Tip jar

If you like CaB and wish to support it, you can use PayPal or KoFi. Thank you, and I hope you continue to enjoy the site - Neil.

Buy Me a Coffee at ko-fi.com

Support CaB

Recent

Welcome to Cook'd and Bomb'd. Please login or sign up.

March 28, 2024, 01:00:21 PM

Login with username, password and session length

Space and time aren't fundamental properties of the universe

Started by Mrs Wogans lemon drizzle, December 01, 2021, 10:36:46 PM

Previous topic - Next topic

touchingcloth

Quote from: Alberon on December 02, 2021, 08:36:21 AMI did watch about twenty minutes of an episode of Universe, but it was so glacially slow and devoid of information I got bored and switched over. There really is a need for a series, and I except probably a much cheaper one, where they can go into things in more depth. Maybe even link to webpages with more info. Just about everyone can pause TV now, they don't need to be so shallow and slow.

Have you seen any of Jim Al-Khalili's programmes? They go much more in depth. He's still hamstrung by the problem of trying to come up with models of quantum and relativistic phenomena that are both accurate and make sense to a lay audience as Cox is, but at least most of the examples he gives involve him talking to camera or mucking about with some physical models rather than the expensive CGI that gets crammed into Cox's shows.

Captain Z

Quote from: Sherringford Hovis on December 02, 2021, 12:58:28 AMOnce we've got an explanation for red, green and brown holes - we got this physics thing all sewn up.

Sir, are you absolutely sure? It does mean changing the bulb.

touchingcloth


TrenterPercenter

Quote from: touchingcloth on December 02, 2021, 11:45:30 AMHave you seen any of Jim Al-Khalili's programmes? They go much more in depth.

Al-Khalili is the absolute boy

touchingcloth

Quote from: TrenterPercenter on December 02, 2021, 12:34:30 PMAl-Khalili is the absolute boy

He is. I love the manner he has. I see the benefit of people like Cox who have extremely broad appeal (this sounds like a slight, but isn't meant as one), but as someone who reads a lot of pop science it's nice to have someone like Al-Khalili who tries his best to explain things rather than just letting you know that the universe is MENTAL sometimes.

TrenterPercenter

Quote from: touchingcloth on December 02, 2021, 12:36:42 PMHe is. I love the manner he has. I see the benefit of people like Cox who have extremely broad appeal (this sounds like a slight, but isn't meant as one), but as someone who reads a lot of pop science it's nice to have someone like Al-Khalili who tries his best to explain things rather than just letting you know that the universe is MENTAL sometimes.

Never been keen on Cox, he is dull.  Al-Khalili is a great scientist, communicator and general all round good guy.   I'll watch pretty much anything with him in it

The Dog

I like Brian Cox. You shouldn't expect much from the BBC now. Al Khalili too.

touchingcloth

Quote from: TrenterPercenter on December 02, 2021, 12:41:42 PMNever been keen on Cox, he is dull.  Al-Khalili is a great scientist, communicator and general all round good guy.   I'll watch pretty much anything with him in it

I don't think Cox is dull - quite the opposite - but when you know the basics his approach to communicating science specifically is quite dull. I suspect if I were a generation younger then he might have been my gateway into an interest in science rather than things like the RI lectures.

JesusAndYourBush

Quote from: bgmnts on December 02, 2021, 12:46:36 AMThis is why I think heaven can technically be real because what if just the last little spark of brain activity lasts for an eternity in your mind's perception, and what influences what you visualise is how you acted on earth or some shit.

I've realised that when science is dealing with that amount of woo-woo there's enough room for religion and science to co-exist with bags of room to spare.

Johnny Foreigner

In the 90s, I used to videotape The Learning Zone off BBC 2 at night; there was some really educational material from the Open University in there. I must have accumulated 100 old Sky at Night episodes. I have not seen The Learning Zone in donkeys; it has probably ceased to exist. Later on, I bought the Sky at Night magazine that always contained the latest episode on a CD, plus additional material.

