Dr Greene makes it look so easy and relaxed meanwhile he's constantly calibrating and recalibrating the conversation for pacing, clarity, inclusion of the whole panel and overall cohesiveness. He's just an unbelievably good host and, of course, always on top of the material. Awesome presenter.

Right now, Penrose's take on conformal cyclic cosmology makes more sense to me.

These talks are great, thanks for putting them out for free

" We should all work on something that is wrong." - Anna Ijjas. I am taking this to the bank 😤.

I wanna know who that guy is that queues up the animations and videos of exactly what the speakers are talking about a split second after they start talking about it.. that guy deserves a raise.

Hi another Anna here, thanks for telling this amazing story Anna, and the other people in the video :D

Always like B Greene and much appreciation for finding Sir Roger Penrose and his C3 theory decades ago of cyclical big bang and his MC Escher inspiration.

Fantastic.Thank you so much for organising this festival, and for its live broadcadting. I have found this conversation particularly interesting.

This was one of the best, even most important programs yet from the WSF. Thanks for letting us eavesdrop on great ideas.

I come here because I have no friends that want to talk about these things. (insert tears)

incredible discussion about the bleeding edge of modern physics and cosmology.

Roger Penrose Cyclic Cosmology

Thanks for the vid and engagement. Great channel for exploring

This is the boldest and most intriguing idea in cosmology that I have come upon since inflation itself. I need to look into this more deeply. If true, then the implications are staggering, and many ideas from Hawking radiation to multiple universes are no longer viable or necessary.

Very nice discussion. Thank you! 👏👏👏

Brian is the GOAT. So captivating the way he gets science accross

I have to say thank you for resuscitating my school education topics that I chose to learn, but had no way to pursue a career in my small country. I have to acknowledge Anna's courage to sit on this stage and hold her ground in the same esteem. You have inspired me so I thank you. I also want to acknowledge that I am enjoying observing the body language of the panel, it is so much fun to see it switch and change about when certain topics are being discussed 😎😁

It hit me like a ton of bricks. Our measure of expansion is what we see, not what is out there, because the information hasn't reached us. I read and accepted 'inflation" back in the 80's, and I always suspected it didn't matter how or why in the first second. The entire universe acts like a black hole, but once it gets too big it breaks, and it will happen again. This talk is simple and amazing. When spacetime warps and contracts, we wont see it coming. Gr8! Peace ☮💜Love

first goes like, then i watch. brian never dissapoints. never

Another exceptional World Science Festival event.

I love these, they are so thought expanding. They make you know not one person is in charge. We will all be a part of that particle in the end.

He must be a joy to be interviewed by like this. Professor Greene is so perceptive, insightful and masterful in the art of scientific communication.

Great talk Anna's directness is hilarious

Your videos are a constant source of inspiration, driving me to explore further into the mysteries of the universe. Thank you for kindling my inquisitiveness.

What an astounding presentation! Many years ago I saw a similar event at Cambridge University where we were introduced to plate tectonics I feel this is going to prove to be equally profound. Four very, very clever people including THE science populariser of our age have come up with an alternative to something that has always bothered me. I can usually grasp the rough idea and communicate it but inflation (in the cosmic sense) had me utterly baffled, I feel a lot better knowing that I wasn't losing it. Utter respect to all of you especially Anna whose passion shows clearly. To have achieved so much while so young is doubly incredible, to explain it in another language with such clarity is staggering.

amazing idea, and an amazing video. I need a second watch.. but still beautiful.

So amazing watching this ringside view of scientists trying to figure out - what do these observations mean for our theories? Brian works his magic of bringing the rest of us wondering human family into this discussion - the modern campfire!

WSF never disappoints :)

I remember when Brian Greene made gis pop sci debut on the discovery channel or TLC or something similar, PBS? I didn't care for his educational style at the time, but i have grown to LOVE Prof. Greene 🥰

Engaging conversation. Thank you. 👍

This discussion contains many profound ideas with some usually hidden ones presented openly that are not limited to a 'cyclic cosmology'. For example, is a simulation based on a 'solid model', i.e. GR, what are the initial conditions used, i.e. spatial shear and is there an arbitrary 'sense' to it all These topics enter the discussion about one hour into the video lead with good questions by Dr. Greene. I, for one, would love to hear/see what Roger Penrose, Neil Turok and Jim Peebles have as reactions to this work.

It makes you wonder if we lived in a contracting universe what would our theories of the origin be... Great episode!! Thank you!

CCC is art. I just love it

Another really excellent panel discussion! - I wish I had the maths to understand all this stuff as well as the panel members . .

Attended this live! Was a great show in NYC. Thanks Brian

Remarkable, these concepts and their explanations. All potential Nobel winners

So fascinating and inspiring.

