Science club north. For anybody who is a first timer for secret science club events we are a series that brings scientists of all disciplines out onto the public stages where they can be part of the cultural life of the city and for people like you can, and interact directly with them and be informed at the same time energized by scientific ideas and discoveries. A regular hangout is that the bellhouse in brooklyn. [applause] we have got the bellhouse fans, very nice but secret science club north back here tonight for the kickoff of our season here better fit for many seasons for the secret science club north. We are also happy to kick off the season right behind the new republic as always. We want to thank the staff particularly kathy landau joined the thompson and darren criss the Rebecca White and merry meet for helping us in that. They are the best and the very special thanks to the bar for creating the quantum cocktail exhibit a. It has in it Bourbon Maple syrup and a topless women. Very delicious im here to tell you when you can get it at the bar is off to the left there. Now is the time to go and do a a pretty want to give a heads up that is part of her many seasons we will be back december 3 with astronaut kathy sullivan, cat tom sullivan. She is a former nasa astronaut the First American woman to walk in space and also a former direct your of n. O. A. A very timely. You might have read some of her thoughts yesterday in the paper. If youd like to know more about the secret science club and her Upcoming Events visit our web site at secret science club. Blog. Come. We have a blogspot. You can sign up for mailing lists there. On to tonights event first off we want to say our wonderful speaker today theoretical physicist sean carol has a new book out and affected came out today and thats why he needed the quantum cocktail. Its a book party. The lovely folks at nyc are our booksellers tonight and sean carroll will be signing copies after his talk and q a with you our wonderful audience. We are pretty excited to have sean carroll with us tonight and we are also excited to have a very special guest to introduce sean carroll. Brian green is a physicist, a mathematician, professor at Columbia University and your other center for theoretical civics. Hes also a playwright sometimes an actor in the bestselling author of several science books including the elegant universe in the fabric of the cosmos. He is hosted to Emmy Awardwinning miniseries based on his books. He is also the founder of the world science festival. Please welcome dr. Brian green. [applause] thank you. Thank you very much. The quantum cocktail. I was shocked that i did not follow up i sang you get it at the h bar. I will leave now. Youve been a great audience, thank you very much. Tonights focus with sean carroll is on Quantum Mechanics and as i think many of you know in the early years of the 20th century we have a wonderful quite straightforward understanding of the universe are classical physics, right . Tell me how things are today and i use the questions of newton or the equations of maxwell or even the equations of einstein to figure out what they will be like tomorrow. Then it all changed. The early decades of the 20th century beginning with the work of einstein himself. A paradigm change and now the new way of thinking about the world is you tell me how things are now the best we can do is create probability of what they will be like tomorrow. That was not an easy transition for physicist in that era to take on board. It was an emotional upheaval for many of them to make this transition but heres the thing. Sean no doubt will describe for you in more detail the laws of Quantum Mechanics even though they were problematic can be in use to make predictions. Decimal point digit, due to downward nine or 10 decimal places in that agreement between theory and experiment is so potent and so powerful that people begin to stop thinking about what the theory actually means and at what it us about the nature of reality and they used it as a wonderful structure to make protections about the world to begin to control the microworld and all the wonderful technological gadgets that we walk around with all the time. In fact its more than that. It got to the point where anybody who really is a physicist want to think about the meaning of Quantum Mechanics and what it was really telling us about how the world works, they were looked on as somebody who had lost their way. It wasnt something that we were supposed to do. There are a few people who say that and im trying to figure out in particular how we transition to the definite reality that we all experience in many ideas were put forward, wild ideas. In fact sean is going to talk about perhaps the most wild of those ideas the possibility that we are part of a multiverse, many worlds, parallel universes. A very strange idea but i will say this. Ever since the events at least i have found in talking about this ever since the events of november 8, 2016 people have a much easier time understanding the concept of a parallel universe. And without a gives me great pleasure to introduce tonights speaker. You all of course know him from his many bestselling books on the nature of time and the hicks particle, the nature of reality. We physicist known love sean is one of the great leaders and pioneers in understanding cosmology and quantum physics. Tonight you will have a great trees here from one of the profound thinkers who are willing push in the meaning of quantum physics to figure out what its telling us about the nature of reality so please give a warm welcome to my friend and colleague, sean carroll. [applause] thank you brian. Who do i need to thank . Thank you secret science club. Thank all of you folks for figuring out the secret and figuring out you can come here. I dont know how that happens but im happy that it does. When you become a physics professor they teach you that what you teach other people even if