Patrick's been dead for nine years now; I was rather obsessed with the man for some time. I read his rather embellished autobiography and Mobberley's biography, collected his music. I shall always regret never having met him; he was really kind to white people. I wanted to go down to Selsey, just knock on his door and conceal the fact I can speak German, then randomly chat with him about the stars and planets – alack, 'twas not to be.


Ambient Sheep

I'll always thank him for introducing me to the delights of a King Prawn Jalfrezi, which is apparently what he was eating in his local curry house when his home observatory got damaged by the Selsey Tornado in 1998.

Sherringford Hovis

Quote from: Captain Z on December 02, 2021, 11:50:14 AMSir, are you absolutely sure? It does mean changing the bulb.

There's blue holes now? I can't keep up.

Quote from: greencalx on December 02, 2021, 09:11:11 AMQuantum shit and cosmology is at the opposite end of physics to what I do, so I'm as much in the dark about what Cox might have meant as anyone else. I'd be surprised if he had the special theory of relativity (which is the one that unifies space and time) in mind when referring to something that he didn't understand, as this is fairly bread and butter stuff in a physics degree (although it makes my brain hurt on those rare occasions that I have to revisit it). I'm guessing he has one of the more esoteric theories (like string theory) in mind, but my understanding is that such theories don't (yet) hold any explanatory power beyond the more mainstream ones and are treated with caution by most physicists.

I'm not sure that's true: the time-dependent Schrödinger equation certainly has time in it, although this is the classical notion of time (not relativistic spacetime). That said you can do relativistic versions (Klein-Gordon / Dirac) both of which are defined on spacetime. My relativistic QM is very rusty, but certainly the Schrödinger equation describes phenomena like the broadening of wave packets (particle starts off with a fairly well-defined position, but becomes more spread out over time) and scattering processes (chuck a proton at something, see where it goes). Indeed it's the latter that's used to analyse the very much time-dependent processes of smashing things together in particle accelerators to see what comes out.

Perhaps what you're referring to is that quantum and classical mechanics both involve reversible equations of motion, in the sense that if I run a system, pause it, turn everything round, and press play again, the system will retrace its steps. Another way of saying the same thing is that you can't tell whether a movie of a reversible system is being played forwards or backwards. This is an idealisation: clearly in the real world we can tell the difference between things going forwards and backwards. It's easier to hack irreversibility into classical mechanics than quantum mechanics, by including dissipative processes like friction that then allow you to identify an arrow of time. There's some recent(-ish) research on open quantum systems that have some sort of coupling to the environment and entanglement going on that I believe also includes dissipation, but this is yet to percolate into the undergraduate curriculum and is not that widely understood. I have a hunch that wave function collapse is a dissipative process, and you therefore need thermodynamics to properly understand it, as thermodynamics is the only branch of physics that properly respects irreversibility and dissipation. One of the things I'd like to do if a sabbatical year ever materialises is to dig into this literature and see if I'm right...

I'm fairly sure that didn't answer your question.





Thanks, that's really intresting.
If it helps at all, here's what Brian Cox says, i just jotted it down as he said it, so there may be some mistakes/typos:


Quote"If information somehow escapes from Sagittarius A* (black hole he's been talking about) the implication is profound - black holes arn't tombs, they're gateways.

We now believe that anything that falls into Sagittarius A* will live on, not as a phyical object, but as information, escaping from the heat of darkness encoded in the Hawking radiation in the far future.

