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TEDxBuenosAires - Matías Zaldarriaga - 04/08/10

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Our Universe is very big, and the word Universe meant different things at different times. At some point, we thought that the Earth was the center of the Universe, and that planets, stars, revolved all around us. It was reasonable to think that, but today we know it is not like that, that there are innumerable other stars, that in many of those stars, we have discovered other planets, we have even discovered other solar systems. So we know that the Earth is only another example; it is only another example of the possible conditions of the other possible planets, and even though for us the Earth is very beautiful and it is very useful for life, well, we have been the ones who have got used to living on this Earth, we have evolved to live with the conditions of this Planet. Our Universe is not the Earth, our Universe is not our Solar System, our Universe is not the nearby stars, our Universe is very big and to study it we use our telescopes; our telescopes allow us to travel very far, they allow us to explore very distant regions of the Universe, and they also allow us to travel through time, because when we look far away, the light takes a considerable time to reach us, so we see how things were in the past, so our telescopes are our way of traveling through space, of traveling through time, If there is anything I want you to remember from this speech, is that the Universe is ruled by simple laws, laws we can describe mathematically, Physics laws. We can discover those laws in our laboratory, with experiments, with our telescopes, and when we apply those laws to the Universe, they work, and by using them, we can understand how the Universe is and how it has become the way we see it. That is what I do, use Physics laws to understand how the Universe is, and how it has become the way it is. Well, how is our Universe? The first thing to say, is that our Universe is huge, There are a great amount of stars. When we go to a dark palce, like the top of a mountain, in that video, the best place to do astronomy in the whole Earth, is the top of Mauna Kea, in Hawaii, you see innumerable amount of stars, those stars form our galaxy, the Milky Way. That galaxy is huge, but today we know that is nothing. As there are thousands of millions of stars in our galaxy, there are thousands of millions of other galaxies in the part of the Universe we can observe, thousands of millions of other galaxies, like ours, and they are at even more incredible distances. We also know the Universe is very old, it is 14000 millions years old, 13750 millions years old, to be more accurate. The interesting thing about that number is not only that we have been able to measure it so accurately, that I can stand here and tell you the Universe is 13750 millions years old, but that that number is endless, that the Universe has not been forever, at least the Universe as we know it, it has started 13750 millions of years ago. We have begun to understand that when the astronomer Edwin Hubble discovered the expansion of the Universe, back in the 30s He discovered that the Universe was expanding, that it changed, so the Universe had a beginning; that idea was very opposed to what people thought at that time, it was hard to assimilate, people wanted an endless Universe, which would be forever, even Einstein, after having discovered the general relativity, he was using the general relativity equations to understand how the Universe worked, to build an Universe with its equations, and the Universe wanted to move, expand, contract, it did not want to stay still and eternal. This was before the discovery of the Universe's expansion, so he tried in every way to make the Universe not to expand, he added terms, he juggled. When Hubble discovered the expansion of the Universe, Einstein abandoned all that, recognizing that was one of his biggest mistakes, his biggest mistake. That era of cosmology, the 40s, 50s, 60s, was a golden age for cosmology, since we have learnt a lot about our Universe. People have realized the consequences of the expansion of the Universe; the fact that the Universe expanded, caused the past to be much hotter, so hot as the inside of a star, so in that Universe nuclear reactions took place, and many elements around us, as for instance, helium, with which we fill balloons for kid's birthday parties, appeared minutes after the Big-Bang, in our Universe. And not only that, as I have already told you, the Universe is ruled by simple Physics laws, which we can use to calculate things, so we could calculate how much of that helium we expected, and of some other elements we expected to be in our Universe; we looked for our telescopes, we measured it and there it was, the amount we have calculated. And not only that, as in the inside of the stars is full of light, also at that time, the Universe was full of light, and that light, we could calculate, from Nuclear Physics, from Gravity Physics, we were told that we were to observe that light today as microwaves, and Penzias and Wilson, in 1965, discovered what we call today the Cosmic Microwave Background; they discovered it a little bit by chance, they worked at Bell Labs, in New Jersey. So that was a golden age for Cosmology, but the last ten or twenty years of Cosmology have suffered a similar revolution, we can say that thanks to the observations and calculations we have made, in the past ten or twenty years, we are able to understand how the matter is distributed in our Universe and how it has been distributed the way it is. As I have already told you, when you