Amazing - Thank you Brian Greene/Team .. amazing content

Muito obrigada queridíssimo Professor Brian Greene, abraçãoo ! Amooo demaaiiss este Planeta Terra Universo Magníficos e Fascinantes ! 😊👏🏻👏🏻👏🏻♥️♥️♥️🌍🌳🌴🌲🌳🌴🌲⛰️🏔️🌋🌳🌴🌲🌴🌲🌴🌳🌎🪐🌕🌍🌳🌴🌲🌳🌴🌲🌳🌴🌲🌳🌴🌲🌳🌴🌲🌏🌕🪐🌍🌕🪐🌏🌎♥️♥️♥️♥️♥️♥️♥️♥️♥️

Did they explain how entropy doesn’t ultimately WIN over accumulating cycles?! This was so interesting that it is worth a second watch. Many thanks for bringing such high quality content.

interesting. I need to re watch so I can better understand, but their idea does make sense.

I just love science programs like these. Hypothesis are postulated and then discussed until there is nothing left but facts close to be 100% true. Religions, in contrast, postulate theories that may not be questioned and are almost 100% false, yet people can't let go of it. Like a ship that kept one safe for years, but is sinking now, goes down with those that hang on to it, while those that accept the fact, start swimming and stay on the surface, at least for a while

I've latched onto this theory since we first heard of it

Amazing talk, great theory strong again. ....

There is a mathematical description of the universe by a man called, Sotade Olusegun. His research publications are so insightful to explain the nitty-gritty of the Universe. I will suggest that you get his KZfaq videos as you search through KZfaq by his names. He usually puts the links to his research publications in the description sections of his videos on KZfaq.

Great show

I was probably happy being nonexistent before I was so rudely interrupted.

💭 💭💭💭 If time in the whole universe stops for billions of years long then resumes, we wouldn’t be able to notice! 🤯🤯 🤯

what they fail discuss is the causal mechanism for the expanding universe (currently reported with a large time lag) to reverse to a contracting universe in the observable space. Otherwise an excellent presentation.

thank you so much.

I think the Universe is dynamic & animated, & pulses like a wave, producing a series of Big Bangs like a celestial sausage machine. There is no beginning and no end, except for the birth of consciousness which was needed to give meaning to all material existence.

I am not sure about the 'Big Bang' but my mind is blown by this episode. Wow!

fantastic panel.

Very well done, thank you. Peace 😎 ✌️

I'm not sure I fully understand this stuff, but thanks for producing such great content!!!

there are reasons why this leads to layers of abstraction, that is necessary to do cosmology in some for or fashion, and it turns into half and half conceptual and numerical curve fitting, which is not an insult btw, this is what we have been stuck with in part since newton, but this kind of physics model is always open to changing principles, and so we shall see. this is not to say that the work already done on cosmology is wrong, or unimportant, it might just take a more complicated and constraining set of principles to make progress.

Great respect for the skills of the facilitator here.

The universe won’t ever end

I'm eager to see this talk.

Great Great question! I bow to you Profesor Greene. Like a great book you open our minds and I thank you daily. Question: one implies a God if pre bang didn't exist. And time may be man made but pre big bang may of been a plate of gasses that came from even mutation and or evolution where and how did they start.? And think that the universe is still forming and it will expand as it cools it may slow and retract and effect gravity as the stars burn out billions and billions Of years from now; note new Suns are being born so this may take eternity. ?

Might it be that expansion and contraction are both present together, working in tandem? Galaxies can be expanding as a whole, while within each galaxy pockets of contraction might provide the smoothing until an equilibrium is obtain?

how did they get to be the same temperature? gravity on the PODE. the PODE itself would be extremely close to uniform and the mechanism that actually made the big bang expand is still not yet understood. so that could also play a part.

this talk sheds a lot of insight into how the scientifice oligarchy works to stifle new, emerging, and innovative ideas.

I like the Roger Penrose theory, way more elegant!

Very thought provoking

A "multi"-verse remains a SINGLE UNIVERSE composed of multiple universes (like ours, which could be inside a black hole), ETERNAL and INFINITE that is continually TRANSFORMED and manifests itself in many, infinite ways, whatever they are called: Human beings, Galaxies, Quasars, Black Holes, Dark Matter, Singularity, etc... The Universe or Multiverse only transforms: It is PURE ENERGY.... It is impossible to prove it, but it makes no sense to have a Beginning, or an END in time, or any Space LIMIT: What could be BEYOND the Space "limit" of the Multiverse? Well, ANOTHER Universe... And what could have been BEFORE the BIG BANG? Well, another Universe or Multiverse... And once ours cools down and perhaps COLLAPSES into a SINGULARITY, perhaps it will give rise to another Big Bang... ETERNAL...!!! And most importantly: That Universe-Multiverse is GOD! A God who does not reward, punish or monitor anyone. That he is not looking out for anyone. So ENJOY your life!

