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Roger Penrose claims our Universe has been through multiple Big Bangs

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Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#151

Post by canadianfella »

auntienomen wrote: post #145
elashri wrote: post #87

Earlier quoted context omitted.

But Penrose's field of expertise is Cosmology. So I don't think I get the analogy? I understand that this is a speculation because it is very hard to collect evidence for that claim but it is still within the wide umbrella of what Penrose devoted his career.

Penrose's expertise is general relativity. He's not at all expert in particle physics, which is an essential part of cosmology these days.

I’m pretty sure Mr. Penrose is at least somewhat of an expert in particle physics.

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#153

Post by sitkack »

tcmart14 wrote: post #148
karaterobot wrote: post #51

I think the tone of the article is a bit too judgmental. He himself called it a 'crazy theory'. I took it to be a pet theory he thinks is interesting, personally would like to believe in, but knows he can't prove. We've all got some of those, there's room to talk about them without being called a crank.

Yea, that is my understanding. He does call it a crazy theory, but its a whole different kind of crazy that most people think of. I've listened to him talk about it and yea, when you actually listen to him you get the vibe of, "its an interesting idea that the math can't really prove or disprove, it may not be right, but it is an interesting thought experiment." I would say it is a step below Fred Hoyle. For those wh…

Should we entertain unfalsifiable theories?

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#154

Post by sidcool »

The concept of infinity seems impossible to me in physical world. It's a great mathematical concept to model our understanding. Just like imaginary numbers.

I cannot imagine anything being infinite in the physical world. I find the simulation hypothesis more probable than Universe being infinite. Space and Time is not infinite. It may be Gazillions of centuries old, but not infinity. It can't be.

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#155

Post by threeseed »

markhahn wrote: post #58
truculent wrote: post #14

IANAP - why are these ideas so controversial? The article seems to suggest he has some (potentially) supporting evidence, and I don't have an intuition for how damning the counter-argument is ("This would necessitate making all particles lose mass as the universe gets old." Again, IANAP and physics can get weird).

it's fringe because it's almost certainly nonfalsifiable

Based on a previous talk [1] there was a claim that you should be able to see events from previous aeons in the background microwave radiation.

In particular rings caused by the collision of black holes.

And from his talk he had reached out to colleagues from around the world to see if they did exist. So it seems like he does care about it being provable.

[1] https://www.youtube.com/watch?v=ftjwnjR0apY

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#156

Post by jstanley »

sidcool wrote: post #154

The concept of infinity seems impossible to me in physical world. It's a great mathematical concept to model our understanding. Just like imaginary numbers. I cannot imagine anything being infinite in the physical world. I find the simulation hypothesis more probable than Universe being infinite. Space and Time is not infinite. It may be Gazillions of centuries old, but not infinity. It can't be.

If you're happy for mathematical structures to be infinite, why can't our universe (including ourselves) just be one infinite mathematical structure?

Yes, it's very complex, but there's plenty of room in infinity.

It doesn't need to have a "real" physical instantiation anywhere. It's like the simulation hypothesis, except you don't need the simulation. We're just the inside of an infinite self-experiencing mathematical structure, with nothing on the outside.

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#158

Post by chimprich »

sidcool wrote: post #154

The concept of infinity seems impossible to me in physical world. It's a great mathematical concept to model our understanding. Just like imaginary numbers. I cannot imagine anything being infinite in the physical world. I find the simulation hypothesis more probable than Universe being infinite. Space and Time is not infinite. It may be Gazillions of centuries old, but not infinity. It can't be.

The universe being finite in any way is even harder to grasp for me. How can existence itself have a beginning?

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#159

Post by threeseed »

sidcool wrote: post #154

The concept of infinity seems impossible to me in physical world. It's a great mathematical concept to model our understanding. Just like imaginary numbers. I cannot imagine anything being infinite in the physical world. I find the simulation hypothesis more probable than Universe being infinite. Space and Time is not infinite. It may be Gazillions of centuries old, but not infinity. It can't be.

Based on his talks Penrose doesn't either.

It's just that we are talking about googolplex timescales.

Re: Roger Penrose claims our Universe has been through multiple Big Bangs

#160

Post by DannyBee »

pyrolistical wrote: post #29

I don’t see what is the alternative. If it’s not cyclic how can there be something from nothing? The only solution is every thing has always existed and there is no such thing as nothing

Our perception is fairly limited. It's a very human notion to believe that everything must have had something come before it.

But keep in mind we are also the ones defining before and after based on our perception.

It happens that this matches our view of light propagation/etc, and our understanding of time. But that is today. Not during the big bang or "before" it.

In fact, we also know there were times where the current physical laws did not necessarily apply, shortly after the big bang for example. Currently we believe fundamental forces took time to separate. Heck, even subatomic particles took a very significant amount of time to form.

At a time when physical laws may not apply, things like "our view of the direction of time" would not have applied, either, for example, since most arrows of time boil down to the second law of thermodynamics, see, e.g., https://en.wikipedia.org/wiki/Arrow_of_time. Which means even causality as we think about it breaks down somewhere in there.

This is hard to wrap your head around because it's so alien to how we currently perceive the universe. We want things to fit that perception.

Honestly, even before you get to "before the big the bang", we still can't explain why the universe inflated during the big bang (IE we have no idea what field did it, though we know some things about it, and just expect we will eventually discover it).

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