Before the Big Bang 1 - Loop Quantum Cosmology Explained

there's an abundance of all inspiring sites to see in the night sky but when I look up I can't help but wonder where did it all come from what really happened at the Big Bang to really address this question cosmologists need a quantum theory of gravity and in recent years the ability of loop quantum gravity to confront this question has been gaining increasing attention loop quantum gravity is an attempt at treating gravity quantum mechanically instead of a continuous space-time which can be divided indefinitely as in general relativity loop quantum gravity tells us that space-time has a discrete structure that it's made of individual units which cannot be subdivided and this has dramatic implications for the origin of our universe to learn more about it we visited one of the rising stars in the field Ivana Gullo at Cambridge University's Centre for Theoretical cosmology we also traveled to Florida where a by ashtekar one of the founders of the field was giving a public lecture on the topic it's really kind of began when I was in high school and I grew up in a very small kind of Indian towns my father was in this civil service and I know the British had this tradition that the civil servants were transferred every three years and so we would a lot small towns and then somehow almost I don't know how exactly this happened but I got hold of books by George Gamow and particularly the book which was called 1 2 3 up to infinity which had things about cosmology in it that really fascinated me I think since I was a child I was interested in science and maths but I really think that I fell in love with physics maths high school when I started to study precise terms calculus algebra mechanics rectangles I think the time I felt that my life was engaged with science Einstein tried and failed to make his theory consistent apart independence so do you find it a bit daunting to do what he and others can do of course but if I was the only one doing this I would be strictly worried but fortunately there is a lot of people in the field working on the same ideas theories and I believe that if each of us make a small contributors pull together may solve problems that single genius Einstein gave us this beautiful theory which is general relativity in which gravitation is coded in a very job it rips space-time that theory is very geometrical it's very precise there are very definitive predictions caught-up theory on the other hand uses completely different concepts completely different ideas fundamentally the theory is probabilistic there is nothing definite we predict only probabilities and rather than being geometric one uses of jabrai methods so even mathematical tools that one uses are very very different in the two theories and therefore there is a general belief that in fact these are two special cases of some bigger grander theory which are of unifies the principles of both of these these two theories and one recovers these theories as special cases that is why we will need this bigger theory and it has always happened in physics that once you have such a bigger theory then it has applications it has predictions which are far beyond what one could even imagine in the individual theories and that is why this lab is this particular if you like chase or this particular hunt for a bigger theory is very excited so loop quantum gravity is an attempt at unifying principles general relativity and quantum physics and the basic idea is to take to heart the central message of general relativity and the message is that gravity is encoded in the very geometry of space study now we know in nature that various fields like the electric and magnetic fields for example feels that in that in to describe weak and strong interactions they are quantum mechanical in nature therefore we all expect that gravitational field is also quantum mechanical in its fundamental nature on the other hand I stand told us that that true general relativity that gravity is encoded in geometry and therefore if in fact gravitational field is quantum mechanical then even the very geometry of space-time should be subject to laws of quantum physics and this is a central lesson of loop quantum gravity this is a central viewpoint of the quantum gravity everything is Brahm Bourne quantum and there is no background there is no everything is interacting with each other so it's not that there is actually space and time there's geometry which is given to you on which things happen job eight rich self is called a mechanical just as things are quantum mechanical and what the drama that unfolds is subject to some equations which are quantum error logs of Einstein's equations and these are the basic equations of the form cavity in look under gravity what really focuses on space-time structure very much if sort of people working in the quantum gravity came from a general relativity background people working in string theory came more from particle physics background so in string theory at least the beginning and even now the emphasis is much more on unifying the interactions all interactions of nature and not so much about the peculiar property of space and time itself in string theory higher dimensions and supersymmetry is essential there is a new problem gravity it is not essential now it doesn't mean that the two are absolutely incompatible because it could be and I think that is the most likely situation scenario that whatever the final theory is it will assimilate in itself some ideas from loop quantum gravity which particularly have to do with geometry of space-time how in the real world quantum world the singularities of general relativity the infinities of general relativity are removed and it would to pick up some ideas from string theory which have to do with unification of all interactions and some of the very powerful mathematical techniques that have arising from this so-called a deus CFT correspondence that I referred to before so in my view in fact it is very likely that the final theory would have signatures coming from both these asked both these camps the main goal of a theory of quantum gravity is to tell us what happens with the theory of general relativity plates and this happens when