Degrasse tyson, director of Hayden Planetarium in new york city and the author of many books including welcome to the universe, death by black hole, and his latest, astrophysics for people in a hurry. Host dr. Neil Degrasse Tyson, in your new book, astrophysics for people in a hurry, you open it by saying that the universe is under no obligation to make sense to you. What does that mean . Guest get over it. [laughter] i think up until, well, really up til the year 1600 when we didnt have any particular tools to investigate be the natural world, our five senses were the primary means by which we obtained all information about the universe. And not even knowing that our five senses had limits. If its everything you know, you think its everything the universe is trying to give you but, in fact, its not. And so around 1600 with the invention of the microscope in one direction and then the telescope in the other direction, each invented within a decade of one another, then all of a sudden pieces of the universe come available to us that transcend our senses. The fact that lieu went hoping would look inside a drop of pond water and see microorganisms just doing the backstroke, right . Your eye brain sensory system could not have detected it were it not for the microscope. And you can see does that make sense that you have entire living creatures inside of a drop of water . Well, today we know that because we learn it from childhood. But in the day, it made no sense at all. In fact, he had communication with the royal academy, Royal Society in london which is what you would normally do when they make a discovery, and they thought he was drinking too much gin. [laughter] its like, write another letter when you recovered from this stupor, from this drunken stupor, and then we can continue our scientific communication. So they were in denial of it until they sent someone up, which is a natural thing among scientists. One eyewitness testimony about one result is not a scientific discovery. You need verification of it to confirm that its real. And especially in modern times, the 20th century and onward. We have particle shedderrers accelerators. We have rules that fall completely not only outside your senses, but our expectations for how life or the how anything should work. Particles popping in and out of existence, matter turning into energy and back and forth so then we discover, like, black holes and the expanded universe. How could everything there is be expanding at all, right . So if you keep invoking that doesnt make sense, youre going to miss out on a lot of what we have learned, discovered to be true about this universe. Host whats significant about the year 1600 . Anything . Guest well, optics had taken, there was a lot of the dutch were very good at optics and lendses and this sort of thing lenses and this sort of thing. We knew about what lens would do, you could make a magnifying glass out of it. But when you start combining them, you get other properties of your optical system enabling you to get a microscope. And once you did that, that just opened the floodgate toss what else you would do when you combined lendses. And galileo made a good version of it back in the 1600s. Host was galileo treated as kind of a devil, in a sense . Guest theres a little bit of cleansing. Depending on how long is the writeup on the account of his time, life and times, thatll determine how much back, you know, Background Information youll get. So the simple story is he makes these discoveries, they conflict with the teachings of the catholic church. They put him on trial, they find him guilty of saying the earth goes around the sun and not vice versa as well as other discoveries hes made with his devils instrument are. And then they put him under house arrest. What they dont tell you or they would tell you if you read a longer biography be about him is that he actually made fun of the pope. Public fun of the pope. He wrote a book in italian. Not in latin, which is the academic language of the day, in italian. Which means the local people can read it. And in it he invents a conversation between a simpleton and someone who was wise of the ways of the universe. And all [laughter] if you track the statements of the simpleton, theyre all statements that have come by official decree from the catholic church. So hes, hes really a pompous ahole, basically. [laughter] can i say that . Host yeah, were on cable. [laughter] guest this is cspan. So socially he did not express the respect he really should have for people who had much more power over him. He could have published in latin, had it spread around the world among academic circles, and im betting he probably would not have gone to trial. Thats my read of this. And in the period it is the renaissance, after all. And, you know, new thought and fresh thought was not some weird thing. So, yeah, he was just he had it coming because he, he didnt know how to appease authority. [laughter] host back to your book, astrophysics for people in a hurry 14 billion years ago the universe started, you say. How do we know . Be how do we know that . Guest so the way knowledge is acquired scientifically is you have an idea and you propose an experiment to test the idea. And then you, if its an expensive experiment be, you probably dont have the money to do it in your garage. So now you propose to get funding from sources, typically if its pure be research itll be a government source, the National Science foundation, nasa has a research arm. If youre in the other fields like biology, human physiology, you might be getting a grant from the National Institutes of health. And so you have this idea, you build an experiment and you test it. And if the results of that experiment match your expectations, then the foundation of your idea gains some currency in the conversations you might have be at the scientific coffee lounges, at workshops or in the journals. Then youre a competitor of mine and you say, you know, i never liked you. [laughter] i, i have a different finish you know, scientists are human. Were people too, right . And i think youre wrong. And heres the experiment im going to build to show that youre wrong. So then you build an experiment, and then you get a result that kind of matches my