Krauss on Science

Ted Simons: Arizona State University physicist Lawrence Krauss joins us every month to talk about the latest science news, which this time includes new ideas involving the Higgs-Boson. We welcome Lawrence Krauss, it's always good to see you.

Lawrence Krauss: Always good to be back.

Ted Simons: And I love it when there's new stuff, you're now instigating this thing. First of all quickly, what is the Higgs-Boson?

Lawrence Krauss: The Higgs-Boson is the particle that's responsible for our existence, a field going through all of space that gives the particles in our bodies mass. At least it was speculated to do so for years, but we never saw it. We talked about it a year ago, July 4th, a good day for science as well as this country. A year ago they announced the first tentative evidence for actually finally discovering the Higgs-Boson. That was the reason the large Hadron Collider was built.

Ted Simons: Everyone agrees they have found it. Are there still skeptics out there?

Lawrence Krauss: That's one of the things I wanted to talk about, it's interesting how careful everyone is in science. When the announcement was made tentatively, on July 4th, it was announced that it was probably the discovery of Higgs-Boson. That meant there was a probability of only 99.999% likelihood. When it's something that important we have to be very, very careful. So that's why in fact in particle physics, things need a much higher statistical level of certainty before we claim a discovery. And a year later the large Hadron Collider is now closed for renovations. It'll be started up in a year. But what's exciting is that this year they analyzed a lot more data. What was seen before was something that sort of walked like duck and quacked like a duck so it was probably a duck. It was a particle that existed with the mass we probably might have and it looked like it decayed into some of the particles we thought it should decay into. The theory actually predicted our standard model, which is probably in my mind the pinnacle of our intellectual achievement as a human species. It explains three of the known forces in nature. This was a central feature of that model that otherwise explained all the experimental data we've performed on elementary particles and forces, but it hadn't been seen. It was amazing, the whole intellectual house of cards might have come down had it not been discovered. This particle that was discovered seemed that it's been exposed but it's really exciting as we've been able to measure it more carefully. It's virtually certain it is the Higgs particle. We can measure all of the decays of that particle and its properties and say for certain that it now exists.

Ted Simons: Saying that and now able to measure that, I understand you're thinking of dark energy, maybe a portal to dark energy. What are you talking about?

Lawrence Krauss: The great thing is, again, as often happens in science, every new discovery brings a bunch of new questions. The Higgs-Boson, the fact that it's there, solidifies all the ideas we have about these fundamental forces which is really amazing. There are still really profound questions. Such as why are the forces in such different strengths? Gravity, the first force we notice every day, is actually the weakest of all the known forces. It's 40 orders of magnitude weaker than electromagnetism. It's even weaker than the force that holds together the particles in protons and neutrons which is 10,000 times stronger than electricity and magnetism. Why are all those forces- why do they have different strengths? We know the Higgs particle exists but why does it exist at the scale it does? Now we can begin to speculate a little more, theorists like me. The interesting thing is there may be new physics at fundamentally much smaller energy scales that may explain why these three forces are very different, the strong force, the weak force, the electromagnetic force, on a very small scale. Perhaps 19 orders of magnitude. That's a billion, billion times smaller than the sizes of a proton. All of those forces may come together and be unified as what's called a grand unified force. And what's neat is that the Higgs particle, should it exist, there may be a new portal, new interaction that allows it to probe physics at that scale. One of the things I proposed in a kind of speculative paper, if the Higgs-Boson particle is coupled to the new physics in that scale, it might explain the other big mystery that we have talked about. The fact that empty space has mass and the dominant energy in the universe, it's a very speculative idea, I must admit. It's exciting to me as a theorist. I don't tend to think about things seriously until experiments demonstrate that they are there. And I really never believed the Higgs particle was there, I thought it was too simple an explanation. I thought nature would surprise us. I was surprised that nature- that we were actually right. If you're a theorist writing down some equations, it's daunting to think that nature actually validates that, and it did. Now that the Higgs particle is there, we should think more carefully about what it implies.

Ted Simons: So the Higgs particle might be combining with a whole different micro-particle or something. It makes for a whole new something out there that results in dark energy.

Lawrence Krauss: And may explain why the forces have the different strengths that they have. That's really important. The Higgs particle, as important as it is, doesn't solve the mystery of why the forces of nature exist in the scale they do, why there are only four of them. There are tons of open questions. We may never get the answers to all of them. It's kind of exciting to think that every time we make a new discovery it opens up the possibility of even more possible discoveries down the road.

Ted Simons: Can that explain why the universe seems to be expanding and going at different speeds?

Lawrence Krauss: It might be difficult explain- the energy that resides in empty space is absurdly small. 120 orders of magnitude smaller than we would have predicted if we would been writing it down as we did naively predict many years ago. The fact that it's so small is difficult to understand. What happens is, if the Higgs particle exists at one scale, and a lot of new particles at a vastly higher scale, they differ by a ratio that's a very large number. You can use that large number in a different way to explain another large number, in this case 120 orders of magnitude smaller, that ratio.

