Director of the hayden planetarium, place we all went to as a kid and i was never the same after that. I came back and actually became director. We also want to welcome cspan into this event. They are recording it for book tv. Cspan inhouse. Pan is [applause] tonights book is called welcome to the universe. I love saying that, welcome to the universe. When you go to the planetarium director school, they teach you how to speak like that. Let me immediately introduce my coauthors. First, michael strauss. [applause] these are my two coauthors. [applause] have a seat so just a bit of an introduction, i talked fori t ten years at Princeton University from 1994 through 2003, and before i transferred all of my activities here to this museum, over that time, i taught a course on introductory astrophysics and i got very popular and people liked it and we moved to vickers pace and we realized we could charge, we could energize the course even more by adding other talent that has particular expertise that could feed their curriculum. In particular, Michael Michael strauss is an expert on our on r galaxy and its structure, largescale structure structure of the universe in particular. Your phd thesis was mapping the universe. Thats right. In fact, we met in the andes mountains, both of us doing our phd back in the 1980s and we became good friends and later colleagues. J richard is one of the worlds expert expert on the theory of relativity. While michael and i take you from stars, planets, galaxies, to the big bang, we hand off to rich and you say where do you go after that. Can you have a deeper understanding of the universe than these descriptive things they contain and what it does, and there we learned all of the beautiful and bizarre nuances that makes our universe what it is, pivoting on the brilliance of people like Albert Einstein and his theories of relativity. Rich, why dont you begin, i have to tell one quick anecdote, we are equal coauthors in this book and the chapters have our names associated with the lectures we had given. We speak to the publishers who is Princeton Press and tyson you are better known, we have to make your name big. I said no, we are equal authors. They said no, we need your name big. In the publishing industry, your name starts out small and as you get more known, then your name is like the same size as the title and then eventually its just your name and the title is somewhere on the cover. They are selling your name rather than the title of the book. I said we cant have that, we are are colleagues. Then they handed it to the artists and the artists figurehe out how to do it. Hat, w my name, yes its its the biggest thing on the cover. Ha what they do is they put it on a planet that happens to be closer to you. We are all just on planets receding to the background. T its like okay, if you gotta dof it, be artistically clever about it. So rich, please give us a perspective. Rich has show and tell here and will just that back and watch because i never know what he pulls out of his bag. What you have. Okay, let me me start off, one of when my granddaughter allison was born, i said welcome to the universe. Its a phrase phrase you often hear from neil. When youre born you become a citizen of the universe and it behooves you to get curious about your surroundings in this book will help you with that. We start off with telling you about how big the universe is so i brought some models to illustrate that. This is a Hydrogen Atom. Its a billion times bigger than it supposed to be. This is enlarged by a factor of a billion in. You noted billion is. If you have a dollar you can get a hamburger. If you can have 1 billion, youre a billionaire. 1 billion is a big number. This this is a billion timesis bigger than a Hydrogen Atom. Its a model. This is the electron in orbit around the pro tron which is the central nuclears of the atom. This is a pro tron and the actual size on this scale woulde be 110,000th of an inch. Most of the hydrogen is actuallg empty space. Empt this is the most common atom inn the universe and your body. Mostly one might think that the only thing, theres nothing really intermediate in size between and adam and the nuclears of the atom, but we found a couple of things. One of them is a type of hydrogen that was instead of an electron orbiting around it, it has a a neuron which is a heavy cousin of the electron. It weighs 207 times as much as the electron and so the orbit of it is 207 times smaller on this scale scale it would be about a 20th of an inch. It reminds me of that movie, i dont know if you saw it, honeyy i shrunk the kids, did anybody see that. The professors shrink down their kids to about a quarter inch in height and then they have inventors in the backyard. Its not quite as crazy as it sounds because if all your electrons were replaced by neurons, you would shrink in size by a factor of 207 so you would be tiny. Unfortunately, they decay back into electron by emitting an anti electron and they do this on a timescale of 2 million of a second so it would be a very short film. They should go for the short film oscar. Another thing that is intermediate in size is if you take uranium, uranium has 92 protons and a hundred 46 neutrons in its nuclears. If you stripped all the electrons off of it except for one, because of the largee on charge, it would be 92000 times smaller than this so about a tenth of an inch. There are some things, we have made these in the lab, both of those things. There are some things that are intermediate in size between the atom and the nuclears of the atom. This is small, lets go the other way. Can i hold that. You can hold it. Thank you. Okay. Use of bended something in the middle of it. Will thats symbolic of the pro tron but its too big. You can see it. Now let me go the other way. Im in a go up by a factor. Suppose we shrink the earth by a factor of a billion. Here it is as a marble, half an inch across and believe me up got continence painted on here. This is an actual globe of the earth shrunk by a factor of a billion. This is a scale model of thehe is earth. Ive got the moon in here, but the moon is so small. So here is the moon. Yep we can all see that rich, really good. Aughte [laughter] its an eighth of an inch and the moon would be 15 inches away. This is how far humans have gone in the apollo program. This is all the further we have gone in the universe, 15 inches with a scale of one and 1 billion. ,000. Thats how far the moon is away from the earth and how big is the son . Well ive got the circumference of the sun up here. Ea this is how big the sun is. Ys [laughter] but youve got to spin it so it makes us fear. This is how big the sun is. Its about 500 feet away. Thats how big the sun is. So for a marble, wheres the earth, its a blue marble. There it is. This is the son, how big big the sun is and its 500 feet away for the sun. Now the question would be, how big is the next nearest star. The sun is a star, but the next nearest star is right here. This is a red dwarf star and its moeller than the sun and its 4. 