result. Thats kind of, thats interesting. Because you had no intent of matching me. You dont even like me. But now the results match. And someone else does it. Youll always have some outliers just because of the experimental uncertainties that exist in all experiments. Therell always be some outliers. But when theres a general lean towards a truth, an emergent truth, you look back and say, oh, okay. All of these experiments point to approximately the same result. And you have these few outliers here. So now we come to recognize that this is the new truth. The new objectively established truth. And thats what science does. It is the most effective way we have ever devised as a species, as a culture in decoding what is and what is not true about the natural world. Nothing rivals it at all. And so once weve done this, then i say here is how the world works. Then we go on to the next problem. And this is a celebrated thing. I mean, its what got us relativity in quantum physics and gravity, and it powered the entire industrial revolution. You couldnt have these machines what is a machine . Its something that converts energy that lives as one form into energy thats useful to us in another form. So what is a car . It takes Chemical Energy and gas and turns it into energy of motion, kinetic energy, of your car. And that requires machines to do that. All this came out of the industrial revolution. Before the industrial revolution, there were no, there were no machines such as this. Theres something they had what we call simple machines. A lever and a pulley. Those dont require high technology. Technically in the world of physics those are called machines, okay . A lever, a pulley, an inclined plane. What they do is they make your job a little easier. So its simple. So watch how this works. So i have this ledge and i have a very heavy thing, and i want to lift it up to that ledge. Im not Strong Enough to do that. But if i make a ramp, then i can just lift it up little bits at a time. Now, the distance can over which i have to lift it is longer, but it takes this height and spreads that out over time so that it makes it easier for me to complete the task. The same amount of total energy is exerted, but the rate at which i expend that energy is different, and thats what, thats what simple machines have always done for us. And modern machines basically empower all civilization. Host first ten seconds of the universe, what happened . Guest well, thats some busy moments oh, sorry. I didnt want really focus in on your i didnt really focus in on your question how do we know 14 billion years. So heres what we do. We look up in the universe, and we say, okay. We see galaxies. Hub el discovered these fuzzy things in the night sky are entire galaxies. Then in 1929 he discovers these fuzzy things that we now identify as whole Goldman Sachs sachs gal ax is and this is the first evidence that the universe is expanding. People didnt just think this up. No. It was an observation. And then we looked to see if it fit einsteins general theory of of relativity, and it did. Its the modern understanding of gravity. And if anythings happening in the universe, its going to involve gravity. So you check to see if it works with his equations. It does. And so that means we didnt have to reinvent the theory of the universe. Because it worked. And so then we say, all right, if the universe is getting bigger, is if the universe biggr than it was yesterday, that must mean its bigger than it was the day before and then the day before and then the day before. So what happens if we just turn the clock back . When you do this, because you see how fast were expanding, just reverse that, you can do it on a pen and paper on the back of an envelope. Just calculate what happens if you reverse this rate of expansion. And the whole known universe is in the same place at the same time 14 billion years ago. That is the origin of the idea of the big bang. Host first ten seconds. Guest first ten seconds. So everything we know about matter that is compressed and under pressure be tells us that the temperature will rise. The simplest example be of this is if you ride a bicycle and your tire gets a little flat, so you pump a hand pump. You pump air into the bicycle tire. And then you feel the valve when youre done. Its hot. You are come pressing air compressing air through it, okay . So thats just as an example. Its related. Its not exactly the same thing, but its related. Thermodynamic, the science of the movement of energy from one medium to another is called thermodynamics. So as the universe gets smaller and smaller, it actually would have been hotter in the past than it is in the presence. And so now you keep, because the universe now actually has a temperature, you can measure it. It got measured in the 1960s. Very cool. You look at every direction, and you see the heat signature left over after the 14 billion years. And so now you go back in time and you say, okay, the universe was hotter and hotter and hotter. How much hotter would it have been 14 billion years ago when the universe was this big . And you get a stew pep dousely stupendously High Temperature. And now you ask what is the behavior of matter and energy under those temperatures. Is so now you turn to the particle accelerators that slam particles together under high pressure, high energy, High Temperature i mean, high so you start approximating the early is that what an atom does . Be is that what a nuke louse does . Nucleus does . Now you apply it to whats going on in the first few moments of the universe when it was hot, small and dense. And that gives you a pathway in, a pathway of insights into what was going on there. You know what we find . That you have an area when all particles are formed, the basic foundational particles that Everything Else is comprised of. We have light in the form of pro tons. We have quarks. Weve all heard of protons and neutrons. Theyre made of what we call quarks. And they all have antimatter counterparts. Proton has a positive terror positron, something that science 2006 people rapidly Science Fiction people rapidly picked up on. Just to be clear, we invented antimatter and discovered it. That was not a Science Fiction invention. It happened in the real