Ted Simons: I gotcha. 8:40

Lawrence Krauss: It may allow us to understand a number we wouldn't have understood or understand otherwise. It was a fun idea, but for me the most exciting thing is that this particle is actually there, and that our tentative evidence a year ago was absolutely right. I think that leads into some of the other things we may discuss today. When you're at the forefront of knowledge, at the edge of what we know, you have to be very, very careful when you see things, even if they seem 99.999% right, you have to be very, very careful before you jump and say, that's true. When you're at the edge of knowledge anything goes. The Higgs particle was very well-defined and the data seemed very clear. But I'm very pleased it took a year before the Hadron collider really said we have enough data to definitively say it's there. The game isn't over yet. The Hadron collider is down, to be upgraded over the next two years. In two years it'll turn on with a much higher energy and intensity, and it'll be able to explore for what we think is a whole bunch of new physics with the Higgs-Boson. And if that new physics isn't there, some of our ideas may be toppled.

Ted Simons: Oh, my goodness, we'll get you on for that. What is the Hubble bubble and what does that have to do with the expanding universe?

Lawrence Krauss: We talked about the fact that the expansion of the universe is speeding up, this weird dark energy that we can't explain and I tentatively tried to give one idea. When you're measuring things they are often strange and weird results. The Higgs might have been an accident, a statistical fluke. We often assign significance when something strange happens to us. In science you have to be skeptical and statistical flukes happen all the time. We've measured the expansion of the universe, but the fact that it's expanding was one of the greatest discoveries in cosmology in when Edward Hubble made it. If you had to pick one number to accurately portray the universe, the expansion rate of the universe tells us how old the universe is, because you work backwards to when everything was in one point. And in that case it gives us 13.8 billion years. We have different ways of measuring it. What's happens recently is the two different ways of measuring the expansion of the universe differ slightly. In the old days it wouldn't have bothered us but now cosmology is a precise science. And the cosmic microwave background radiation which is the farthest thing in the universe when we look out, we're looking at a distance almost back to the beginning of time, only 100,000 years after the Big Bang. Measuring the properties has allowed us to measure the parameters of cosmology, some of them to high accuracy and some of them 4 or 5 decimal points. But of course one can look at different ways of measuring the expansion rate and other ways to measure the galaxies moving away from us and see how fast they are moving away from us given their distance away from us. It's a very different measurement and what's happened is those two measures have been done to a much high position and they disagree at the 95% confidence level. We have 95% confidence there's a disagreement between these observations. Now in a lesser field, if it wasn't so important, you'd say 95% confidence, well it must be true! But the interesting thing is, we're the edge of knowledge. We have to think about the possibility that these measurements, that the difference could be a statistical fluke, that it could be a statistical fluke or maybe it could be a property of our universe that systematically would lead to one measurement being different than another. Recently two sets of papers have come out and said, you know, if we live in a Hubble bubble, in a region of the universe that's less dense than the overall universe, around us there are fewer galaxies than there are in the universe, then it may turn out that the galaxies we see near to us, the ones moving away from us are moving systematically faster than they would be otherwise, because there's less matter pulling them inward. We could be living in a region of the universe that's not the same as the other regions and that might explain this discrepancy with the measurement of galaxies and the expansion rate.

Ted Simons: Can you make that explanation with something unique to us or are there other bubbles out there, if you live on planet X, Y, Z, we're living on a bubble, too.

Lawrence Krauss: The universe has fluctuations of density and there will be regions more dense and less dense than average. We're used to thinking of ourselves as average. Undoubtedly, there are other places with less dense and more dense regions. If there are astronomers around those other stars they will be looking at the cosmic background. They will measure their local expansion rate and come up with a disagreement. They will say is it just an accident or new physics? The point is we don't know the answer because we're at the edge of knowledge. It's exciting when there are discrepancies because it offers the possibility that there's something new to be discovered. But 95% confidence is just not good enough in science.

Ted Simons: Before you go, speaking of the edge of science, voyager 1 is now the out in the interstellar heather regions.

Lawrence Krauss: Maybe. We have to be conservative.

Lawrence Krauss: Voyager 1 was sent out in 1977, it was sent out and going out there to ultimately happily boldly go where no machine has gone before, at least human machine. It was clear it was heading- it had enough speed to eventually leave the solar system. We talked about this actually almost a year ago. There was some evidence that it was leaving the solar system. What that really means is leaving the protective womb of the sun. The sun spits out particles and radiation and that sort of blows away the radiation particles coming in from the rest of the galaxy. It has magnetic fields to protect from that radiation. Ultimately it was clear there's a heliosphere, the region sort of protected by the sun. It looked like voyager might be leaving. Now there's much more definitive evidence that in fact there's many more particles, so-called plasma, charged particles, out there in the interstellar medium than there are on the protective womb of the sun. Recently a solar storm went by voyager and caused the area around it to ring. Boom, it's much greater than it was before. That's caused some people to say it's left the solar system, it's now gone off into the galaxy. But there are other observables that haven't been seen. The sun's magnetic field dominates in the solar system but outside it's very different. So we should see a change in the magnetic field hasn't been observed. Maybe our physics is wrong or maybe premature. We don't know. Even though a press release has been stated, I think we should wait before we open the champagne bottles.

Ted Simons: Does it still have that disk with all the photos of the sun?
Lawrence Krauss: It does. One day far, far away maybe some observers will look and hear Elvis Presley. Or whatever was hot back in 1977.

Ted Simons: Lawrence, good to have you here. Thank you for joining us.

Lawrence Krauss: It's great to be here. 

Arizona State University Physicist Lawrence Krauss makes his monthly appearance on Arizona Horizon to talk about the latest science news, including the most recent on the Higgs Boson particle.

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