Before the Big Bang 5: The No Boundary Proposal

cosmologists can trace the evolution of our universe back 13.8 billion years to the Big Bang but the Big Bang itself is an event still shrouded in mystery in this series we explore competing models of the early universe while cosmologists may disagree as to the true nature of the Big Bang what they do tend to agree on is that when the entire observable universe is far smaller than an atom the strange world of quantum mechanics surely becomes relevant at Cambridge University one of the first attempts to build a cosmology based on quantum theory was pioneered by Stephen Hawking Thomas her talk and James hartal their theory is known as the no boundary proposal in this episode they'll explain how there are no boundary proposal may be able to tackle some of the deepest mysteries of our existence from why is there an arrow of time or is there a multiverse and how do we resolve the Big Bang singularity itself roger penrose tonight showed on theoretical grounds that if Einstein's general theory of relativity is correct there must have been a singularity in the past by point of infinite density of space-time curvature where time has the beginning however although our singularities theorem predicted that the universe had a beginning that didn't say how it had begun the singularity therms Penrose Hawking and others showed gravity would become so strong in the beginning that the classical physics would break down that meant the quantum physics was inevitably going to be important the idea to use quantum cosmology to understand the origin of the universe goes back way before Penrose and Hawking in fact it came along with the discovery of the expansion of the universe so even in the 30s people began to ask the question well what happens at the origin of the universe and the suggestion was made back in the 30s that at a very early phase of cosmology in the very early phase of cosmological evolution quantum theory would come into play but of course in the thirties the in the 30s that the tools were not available to say anything about the origin this was just an idea for an idea as John Wheeler would have said the initial singularity theorems developed in the 1920s by Friedman and Lemaitre have the unreasonable assumption that the universe was perfectly symmetrical in the 1960s Penrose and hawky developed new singularity theorems that did not require this promise so in the early days you could have said well the initial singularity the initial Big Bang singularity is a feature of very specific universes but Penrose and Hawking showed that in fact this initial BIGBANG single earth he's a generic feature therefore that we need to combine the general theory of relativity with quantum theory in order to understand the origin of the universe in the 1970s Stephen Hawking discovered that when quantum theory is applied to black holes it causes them to evaporate giving off what is now known as Hawking radiation Stephen and Jim both realized that if quantum theory has such a big effect on the singularity inside black holes presumably it also has something to say about the cosmological singularity that was centre conference in the Vatican the 1981 that I first put forward a suggestion that maybe time when stage together formed a surface that was finite in size but did not have any boundaries or edge together with James Arnold from the University of California I worked out with physical conditions the early universe must as high the space-time had no boundaries in the past our model became known as a no boundary proposal that says that when we go back towards the beginning of our universe space and time become fuzzy and Kappa somewhat like the North Pole and the surface of the earth in the singularity the Big Bang is a moment of infinite density and curvature but in the no boundary state there's a smooth surface which although finite does not have a single point of origin the key concept is the idea of a wave function that sometimes a particle connects sometimes like a wave and sometimes like a particle photon say right when it's acting like a wave it's described by a wave function the no boundary proposal treats the universe quantum mechanically and therefore the mathematics needed to describe this strange quantum world will be needed for the universe as a whole and the starting point to do this is Richard Feynman's sum over histories formulation of quantum theory so unlike the Copenhagen interpretation of quantum theory where you have an external classical world in fineman's sum over history's formulation everything is part of the system it says essentially that if a particle goes from A to B it doesn't follow a single history but it follows all possible paths connecting A to B just like in the famous to split experiment of quantum theory where you have a particle that goes through both slits and the superposition of paths a path integral assigns a weighting or relative probabilities to different possible histories of the universe the know proposal is a selection principle that selects the subset of histories of the universe that close off in the past and so allows us to determine which histories of the universe have the most significant contribution the most significant contribution will come from a geometry that is there cluding on the bottom of the shuttlecock and an expanding de sitter universe on the top of the shoulder what I mean when I say the geometry is Euclidean is that has four space dimensions and no time dimensions what I mean when I say that the geometry is lorenz ian is it has three space dimensions and one time dimension just like the geometry we experience every day in this room no boundary proposal is a model of a big bank that is based on quantum gravity that is given by the past integral for all your clinic metrics without boundaries by contrast the harkin Penrose theorems are about Lorentz in space-time which has no boundary at the singularity to describe the wave function and its superposition physicists use imaginary numbers but what are these imaginary numbers and why are they so important for the no boundary proposal but imaginary numbers of numbers which Square to something negative I is an example in I squared is minus 1 the no boundary wave function