, then it works.
Ted Simons: How do you assure that?
Lawrence Krauss: One of the ways you can do that is - simplest way is to put them in a vacuum, so they're non-interacting. Other ways, you can use frequencies of light that you can be relatively sure can travel through the atmosphere without a single interaction. We can see light from the sun, it makes its -- if it interacted alot it wouldn't get to us. In fact, that's why it's red at sunset and blue during the day, because certain light gets scattered down and certain light doesn't. If the blue light is scattered away the red light comes to you. If you use frequencies of light that can make--or microwaves or radio waves that can make it through the atmosphere without interaction, then you're OK.
Ted Simons: Is that relatively easy? Can you do satellites? Can it just be satellite technology?
Lawrence Krauss: You could -- I could definitely imagine this being used for satellite technology in the future.
Ted Simons: Before we go, we've talked a lot about quantum mechanics and obviously, goodness gracious, it can be so confusing. It doesn't seem -- give us --
Lawrence Krauss: no one understands quantum mechanics, we just use it.
Ted Simons: There you go. There it is. There you are.
Lawrence Krauss: Equations are smarter than we are.
Ted Simons: Give us a quick explanation, as quick as you can, of everything we've talked about here deals with quantum mechanics. What are we talking about?
Lawrence Krauss: Quantum mechanics really says that at a fundamental level, the universe is very different than we see. In fact, at a fundamental scale, what quantum mechanics said is that objects are doing many things at the same time. That's the weirdness of quantum mechanics. There's many different ways in thinking about it but Richard Feynman, who I wrote a book about, really demonstrated that's the heart of quantum mechanics. If I take a baseball and throw it to you, it will take some trajectory. But if I take an electron and move it from here to there it turns out it doesn't take a single trajectory, it takes every trajectory, it goes to the moon and back, it -- and in fact the probability it will end up at your position if it starts on my position, requires you to sum over all the possible paths it could take. It's doing many things at the same time. An electron is spinning, but it turns out -- we can measure it spinning in a certain direction. But it turns out before we made the measurement; it's spinning in all directions at the same time. It sounds crazy. It's completely impossible for us to visualize. And part of the reason is as my friend Richard Dawkins was saying, we evolved to avoid tigers in the wild. We didn't evolve to do quantum mechanics. So our brains visually can't understand this behavior. It's amazing that with our experiments and our theory we've been able to do -- use it. The semi conductors in my computer depend on that weird behavior all the time.
Ted Simons: So, If all things are possible, is possible for me to put my hand through this desk? At some point in the history of all time and energy, am I going to be able to put my hand through this desk?
Lawrence Krauss: Maybe. The answer is maybe. In a sense that effectively no. You are very classical. If you were like an electron you could run from here towards the wall at the end of the room head first, I suggest you try it, as fast as you can. If you did it enough times you'd disappear at this end and appear at the other side of the wall. Electron do it, it's called tunneling. We're so classical, such big objects, the rules of quantum mechanics get washed out and we behave quite classically. While there's a nonzero possibility that your hand could go through this table, the probability is so small you could do it from now probably until all the stars in the universe burn out and all you'd have is a very sore hand.
Ted Simons: All right. I think I understand that. Probably don't. Next time we talk I want to talk about this business about Gama rays, 7 billion light years away. They wind up on our shores and it looks like they didn't disperse hardly at all.
Ted Simons: We can talk about that. It's interesting. It tells us something about the properties of space and time.
Ted Simons: We'll do that next time. Always good to see you.
Lawrence Krauss: It's a pleasure.

Lawrence Krauss:Professor, Arizona State University;

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