3 light years away, roughly. That means it takes about four years to get to it from us. Thats the actual size relative to the sun and relative to the earth. Yes. This is a scale of one and a billion. Its smaller than the sun and this would be the model, this would be 24000 miles away. We could go all the way around the circumference of the earth and hand it to you. You can go stand over there. Hold so he is holding the alternate son that is 25,000 miles away from us on this model scale andi then we recently discovered a planet, heres a planet going around the star. Its a little bit bigger than the earth and so its about 24 feet away from it star. This is a planet a little bit bigger than the earth and its close enough to the star that its locked. It should always keep one faced forward and one faced away as it orbits around. One side will be too hot and the other will be too cold. Not too likely to be habitable but this is the nearest to us that we have found and thats how far away it is. So rich, keeping the same scale, youve got the moon which is a blue marble no of the earts is a blue marble. The earth is there an the sun and 24000 miles away. Thats a lot of empty space. Thats the nearest car. So if the furthest weve been is the moon, what hopes to have for the future of space travel. You just have to get that much better. Okay. [laughter] you have to spend more money. Okay. Y. [lau so okay, lets go up by another factor of billion and i will show you a model and a scale of not one over a billion which is what we just saw but one over 1 quintillion. This is a billion times smaller also. Heres the sun and there is alpha sentara. This is another solar type star. It is a triple star system but the brightest one is the solar type star and its again about 4. 3 light years away and here, on the same scale is the blue star that youve seen in the northern sky, this is, its about nine lightyears away so these are some near stars to us and were living in the milky way. It has 300 billion stars in it and it would be about 8 10 of of a mile across on this scale, big disk of stars and theres about, if you went through this model on a scale of one over 1 billion billion, it would would be likeu going through a snowstorm of stars and the next nearest bigin galaxy to us is another galaxy about 20 miles away on the scale so rich, if you got another 299 million lights. [inaudible] i need to work on this model but more. So now we have that scale but lets go up another factor of the billion now lets look at a model that is one over a billion, billion, billion. Then you can see the entire visible universe here. We are at the center of this. The cosmic microwave Background Radiation is. Its as far as we can see. The universe is 13 billion years old since big bang in the radiation since this microwave background has been coming toward us for 13. 8 billion years so the radius of this and what we call look back time distance is 13. 8 billion lightyears and so we look out in space, were looking back in time so this is as far as we can see, and inside the sphere there are 130 billion other galaxies, each one of them with several hundred billion stars in them. This is the cosmic microwave background that we can see. We cant see anything beyond this, but light from those regions hasnt had time to get through a. Hey rich, you just put yourself in a rather privileged Vantage Point to even show that. Yes, well this is what we see. If you stand on top of the empire state building, you are going to see a circle out to the horizon, thats as far as you can see on the empire state building. If you go to the willis tower in chicago, you can see part of chicago that is centered on you. The part that you can see is always centered on you. That doesnt mean youre special. Everybody sees that. Ered o everywhere you go, there you are we see this and we have reason to believe that the universe is much bigger than this because the fluctuations in this are only one part it 100,000. We believe the universe is at least 100,000 times as large of this and probably much larger. The best theory for explaining in detail, the pattern of fluctuation that we see in this cosmic microwave background sphere which is based on thery f deadly satellite is the theory of inflation which they put forward in 1981 and in that theory, that that explains how the big bang got started and what it says is you could have started the universe with a very tiny region, of high Energy Vacuum state. What is that . Well we are used to thinking of the vacuum as being empty. If everybody left the auditorium here and if we took away all the air and all the protons, you would think it would be zero energy, but in fact, because its going through the universe, the universe and have a nonzero vacuum energy. Rgy. If it has that, because we would like the vacuum not to have any privilege standards of rest, its going through this vacuum a different speed, it must be that this vacuum energy is associated and it operates in three directions. This is uniform pressure. In the room here, you dont notice it because its uniform. You have have difference in pressure. This is or pressure with no effect but it has a gravitational and energy so that means it has a repulsive effect, a negative pressure so its three times more potent and causes it gravitational rotation in the first ten to the 30 2, it seconds, it could double in size a thousand times so it can become truly enormous. This describes why its so enormous and in detail it can explain the pattern of fluctuations that we see. The theory of inflation is very effective at explaining this. One of the problems it has had is what you want to have happen is you want this high energyum n vacuum in the universe to decay into normal particles. We wanted to dump its energy in the form of normal particles so the problem with this was that its like youre trying to boil water on the stove and have the water represent this insulating speed of vacuum energy which is inflating very, very fast and you wanted to turn all into steam and ordinary particles, but what happens, if youve ever boiled water on the stove,le informs bubbles and so we expected to get bubbles of particles forming in this and that didnt work or look uniform some propose in 1982 that what happened was that we were living in one of the bubbles. These were individual bubble universes that were expanding in from inside the bubble it looked uniform to you and the other bubbles are so far away that the light hasnt gotten to you yet. [inaudible] with that theory, its just going to keep making more and more bubble universes as it continues to double and double in size and eventually get an infinite number of bubble universes and this can haveyo different laws of physics and so you get a multiverse, verse, we actually think we live in a multi verse and this is all compared with the tiny region that we can see. One of the reasons we believe that these other universes out there exist is that the theory of inflation predicts it and the theory of inflation as we show in the book beautifully explains the pattern of fluctuations that we actually observe in the cosmic microwave background. Ou the other reason we believe in inflation is that we are actually observing inflation starting again in the universe in a rather lowkey fashion. We are seeing the universe today in an accelerated expansion, two groups groups founded in 1997 who won the nobel prize for this and the universe is going to be doubling in size once every 12point to billion years and today which has a very low vacuum energy of seven times. [inaudible] weve seen a low grade form of inflation even occurring today so this is another reason we believe in inflation. Ive talked about sizes and the universe and one of the reasons that people think that pluto got demoted was because of its minuscule size and so i would like neil to tell us about that story because he was a big participant. [applause] rich, you took us from the Hydrogen Atom and multiverses and then you dumped pluto in my lap, just to be clear. [applause] i think in the visual above my head we have what are called the terrestrial planets. These are the planets