describes or assigns different probabilities to different histories of the universe and it does so by associating each history to a geometric construction the famous shuttlecock construction in which a history is in fact rounded off in imaginary time in this context when we say imaginary time the no boundary proposal we are really talking about geometries with in which time behaves as a space that direction the no boundary proposal does not describe a single history for the universe but it describes an ensemble of different histories the past is probabilistic just like the future it's symmetric so in that sense it is similar to a wavefunction of an ordinary quantum mechanical system which describes an ensemble of different histories or paths just like in the two-slit experiment so if that's true then there must be a wavefunction for the universe and the question is what is it [Music] so this is the formula for the new boundary mail function what does this mean the no boundary wave function prescribes the no boundary wave function gives you an amplitude a waiting for different configurations at some moment of time different kind of universes you could think of each H and Phi as the universe the amplitude of each universe according to the no boundary wave function is given by a Euclidean particle there is no notion of time at this level time does not appear in this formula now there's a special condition the no boundary condition which asserts that those histories contribute to the part integral which have no other boundary except the one at which you're evaluating the wave function and that's what leads to that shuttlecock picture how am I going to write to draw a geometry which has no other boundary than the boundary at which I'm evaluating the wave function I am naturally draw something like this right so these shuttlecock geometries they are geometries complex geometries which start out with all time mentions behaving as a space dimension this region which is Euclidian and where all dimensions behave as space changes one time the spatial dimension remains a circle but the time dimension opens up and becomes distinct from the space dimension and describes a universe in which a spatial circle grows and grows and grows I cannot longer interchange time and space here this is the way time Laurentian time evolution emerges when the universe gets larger from what is initially a quantum fuss classical physics is not fundamental it's an emergent phenomenon we believe from a quantum mechanical theory the notion of classical evolution emerges from the no boundary wavefunction when the universe gets sufficiently large according to the new boundary proposal the only way to get a classical universe with a deterministic notion of time is via a period of inflation inflation is a period of incredibly rapid cosmic expansion believed to have occurred in the early universe inflation is thought to solve a number of problems with standard Big Bang cosmology and it's driven by a form of matter known as a false vacuum which causes the expansion to accelerate instead of slowing it down when this form of matter decays inflation ends creating a hot soup of particles the no boundary proposal explains how inflation started in the first place inflation produces a very large uniform universe just as we observe however that would not be completely uniform because in the new Clinton path integral histories that are very slightly direct nor have almost as high probabilities as the completely Luna firm history the theory therefore predicts that the early universe is likely to be slightly non-uniform this produces small variations that the intensity of the microwave background from different directions some regions will expand slower and others which eventually leads to the formation of galaxies detailed observations had confirmed there are deep changes in the intensity of irradiation at the level of about one part at 100,000 moreover the observed pattern is in excellent agreement with the predictions of inflation combined with the no boundary proposal [Music] the standard theory of inflation predicts the generic features of the prime world fluctuations but it doesn't predict the details there are all kinds of inflationary universes you need to know boundary wave function and in particular the probabilities that it predicts for different inflationary universes in order to complete the theory and make specific sharp predictions the predictions of the no boundary proposal will be a combination of the probability is given by the no boundary wave function and the possibilities coming out of the dynamical model of the earlier it's the two combined which lead to very specific predictions now of course we don't have a complete theory of the dynamical model so we are not sure yet what are the possibilities but in a specific corner of the string landscape the corner described by D brane inflation that is a regime that is a model of inflation in string theory in which the accelerated expansion is driven by the motion of a membrane through an extra dimension within the context of that dynamical model the no boundary wave function will make a very specific prediction for things like the tilt so for the spectral features of the pattern of Microwave Background fluctuations such as the contribution from gravitational waves and the tilt and so forth but I don't like to stress those predictions precisely because of the uncertainty on the dynamical model what the point of our program on the row boundary wave function is to demonstrate that if you have a dynamical model for the early universe and you have a theory of its quantum state the two combined yield a predictive framework for cosmology in other words the two combined turn multiverse cosmology into proper verifiable scientific framework [Music] the global cosmology district which director model of the universe that makes falsifiable predictions that can be tested by observations by to falsify the no boundary wave function you would have to identify correlations that are impossible within the theory such as for instance spectral features of the primordial perturbations which are incompatible with inflation so for a long time it was thought that a no boundary proposal predicted essentially an empty universe