the gravitational field the curvature of space-time and the energy density of mother is very high close to the Planck scale and and and in general relativity tell us that go straight in there the universe we have big plans in the vertical but it's important to emphasize that this big bag is not a prediction of general relativity it's just a prediction in a regime in which the theory fails so it's the result that one gets by pushing the theory beyond its domain of validity so adopt regime we need to extend general relativity to include the quantum nature of reality and this look onto gravity to put the first notice one of the approaches and in that theory we see that the progress in the quantum effects of gravity totally dominate the physics and and technically there is some kind of propulsive force due to the quantum nature of gravity afterwards the difference of singularity replaces it twenty bucks one analogy given by Martin volure wold is that of a sponge a sponge will absorb water poured onto it but only up to a certain limit once that limit is reached anymore water will be repelled similarly in loop quantum gravity space has a maximum density one that density is reached space becomes full and will repel any excess energy in the classical model the universe begins from a state of infinite density and curvature but according to Luke quantum cosmology the density of the universe has an upper limit it cannot become infinite if we were to rewind the cosmic expansion back in time we would not arrive at an infinite singularity instead as it approaches maximum dense two space runs out of room and found six a quantum bridge connects our expanding universe to a previous contract includes bloom quantum cosmology predicts a big balance rather than a Big Bang singularity but why does this prediction arise why are the physics of loop quantum cosmology so different from that of general relativity well the answer of course lies in the mathematical equations which govern the two theories so we asked dr. a Gullo for a layman's guide to exactly how this happens what happens here is that when you approach the Big Bang singularity the energy density grows and goes to infinity facially go stability because the amount of matter is the same and the volume of the universe decreases so the energy density which is total energy over volume increases because the volume decreases so Rho goes infinity and 8 goes to infinity that is the d-plan single entity in loop quantum gravity this is the effect this equation that one gets and in that equation when row increases so bra critical is close to the Planck length scale hopefully becomes around 0.4 in line time to the Planck energy density and this super high so when the energy is it is much lower than this constant this term is 0 so we recover the same equation because it's a web however when the energy density is of this of the same order as this quantity this factor is important so we deviate from the GR equation and at some point when Rho is equal to Rho critical this is 1 1 minus 1 0 and 8 doesn't imply bed is not infinity 3 0 and this is the Big Bang because H is essentially a dot the derivative of a Ramanujan of 80 over 8 so at the bounds 8 a changes from big contracting to expanding so pay to be zero and Woodrow is if I rock with eagle we have teddy that so this equation tell us that the Big Bang is replace by the important thing is that this occurs without putting my hand on physical matter or without adding to the theory some ex boundary conditions it occurs it comes out of just the quantum version of Einstein's equations that I use in lieu quantum smallish and that was a surprising element for all of us in the first papers were actually written they were the detailed papers where with these two postdocs but impressing and Thomas pavlovsky and when this effect was first found I thought that this couldn't be true in just in completely general general you know that without putting anything behind back at all this was first done by numerical simulations so actually I postponed publication of the papers by repeating the numerical simulations back as varying the initial conditions varying the parameters to see in this is completely opposite cetera we postpone it for about six to eight months and then finally was cos got convinced that this really is there and since then this has been verified by the simplest models even biological calculations that other people and I have done that this effect is a genuine effect the standard Big Bang model has many problems which some claim can be resolved if we introduce an extremely brief but rapid period of expansion known as inflation in inflation the observable universe doubles in size every 10 to the minus 37 seconds and these doublings are known as efj Olding z-- inflation needs at least 60 of these a folding some scientists argue that inflation is simply too unlikely can loop quantum cosmology help to resolve this debate the problem is that the answer depends on what instead of time you actually choose and if you choose a late enough instant of time then the probability of inflation turns out it is very small if you started with at an early instant of time for example the plant dope domain then as was pointed out by by Kaufman Linda and mocha now the probability of inflation is close to 1 so the also seems to depend on how you phrase a problem and basically and and that's a fact therefore to me the important question is really is there a way to choose a preferred instant of time and now in Lipkin cosmology fortunately there is a preferred instant that is to missile bombs in classical general relativity there is no prefer instant and you could say that well I choose a plan time or something but then first of all that prime time you should not trust classical relativity and why do you choose prime time as opposed to some other time it's not so clear turok-han Gibbons choose late time and then they get a very tiny probability but look on gravity look on cosmology since there is a preferred instant which is really the bounce time take this initial takeoff at the bounce time and then there is in fact a nice finite measure on this space of initial date time and I just ask what fraction which is induced by the lugal venture and