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assical general relativity, given some minimal assumptions the origin of an expanding universe is a singularity: a point of infinite density and spacetime curvature. But this and other singularity theorems do not take into account the strange world of quantum mechanics. So in the 1980’s Hawking and collaborators started to build a model of the big bang that included quantum effects.The result is the No Boundary Proposal, a model that may be able to explain some of the deepest mysteries of the cosmos such as, is there a multiverse? how is there an arrow of time and what really happened a the big bang? This is the fifth in a series of films exploring competing models of the early universe. To see the other films click here: https://www.youtube.com/playlist?list=PLJ4zAUPI-qqqj2D8eSk7yoa4hnojoCR4m Subscriptions and shares are very much appreciated. Produced and written by SkydivePhil and Monica Producers NIck Franco & Ernie Pay Director Nick Franco Original Score Pete Blyth - PETEBLYTH.COM Ernie Pay : Director of Photography Presenter: Monica C Sound:William Corbet Animations Morn1415 https://www.youtube.com/user/morn1415 For this film we hope you will notice a significant improvement in quality and this is very much down to 1185 films who co produced the film to ensure it has a beautiful cinematic look, feel and sound. To see more of their work click here: http://www.1185films.com Timeline of topics discussed: 00-1:19 intro 1:19 Singularity theorems 3:44 Hawking’s work on black holes and what they mean for the origin of the universe 4:11 Introducing the No Boundary Proposal in 1981 5:13 The key concept is the wave function 5:39 Feynman’s sum over histories 6:15 Explaining the concept of a path integral 6:40 What is Euclidean Spacetime? 7:36 Imaginary numbers and imaginary time 9:12 Explaining the Formula for the No Boundary Wavefunction 10:19 The shuttlecock 11:59 Inflation and the No Boundary Proposal 14:22 Predictions of the the theory 16:20 Falsification 16:55 Bottom Up versus Top Down 20:12 Eternal Inflation and the Multiverse 22:46 The No Boundary Proposal implies Inflation is not fine tuned 23:31 The No Boundary Proposal and the Cosmological Constant problem 25:33 Measure Problem, there’s a simpler way of doing it 26:532 Fine tuning and probability 27:16 Weinberg’s prediction of the cosmological constant and The No Boundary Proposal 28:30 Could the constants of nature be necessary? 29:25 Is the multiverse science? 31:03 The Boltzman Brian Problem 32:53 Stephen, Jim and Thomas’s latest work : holography and the No Boundary Proposal 35:18 Next Steps in Making the No Boundary Wave function more precise 37:14The Ground State 38:18 The Arrow of Time 39:27 Roger Penrose 39:50 A Big Bounce? 40:14 Aron Wall claims the No Boundary Proposal is eternal into the past 42:14 More on the Big Bounce 43:50 Alex Vilenkin alternative to the No Boundary Wavefunction 46:41 String theory 46:37 Unifying the Dynamics and the initial conditions of the universe 47:14 George Lemaitre in the multiverse in the 1930’s 47:58 Summing up