with just a little bit of inflation however the prediction is what we now call a bottom-up probability of the no bond away a function it's a probability which you derive straight from the wavefunction and which does not take into account the condition that we actually exist in the universe when it comes to testing the new boundary proposal against our observations we first must include the condition that we are part of the universe that we are part as a physical system of the universe that condition so in other words we have to calculate a conditional probability in order to compare the predictions of the new boundary proposal with our observations it turns out that this condition has a large effect on the probabilities predicted by the robot a proposal without this condition the no boundary proposal predicts just a short period of inflation and an empty universe but when our observational situation is taken into account as part of the universe in fact the most probable histories of the universe that are predicted by the Rabanne proposal or histories with a long period of inflation and when extrapolated backwards in time in fact with the face of eternal inflation and the reason for that is simple in this first Clause of histories which has just a little bit of inflation they're smaller they don't have many places for us to be whereas the history's with a large period of a long period of inflation they're much bigger they have lots of places for us to be and since we are a physical system within the universe with a certain probability to be anywhere we are much more likely to be in one of these in large histories than in the small histories so in other words what's most probable to be it's not necessarily what's most probable to be observed precisely because there are more places for us to be [Music] what temperature will observe for the microwave background and that question doesn't make any sense because it doesn't say what time we look at it so you need to distinguish between predictions for whole histories of the four-dimensional histories of the universe and predictions for our observations of it which are typically at the moment of time that difference between the two kinds of probabilities probabilities for observation and probabilities for the whole history of the universe I think capture a large part of the difference of what's meant by top-down and bottom-up it turns out that a top-down probabilities given by the no boundary proposal predict that we have a low long period of inflation in our past and therefore we predict a flat universe in fact we predict a universe with so much inflation that it has a period of eternal inflation in our previous film Alan Guth the father of inflationary theory claimed that inflation is generically eternal in other words almost all models in relation lead to a multiverse inflation from the same quantum mechanical effect that leads to the irregularities in the early universe seen in the microwave background this is because the huntress is the universe's history backwards in time deep into the face of inflation one can encounter a regime of eternal inflation the eternal inflation the quantum fluctuations in the energy density of the matter alert the distally thought and this can keep inflation going forever in some regions of the universe our observable universe wouldn't become a local pocket universe a region in which inflation has ended globally the universe would has a highly complicated director and will consist of infinitely many such Parkin universes separated from each other by inflating regions the Lord sophistication chemistry again differ from one pocket universe to another which together form a multiverse [Music] in general in quantum mechanics there's always a multiverse because Konnor mechanics doesn't predict one thing they predicts probabilities for things and the conventional way of handling eternal inflation has led to paradoxes eternal inflation seems to be produced an infinite number of each kind of pocket universe so what should we tell the observers as to in which pocket we are that problem clearly shows that the conventional theory of eternal inflation is incomplete the reason the no boundary wavefunction is a completion of the theory of eternal inflation is that it predicts an ensemble of eternally inflating universes with a probability measure with a probability distribution over that ensemble that probability distribution allows you to extract probabilities relative probabilities for one pocket universe versus another and it's those relative probabilities which are the key quantum mechanical prediction for what we should observe a number of scientists have claimed that many features of the universe are delicately fine-tuned one example is the initial conditions of for inflation so the boundary wave function is a solution for the problem of initial conditions for inflation it's often thought that an inflationary universe requires very special initial conditions but the no binary wavefunction selects those universes which have a period of inflation so the initial conditions for inflation or not fine-tuned in the no boundary wavefunction in fact inflation is precisely what the no boundary wave function predicts [Music] in 1998 scientists discovered the universe is accelerating in its expansion perhaps being driven by a repulsive gravity term invented by Einstein known as the cosmological constant this qu has been claimed as a case of delicate fine-tuning we need to deal with it from this top down or first-person point of view right in which were asked not what is the most probable value of the cosmological constant but what's the most probable value of the cosmological constant that we can see the reason is because as we explained by Barrow Tipler Weinberg and others if the cosmological constant is too big the universe expands too rapidly and then based on calculations by tegmark Reis and others right galaxies wouldn't form and we wouldn't be here to see what's going on in a multiverse you will naturally have different values for constants of nature in different universes a famous example is the cosmological constant which can take different values we could for example have a universe that eternally inflates a cosmological constant and within