It's nice to see such brilliant people laugh at pure nervousness when there is not a shred of humor. Eases my anxiety.

Waves at a beach can be very turbulent, picking up material on its way, yet on the beach the sand is flat. Gravity could be the turbulent fluid in some gravitationally overloaded universal sized black hole, by time particles can get together again still expanding compressed gravity is in the beach, calmer state.

also, if we run with this Einsteinian dream that all relations are self defining in a sense, the size of the universe changing isn't actually what expansion means, expansion in that sense means the changing of relations inside the space. in that language the notion of a singularity just doesn't exist anymore or it changes into a different kind of statement which can just as easily have a past as any other point or volume.

Great expert!!❤

My belief is that the big bang was a somewhat localised event in a much larger universe. Like a rock dropped into the ocean, its effect is localised when compared to the whole universe. Maybe black holes collapse even further when they reach a critical mass, they implode more then explode

There's a concept of cyclical time and the universe in Hindu scriptures, especially Rig Ved . It talks of eternal creation and destruction of the universe and time. Shiva is the entity that drives the time and Vishnu controls the space. Shakti is the energy that gives birth to matter. Time dilation , which has been proven, the Mahabharata says 100 years of Brahma is 311.04 trillion years, which is roughly the life span of our universe.This concept given in these scriptures make me see everything with a scientific eye and encourage my curiosity to know more and more about our universe. " There was neither non-existence nor existence then; Neither the realm of space, nor the sky which is beyond; What stirred? Where? In whose protection? There was neither death nor immortality then; No distinguishing sign of night nor of day; That One breathed, windless, by its own impulse; Other than that there was nothing beyond. Darkness there was at first, by darkness hidden; Without distinctive marks, this all was water; That which, becoming, by the void was covered; That One by force of heat came into being; Who really knows? Who will here proclaim it? Whence was it produced? Whence is this creation? Gods came afterwards, with the creation of this universe. Who then knows whence it has arisen? Whether God's will created it, or whether He was mute; Perhaps it formed itself, or perhaps it did not; The Supreme Brahman of the world, all pervasive and all knowing He indeed knows, if not, no one knows. " --- Nasadiya Sukta, Rig Veda

This is surely interesting. But what got the cycle going in the first place? What started the first expansion/contraction?

If you see a pile of broken glass on the floor, you don't know what it was until it is all put back together. In a broken state it could be a bottle or a glass. Our universe is the pile of broken glass, how can you think it was a bottle when it could have been a glass?

you see it depends on the coordinate interpretations, because at a certain expansion rate the rate of change in the energy density can also be corresponding in a funky way, but this only makes good physical sense for these types of equations when you define energy in a certain way, and this business has to do with derivatives of the metric and so on and the energy densities even when they are 0 and so it isn't as un-tricky as either Einstein or his contemporaries knew anything about, the essential boiled down version is that you can pick a convention and it will sort out your derivatives independently of what the energy densities actually are without changing the equations so to speak in this more involved language, so in a sense they where both right and wrong. this is the gist anyway :)

Their explanation of how their system cycles is so convoluted and poorly explained. In comparison, the Penrose CCC explanation is very simple and clear.

The pronunciation of Anna is very similar to the pronunciation of Neumann, Wigner, Szilárd, Teller and Kármán

Greetings, Brian, I've been watching many of your videos and i've learnt a lot. I'm not physicist or scientist, merely interested in learning. I'd like to ask you a question, if i may. You've been talking about all these issues and problems, such as the quantum entanglement. I am curious, you believe that nothing can go faster than the speed of light, as i can presume from your works. I'd like to ask whether there is a possibility that Dark Matter or Dark Energy may be able to go faster than the speed of light, and whether the question of entanglement may be solved by the presupossition that two particles are connected by Dark Matter or Dark Energy and therefore no matter how far apart they still click together. Thank you for your time. Bless your heart for the hard work you put in and enlightening the world for free :)

Nothing begin and will never end...

It makes sense it's a cycle. Look out into the universe and all we see is cycles. In fact a black hole changes time into space, another black hole within could cycle it back again. Nested black holes might be the mechanism.

I like the theory presented by the lady!

Personally I think the event of the big bang has happened multiple times in different regions of space creating different "universes"

This theory actually makes sense: how the universe was once in a condensed ball of mass and energy and the world sort of like "exploded", giving birth to the universe.