its an abstract physics concept its best to do demonstrations and bring it down to earth. Im going to start by doing a demonstration. Im going to push above, i phone which will send a signal over the internet so laboratory in switzerland will send a photon particle of light down the tube and it will hit a splitter and go either left or right but 50 50 probability and depending on whether its observed to go left or right the signal will come back here and it will tell me whether i dashed to the left or the right. Here we go. The photon is amended. The universes are split. Ready . Thats the demonstration. Thank you. Why is this demonstration worth anything at all . Its because in my favorite version of Quantum Mechanics the many worlds of Quantum Mechanics which i will tell you about it protects and i actually believe it is true that there is an entire other reality where i hop over there and the person standing right there theres a different version of me that did something different. Like i said i actually believe this is true. Now what you should be saying is what kind of crazy person would leave this is true . That is why we are here, to figure it out. Let me see if i can do the technology. Technology is a good thing. The reason why we are talking about these things is because Quantum Mechanics is brian alluded to to is anonymously successful. We needed to understand lasers and transistors, particle physics why the sun shines and even white chairs and tables dont collapse. But as my illustrious predecessor at caltech says Richard Fineman i think i can safely say that nobody understands Quantum Mechanics. They usually dont like to appeal to authority but by bringing up other physicist but when the claim i am making is that nobody understands something the person who understood the thing the best is a Good Authority to say that nobody else understands it anyway. How when the world can it be possible that even though we use Quantum Mechanics to make these predictions someone like Richard Fineman who says we dont understand it. Because we can make predictions but if you ask the professional physicist what is going on, what is the reality its predicting they will say i dont know. In fact they would say i dont want to know. Who cares about reality . Im a physicist and we make addictions. This is a terrible attitude and he should be embarrassed. Wasnt always like this. No one would have said this 100 years ago but only since Quantum Mechanics came on the scene that people are tempted and single only reasons for physics is to make addictions and not to understand how nature works to give them we dont understand Quantum Mechanics what you would imagine a since Quantum Mechanics is so important the path to understanding Quantum Mechanics is the most important thing of all of physics. The people who specialize her superstars of physics. We have in the room tonight several of the worlds leaders in understanding the foundations of Quantum Mechanics. These people could be millionaires and living in penthouse apartments. They are not. They are great people and they are underpaid and undervalued. Its not only that we dont understand Quantum Mechanics, its that we havent even tried. There are complicated complicated set of reasons why but thats for a different talk. Right now i want to remind you of aesops fables. The fox season grapes and once the grapes that are juicy and delicious and pops up trying to get the grapes that they are too high in the fox cant get them so the boxes you know what why but i didnt want this grapes anyway. They are probably sour. In case the parable was not perfectly clear the fox represents a physicist and the grapes of represent understanding Quantum Mechanics. We tried and we couldnt do it so we said we never wanted to understand Quantum Mechanics anyway. Until tonight. Everyone is going to understand Quantum Mechanics. Im going to do a very whirlwind tour of why we came up with Quantum Mechanics in the first place and white let us to these crazy suppositions that im going to try to entertain not particularly accurate. History is messy and we dont have time for that stylish tell you when and relatively brief period of time. Scientists are putting together the picture of the atom. Everyone has seen this picture. The picture of an atom. As a nucleus, theres a center and today we know the nucleus is made of protons and neutrons. They didnt know that. They knew there was a nucleus and orbiting around, orbiting around the nucleus like the planets orbit the sun are these particles called electrons. It also cannot possibly be right the reason why and brian mentioned before Quantum Mechanics came along we had a theory called classical mechanics. The theory that was given to us by isaac newton and his followers and the classical mechanic makes the prediction that we take an electron charged particle and send it around in circles are jiggling up and down it emits radio or infrared or physical electromagnetic waves. All the light you are seeing comes from electrons jiggling up and down so here you have electron zooming around being accelerated. They should lose energy and what they should do is according to classical mechanics they should spiral into the center and collapse into a nucleus. The timescale for this to happen you might say doesnt take a longtime . Less than a pico second which is a very sharp period of time. So if you the chair youre sitting on an everything you see in the world would collapse. It would collapse into a black hole. Apparently doesnt. Scientists had a gut eerie it was conceptually completely inadequate family needed to do better. It was hard to do better. Theres a long set that im skipping but eventually they came up with the following radical idea. Maybe electron is not a particle. Maybe the way to think about electrons is as waves, not as particles. There was previously a long debate about whether light is particles. Someone said the electron is a particle. It is wave flights in