that universe the that false vacuum as its goal would decay by bubble nucleation and we live in one of the bubbles right that's already a multiverse if quantum mechanics generally predicts probabilities for ensembles of histories as a multiverse if the dynamics permits the cosmological constant to differ from one of those histories to another we predict probabilities for the value of the cosmological constant so those constants of nature in classical cosmology they're just numbers without any explanation in quantum cosmology you can hope to explain those numbers or to explain at least certain correlations between those numbers from a deeper underlying theory let's come back to this universe that has a false vacuum that's expanding and but also decaying by a nucleation of bubbles a true vacuum if you run that forward for any bit of time you get a very complex structure a roiling sea so to speak of bubbles that's very difficult to calculate in fact it's so difficult that people assume for the minute that there's only a finite number of them and then try to let the number go to infinity that's called a measure calculating probabilities in an infinite multiverse is no easy task it requires a counting procedure known in mathematics as a measure but there's no agreement among physicists as to what measure to choose is there another way out of this measure problem there's a simpler way of doing it which is this first-person top-down idea that you should focus on just what it is you observe one bubble right and ignore all the other bubbles and there is a way of doing that in quantum mechanics called coarse graining to me fine-tuning is a top-down question it doesn't mean very much to say well the theory is wrong because it predicts some universe which we can't observe to me the real question is whether the constants of nature that we observe given we exist within a universe or likely or not so 10 years before the cosmological constant was discovered Steven Weinberg pretty much predicted its value based on this kind of reasoning that reasoning is pretty much automatic in quantum cosmology because we are very much physical systems within the universe in this theory we'll part of this final configuration so the real question is whether the no boundary wavefunction predicts correct correlations between our existence and the observed values of the constants of nature and if we do this for the cosmological constant for instance in row boundary wave function we're actually able to sharpen Weinberg's predictions precisely because we have a more definite theory of initial conditions that's the way the no boundary wave function can be tested against observations and support of course this may not work or agree or for all constants of nature we're not even sure that all constants of nature can really vary from one universe to another in the multiverse but those constants of nature which can vary can be predicted using this kind of method for the other constants I don't really know some of them might be determined by the theory so in a way they they might be necessary [Music] it's easy to get the cosmological constant a very appropriate dynamical theory I think we don't know whether other constants are put in or very depth of it in other words to say that there's a proper collection fine-tuning and you have to have a mechanism for the constants of vary and not simply be fixed by the fundamental theory critics of the multiverse have said that as other bubble universes are not observable the multiverse is not science well I think that's rubbish physics always involves concepts and ingredients which are not directly observable an example is the Higgs boson we don't observe it directly we observe its decay products all theories of physics have ingredients and concepts which don't directly are not directly observable but play a role in deriving predictions for features which are observable similarly we saw for the multiverse my goal or the goal of the program of the no boundary proposal is to turn the multiverse into a verifiable falsifiable predictive framework how do we do that well we use this multiverse to derive predictions for observations in our universe so of course it's true that we're not gonna be able to observe wildly different universes from ours but we use the entire framework we use the entire multiverse we use the ensemble of histories to extract predictions for our universe so in that sense it's not fundamentally different I think from what is happening in other branches of physics the second law of thermodynamics tells us that a random fluctuation of something very ordered is incredibly on likely but it isn't impossible Ludwig Boltzmann one of the fathers of thermodynamics wondered if our entire universe might be just such a rare fluctuation the problem is a brain would seem more likely to fluctuate than an entire universe so some have argued that these Boltzmann brains would dominate the multiverse and hence disprove its existence well Boltzmann brains would be a problem even in a single universe if the history continues to expand for instance because there's a cosmological constant you create infinite volume and eventually Boltzmann brains will appear therefore Boltzmann brains are not directly associated with theories of the multiverse one issue is whether those fluctuating brains in the far future in an otherwise called an empty universe represent in fact fluctuations that decohere in other words represent branches histories of the wafer histories and branches of the wave function to which VA can assign meaningfully a probability we have to be able to assign meaningfully a probability in order to draw any conclusions about whether or not we are more likely to be a Boltzmann plane I think it's far from clear that those kind of fluctuations in fact decohere Jim Thomas benign had recently studied eternal inflation from a different viewpoint our approach has based on the concept of holography and string theory the log Rafi says that Einstein's theory of gravity and space-time is equivalent virtual to a theory without gravity that is defined on the boundary of space-time we have used a lot Rafi to excite the face of maternal inflation in our past and replaced it by a dual theory defined on the global exit surface