universe first. So now you put, you bring your insights to those first few moments of the universe and say what must have happened then given what we know goes on in our particle accelerators. And it will tell you at the rate we were expanding, at those temperatures you would be making hydrogen as the predominant atom in the universe. The simplest atom has only one proton in the nucleus. You make this much hydrogen, you make this much hemoyum. D helium. Youll make trace amount of lithium, the third element on the periodic table of elements, remember, from chemistry class. And nothing else. We will be a universe born with hydrogen and helium and barely any lithium. Wait a minute. And you say, if thats so, it would mean that the very oldest stars we can find, ones born closest to the big bang that would still be alive today would be comprised of only hydrogen and helium. That is exactly what we measure. The very oldest stars have the least amount of heavier elements which we know, we know this from the mid 20th century from calculations enabled by the Nuclear Research from the Manhattan Project and the atomic bomb, because were calculating what atoms do. We know that after that time stars are born, Pure Hydrogen and helium, they manufacture heavy elements in their core, then some of them explode scattering this enrichment to gas clouds that have yet to form clouds. Now, they form a next generation of stars that have a little bit of extra enrichment. Theyll make even more enrichment, explode and then carry that extra enrichment to the next generation. And this continues through. We, our solar system, was born four and a half billion years ago. So thats more than nine billion years after the start of the universe. So weve had the benefit of multiple generations of enrichment. So now when our protocloud collapsed to make the sun, it had all these other ingredients in it that it used to make planets. Because rocks are not made of hydrogen, theyre not made of helium. Theyre made of silicon and oxygen and aluminum and arsenic. All these other iron. Cobalt, nickel. All of that manufactured later is in abundance in very late generation stars that were formed. So the lesson here is however weird it is to assert that 14 billion years ago the universe was this big, literally this big, it exploded from there. You say, well, you werent there, how do you know . Okay, youre right, i wasnt there. But if everything we know happens to matter happened then, then it accurately predicts things we do measure. Thats what gives us the confidence to sit here and describe the first ten seconds of the universe like we were there. Host and it all started with a big bang. [laughter] guest is there a song in there . [laughter] host do we know what that big bang was . Guest do we know what it was . Host yeah. Guest what we can tell you is that the big bang account of the beginning of the universe is a description of what matter and energy was doing from the earliest moments onwards. Now, theres a point before which its a little mysterious to us. Its called the plank time named after max plank. One of the many fathers of quantum physics. Theres a point earlier than which is kind of the limits of our ability to understand what nature is doing. So we pick it up right after that plank time. I forgot the exact the plank time is like one trillionth of a second after the big bang. No, one billion, trillion, trillionth, is that right . 15, 24 yeah, thats about right. [laughter] one million trillion trillionth of a second after whatever was the beginning, then our physics that we now measure in our lob lob in our labs apply. And then we can talk about whats going on. Host in your book, welcome to the universe, from 2016 you write that in five billion years the earth will be a charred ember. Guest oh, yeah. You know, its weird, every now and then i tweak that. Every couple of years i tweak that. And apparently, it blows peoples minds. And i dont know if thats a good thing or a bad thing, but so the between varies anytime tweet varies anytime be i do, but in five billion years the sun will expand so large that it will ening gulf the entire engulf the entire orbit of our planet. As we itll engulf the entire, itll engulf earth as earth, and earth will be a charred ember as it descends into this star while it vaporizes. Have a nice day. Something like that. [laughter] and people, so its just a reality. Its remarkable that we can know our fate in that way over that much time. But how do we know it . Will we be there . Probably not. Is so how do we know . Well, there are other stars. Of theres no shortage of stars in the universe. We can see stars being born, we see stars living out their lives, we see stars in the act of dying. And you can staple these bits of information together and create a coherent story. In other words, we dont live long enough to see a star born, live out its life and die. It takes millions and sometimes billions x in some cases, trillions of years. And were around for a few decades. So how is it that we know this . Because there are so many stars that in any snap shot of the universe we see stars being born, stars in middle age, stars dying. And we look to see, oh, these are the thats the same arc of a star, theyre just different stars. Were catching them at different times. It wouldnt be any different from if you were an alien and took a snapshot of civilization, you would see some humans in a box underground. Youd say, well, what are they doing there . And youd see other humans who are Little Things crawling on the carpet. Youll see other humans who are, who dont have any hair that are lit and others that dont have any hair who are older, right . Be its just a snapshot because you dont live long enough to see the whole thing. If youre an alien and you live just 90 seconds, hurt . So youll say how do i make sense out of this . Are people born in a box be in the ground box in the ground and theyre all shrivelly and they come out of the box and then they get littler and littler and littler and then disappear inside of another perp, or is it the opposite another person, or is it the op to sit . So you keep studying all these photos that you have, and then you can piece together a coherent story of whats going on. And for the stars i