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Professor Lawrence Krauss


Professor Lawrence M. Krauss is an American theoretical physicist and cosmologist. He is the Foundation Professor of the School of Earth and Space Exploration and director of the Origins Project at Arizona State University.  He is also a best selling popular science author and documentary presenter.


The Big Bang was an experiment, it’s now just data analysis.

On getting interested in science

Well, I became excited by the ideas of physics, I mean that’s, cosmology is just one area of physics that excites me because I want to understand how the universe works. I use cosmology, I use astrophysics, I use geophysics, whatever I can use to try and understand that.  And those ideas, I guess, the first time I got excited, probably, may have been in reading a book about Galileo when I was 10 or 11.  My mother wanted me to be a doctor, she told me doctors were scientists and I got interested in science, and then by reading books by people like Isaac Asimov and Albert Einstein I began to get interested in this incredibly exciting and sexy pursuit, and what seemed to be a brave pursuit, because of Galileo, of trying, no matter what, to understand how the universe works, but it was only later, probably reading Feynman that, in high school, that I began to realise there are still questions to solve, that it wasn’t all done, and that there was an exciting future ahead.  And that’s probably when I began to decide that maybe I’d be a physicist but, you know, I wasn’t certain for quite a while.

On the field of astrophysics

My particular area of scientific interest is the universe.  On the largest scales and on the smallest scales.  The neat thing, of course, because the universe is expanding, those two scales are connected, because large scales now were once very very small.  And so the areas in particular that I like looking at, one involves dark matter, the dominant mass in our galaxy and all galaxies and all clusters of galaxies is invisible, it doesn’t shine, and we don’t know what it is, we think it’s a new type of elementary particle and for many, many years I’ve not only been thinking about what types of particle it could be but how to detect them, so I’m involved in thinking about a new kind of detector for dark matter here on earth, because the neat thing is we think it’s this new type of elementary particle so it’s not just out there, it’s in this room as we speak therefore we can do experiments here on earth to look for it and that’s one of the things I’m interested in.  The other thing is to look for new signatures from things that happen in the very early universe; what’s amazing is as we look back and study the universe back to literally a millionth of a millionth of a second after the Big Bangand that’s just remarkable that we can even do that with a straight face – but we want to get back earlier and one of the signatures of processes that happen at very early times is a generation of what are called gravitational waves, ripples in space, and the ways to try and measure those waves, and they might be able to give us a direct signature of what happened, much much closer to the beginning of time itself, and so that’s another area of interest of mine. I’ve also been thinking about ways to understand new processes in the universe by new types of elementary particles.  My main interest is constraining fundamental properties of matter using the universe as a laboratory because the universe, the Big Bang was an experiment, it’s now just data analysis.  And then finally I guess it’s thinking of the long term future of the universe and what we might say on it based on what we know.  And of course, ultimately I’m very proud to have proposed the idea, somewhat facetiously I will say, but nevertheless it was right that the universe is dominated by something called dark energy and we really don’t understand it at all, it’s the biggest mystery in science.  I keep going back to that question to try and understand what that dark energy might be.

On trying to find out if dark energy exists

Well we know dark energy exists in the sense that we know that the universe, the expansion of the universe, is speeding up and Einstein’s Theory of Relativity, assuming it’s correct, tells us the only way to do that is to put energy into empty space.  We don’t have the slightest idea how it gets there and there are really no good ideas about that really explain the nature of dark energy except that empty space happens to have energy and happens to have that much energy for reasons we don’t understand.  It turns out in quantum physics empty space always has energy but when we try and estimate the amount it should have we get orders of magnitude more than we actually see, 120 orders of magnitude more, the worst prediction in all of physics in fact, and so to try and fix that we’re thinking about lots of new mechanisms but we’re really nowhere there and I’m not sure this century we’ll get the answer. There’s probably something fundamental about the nature of gravity and quantum mechanics that we need to understand first.  I constantly think of new ways to probe it and cosmology is the only probe of dark energy right now, you can’t measure it on laboratory scales, it’s just too small.  You have to use the whole universe to measure it and I think what we’ve done is about as good as we can get and probably what we need is a good idea and good ideas are a lot harder to come by than good observations.

On coping with living in an uncertain universe

Yeah, Feynman would say and I say mystery is what makes the world worth living in. Not knowing, as Feynman said, I’d rather not know, than know something that’s wrong. And mystery keeps the excitement going, so recognising that we are limited in our knowledge but we’re learning gives us hope for understanding things in the future; we should convince people that the mystery of existence is exciting enough to keep looking at the universe and asking questions, that absolute certainty would make a very boring universe if we ever had one, what would be the point, it’s the search more often than the finding, so we just have to convince people that the search is exciting enough and enabling and gives meaning to life.  Some people think the answers give meaning to life but for me it’s the questions.

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