that have surfaces you can walk on, mercury venus earth and mars. The moon is also shown there which looks quite small, but something to know about our moon is it is one of the largest moons in the solar system. Even most of the moons of. Jupiter and saturn are dwarfed by the size of our moon. We have an uncommonly large moon relative to us, in spite of how small that looks. The point i want to make here is pluto, we have history here with pluto in this institution. Back in 2000 only opened the row center first in space, we werere the first outofthebox to reassociate plutos identity from the planets to the dirty ice balls in the outer solar system. So we were raked over the coals by the press saying, especially little kids, say there are angry, pitstop thirdgraders thirdgraders saying just because its small, how could you do that. Thinking that size was an issue and in fact, it had much less to do with size than you might imagine. If we just go to the next slide, what we have . Now we have the gas giants,ize n jupiter sat saturn uranus and neptune. And then you get to see how small earth is relative to the rest of the action there. This group was included in this for scale. Heres here is a point i will make and i cant make this often enough. Jupiter is more bigger compared to earth than earth is compared to pluto. I dont know how else to conjugate those verbs in that sentence. So in other words, if we were on earth saying were big enough to be a planet but pluto isnt, then imagine what they are saying, they could say it only has four planets, jupiter uranus saturn and neptune andnd Everything Else is just debris. [laughter] im certain all life forms of jupiter are thinking exactly that way. You cant invoke size exclusively to just pluto in this regard, but allow me to tell you that our moon, as small as it was compared to earth has five times the mass of pluto. Pluto lovers were never told that were you. Welcome to the company ofhe coma informed people regarding pluto. So, we knew this, pluto had other issues and so after some thinking about this, pluto got demoted to a dwarf planet status on several grounds, one of which that it orbits the sun in the solar system where there is plenty of other stuff orbitingng their which in total dwarfs the massive pluto itself. Pluto does not own its orbital place in the solar system. It is shared with countless thousands of other icy bodies that rival pluto in size and composition. What we really discovered was that pluto really never was thee planet we wanted it to be. In fact, it just went 60 years before we had discovered the icy brethren orbiting beyond neptune they hypothesize there could be a dispositive depository repository of debris that did not participate in the rest of the planets. So pluto is a very healthy object but a really lame planet. Okay, so just just to make that clear. Now, when we look for other planets which has been quite the pastime these last several years, by the way, im, im curious if theres anyone in the audience that is 21 and younger, raise your hand if youre 21 and younger. There are several of you. That means you were born in 1995 or later. Bor 1995 was the year our community of astrophysicists discoverednif the first xo planet, the first planet in orbit around another star. I want to invite all of you born since 1995 as generation as generation xo planet because youve only known life in a world where weve known world beyond the backyard of the solar system. What a privilege that is. So, in our book, we calculate how you might go about finding xo planets that would be of particular interest to us. What would you be after . Not necessarily rings although rings are beautiful, at the endh of the day you are after whether or not it can harbor life and life as we know it or perhaps life of any kind. So, there are are ways to approach that problem and one of them is called the drake equation named after frank drake lets put him up, and image in the corner. I think he is much older than that now. Is he still alive. Yes. Okay good, good to know. So frank, who was early in this exercise of asking what is the likelihood of us communicating with alien intelligence that could lurk in a planet out there in the galaxy. He came up with a clever way to attack the problem. You come up with an equation, and thats him writing the drakg equation sitting under his pen in that photo, what ive done in this slide is make a simplified version of it to get the idea across, but there are several other turns in the equation that he has written. Lets start with the simplified version so we get the idea. D be what we want to calculate is the number of civilizations i could be out there. Lets start with that. This would be life that is achieved intelligence and created organized societies, civilizations. I would you go about doing that . What you want to do is split the problem into multiple bits. Each bit could be entire science projects to try to address. That way, what we say is you unpack the problem, separating the variables. Ow if otherwise you dont know if you are coming or going or whats influencing what. We start out with how many totai stars there are that you could be searching. In this case, that would be the number of stars in the galaxy, the Milky Way Galaxy. Its coming in at about 300 billion. Over the years years you mightve seen hundred billion, all those numbers are the same to us. Whats a few hundred billion between friends, really. I say that not facetiously. There are galaxies that have a trillion stars, galaxies that have only a few hundred million. If you are within a few factors of a hundred billion, thats the same number to us given the range of sizes of things that are out there. O start so, start with the number of stars. What you want to do is ask, what fraction what fraction of those stars have planets because youre going to look for life. Ts you dont expect life in stars. That is hazardous to molecules. What fraction of those have planets . That would be its own astrophysical exercise. You would create a telescope, mounted on a satellite, which we have done and it measured a piece of the sky and it looked for what fraction of the stars in that piece of sky have planets. You can do that. Now it turns out not all planets are good for life. Some might be too close to the host are and be too hot. Too far away, too cold. Well too hot or too cold for what . Life as we know it requires liquid water. You would want the zone around a star to be just right, the goldilocks zone. If youre looking for planets, you kind of want a planet in that zone if youre looking for life as we know it. While we didnt specify that as its own term, fraction of planet in the goldilocks zone, you can imagine that it has its own term. Separately measured from just the fraction of stars in the planet around it. Okay. Nets, you so now weve got some fraction of total stars left that have planets that have planets that can sustain life in the goldilocks zone. Now you want to ask how many do sustain life. Is that half of those . Is an attempt . Ne ten we dont really know so not all these terms have equal competence in the numbers we insert. But you keep going. If it does have life, what fraction of those planets of the stars that have planets in the goldilocks zone that have life, fraction of those have intelligent life . So here we are packing away at that numberwe 300 billion. Is it one in a hundred times one and a thousand times whatever these fractions are, we are hacking away at the number, but its a big number. Theres a lot of wiggle room to give you something left over at the end. You keep