from eternal inflation one can lose a dual theory to calculate more reliably a global director of the universe produced by eternal inflation we find that the probabilities for highly complicated universes were much lower than what we know of maternal inflation indicated this range is doubts about the widely accepted idea that eternal inflation gives rise to an infinitely large multiverse instead we conjecture at the end of eternal inflation is reasonably smooth leading to a much simpler universe which is globally to highlight what we find is that even though there can be a phase of eternal inflation the late time universe is smoother than what the traditional calculations suggest so now you might say well where is the multiverse then if my universe is smooth then it seems to be pretty much the same everywhere but remember that the no boundary wave function is a function of the late time configuration therefore the multiverse is still in there the no boundary wave function describes or science probabilities two different kinds of universes it's a multiverse not consisting of pocket universes in a single space-time but it's a multiverse consisting of an ensemble of different universes okay more quantum if you like all theories are approximations in order to move from interesting proposal to something widely accepted a theory must be precise enough to allow for unambiguous predictions so what must quantum cosmologists do to achieve this we must find a better way to define that particle this shuttle construction is really an approximate construction it's an approximation of this part integral which has never been defined mathematically precisely so that's where holography comes in holography provides a new route to specify the new boundary wave function which in the long term might it give us a more precise formulation of the wave function perhaps not even based on traditional notions of space and time we are most interested now right in learning how to compute right quantum mechanically what goes on and the early reverse irrespective of what the particular proposal is how do we get between the wavefunction in the universe which is a fundamental theory part of the fundamental theory and predictions for observations and that's a fairly hard thing to do we're we can do that in a sector if you like of the wave function of the universe that's close to classic ality and there we think we know what we're doing Susskind page and other people speculate right that the if we look for big quantum fluctuations right then we would predict more probable things that are not like what we see we don't know yet right they might be right but we have to develop our techniques of computation in the meantime we're making progress on how to compare things [Music] the aurora borealis is caused by electrons in the upper atmosphere being excited to higher energy levels as they fall back down to their lowest energy level known as the ground state they give off light this notion of a ground state is helpful to understanding how the no boundary proposal explains many mysteries of physics the universe as we see it today was simpler earlier than it is now more homogeneous more isotropic more nearly in thermal equilibrium so you would expect it to be described if there was a wave function by the simplest possible wave function in ordinary quantum mechanics that's the notion of the ground state the simplest possible state most ordered most simple the no boundary wave function is the cosmological analogue of the ground state for closed universes and it seems to work when it comes to the arrow of time the dynamical laws of physics are typically invariant and the reversal of the arrow of time so the observed arrow of time must have something to do with the initial conditions the fluctuation started out small and grew complexity the universe started out simple and became more complex those are the basic features right of errors in time complexity is increasing and that can be quantified by appropriate entropy s that also increase the regularity of the shuttlecock geometry implies that all fields are initially in the ground state so the no boundary proposal implies that when a classical universe emerges this will be in a very very much in its ground state no structure so it implies that the structures develop away from the big bang towards the future in one of our previous films Sir Roger Penrose argued for a cyclic cause nology to explain the deep mystery of why the entropy was so low at the Big Bang the Nomad proposal predicts that so it may be a mystery I think the Roger right why the no boundary proposal but once you accept that then I think you have that rise of time interesting love the the no boundary proposal predicts bouncing universes as well then it predicts arrows of time that are in one direction one side of the balance on the other direction on the other side of the balance now if you have a bouncing universe the collapses rates as a minimum I mean grows invite us where the fluctuations that small it's not it went in not the other end it's in the middle Eryn wall a former student of Jim Hartle has argued that the no boundary proposal is not really a universe with the beginning because the beginning only occurs in imaginary time in real time the no boundary proposal implies the universe that is eternal to the past and future first of all it's important to stress that what one means by real is not imaginary in the sense of fictitious but imaginary in the sense of complex numbers it's a closure of the universe so it's very much like a beginning of time it happens in imaginary time as Aaron says you might wonder how how that shuttlecock construction is connected to the histories of the universe in real time you will typically find that the classical extrapolation of the history backwards in time exhibits a kind of hourglass structure it's sort of you have a contracting phase going backwards in time and then you have a kind of bounds and you have another expanding phase on the other side of the mounds so you might think well this is very different from the robanukah proposal but in fact it's not because the no boundary proposal predicts that near that bounds all fields or in their quantum mechanical ground state their minimum energy