certain way. We call the waves to represent the electron the wave function the least romantic name but thats what we called it. We said there is a wave that spreads out around the nucleus concentrated in the middle and then it fades away and basically you can do the math problem saying what is a different way that unlike tom wave can settle down into an atom. Even though the wave itself is energetic waving back and forth there are certain discrete very specific shapes the wave can have where it has a specific energy that can just sit there and not change. The electron settle into this data and i think this is the only time the talk i will tell you any data. This is the picture of an electron around the helium matter where its located. Its not in some simple elliptical orbit. Spread out to what we know call the wave function. This way of electrons dont behave. They arent actually moving but i want you to think as electrons is not a little point of the circle. It really is this function, this cloud, this wave and the wave can be static and unchanging and thats why it doesnt radiate. Thats pretty good tree thats progress. More progress can come years later as an equation. I need to show you the equation because of the quiz we are having at the end. You are going to have to solve the quiz with boundary conditions and i hope everyone is happy with that. Conceptually its not that hard. Conceptually the greek letter pi indicates the way it functions and on the left you have a question that is asked of the wave function namely how much energy does he use . On the right you have an answer which says how fast are you moving . As a typical wave function will have a different part to it which has different energies the equation simply says the highenergy parts change rapidly in the low ngugi parts change slowly. What matters is the arizona case equation. Scientists love equations and physicists love equations. An equation is full employment for scientists and the student who do the homework in solving the equation. The equation says now that i know this particular circumstance of i can figure out what the wave is in any situation. It gives scientists the ability to say how things develop in time. Everything is looking good except for one obvious huge somatic flava says when you look at what comes if you are not hightech and this is a very recent picture of reconstruction based on delicate stuff usually when you look at electrons they dont look like waves. They look like particles. This is actually a movie of a chunk of uranium that is radioactive soot emitting particles and this has been a Cloud Chamber which means when a charged particle sees a string of opals every one of those little lines it created is the result of a charged particle being emitted by the radioactive uranium. I showed you mostly because its cool but what i want you to learn from this picture is the prediction of the equation is when the uranium atom is hit with regular tivoli is embedded in a spherical shell that goes off in all directions equally. Its not what you see when you look at it. What you see is a little particle like saying. Thats why we call them particles in the first place. And on the right and then take a picture of it, you dont see that cloud and then a particular location burqa why is that . The measurement process so there is something that happens this is what was figured out thats what they told themselves in 1926 to 28 people. It was codified it was the copenhagen interpretation and this is what we teach our students today. There are two sets of rules. And if youre not looking at them then they do another kind of thing and the probability and near the peak is relatively large this is what we teach our students. And it is Utter Nonsense and clearly unacceptable this clearly cannot be the right answer i will highlight two of the problems one is the oncology problem. To talk about what it is real. Not just what you observe but not observing and then we slid around on that question. That is that function with the reality is is that only part of reality . Has nothing to do with reality to do all these things to do not agree and then the measurement problem what do you mean . Looking at things changes them what about something nonliving quicksort video camera . In the agency and consciousness from those that believe all of these things so there is a problem so what are you going to do . There is wellestablished tradition of highlighting and never telling you how to get it right and a graduate student in 1957 and what he said was you are working too hard. So chill out a little bit. Okay . We have some good look one dash looking rules. So they obey a lot of the time clearly the most straightforward thing and what it does is obey the equation all the time naturally he left academia right away because it is interesting and they said no its not. So here is the interpretation of Quantum Mechanics. There is one set of rules that applies all the time no matter what is happening and through every other theory of physics general relativity positions of momentum or fields and they are to the equation and all of this stuff of Measurements Get rid of it. You dont need it. Okay. So that stuff about measurements you follow the picture with the particles. With that version of Quantum Mechanics to possibly match our experience. Now here is a little feature called entanglement. So now to put it into modern terms i also wrote a book about take out your phone right now to order that. Thats okay. But the only particle we have ever detected that has zero that has zero it is very much similar to the spin of the earth so the spin is zero. So one way is that the electron and positron. And then to spin one half so it must be the case that the spin of the two electrons cancel out from each other because a has to add 20. So the electrons spin up or down electron number two could be up or down but they must be opposite thats what we know. So the way that happens in <