they just ask what fraction of this initial data at the bounds of time if all some into into a new fashion you face some time in the future undergoing 7g at least sixty or seventy four links that are needed so we're saying look at the initial data at the bounds and then you ought to know what fraction of this initial data actually evolves our encounters a slower inflation with sufficiently four things sometime in its future and then that calculation is completely unambiguous is no problem automatically well posed problem automatically available solution and then the answer turns out to be extremely close to one before 1998 it was thought that universe might wreak elapsed but with the discovery of dark energy it seems that that will not happen so it doesn't that rule out any sort of oscillatory universe that lqc mine and pot look on the cosmology does not predict that the universe will rech elapsed what the quantum cosmology says is that if the universe we're to reg elapsed in the future then the end of that collapse is not a oddly like the big crunchy singularity that happens in in general relativity but doesn't imply the universe will collapse the reason the universe whether the universe will develops or not has to do with the energy content of our universe today and the equations of G our general relativity right now has nothing to do with quantum reality and current observations are compatible with the universe that will expand forever so in that situation the picture that loop quantum gravity provides is that the universe started in the past being infinitely deep was contracting and really fixed the minimum size at that time the quantum attacks of gravity were important and avoiding the collapse and bound and produces a bounce and then the universe expands again and will continue expanding forever so loop personality is important close to this to the Big Bang and if the deep grunt would happen close the big craft but doesn't implying that the universe had to wait why was the entropy of the universe so low at the Big Bang big balance how could it have been in such and runs state if under lqc the universe has a much longer prehistory so shouldn't it have built up to intolerable levels in the previous universe that's a good question and the present in many cosmological models my point of view in the context of quantum cosmology is that in our observable universe in the patch of the us that we have access the entropy was reset at the balance so in the presence of of a pace of inflation in our universe the size of our path at the bounds was just a few plant lengths then brandon's at those small scales the effects of gravity are crucial and they are repulsive they produce the bounds of these repulsive effects may be able to to iron any structure present due to the previous contracting phase so this one because our unit was so small I would offset over Dunamis was so small at the mouth this wonderful text may wash out any structure coming from the previous right in such a way that even when the entropy of the universe's is big and there are structured Latta scales at the scales that we can see today that there was no structure the inter vivos please say dr. Guha focused on the patch of the universe which is observable today at the big balance it was unimaginably tiny and the repulsive force of loop quantum cosmology drove it to a nearly homogeneous low entropy state but what about the whole universe we asked dr. rush to card to clarify this then we talked about entropy we often just take into account Matt entropy and not the entropy due to horizons like gravitation entropy and lots of entropy has to do with coarse graining as we saw before it has to do with not looking at the microscopic scale but just looking at some every doubt macroscopic states up here look at the look on cosmology solutions then in the collapsing branch just before the bounds a cosmological horizon develops and this cosmological horizon grows extremely rapidly and in fact fills the whole universe at the bounds and that disappears after the bounds so what could be saying that I should use a coarse graining which is at the source of this cosmological horizon in other words I should already broke at the macroscopic state I should trace or I should add we should integrate out what is happening in the inside the horizon if I did that then there entropy is increasing very rapidly and this rapid increase of entropy increases in fact much bigger than then drop increase duties matter but at the horizon at the bounds the horizon engulfs the whole universe and therefore the entropy see Philip becomes infinity and then after the bombs the horizon I just disappeared this is a mathematical fact about local cosmology does not happen in freedom in classical solution of Einstein's equation the Friedmann model so this is issue about how we should phrase this question whether we should take into account this gravitational entropy which comes due to gravity due to cosmological horizons and if we add that then the mystery disappears because one it just led to reset the entropic clock if you like at the bumps because the bubbles the horizon just and good the whole universe and then disappear in the future there's nothing in the future there is no or political horizon to the future of the past and therefore we start all over again if a quantum dance replaces the Big Bang singularity does the idea apply to a black hole I think the answer is yes and everybody in the theory believes that black hole singularities will be also resolved the theory they want is that right now there are no precise computations about the details of what happens inside black holes the particularity is easier technically because of the symmetry is present but I believe that in the near future people will work out the details of the whole materials as we near completion of this film there has in fact been further progress rodolfo Gambini of the University of Montevideo and Jorge Poland of Louisiana State University have shown that in the simplest non rotating black holes loop quantum gravity does remove the singularity and replace it with a new extended region of space-time we came across an old paper by Alan Guth entitled the impossibility of bouncing universes so how