look at the sky, you see lots of stars, and those stars form our Milky Way, and I have also told you that there were many other glaxies in our Universe, well, those other galaxies form even bigger structures, called Galaxy Clusters; they also form filamentary structures, empty spaces. Matter is distributed in a singular way, and today we can say that thanks to those calculations, thanks to those observations, we can understand how the structure has become the way it is, because we could take pictures throughout time, of how the Universe was in different times, because our telescopes allow us to travel through Time, so we could take pictures of this process, of how the structure has been growing, has being modifying through these 13750 millions years. Today we can say we understand it, that it is due to the gravity force, we can say we have understood of what our Universe is made, having measured this, we understand how fast it has expanded in different times, major breakthroughs, In fact, in the last years, we have been able to get a picture of the Universe, a picture of the Universe in its infancy, when it was only 400000 years old after the Big-Bang, when it was only 400000 years old. We have been able to measure the temperature of the Universe in different regions, at that time, 400000 years after the Big-Bang. and that is a map of that temperature. 400000 years do not seem the infancy, I tell you, we have been able to measure how the Universe was 400000 years ago, after it seems quite a lot, but remember: the Universe is 13750 millions years old, that is like taking a picture of me when I was ten hours old, it is not a small thing; I leave you as an exercise to calculate how old I am with the data I have given you. So the last years of Cosmology have been really interesting, the last ten or twenty years. Now what? what do we want to find out now? Of course there are many questions, and I could focus on different ones, but today I want to talk about the principles of the Universe. As I have already told you, today we know that fractions of seconds after the Big-Bang, the Universe was very hot, it was expanding in such a way, temperature was not all the same, we have been able to take a picture of that temperature, we understand how the Universe was fractions of seconds after the Big-Bang. How has become like that? That is the question we want to answer in the next ten or twenty years. It is not a simple question to answer. And one of the reasons why this is not an easy question is that as a consequence of its expansion, when you go back in time, the Universe was hotter, and by being hotter, particles moved with more energy, and crashed with more energy. In the past, we were not able to produce such high energy in the laboratory. So which Physics laws applied at that time, we still do not know; we have never tested them in the laboratory. That concept, in order to understand the principles of the Universe, you need to generate bigger energies in the laboratory, maybe, many of you are a little bit acquainted, since the accelerator LHC, broke the energy record we could produce in the laboratory in the last weeks, and there have been many pieces of news in the newspapers, so some of you may have read that. And it is true, it allows us to understand the Universe a little bit more, that accelerator allows us to understand the Universe a little bit before; what those pieces of news do not say is that to understand the true origins of the Universe, of the ones I am talking about, we would have to build a machine which could generate energy thousands, millions, even thousands of millions billions bigger than the ones the LHC can make, and the truth is we do not have the slightest idea of how to build a machine which can generate those energies. So what we will do in the next ten or twenty years, is try to understand the principles of the Universe, but without knowing the Physics laws that are applied, different from what we have done so far, which we already knew them on the laboratory. So we are starting, entering a stage a little bit different from Cosmology. And the fear from many of us, who spend all day thinking about these things is that with the data we are going to obtain from the telescopes, only observing, looking back in time, be not enough, that data would not allow us to know how the Universe has become the way we observe it. But there is a positive side of the story: back in the 80's, thanks to the job which begun with a physic who is in the Massachussetts Institute of Technology in Boston, Alan Wood, we know there are modifications in the Physics laws which we have already measured in the laboratory, not dramatic modifications, but small modifications, which if we apply them to the beginning of the Universe, they could generate the Universe as we observe it fractions of seconds after the Big-Bang The idea is called, the idea of the Inflationary Universe, and luckily it is not the inflation we are used to in these latitudes; this is the joke of my speech so you can laugh about it. The idea of the Inflationary Universe is very very very nice, it states that the huge Universe we see, actually, as big as it is, comes from such a tiny, tiny part, smaller than the nucleus of an atom. Imagine, inside the nucleus of an atom, which probably, for everybody, what I am trying to say may be impossible to understand, all our Universe, very quickly, emerged there. And that idea, details of that idea, calculations related to that idea, the mathematical formulas of that idea, accompanied with quantum mechanics, which is the other mainstay of Modern Physics, would allow us to explain the conditions of the Universe as we see it in the