going. By the way, these are civilizations you would talk to in some way. Y. Well, how would you do that if they dont have technology too send signals through space . Hu think about it. Most of human cultural history we have had what we would call intelligence but theres no way they could have had a conversation with an alien. They didnt have technology or radio waves. They c they didnt know anything about it. So just because youreou intelligent doesnt mean you are a candidate to communicate with. As this is set up, which is counting civilizations, but, but if you add up all those terms and ask how long have we been able to use radio waves . Maybe a hundred years out of thousands of years of human history. If you threw a dart at the timeline of civilization, whattt fraction of the time does that dart hit us with our capability to communicate with aliens. Its a tiny fraction if there were any measure of things. You can call upon a planet randomly in its life, what are you likely to find . Thats the kind of questions that are addressed in thishe equation. The l when you put in the very latest numbers, you you put in all theh numbers and all the terms, what we come up with is, whats the number of civilizations in the e galaxy . 1. 8 billion habitable planets so these are planets in habitable zones. 1. 8 billion. And maybe as many as alright so those those are planets capable of hosting life as we know it. Capabho and the other one could be as big as, maybe smaller than, but could be as big as a hundred that are communicated with radio waves now. 100 in the galaxy . So thats hopeful. And there are other galaxies, dont forget forget about that. Lets go to the next slide. Heres an image taking from the Southern Hemisphere of the Milky Way Galaxy to let me explain to new yorkers, this is is what the sky looked like, if you remove the buildings in the light and the pollution, one day i want to write a novel that implicates the amateur Astronomy Community for all the major blackouts that new york has experienced. You park and there they were unplugging new york. Theyre forcing you to come out and look up and notice venus and the moon and things. K it is stunning how do they recognize that there are 180 billion planets in habitablo zones scattered across the galaxy. That is the plane of the Milky Way Galaxy. We are in the galaxy within it. All the other stars you see above and below are also part of our galaxy. They are just really close to uu theyre like a blueberry embedded in a pancake. Ke a blu you can look out, above and below and escape the dough with a pancake, but if you look within the pan of the pancake its just pancake all around. S we have galaxy all the way around us. This completely wraps the sky. l i want to note for you, rick scott mentioned our nearest large galaxy is named because it appears among the stars identified in the constellation but of course its much further away. The stars in the consolation iat just constellation are just part of our galaxy. D this image in the Southern Hemisphere has two fuzzy cloudy things off to the bottom. There we are just in the middle. My people know where im inting. Was that not clear . I said two fuzzy things down there. So they look like clouds and while native inhabitants surely knew all about this, we in the west first learned of it from the journals of magellan who upon circumnavigating the globe went through the Southern Hemisphere and saw these clouds, notice they never left but he still called them clouds because thats what they looked like and to this day, we refer to them as the Magellanic Clouds but we know their dwarf galaxies inin orbit gravitationally bound to the milky way. They are nearby. Its not all roses for small galaxies in orbit around big galaxies. We have a record of small galaxies that once orbited us that have been completely cannibalized and we see just the remnants of streams of stars fully absorbed into our own solar system. So dwarf galaxies have very limited lives when they have to hang out around these systems. I mention that because we willli make reference again to the large, the larger of these twoin fuzzy things in the sky. Just to be clear, i dont know if we can dim the lights just briefly and then bring them back up and we will see if the fan can handle it. There we go. What you have here is one of the most famous images ever taken and its by the Hubble Space Telescope and its called the Hubble Ultra Deep Field and by deep we mean how far into the universe is that picture reach, and of course its a nasa photo. Notice there is a red object, thats a star sitting on our nose in our own galaxy and it might be the only star not photo. Every other smudge, every other speck of light is beyond the stars of our milky way and they represent entire other galaxies each containing hundreds of billions of stars so when we talk about the probability of life, we generally contain it within our own milky way, but if you want to multiply up by the scale of the universe and all the galaxies contained within it , you would be inexcusably egocentric to suggest we are the only life in this universe. By the way, this area on the sky is a tiny fraction of the area of the full moon so you takeoo this and multiply it out by all the points and all these tiles that you can fill up the sky with and thats how you recover these numbers such as 130 billion galaxies. We can bring the lights back up. Let me now and off to mike. Up what can you tell us mike . Ive got to move. Okay sorry. Were going to go back to the milky way. This is a view of the milky wayn from the observatory where phil and i met almost 30 years ago. No it was just a couple yeary ago. [laughter] neil, i think you were using the telescope. Replay but i was on the. 9. You can see the milky way rising dramatically and coming over our heads. One of the frustrations, even if you get away from new york t citys bright lights, one of the frustrations of being in the Northern Hemisphere is up around us parts of the milky way are not visible to us. You have to travel to the Southern Hemisphere to see this dramatic part of the milky way where we are actually looking i straight to the galaxy center. We will have more to say about that. Can i just add something. This is memory lane now. This is at the summit of a mountain in the andes and occasionally you get weather that is below you, total cloud cover below you on the top of this mountain. If there is any moonlight at all , you just look out over the edge of the mountain and it is like you are somewhere unreal. You are an island, you are in the middle of clouds and there is no earth. Its just you and a telescope in the cosmos. So with that. [laughter] so, we may be the last generation of astrophysicists who actually went to mountaintops to obtain our data and the pilgrimage this represents, a plane to san diego and practically mule train up the mountain and you invert and lift nocturnal he because the night becomes your day as therau day becomes your night. T within a few years of that, we now have whats called service observing where you just send your coordinates and give the specs and they. The telescope, its all automated, year get the data back and youve never left your office. Its way more efficient but itit lacks some of the romance. Okay sorry, i will shut up. Go. We met what we do is we set up a long enclosure with her telescope and the telescopes even 30 years ago were fairly automated so they took care of some of the spread we comemeauto outside enjoy the spectacular view. There are several telescopes at the observatory and we would often bump into each other there