has this idea come back if it was disproved 30 years ago the result of Alan Guth was to invent specific contexts and was in the context in which gravity is is provided by general relativity classical general relativity and but they had a peculiar concept of matter they were wondering if the effects of matter can avoid the singular if you put the cosmology what happens is that gr general relativity is not longer valid close to the Big Bang so one has to generalize the theory to good quantum effects and when those quantum effects are included the Big Bang singularities so and the bounce is possible it's really column geometry that is doing doing this I given these talks in fact just last month but in February in Boston MIT talks angular and was there they all agree that this is a viable you know completely interesting viable scenario we've also heard that contracting universes are unstable and produce messy singularities in Luke 1 to cosmology people have analyzed more complicated models not just the simplest model of a spatially flat Freeman resume working people have analyzed models containing anisotropies anisotropies is just a beauty verse in which the geometry um mother has dependence on the direction is not isotropic so that is dependent dependence in the direction people people have considered more complicated models containing in opportunities and all of them the singularity does not appear so we don't believe that missing singularities will appear the visible universe is the size of 10 Planck length cube and that it turns out that in fact this repulsive force is exactly operating that domain is very very strong in completely Oregon's classical attraction that because of that that one is able to not worry Mesa Singh that are happening at much longer wavelength much largest length scales and focus just on this this this little ball and that is why we don't have to worry about all these issues so much where to worry about this boss of over 10 planets size that changes qualitatively the question and again before the Congress mala G the people that of course pose this idea but the question was even then you need some mechanism even for the even for the 10 blunt length cue ball to become so extraordinarily homogeneous and isotropic and look one of the small G appears to have at least qualitatively a mechanism a number of theorists from Lee Smolin to nikodem Poplawski have suggested that black holes can give birth to new universes so is it possible that the Big Bounce is from a black hole rather than a whole universe that collapsed right I don't think so and the reason is basically because the differences I just pointed out in between the bounds and the black hole for the black hole most of the energy comes out through this quantum radiation which initially looks like the Hawking radiation it looks like a thermal mixed state but in fact isn't the toggle state is a pure state you just Isabel approximated by thermal State in the early times and so it's quite different from the from physically and/or bounces is really what is left over to remember them small thing whereas in cosmology because a special neo special originating assualt repeat the whole thing bounces as we don't see inflation in the universe today the in photon field driving inflation must have decayed but in any one half life the remaining field which has not decayed is undergoing exponential expansion and so cosmologists such as Alan Guth and Alex Vilenkin proposed the inflation must be eternal creating an infinity of pocket universes can loop quantum cosmology determine if this is really the case return inflation they also have to take into account some quantum processes some tunneling amplitudes which might for example the in flatten is rolling down the potentially this quantum fluctuation puts it up off of the potential again and therefore it draws down again and that causes this little portion of the universe to expand out very much so this quantum processes are very important for this turtle inflation what are we good to do it would be to actually in loop on cosmology we have actually a wave function of the universe and we actually have evolution of this wave function of the universe now so far what we are then is really involved this wave function until we're used reached general relativity era and says that well after that we just use classical general relativity we don't have to use the full quantum mechanical wave function of the universe in the future and that is a very good practical point of view loop quantum gravity under chemical biology might actually give you does give you these very functions and therefore if you actually evoke bear to evolve these wave functions carefully you might be able to see whether there is it is true or it is not true that the in photon has a large corporation and rolls down the potential I mean it's true that people who believe in eternal inflation seem to things obvious that this should happen I don't have an intuition so I think it would be good to see if this actually does happen or does not happen can we ever learn what caused the previous universe to collapse or any other features of the previous universe I believe that it is unlikely that we have observational access to the contracting phase of the and the reason is as I said before because it is likely that one to physics washout information on a premium brand our power units the new scientists ran a front cover story recently saying that the universe must have had beginning they referred to work done by board Goutham the Lincoln and the Leica nimittani but there was no mention of loop quantum gravity at all about car said that this conclusion reached by board grew from the Lincoln is violated in the country cosmology and on a recent TV show cosmologists at Copeland said that we simply don't know if the universe has a beginning so which one should we believe I think that the the result by Bohr the booth on the line team is very interesting but one has to interpret it correctly what they say is that inflation and not be eternal in the best let me explain what they do was to consider general relativity so no quantum gravity classical gravitation and inflation and in general relativity Hawking bedrooms Garrick and other people they