Consider, the universe itself is living. If it is, we can surmise that it was "born" from the interaction of other pre-existing universes like our own with an endless number of other related universes filling the proverbial night sky beyond the realm of our expanding universe. All of it is alive and growing.^

Zero entropy is a weird way to look at anything, as you can simply assume just limiting space/time to a point could be all entropy at the same look. It doesn't have to make sense that way of looking at entropy. Entropy is a deceiving concept. Personally it's always bugged me. Why isn't a singularity entropy anyway you look at it? Gr8! Peace ☮💜

with respect to this comment i just made, pauls point makes a lot of sense, but i think it is a mix, i think he thought he had some notion of self consistency baked in and the observations carried it, little did he know that to explain the broken scale in variance in the physics of atoms in the same language as curved spacetime you need the universe to expand, it turns out it cannot bounce outside very spacial cases that are ultimately local fluctuations and shouldn't really be viewed as contraction, it could never happen for a large universe like ours, but essentially the mechanisms you need to explain the broken scale invariance of matter and a lot of other feature of the forces you absolutely need expansion in the context of this ever increasing entropy to explain features that look driven and damped in equal propotions in relation to a moving definition of energy related to the broken scale invariance. but he could never have known that something as simple as self consistency could tie all these things together, and that is the curse of being a pioneer, you never know what might come next, and so we shouldn't take our principles so seriously outside understanding their application and intent in a separated way.

amazing

So at 1:14 Steinhardt posits: Evidence is that inflation rate is increasing (due to dark energy) but if the potential energy curve (driving this expansion) is positive but declining than at some time it could become negative and the universe changes to slow contraction. I don't understand what he means by "the potential energy curve" so will just take it on faith. Next at 1:18 to 1:20 Galison talks about polarisation of gravitation waves (recorded in the CMB?). Again, I don't understand this. The CMB is light. Can it record a gravitational signature? (analogous to gravitational lensing?) And at 1:21Anna mentions the Simons Observatory is looking for such signatures. Such a signature would be proof of inflation but not finding a signature doesn't prove the Steinhardt model. Merely that the inflation signature is beyond the sensitivity of the Simons Observatory.

The competing cosmological models are pretty dependent on principles. What if the universe's minimum a(t) never was microscopic due to space requirements of its total energy content (then of an extremely nonlinear, selfinteracting system)? And time, whatever this is in the spatial bottleneck situation, could it have slowed down enough to guarantee sort of thermodynamic equilibrium to be reached without any inflationary necessity? And kind of a Feigenbaum scenario with a plethora of phase transitions would then have had the time necessary to evolve and generate complexity...

One thing that remains unclear to me in this discussion: If, in the cyclic model, inflation can't smooth the universe unless it was already very very smooth to start with, then how can the cyclic model produce a smooth universe even when it lacks the smoothing inflation? Or maybe I need to watch this again with greater care...

Does this theory rule out the "need" for quantum gravity in black hole physics as well? Anyway, really interesting talk. Thank you!

When I was in high school, I thought that a universe and its energy would dissipate beyond its event horizon in akin to hawking radiation, but only after achieving entropic equilibrium; returning its energy to the environment that birthed it.

Не может ли быть так, что расширение вызвано самим квантовым явлением, которое нарушило суперсимметрию энергии и вернуло её в так называемое состояние со вновь возможностью квантового явления в этой суперсимметричной энергии?

Very interesting

There is no beginning and no end other than, The Eternal Now. (universe in T.E.N. dimensions)

Wonderful! Scientists fight to learn, not to kill.

What if spontaneous creation / destruction of matter and energy at the quantum level AND expansion / compaction at the cosmological level are not mutually exclusive? And what if the expansion is heavily biased in the spatial dimensions and the compaction is heavily biased in the temporal dimension? Can you run your models using these assumptions and see how they might influence the model's ability to describe observation?

I'm convinced from a philosophical and meta physical view that it's cyclical and infinite not necessarily in space but in cycles. Your multiverse is one in cycles not in dimensions.

And so here we are now…..and in x billion trillion giga years all the supermassive black holes evaporate into 🌑 and 🌚….😘Great session! Thanks so much! Perfect New Years launch💫💙

The idea of a cyclical universe was popular in antiquity. Many Greek philosophers propounded this idea. It was particularly common in stoic philosophy. The idea fell out of favor however with the advent of Christianity. Writing in 400 CE, St. Augustine argued that if the universe were cyclical, Christ would have to die an infinite number of times in cycle after cycle. The Idea was then abandoned in the west for centuries. It reemerged in the 18th and 19th centuries, perhaps most notably in the works of Fredrick Nietzsche. This idea of a cyclical universe is commonly call eternal return.