on the mountaintop enjoying the view. In addition to neil and myselflr working on our respective phdd thesis, i also met the woman who would later become my wife. She was also on the. 9meter so i just wanted to mention that. So so lets talk a little bit about what the nature of the milky way is. We have seen 300 billion stars. Some of the questions we want to ask ourselves is really what is a star . Theyve already told you they are tremendously hot and enormous. A star is a ball of gas held together by its own gravity but held up by pressure. Weve seen a great deal of heat and light which is what keeps us alive. One of the great triumphs of thg astrophysicists in the 20th century is learning what the stars are actually made of one of the great discoveries indeed is that stars are made up of hydrogen and helium. What we have are the elements of the periodic table indicated the size of each that is proportional to the mass ofhavea atoms that you find in stars. Hydrogen and helium dominate the universe by far and Everything Else represents just a trace. The carbon and oxygen, the makeup of our bodies and neon and magnesium and on and on are just a small fraction, a tiny fraction of the atoms in the universe. One of the fundamental questions that we next want to ask is why is that the case . How is it that the universe has come this way . U we described as in the book. The hydrogen and helium in theem universe came to us from the big bang itself. The Early Universe was tremendously hot, much hotter than the surface of stars, temperatures that range up to billions of degrees it was so hot that stars cannot exist. Climates cannot exist. Molecules could not exist. Even adam could exist. Was so hot that the only thingms that could exist were protons and neutrons, protons being the nuclear of Hydrogen Atoms. As the the universe expanded and cooled, even in the first few minutes some of those came together to make helium, and indeed one of the great triumphl of our understanding of the Early Universe and the expanding universe is that we can predicte the amount of helium that were produced in the early phases of the big bang and it matches wonderfully with experimental values now measured with the spectra of stars. Basihats it. Basically the earth, the Early Universe gives us hydrogen and helium and it was first thought that we would be able to explain the rest of the periodic table, all the other elements of the f universe from the big bang itself, but it turns out not to work. We need another explanation to see how those heavier elements are made, and the answer is going back to the stars. If you go back to the sun, is that going to work . If we go back to the sun and asked the question what is happening in the center . What is happening in the center thats causing the sun to shineh it is tremendously highpressure and hot. The. Ns trons can fuse together to make helium nuclei and release some energy in the process. We describe that process in the book. A pro hydrogen is formed into helium and that is the process thatsel going on in the sun right now. In the story gets much more interesting when more massive stars, our own son would be able to burn hydrogen into helium and later turn helium into carbon and oxygen which are primaryed l elements that make up our bodies, but if you want to get the rest of periodic table, you need more stars, a star maybe eight times as massive as the sun as it continues to grow and use up the hydrogen and then the helium and then the carbon and oxygen burn heavier elements and start creating elements of ever larger masses, working working your way up the periodic table. It turns out iron, which is element number 26 in the periodic table is the end of the story. You cannot combine iron with anything and get energy out. It requires energy to combineroh iron to make a heavier element. So, when they get to the point where the core is made purely of iron, then the interior Energy Source is gone. The star is being held together by gravity. I told you the furnace in the center is giving you a pressure thats holding the star up. Weve turn that furnace off and the star has no choice but to collapse. It collapses catastrophicallyac and in doing so it explodes the outer parts of the star that have not reacted and they undergo Nuclear Reactions at a tremendous rate and a star explodes and what is called a super gillis. Lets go ahead, we know these supernovas exist because we can see the leftovers. This is a famous supernova observed by the Hubble Space Telescope had what we areab neb seeing, neil its your favorite word, the smithereens of the st, star broken into, this this is known to be a star that exploded in 1054 a. D. How do we know this, because the chinese left records that they saw it explode. Left r there was a guest star that s appeared in the sky. Eks ev it was bright enough to be seen for several weeks even during the day. We look at this position in the sky and we find this dramatic residue of that exploded star and the gas that we see here has all those heavier elements built into it. Just be clear, this is the got the star, not the start self , this is the blown apart got. Thats right. Its really nasty looking, but also, astrophysicists todayo celebrate that explosion every year because the chinese observed it on july 4. We have fireworks and astrophysics community celebrating the crab niclas, just fyi. It didnt destroy the star completely. Right in the middle is something called a neutron star and its a dense center part of the star, a be about the mass of the sun made up of essentially. Neutrons, tremendously dense. One thimbleful of neutron star stuff ways hundred million elephants if you can get your mind around such an incredible thing. So remember, i said, the iron that the star can make only iron and then the process stops. Then the star explodes into the supernova. There is so much other elements to be made. There are two different stories that we are trying to understand as possible ways to make the heavier elements beyond the iron in the periodic table. One is they are formed in the explosion of supernova and the other is that you may have two of these and they collect together which can happen under special circumstances. Thats another way to give you that energy to give you those heavy elements. S hehe think about it, the goal is formed in the center of an explosion just like the one we see. In fact, most of the atoms in our body, and all the other elements other than the hydrogee and helium were forged in the interiors of stars of one sort of another. Its an awesome thought to think about. That was a supernova in 105480. In 1987, february 23, it was observed in a picture of the night sky, supernova went off. This particular star exploded. Boom. For weeks after words, the astronomers meeting in the hall would just say boom and be extremely excited. It was a very fun time to be an astronomer. I was lucky enough to be a part. I was able to travel to the Southern Hemisphere and actually see the supernova with my naked eye from 150,000 lightyears away. That light of a single star was visible. The guy who discovered it was in the telescope home when it happened and he just didnt believe it. He just went outside and looked up and there was. It was really very dramatic. It was certainly one of the most dramatic, actionable discoveries of our time. It was the first since 400 years, since the invention of the telescope. The literal translation ofatn supernova means new, but in fact it is a dying star which we later learned. Its a new star to you if you dont know astrophysics. So, i want to go back to