came out with what is called singularity theorems and they say that if the matter content satisfy some conditions then singularity are unavoidable in their lives however the the matter that produces inflation doesn't satisfy that condition so people were wondering that maybe inflation can avoid the dictum singularity so if you continue inflation in the past you will never find feedback and facial to be a devil in the past then what for the valentyna group shown is that even if the matter during inflation doesn't satisfy the conditions of the single is already the victim happens equation cannot avoid the d-plan so so if you extend the inflationary space-time to the past you will always find the big pipe singularly in general relativity but that doesn't mean that the universe has to have a big bang what that means is that when you get closer to the Big Bang you have to replace general relativity by a theory of quantum gravity and this during ordinary we should tell you what happens the Big Bang and look what the cosmology there is noting that that is about obviously there are other approaches pasen pasen provision balance pushpot the result all these theories are new and we don't have a complete theory of quantum reality so it is natural that people that they decode and answer is that we still don't know what really happened these theorems of the link in good and more day on which much of this discussion is based they basically assume that the universe was eternal inflating that is to say there is no contracting faith in the past I look correspond there is a contracting phase of the past and therefore the basic assumption of the theorem is violated and therefore there is a occurrence which is not compatible with the conclusion I mean theorems are theorems but you know the assumptions are violated then the conclusions or theorem are not true tell us how we can test for loop quantum gravity and the quantum cosmology in general relating quantum gravity observations is a very difficult task and the reason is simply because of the difference between the energy scales at which quantum reality is important and the energy that we can check in laboratory so so far people have checked consistency or people have test quantum gravity just by mathematical self-conceit so the only way that we can hope to see quantum gravity exists in the universe people have argued that maybe gamma-ray bursts are able to provide information other people have proposed a black hole operation and and other people have to goes to see the C and B and the galaxies division from my point of view I think that the most promising thing that we have is the CMB and the inclusion galaxies because we know that the way in which the galaxies are distributed and the you know maternities in the CMB were originated in the very early universe it is possible that quantum gravity were contributing to that so this is why the information by Planck and so important at this point so what is really difficult is to disentangle the effects from quantum gravity from other contributions which is a very difficult task anything is not impossible one who say that every year we are saying today is actually compatible with the with the starting at the loop on cosmology and at the Planck scale and so we are complete theory from the plant scale to these 11 orders of magnitude in curvature and dense and density to the uncertain translation and then from onset of inflation to C and B and from CMB to the present epoch so one could say that this itself is a you know every observation we're seeing if you like is compatible is look for cosmology from that point of view but one would like to see is in fact there is some observation which is signature upload a small G which is not seen in standard inflation so far this result recent work or the last year i meanwe been doing it for two years is a hard problem we did it very slowly and the paper spread is published in the last few months so the three papers with the I'm gonna give you that you will see and Gilliam Nelson and what we have found is that there is actually a very small window in the parameter space for which look on cosmology predictions are completely compatible to the present observations but would give you some distinct signature from standard deflation for future observations basically because we started the bounds we as of quantum state we evolved it to the onset of inflation through the syllable orders of magnitude and there the state can be closed the of state of this perturbations of these fluctuations can be close to what is assumed in inflation but it's not exactly the same and because of that is sufficiently close that there is no problem about current observations but it's not exactly the same therefore it does have potential for having put the scene in huge observation it's been suggested that light from a distant gamma-ray burst could be affected by the discreteness of space assuming that these effects can occur at the scale of the ratio of the gamma ray energy to the Planck energy attempts have been made to observe them some observations have failed to see such a modification or as others have claimed a possible detection the do quantum gravity theories really predict such an effect almost any kind of reasonable thing you see in look on cosmology or gravity or anything else so suggest that you get least just probably an hour you can this matter physics well there is actually discreteness and we see that discreteness right in the crystals and source of that the effect will be square of that and square of that is very very small is true that you know gungho people have some cosmology in other areas how often proposed well maybe it is defect of this order which is energy density divided by the plant density which is small number and these effects these results are basically saying that well noise there are no such effects but that doesn't say anything about me these are already zero observations and have been nice and don't take anything away from them and we want to encourage people to make more and more accurate observations but if we just go and tell them that well what one needs to square then the effect is so small that nobody would ever look for those effect services a number of future