The memoty of all those worlds that fell into sagaterious a* and over the entire histroy of the milky way galaxy is somehow written in the ashes of the universe in the far future.

but the real treasure lies in the explanation of how the information gets out from those eternal prisons.  now what im gonna tell you will sound like science fiction but here goes.

when the black hole has evaporated away and about half of it has gone, the interior becomes in some sence the same place as the distant hawkin radiation that was emmited eons ago out there in the far reaches of the universe.  it seems that space time wormholes open up between the interiror of the black hole and those distant parts of the universe, and its that, that allows us to read the infmration inside. 

he then goes on to caviet the above by saying not everyone agrees on the full picture, but that they do agree that our picture of time and space is wrong.

Quoteno one really agrees on the phyical picture of whats happening, but what everyone agrees  is that black holes are telling us is that our intuative picture of reality, of space and time, is wrong. there is a deeper picture of reality in which space and time do not exisit.

Mister Six

So spacetime is a phenomenon that emerges from other underlying properties that we've yet to grasp? Our 3D world (and its fourth dimension, which we can't really "see") is just a small facet of a larger, incredibly complex super-reality?

That makes sense to me, as an idiot who got a D in GCSE physics but reads a lot of sci-fi. That's not supposed to be a criticism, BTW.

Now, can anyone explain the holographic universe theory to me?

TrenterPercenter

Quote from: Mister Six on December 02, 2021, 05:56:15 PMNow, can anyone explain the holographic universe theory to me?

The universe is a surrounded by a 2d boundary that creates the perception of depth/volume like a hologram does.  What's more important is how this means information is encoded onto the surface of things which would answer aspects of what happens to information in blackholes but it also has implications for how brains work as well.

Mister Six

So our 3D universe is contained "within" the 2D boundary, as 3D information that actually exists in 2D, so our perception of the universe is kind of an illusion or (sorry, can't think of a better word) simulation caused by viewing the information from the inside the 2D superstructure?

touchingcloth

Quote from: Mister Six on December 02, 2021, 07:39:43 PMSo our 3D universe is contained "within" the 2D boundary, as 3D information that actually exists in 2D, so our perception of the universe is kind of an illusion or (sorry, can't think of a better word) simulation caused by viewing the information from the inside the 2D superstructure?

So that thing's spewing time back into the universe?


purlieu


Johnny Foreigner

Remember, whenever someone says: 'Give me some space here!' or 'I don't have time for that!', those utterances are meaningless. Space is everywhere and cannot be given; furthermore, as time and space are intrinsically linked, it logically follows that everybody always has time for everything as well.


Mister Six

Quote from: touchingcloth on December 02, 2021, 08:19:03 PMSo that thing's spewing time back into the universe?

No, that's a different thing entirely. Unless you're just taking the piss.

touchingcloth


Cold Meat Platter

When you watch BBC science documentaries from the 70s and 80s (and 90s to an extent) there's one thing that strikes me: there's no music. Other than sometimes some Radiophonic workshop analogue synth it's usually just boffins talking boffinry over some animations or diagrams, or more likely just them in an armchair with a fag on.

Bence Fekete

Mentioned this before but Donald Hoffman has an interesting theory about time and space not being fundamental. His argument is that evolution selects for fitness (survivability) much more often than what we might call objective truth. So our entire historical development could all have been going in one, linear, semi-bogus direction (time/space) and further and further away from the multitude of dimensions that actually create ✌reality✌ reality.

Which he thinks is consciousness. I haven't got that far with it yet to understand why that isn't just projecting more time/space mind onto it.

But given our general track record for stunning collective arrogance and that our best scientific models break down in key areas it's easy to imagine such a deep cosmic ignorance could actually be true on some level though. It might never add up because we weren't built to innately understand the key components of what's actually there. Which is why they call us sapien-man: the dunces of the universe.

Bence Fekete

Wasn't Roger Penrose's theory a year or so back about how black holes might be able to smuggle information between aeons/sequential big bangs? I thought you could make a fun game set before the big bang where you played swirly gaseous gods who could seed different universal outcomes that would alter how universes ended and then subsequently recreated themselves. but then I realised you'd have to code a game universe the size of the actual universe and thought maybe not then.

mothman



mothman