the milky way and talk a little bit about this. Neil did not mention that his own specialty in his thesis was studding the stars at the center of the milky way. This is a movie from the southern observatory. Cial its a special place, but at the very center we find something that was truly dramatic. There was a black hole sitting in the center of the milky way. No a black hole is black. It is, as you probably know, something so dense that nothing can escape from it, not even look light. How can we infer its existence if it is almost by definition, black. It has no light for us to see but we do see its gravitational influence on the stars around us. one from the colleagues at ucla but she has mapped the orbits of individual stars at the very center of the milky way and they all seem to orbit around a single point to write in the middle. No light is seen buchanan for how much mass must be associated and also get a limit on how large the object is his invisible very tidy incredibly massive. And what is that object . Hit did say black coal. But all large galaxiesll lar have a super massive black coal. One up to a few billion so what does the things that has been part of mygs Scientific Study is to study the massive black coal. But it is a dense light cannot escape but imagine there is gas flowing into a the black hole and it is soa bright that it is if which we call the quasar can be seen all the way to the edge of the observable universe 13. 8 billion light years away and therefore that represents a visible universe that has had time for the light to reach us. So what we see here and appoints to the quasar that is seen 13 billion light years away. Light travel time distance. So that is just in year 900 million years well looking back at a time when the universe and the study of the objects gives us important clues. The guy who discovered pluto davis series of lectures that there is so little doubt with a narrow n they said how did you know that was played no . He said there was a narrow pointing to it to. [laughter] black hole are interesting one of the dramatic discoveries off the week to get into the book justintime was the most direct evidence yet a with proved that as the general theory of relativity imagined to swirling around each other. If predicts that those two black kohls will warp space and time to send ripplese when like throwing a stone into a pond did turns out from traveling at the speed of light. It causes sows to get closerhe together. Be observatory with the gravitational wave was built to measure that distortion of the fabric of space and time think consists of an extremely long of the 4kilometer length with the of with the of a single proton. There is 29 of them merging together to make a single black hole and then say that does not make sense . Not ma something seems to be missing. But that missing piece is the energy lost in the gravitational wave. Remember e mc2 and that was lost in the form of energy in the collision of those two black kohls. Annie read track that with the observatory to prove directly to demonstrate that black hole actually easiest. That conversion of those multiple solar masses thein the hit energy at that moment the most energetic force in the universe. So now we are at a threshold in our study of astronomy with this entire window not only see but to listen to the Gravitational Waves and those are the exciting development. This is just a quick hit diagram showing the actual measurements with what was observed. With to talk about the future one of the wonderful things of the universe and there is a lot of exploration. Weirs still very much indeed exploration mode to say what is out there. This is the artists conception that was built in chile literally one mounted over mountain over. And and 2022 to make up a map of the sky. Multiple maps repeatedly asking the question can we see new exploding stars or the phenomenon that we just dont have the imagination yet to discover. I mentioned 30 years ago we were very lucky to travelear last year for the 25th anniversary and also the ceremony marking the construction of the observatory. The mound top where we met mountaintop where weve met. We will lag to stand that close . [laughter] no we will turn back. In the book we have a map of the universe going from left to right this is a panorama looking out from the earths equator a map that preserves with shapes so each constant step out word steps further away from the earth. So let me point out there is the surface. And there are the satellites going around. Is very made clear but the surface is the shoreline of us cosmic ocean that is the adl that has been with us for some time. That is the satellite that measures the cosmic background. Theyd that measurements of the sun. Now we get into the realm of the planet. Talk about those in your objects that could render usinct extinct. [laughter][lau when the thing that project will do is find out if any of those are going to hit us. Cement this is the farthest away from pluto in the kuiper belt. With haleys comet we have and voyager numberone and never to what this uh Julius Caesar comment comment quite. Aikido i. So we have another zone of commons predicted by dutch astronomer and a reservoir of comets coming from any direction. And alpha century is the name of the entire system sigma also going to factor of 10 this is the earliest that the signals have reached base that includes the 36 olympics some of the first signals that aliens will recede. The 300 billion stars you can count and as they come by. Here is the distance you would find the caller fromem us a factor of 10 each tick mark. Now were into the realm of the galaxies but andromeda at the number of others with a name like sombrero laugh laugh. Recall that as we see them. You know that i write. Crab nebula. Here is the of lump all of galaxies and they guinness book of World Records each represents a single delicacy. Finally the most distant will be right here. Then stretching is uh uh cosmetic sphere half of it is up there. There is. All around that it is the light coming to us leftover from the big banks demand that is the universe. [laughter] [applause] and that is about 5 of the book. We do have to microphones for questions and answers we will be involved all out to to was selling books. By a when this is the only occasion or all three of us will be signing the book so this will be unique just so you know,. About 10 minutes and also if you must leave now because you parked too far away, you can pick up a book to have that preselling dont have to wait in line. We encourage the children in particular to come up and ask. The plan to do a video lecturer series on the book . May be. Acks. May be. Not yet. The way to get it is above book. Can you explain why there is no center of the University Look at it from the edge . From the center to the edge . But if you imagine a big balloon with coins as the balloon is blowing up it is the picture of space expanding if the coin is stuck you can see theyre yol running away from new just like grease think wee are standing on top of the earth and the poor people in australia are hanging upside down. Everybody thinks theyre att the center paul all the claimants are equivalent but space is expanding the use a what is around you so nobody is special. [laughter] mediterranean means middle of the earth when translated so wherever people from worked they thought they were in the middle. Great lecture. In your equation of the planets there is another part is unique that you would touchline that had much to do with venous but as those that were stripped away by the satellite