state no structure near near the baths the structure in those histories develops away from the bounds in both directions that means that there is an effective arrow of time which goes away from the bounds towards the future but on the other side of the balance the effective arrow of time goes the other way that means that in those histories there is absolutely no communication between both sides many models for the early universe whether they be derived from string theory loop quantum gravity or inflationary cosmology seem to be converging on the idea that our expanding universe has a mirror image of itself creating an hourglass like structure for the cosmos I agreed that this hourglass kind of picture of the universe is emerging from various angles now but the natural initial condition will evidently make the early universe rather simple and that automatically leads you to that hourglass kind of evolution with the arrow of time pointing in opposite way in opposite page of the Bands having said this there are other proposals for cosmology cyclic cosmologists or ik periodic cosmologies in which there is clearly a distinction those proposals also invoke a sort of bouncing phase but the arrow of time does not reverse the arrow of time always goes forward in other words there is communication from the pre bounce phase or the pre Big Bang face to the post Big Bang phase and eventually I would imagine that both kind of proposals will lead to observation Lee distinct predictions and will be able to rule one or one of them out Alex Vilenkin has proposed a different quantum origin for the universe where space and time tunnel into existence from a state of no space and time similar to the way that virtual particles fluctuate from the vacuum he claims this has a number of advantages over the no boundary state Alex will like you who I know quite well as a brilliant scientist right and we have to take seriously that we're not going to have a slam-dunk theory of the wave function of the universe the no boundary proposal will predict that we come from a regime of eternal inflation and a rather low value of the potential Alex's wavefunction will predict that our universe emerges from a regime of attorney flesh and that occurs at a high value of the potential in these simple Stein amateur models I believe Alex's propose is ruled out because regimes of eternal inflation at a high value of the potential will naturally occur when you when the potential has a polynomial behavior when the potential costs like the fourth power of the scalar field for instance but those kind of inflationary histories predict a large tensor to scalar ratio which we don't seem to be observing so I think Alex's proposal for that reason alone is under pressure so I would rather regard them as two separate approaches to the wave function of the universe and will compete them on their predictions for such things as the large-scale structure the no boundary proposal is a theory of cosmology developed before modern quantum gravity theories like string theory or loop quantum gravity were formulated this ring theory is a dynamical theory and the no boundary wavefunction is a very general idea that should apply to any theory of dinah at least most of them we hope so there probably you can put string theory into the no boundary wave function and then check what it says about predictions they're not separate in fact what the one of the beauties at the no boundary wavefunction is I mentioned earlier the contemporary final theory appears to have two parts a theory of the quantum state and a theory of the dynamics they're unified in the no boundary proposal in the sense given a theory of dynamics you probably have something like a no boundary idea in a way the no boundary wavefunction combines or unifies the theory of dynamics and the theory of initial conditions and you can see this from this formula here's the theory of dynamics summarized by its action and here are the initial conditions in one single formula together they define a wave function and from the wave function you derive both the probabilities of different universes as well as their dynamical evolution the multiverse implied by the no boundary proposal and inflationary cosmology may seem like a modern idea but George Lemaitre the father of the Big Bang may have hinted at the basic concept as early as the 1930s in this quote clearly the initial quantum could not conceal in itself the whole course of evolution the story of the world need not have been written down in the first quantum like the song on a disk of a phonograph instead from the same beginning widely different universes could have evolved the new boundary proposal is the model of the physical conditions at the beginning that describes our familiar notions of space and time can emerge from a quantum state of the universe there are certain questions that you simply cannot ask in the context of classical cosmology an obvious question is where does classical space-time come from classical space-time is assumed obviously in classical cosmology but by deriving so-to-speak classical cosmology from an underlying quantum theory of the universe you can ask in what regime and how classical evolution emerges so you can you get a deeper layer of understanding of the basic building blocks ultimately of our universe [Music] then the no boundary proposal the same loss of nature hold and the beginning s in other places the beginning of the universe would be governed by the loss of science this removes the need for an intelligent creator ever since the dawn of civilization people have craved for an understanding of the underlying order of the world quiet assess it is and why it exists at all there ought to be something very special about about very conditions of the universe and what can be more special than that there is no boundaries and there should be no boundaries of human endeavor [Music] [Music]

Channel: skydivephil

Views: 588,358

Rating: 4.8301086 out of 5

Keywords: Stephen HAwking, cosmology, multiverse, gravitation waves, science, physics, quantum physics, james hartle, thomas hertog, fine tuning, relativity

Id: Ry_pILPr7B8

Length: 50min 48sec (3048 seconds)

Published: Tue Nov 07 2017

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