space-based missions are being proposed to look for new data on the early universe eally set plans to directly detect gravitational waves the Big Bang observer is on the drawing board to detect primordial gravitational waves but this ambitious project requires not three spacecraft but twelve a more realistic goal might be to look for a type of polarization in the CMB known as B modes which originated from primordial gravity waves proposed fourth generation CMB detectors such as epic and core may be able to find these modes if ESA's Planck mission or other projects do not so how can data from these missions confront theory with observation there is a consistency relation between gravitation veins how much energy density that is in gravitational waves and how much energy density there is it matter and certain the thing that I refer to in spectral index to know namely that the energy per wavelength is not the same is not constant but it's light is almost constant but not quite and there are some relations between all those quantities standard deflation gives you one relation which is quite robust but in the quantum cosmology changes that relation so if in fact when we are able to measure these quantities what we'll be able to see if in fact this relation for sub does not hold again unfortunately this is true only for this narrow window the time dispensed but still the ground is amazed and we'll be able to shed light on this there's been talk that the LSA might be able to make tiny black holes could observer if it did cut observations of those help us yes of course that will be extremely interesting there are many assumptions on the existence of black holes in Tennessee and you have to assume that there are extra line answers more than answers that the four line answer that we see and they have to have a peculiar geometry they have to be large extra line answers in that case gravity at large energies may be much stronger that what seems at our scale and black holes may be produce anything if that is true that would be great because we will have black holes disintegrating evaporating inside our detectors in March 2013 ISA CMB probe plank revealed its cosmology results the data is plotted on what is called a power spectrum and was said to fit well with simple inflationary models but anomalies first hinted at by NASA's W map were confirmed by Planck in particular the left-hand side of the plot and large angular scales showed the most deviation from standard predictions at the Planck press conference George F staff you of the University of Cambridge said I think if I were inflationary theorists I would be more happy than disturbed by these results but we have to be you're open-minded that there might be new physics involved in these anomalies and it's perfectly possible from the theoretical point of view that there is exotic physics that our universe is part of a multiverse the we can track our universe back through the Big Bang to previous Big Bang things well that is that the reputation of where they the cosmic instructor are coming from disturbing before inflating the terms of the maths follow them through the quantum gravity regime and then after inflation and then once I see if there is any correction to the standard information due to the pre originally one tunability this has been done and precise computations on the power spectrum scale and perturbations gravity waves are the and they in fact say that the original equation should be corrected at large scales the left-hand side of the plot and this is compatible with Planck displeasure so it is possible that plan is observing the effects of gravity with the amount of that data is not enough to single out look what the response you're getting the proposals that is interesting I think that I would like to understand is much better and in fact just two weeks from now where vitality we were astute enough to do it every year in advance so that that Charles Lawrence who is a chief NASA person and in plant mission so he's keep going to come and give us three talks and then I would like to understand this anomaly is much much better I mean we had discussions on them and we realized that some basic issues anomalies that we don't completely understand so that's why I can only answer the question of the rough mobile level and not anything which is specific I think this possible I think if there is something in it does if we understand this anomalies better it could be telling us something about the initial state that we are talk to talked about which is really at the level of the big bombs this initial state of this type and length cube thing that would prevention before even if you put all these various conditions that I was telling you about before symmetry requirements and various conditions to tell us what this initial state was you still need some freedom and if there are anomalies then it may be that it actually constrains this initial state significantly the real anomalies and that might constrain this initial state significant gain that would be very nice because that would give us really insights into into kind of new physics and that washes table want to make but more detailed predictions because of the moment the predictions are common to this whole class of states so far the results from client are consistent with slave consequence mahadji correct yes correct human beings have long sought or cosmic origins and with modern cosmology and the good bang it seems like we were close to discovering them but if flue quantum cosmology is right the Big Bang is not the ultimate beginning but rather a transition in a much longer history so the search for our cosmic origins is not at an end but perhaps we've opened the door on an exciting new Vista you

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Keywords: Big Bounce, Loop Quantum Cosmology, Cosmology (Field Of Study), Planck Constant (Namesake), Inflation (Taxonomy Subject), Science Daily (Website), Big Bang (Idea), The Big Bang Theory (TV Program), Stephen Hawking (Author), alan guth, physics, Quantum Mechanics (Idea), black holes, b mode, BICEP 2, polarisation, CMB, Cosmic Microwave Background, Gravitational Waves

Id: IFcQuEw0oY8

Length: 43min 27sec (2607 seconds)

Published: Thu Aug 01 2013