so what effect do you have to look for within the goldilocks own. Zone. There is a lot of research, important was the of moon information act of life itself to have that stability necessary to develop the complexities of the of biodiversity has given us. My opinion is a little overstated, important of munis. Yes it does stabilize yes but just think of how diverse life already is in the tropics so what if it is wiggled little more . Level does add more biodiversity l. Lander some extent. That is my personal view ; tennis to get very specificif about the situation. Some parts to make sense. There is a variety of ways to do that. But it is of did more detailed although some people say that the tide could have been helpful out onto a the land. It does not seem absolutely necessary. On so what is the theory why our moon is so big . We have the theory did not take shape when they bought back samples from apollo henry noticed it is made mostly of the same stuff of the earths crust. And it is missing for object that size it should have the earth mixture of the stuff of the solar system with carbon and oxygen and nitrogen but also iron. It should be there in the moon and we have a huge iron core that the moon has hardly any. Ardly an when we formed it is heavier us silicosis to the core of theirs rise to the top and solidifies. If it has no iron anywhere or eight core the what happened to . Alleged people thinking that maybe it was formed after birth already differentiated. I am the its to the hypothesis that a mars solvays object sideswipedsi earth to scoop up the material to reform into what became the moon and that is not farfetched because there are periods of very heavy bombardment with the leftover materials from the solar system. If this small and is absorbed by just to be clear the of moon is a littlehe heavier than 1100 of the mass of the earth. So were really isnt that much material to give of yourself to make a mood. You will miss set. I promised. So that is able separate story line. That is different and how all the other planets got there. We have big ones and they dont. Labor of love for all of us on the team. You are very well known for being on top of science and pop culture lyme care is someone manages to do that . Where do get your news . I am a clone. [laughter] it is nearly impossible. Nearly but i cheat ill look to see what is the iron number one tv show . Then i catch a couple of episodes would is the hottest team right now quick sell will check up on that. Who is in the super bowl quick step up on that. I allocate my energies that garner the deepest and most intense public attention to give me fluency in these places that they care about the n the take the laws of physics of the universe to plug into what they already care about. They cabo if you come to the of party with the scaffold bed then i climbed with the cosmos but then he walked away not having to learn the science as a separate exercise because it is part of something that you already know and love. And one example was i was channel surfing. I have 50 minutes before my movie starts and the Football Game is in to lead tie 15 and over time. I said i can do that. I will watch this. Why not . Y not . There is a duel has to change hands a couple of times than sudden death. Death. Then they get close enough to kick the field goal. And then addressed to the left and it hits the left upright and bounces inside for the win. Is it is a round ball hitting a round of price i checked the orientation of the stadium. [laughter] and i carry the to and i treated this winning field goal by the bangles was enabled by onethird of an inch draft of the trajectory of the ball toward by the rotation of the earth. Died in that have to explain what a field goal or football or the cincinnati bengals. That is your scaffolding i is gave you the quayles and people must have lost their minds on that. It was all over the cincinnati news i got on espn. Any one of my colleagues i dont have any special knowledge i just happen to do it. Will they are busy en la allow the. That is hell happens. With proposed idea is what about getting to the health plus n tarry system . So you talk about this recent announcement of the and and no craft powered by the pressure of the laser lights if you can get there quickly we have led billionaire working on this. The audit is useful. [laughter] several people in our department are working on this. And by the way that groups celebrated so that gives them the goal to go to their working on that. Given that we have the milky way is a collapsing in on the self . Imagine if the sun turns into a black call tomorrow that could be bad news the source of heat and light wood did disappear but that would continue exactly. One has a mental image as a vacuum cleaner that isnt really true but the few or bit to the black hole is just like going around the ordinary star. Neg so i showed the movie and they will keep on going and nothing will change but only when you get very close but otherwise those or bets are stable if we go even longer more interesting things happen but knows of no keyways quite safe on billions of years the time scales 4 million times the amount of the sun. I would say 10 million. Ours is not as big as theres. Backed quasi that i showed you was 1 billion. Site the Hubble Telescope has allowed us to show a super massive black called the is the other ingredient for those who try to make galaxies in the first place on the computer. There is an old joke that there is no such thing as gravity earth sucks. [laughter] how old . 10. [applause] again this is a school like. Just say you were here. That cosmic microwave background so good you bake the cookies inside out . We are in the cosmic microwave oven it is very low temperature of about 2. 7 degrees of absolute zero so we get these all the time. It is left over from the big bang there used to be a shorter wavelength so that Background Radiation is very cool. [inaudible] try this experiment when you go home if there is the microwave oven something you want to cook and set the microwave to its lowest level it will take about nine hours. That intensity matters and it will not cut you from the inside out. We promise i just watch you as the universe expands, it gets cooler and cooler from cosmos laugh laugh. Banks for watching. Is that theoretically possible to harness the radiation of of black hole . Instead eddying microwaves is a faint it is beyond the ability to detect nobody doubts that it is there there is a lot of reasons to believe that theoretically if we would have detected that the authority already got his nobel prize nobody doubts that it is there with a radio wave. From that theoretical standpoint because like the oppenheimer metric it takes the intendant amount of time to form. So could we ever have made black coal as the event bryson proximity say whatever form . And that prevents that from ever happening. If you watch something to fall in you would seem that they would send a signal the then to say things are going badly. University that going badly part. Because that never gets back out to. We saw that to even try isnt to make that one even and horizon. Is happening at that Ainge Buchanan sees things as time dilated with dead existence of the Event Horizon themselves. Eship if that was you. It is the chapter of black hole. This is only 5 of the book. Now were going to the sound bite for answers. Ever accelerating expansion to wonder if it will form another vacuum space . Is it po would that be enough to create another universe within our universe . Guess. A low vacuum energy today. Has of backing