Roger Penrose - Did the Universe Begin?

roger cosmologists today are focused on how the universe began focusing on inflation theory and various other things but there's a more fundamental question did the universe begin uh because in the past uh people assumed that the universal was forever and had different kinds of cycles or steady state or whatever um you've been a little bit of a renegade in terms of the traditional now conventional wisdom of inflation theory beginning the universe how soft well one of the biggest motivations of the scheme which i've been putting for well for about eight years now let me just describe roughly the scheme the current view is that the universe began with what's called the big bang immediately following that was a stage of inflation which was a an exponential expansion which settled down for one reason or another into a more sedate expansion which then became a an exponential expansion which is what we see uh what got the noble prize a few years ago the accelerated expansion of the universe which i regard as a consequence of the lambda term the einstein introduced in his paper in 1917 for admittedly the wrong reason he wanted a static universe just at the wrong moment when he was about to be announced the universe was expanding so he regarded that as his greatest mistake in fact it turns out that it wasn't a mistake but not for the reason that einstein originally introduced it but uh yeah there seems to be this exponential expansion self-similar expansion if you like this the rate of expansion depends on the state of the size of the universe now uh this observed exponential expansion is what we expect to happen in our remote future unless something else happens so and i believe it will extend into the remote future now in inflation theory there was a similar expansion in the very very early stages after the big bang now i've never liked inflation right from the start for various reasons um and i'm proposing a different idea which is that yes there was inflation in a sense but this was before the big bang now an idea like that actually was put forward by the well known distinguished particle physicists gabriel venenciano and he had a scheme in which the inflationary phase took place before the big bang but that was sort of a one-off the view i'm taking is that what we regard as the current picture of the universe but without inflation without the inflation immediately following the big bang expansion and then the accelerated expansion is just one eon i'm calling it an eon aeon which is one of a succession of such eons so there will be another after hours there was one before ours and the exponential expansion of that previous eon in its remote future is what appears to be inflation in our model so there isn't a sense inflation in this scheme but it's not the kind of inflation that's argued for in normal just order of magnitude how long would an eon be to 10 to the what number a good order of magnitude is infinity okay because the view you see you say how can that be infinity yeah well it depends on how you measure time you see this is an issue and the argument is that to build a clock properly you need mass now we have incredibly precise clocks now i don't know what the present record is but if you think of it all the time from the big bang to now clocks are so precise that it's well at least something like only a few percent off it would be to a few percent of a second right so measuring the time from the big bang doesn't mean we know the time from the big bang that accurately but the clocks would keep time to that precision now of course they wouldn't survive in the big bang but don't worry about that now this precision in clocks although it depends on a lot of technology and so on ultimately comes from the fact that we have mass now we have mass in the universe and ultimately it is just the two most basic equations of 20th century physics of course einstein's e equals m c squared c is just a constant so e and m energy and mass are equivalent the other great equation of 20th century physics is planck max plancks e equals h new well f4 did we call it frequency frequency this tells you that energy and frequency equivalent to putting these two equations together we conclude that mass and frequency are equivalent so any stable particle is a clock in a sense with a very very precisely defined frequency now the the other way around is that if we didn't have mass we don't have clocks and if you don't have clocks you don't have a measure of time you don't have a measure of distance in fact the meter rule you see in paris there's no use anymore you would have to start that yes the meter rule in paris is not a good definition of a meter anymore you define meter in terms of how long it would take light to travel you know whatever fraction of a light second it is so it's really time that is the thing that defines the scale of things now that scale requires mass in one way or another either the mass defined by particles or in general relativity we have another good measure of clocks from neutron stars going around each other and again just about as accurate you have another measure of time but that requires general relativity and generativity is a theory of gravity and gravity requires mass so those are things which involve mass in one way or another if you didn't have mass scale is irrelevant big and small are equivalent so the idea is well in the one hand when you go right back towards the big bang energies get so great that the masses of particles become irrelevant way earlier than the higgs particle time if you like then the particles become effectively without mass they're massless and so they don't have a way of measuring the scale going to the wrong future almost all the particles around will be photons photons again don't have a good measure of time so they don't know big from small so the idea is that the very remote future and when i say very i really mean right out to infinity is like a big bang now that's a big difficult thing to get your mind around because we think of one that's stretched out and very and the other is the other is very squashed and very dense and hot yeah they're very cold but when you squash the the cold the cold thing very undensed together you get something very like the big bang so the argument is that the very remote future of what i'm called the eon prior to ours what i'm postulating that existed prior to ours that infinity was our big bang you need equations to make sense of it but that you can do and that carries you through from the physics which was the very future of the previous eon to tell us what our big bang should be like and just walk me through that transition one more time where you you have the previous uh eon being uh expansion into where there's effectively no mass so you can't tell the difference if it's big or small at that point that's right and then then what's that transition to generate the big bang well it's and people always ask me this you say when did it happen well you see infinity is a perfectly good place in this scheme right but you really need the equations and it makes a lot of sense when you start you just put down the transformations which make infinity squash down and then you take the reciprocal and that's the stretching out which gives you for the big bang and uh okay you've got to have some other equations to make this unique so there's a bit of delicate problems and if we would go with that which is a big step but if you go that then you could have that infinite in both directions you don't have to have a beginning you just could have these these endless aeon cycles however long they are even well the beginning is at a definite time because of each one yes of each one that's right yeah but but there's no beginning to the whole sequence there's no big that's right yes no it's in you could imagine a model where they change or something but that's not what i'm putting forward the idea is yes the previous eon was in general terms like ours the one before it was in general terms like ours and so on indefinitely in both directions and when you stop and think about it you know the question comes up why is reality like that questions of this sort i don't think i can go very far towards asking but answering but um [Applause] i don't know why reality i don't know what is reality or why reality is what it is i mean in the scheme it's a bit like the old steady state model you see and i think i was to some extent influenced by that because when i got interested in cosmology first at cambridge that was a time when bondi and gold and hoyle were producing this theory and my good friend denis yama and they were all terribly excited about this idea of a universe that was always there you see and so i think that rubbed off on me to some degree i was worried by how it didn't seem to make consistent sense with general relativity and i think bondi was worried by that too and when people decided yes there was a big bang and the evidence for that is pretty convincing and so i went along with that but nevertheless there's something philosophically about the old steady state model and it's interesting you see einstein wanted a static model newton in a similar way wanted something unchanging forever like this so there's something in this all perhaps which would like a a an eternal universe and uh it so it has an appeal of that kind that's not a very scientific argument no it's a legitimate one but i think perhaps a legitimate argument because you might ask you know why was the big bang exactly as it was and it seemed to have lots of structure to it of various different kinds you see and why was that structure there well if there was nothing before it it's hard to answer that question but here we say yes it had that structure at that big bang because the eon before it had the structure it had of course it's a an endless chain which goes on forever but nevertheless you can sort of at each stage answer that question

Channel: Closer To Truth

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Keywords: closer to truth, robert lawrence kuhn, Roger Penrose, Did the Universe Begin, big bang, big bang theory, quantum theory, stephen hawking, how did the universe begin, sir roger penrose, inflationary model, inflation theory, cosmic origins, origin of the universe, cosmology, philosophy of science, nobel prize in physics, nobel laureate, nobel prize 2020

Id: OFqjA5ekmoY

Length: 10min 56sec (656 seconds)

Published: Wed Oct 07 2020