The Expanding Universe: myths and measurements | Roger Penrose, Sean Carroll, Laura Mersini-Houghton

What is the universe expanding into? Can we accurately measure its growth? Did cosmic inflation really start from the Big Bang?

Roger Penrose, @seancarroll , Laura Mersini-Houghton, John Ellis, Peter Cameron and David Tong discuss the myths and realities surrounding the expansion of the universe.

00:00 Intro
00:37 | David Tong
05:14 | Sean Carroll
08:21 | Laura Mersini-Houghton
12:21 | John Ellis
15:05 | Peter Cameron
16:41 | Roger Penrose

David Tong
Cambridge Professor of Theoretical Physics and winner of the Adams Prize, his research focuses on how the universe is held together on a fundamental level.

Sean Carroll
Cosmologist and physics Research Professor at the California Institute of Technology, working in dark energy and general relativity.

Laura Mersini-Houghton
Professor of Physics at the University of North Carolina. Her work focuses on the birth of the universe from the multiverse, and has been widely covered by the New Scientist, the Discovery Channel and the BBC.

John Ellis
Clerk Maxwell Professor of Theoretical Physics at King’s College London who has worked extensively at CERN, and advocates the extension of the particle accelerator programme.

Peter Cameron
Multiple award-winning Professor of Mathematics Peter Cameron frequently engages the public in how to think like a mathematician. He has an Erdös number of 1.

Roger Penrose
World-renowned physicist, best known for his work on general relativity and sharing the Wolf Prize for Physics with Stephen Hawking for their work on black holes.

#CosmicInflationTheory #BigBangModelOfCosmology #DecayingDarkMatter

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[MrBradogg]

Sean Carrol has a beautiful voice. Roger Penrose has a beautiful mind.

[dichebach]

I'm a behavioral scientist, not a physical scientist. But for me, Peter Camaron's comments at 15:05 through 16:36 are the SINGLE MOST IMPORTANT topic within this area of inquiry, and it is the simplest explanation for all the incongruities and paradoxes which were summarized at the outset. There is a famous quote which I cannot recall precisely, but it is something like 'Wrong theories are nothing to be worried about, because if science is followed, good experiments will eventually dispel wrong theories. But faulty measures, and even worse faulty conceptions of measurement can mislead science for generations.' I wish more of the renowned physical scientists who know enough about these topics to ask well-informed questions about measurement would do so more often.

[ivolva]

20:40 RE: Escher picture - here prof. Penrose has very interesting point about a hyperbolic (Lobachevskian) geometry interpretation of this “boundary” (infinity) situation. Yes this geometry is a conformal invariant. But because we’re discussing a boundary (infinity) situation we need to move away from geometry to topology terminology. I mean to compact topological spaces and boundary behavior of conformal mappings. For this purpose we need to consider a compactifications bX of topological space X (in our case a disk in complex plane). Consider: not only an angles could be a conformal invariants, there are exist a lot of different conformal invariants “near (on) the boundary”. The precise topological term for this is a “conformal invariant boundary”, i.e. this boundary is invariant under conformal mapping. Open disk has infinite number of conformal invariant boundaries. Examples: one-point compactification, Euclid boundary (circle), Stone-Cech compactification (this boundary is an invariant under any homeomorphism of disk, not only conformal mappings) and many other. Another famous example of conformal invariant boundary is the Prime Ends of Caratheodory (introduced around 1913). I believe in your interpretation each aeon glued/connected to another aeon with some special conformal invariant boundary.

[ThestDukeDroklar]

One said that there are 3 methods of gauging the speed of galaxies but didn't elaborate. All I have ever heard about is the redshift. What are the other two?

[philjamieson]

Thanks for putting this on here. I love listening to these experts discussing hugely important ideas.

[crazieeez]

I like Penrose description the best. Conformal Cyclic Cosmology makes sense because geometry of spacetime is distorted at distance and at high speed.

[rotarolla]

The speaker at 16minutes Peter Cameron, he is true and real, hes my standard candle

[bitkurd]

I’m not a scientist nor an intellect but as an observer, from coming to existence out of nothing, I should also have a say. My take is the universe has never started, nor I’m. The universe doesn’t finish neither do I! That’s why in my opinion, it’s very hard to wrap your head around the universe and existence at all!

[Swolecows]

The section with Peter Cameron is not given enough weight. So much certainty over these measurements that create 70% discrepancies in visible matter. Makes no sense to me.

[alexsuited]

So this is very cool 😎 Professor Penrose. Except what i believe your description does is show, ready galacty formation. When u add the entropic principles all it means is eventually galacty conform into much larger structure, and by which the infinite ♾️ space becomes available. So i ask you how does the gaseous state get there. And from which state of matter. I am starting to take a position on this very subject. The model is quite ugly in a beautiful kind of way i must admit. It sure does help. Thank you SIR

[paultorbert]

Given our Rest Frame combined with our peculiar velocity/motion, there is no way to measure whether we are in an expanding or contracting universe.

[Frithogar]

Probably both are happening simultaneously. We just need a better conception of space-time to get our heads around it

[clientesinformacoes]

If the universe has a certain amount of energy, same energy since BigBang and space expands, then energy is decreasing by volume, the reason why things are speeding up is because matter doesn't expand at the same proportion, then inertia decreases over time. If we do the opposite, use energy to speed up matter, then matter expands (increases mass) while energy by volume remains constant in this case inertia increases. Basically this is what I think it's happening.

[proksenospapias]

In all honesty Sir Roger Penrose should stop worrying and start reading the comment section. They've got it all sorted out, it appears.

[tokajileo]

the accelerating expansion of the universe may not be true, search for article titled : "Evidence of anisotropy for cosmic acceleration" by prof Sarkar.

[bballen]

It might help if everyone used the same definition of the universe and distinguish between the visible universe and the non-visible part. Making claims about the universe based on the visible part is speculative.

[maxa]

It resembles a single cell that ends up becoming brain which wonders about all this, whats in that cell and the make up of it by atoms also has space in between electrons.

[marcusfromsweden]

Maaaybee, just maybe scientists should start looking more into the fact that the need for Dark energy vanishes if you allow for the existence (and not denial) of ionized plasma throughout the universe (for which models fit better to the observed "need to Dark energy")

Regards

[wplg]

Another Question is:
Is the universe acceleration, or is time slowing down?

[cameronmurie]

So: ( In the Venerable Penrose explanation) - If I substitute the word "Aeon" as he uses it, for the word "turtle" - as used by a critic of Bertrand Russell - It begins to appear that the elder lady was correct after all - "It IS Turtles all the way down" :-)