beginnings, in the beginnings, those beginnings, first seconds after the Big-Bang. And the story would become more interesting, The story we know, thanks to our calculations, tell us that if that inflationary period happened, made the Universe be as we see it. If we could make maps of the Universe which would cover a bigger region of the Universe, and with a little bit more of fidelity, there would be, inside that data, hidden keys which would allow us to say if that quantum origin, that inflationary origin of the Universe, is what really happened. So, of course, the race has begun, there are lots of experiments trying to measure those, trying to improve those maps we have, experiments in the Antartica, experiments in Chile, experiments in satellites, experiments in balloons, all kind of experiments trying to improve those maps, to see if we can discover those small keys of the origins of the Universe. That would be the positive side of the story. The only bad thing is that we are not sure if with the technology we are going to have in the next ten years, with the technology we can imagine nowadays, we will be able to draw a map with enough fidelity to find those keys. We think those keys are there, but we are not sure to find them with those experiments. In a way, cosmologists like myself, who have been around for the last fifteen years, are badly accustomed. Every year, there have been incredible discoveries, and for instance, I remember when a balloon which measured the Cosmic Microwave Background, back there in year 2000, a balloon which actually, from where a telescope hanged, a balloon which becomes huge, as of the size of a football field, goes round the Antarctica for fourteen days, taking pictures of the sky, well, that balloon measured the temperature, that the geometry of the Universe was flat, and equivalent to the surface of a table and not the surface of a ball, and that was a question we had, and we thought that is was going to be as the surface of a table, as it actually was, but we were all waiting, and I remember that one of my colleagues called me to his office, closed the door, in secrecy, something very unusual in our field, he hands me a paper, I look at it: it was the paper of this experiment, I still have goosebumps, since that data has been analyzed with calculations I have made together with a friend, and discovering the Universe was actually like that: flat. And like that story, I have many more. So the last ten to twenty years, have been very good for us, because there were a lot of questions we wanted to answer and we knew that the experiments we were thinking about, we did not know the answer, but we knew they would give us a yes/no answer. Today, we do not know that answer for the future. But well, we want to spend the next ten or twenty years trying to find that, and trying to prove that inflation idea, which is also related to something very interesting, which is even a crazier idea: the fact that our Universe, as big as we see it, is, in fact, a tiny part of something bigger, called Multiverse. In that Multiverse, there are many Universes and all Physics laws, in each of them, are different, so there are laws for everybody's taste, as there are planets for everybody's taste, and maybe we have got used to these Physics laws, as we got used to the conditions of our Planet. I do not know if we will be able to prove that, but those are the kinds of ideas these experiments are trying to answer. So as to finish this talk, I want show you -on the one side-, a video which shows the map of what we have today of the matter distribution in our Universe; that map we want to improve, widen, do with more fidelity, that map created with real data from telescopes. And if we can do that map better, in there the keys to the principles of the Universe are hidden; that is what we believe at least; at least our theories tell us that if we can improve it, we should be able to find something. Moreover, I want to leave you with one last thought, as I say, the Universe is ruled by simple laws, we can understand, discover them; and we have discovered many of them in our laboratory, and when we apply them to the Universe, those laws work, they allow us to understand the Universe we see, they allow us to understand how it has become the way it is. Of course, there are questions which answers we do not know, questions which may seem deep, such as the question about the origin of the Universe, or the origin of life, or the origin of consciousness. But well, somehow in science, you have to get used to that. It is like the English saying: "the nature of the game", -meaning how the rules of the game are. Every moment, there are things we do know and others we do not. and we have to learn to live with a certain degree of uncertainty and know that maybe we will not find the answer to those questions, but probably someone may be able to answer them in the future. So, actually, I think it is OK the way that is, leaving questions for others to answer. To do science is fun, nice; the ones who do science, generally have a good time, except when we have to write papers for grands and other things which are not fun, but, in general, we really enjoy our work, and it is OK to leave something for future generations so they can keep enjoying this process which is to go further, a little bit, at least, in the boundaries of human knowledge. Thanks.

Video Details

Duration: 18 minutes and 5 seconds
Year: 2010
Country: Argentina
Language: Spanish (Spain)
Genre: None
Producer: TEDxBuenosAires
Director: TEDxBuenosAires
Views: 55
Posted by: luciawang on Oct 12, 2010

Discovering the Universe

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