the experience that there is so lower Energy Vacuum state available. Talk about 138 years and with that but with the champagne and the bubbles. Spirit could expand so fast that space could representative quite. That would be bad. If you think with the backing of energy is going up with time. After that time all of the bodies would be ripped apart then a big singularity. That doesnt look like we are seeing. Its looks like it sustain constant it will just keep doubling in size with the same energy until the of bubbles may form some make usa probably quite. It does not look like it. Explain the dynamo effect. Spent this is a sophisticated. This is a statement of how the earth was formed and i dont have a detailed answer but to me at the very core and the mantle and there are charged currents but the dynamo of fact refers to them building themselves up. Either that case or in the sun. Or that you have molten iron at the core the day complete the cools down respect the Magnetic Field to go away entirely. Im 12. Does the universe expands from the center are from the sides and how quick. The space between the galaxies in is expanding a few imagined that surface of the balloon is just getting bigger so this base is expanding between the galaxies no galaxy is that the center more than any other. But in this analogy the center of the balloon is down in the middle thats where everything was after that there is no center or any accessible place of many galaxies that exist. At what speed does the universe expands quick. What counts is relative speed we think we sit still and more distant with the nature of the extension reach talk about this in thehe book may be only while the bells and kilometers every second but further lay they could be exceeding the speed of light. It is moving fast. What motivated you to become an astrophysicist question mike we will save that for the last. Setaside. Have any black coals are in the galaxy class experiment there is only one really big one but people argue how all many other black hole may exist but we know of about two dozen but they are hard to see. But we can infer the presence of a handful i dont know the current estimates in the of milky way. Keep in mind, avoid them. The hispanic this is a theory that i made up from one i learned. [laughter] what is in your basement . Do your parents know where you were doing their . This is have a go from nemesis to superhero. As you said stars keep compressing elements and then the iron is the last so then eventually wouldnt it all the of hydrogen and helium therefore end because all of the iron. Yes. Absolutely right. The universe will end in exactly the way that you describe all those cloudsun at f will run out of their ingredients and the stars will run and if you will they will burnout no new stars will be made and then they will disappear one by one never to be replaced again we will have an entire universe of darkness. Have a nice day. [laughter] how wall dario. I am nine. Of last two questions we have gone over time but we get in the kids. Andromeda galaxy and milky way will collide will of our species be interfered with . [laughter] still making his nine years old then worried about what would happen in 7 billion years. Our species has been around this 7 billion years from now they chain john time scales of 1 million years not alone billions so we will not be around in back the space between them is so large they pass each other they will not be worried very much of a coalition. But the train wreck because the gravity distorts the spiral pattern that they currently enjoy so now it will be mangled and tangled iowa is wonder if it is like the flyby where the gravitational legions could be compromised we will remember which star puerto or which planet so it is a fascinating future budget is 7 billion years from now so put that on your smart phone to look up you will live unless you invent something that enables you to live to see it. Since you can look back in space is there a of way to see earth back in time . El little bit if you have a black call life from the earth kingdome around the black coal and comeback. So a photon is very small but it is in theory but not really in practice but you can see the earth the way used to be that many years ago. But a practical answerca would be imagining other alien status certain distance if the light is only just now reaching them so think of a galaxy 65 million light years away so they see the light from. Earth that we sent out 65 million years ago was happening then . Dinosaurs were extent by one of our objects, an asteroid. If you are 65 million light years away you would be seen the t rex croak in realtime and that would be really cool. [laughter] one more question. You briefly mentioned earlier houses to black holes merged what kind of dilation when you get with two super massive black hole quite. The europeans are in the process of developing a satellite that will start to measure 4 million kilometers across trying to look for the merger of the super massive black hole that could happen if galaxies collide. But the typical distance you might expect is even larger so the effect could be comparably small. Is this something we may have an answer to in our lifetime but not yet. You are 12 dead negative set how did we get interested price. At eight years old and found a book in the bookstore. Book is made of paper and they used to be sold then these places call a bookstore. And was interested in astronomy and i joined the Astronomers Club i have beenon on ever since. And highschool was reading a lot about astronomy i love to look at the night sky i showed my daddy said economic it a job doing that. [laughter] he is happy that eventually i did and got the entire universe to look. I and hugely visible so people here my story and they think it is special or unusual because they dont hear any of my colleagues also tell their story how they become a physicist but my story is common. He was interested at age eight die was age nine my parents brought me to my local planetarium they would dim the lights and the stars came out and i thought it was a hoax because that is too many stars i am from the bronx. I have seen them. There is 12 laugh laugh so this is a deception. Is this entertaining the you were not fooling me. And ultimately a would learn in fact, it was the sky as actually represented in the actual universe but by age 11 i knew enough with books that my parents had bought me that i had an answer to that question that the adults always ask, what do want to be when you grow up . I said a one to be an astrophysicist. That pretty much shut them up if you say a doctor then a Family Member is a doctor if he astrophysicists bad is it. They walk away. Sewed tune this day i am a little scarred for not knowing and nice guy until i saw one in the planetarium for but to this day when i go meeting with the cosmos and the singularly majestic sight i look at that denies sky i say to myself that reminds me of the hayden planetarium. [laughter] ladies and gentlemen thank you. [applause] we will see you at the year in review in january. Spin again this very easy for them to provide a willingness into the legal economy. The their acquiring the Language Skills and the incentives for the broader economy as opposed to the captive labor market for. There are a number of misconceptions and one of them is all of the mexicans are immigrants from mexico. But just like the people say weve did not cross the border but the border crossed us. Long before the arizona was part of the United States it was a part of spanish then later mexican area so really