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Is Spacetime Real?

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Re: Is Spacetime Real?

#91

Post by richardjennings »

cletus wrote: post #48

Modern physics is well beyond the point where I, as a layman, can really understand it. It still doesn't make sense to me how gravity is put in the same bucket as the other three "fundamental" forces. Since the universe is expanding, are we making more space (or spacetime)? If so, how does that work? I'm not even sure if the universe is finite or not. I mean the observable universe is but how that relate to the actua…

I have come to accept that I do not and almost certainly cannot understand spacetime. I cannot fathom the consequences of the passage of light through circumstances. I do not see how the concept of 1 Billion years can be thought to apply universally; how the Universe can have an age when as I understand it, time is circumstantial and potentially as meaningless as speed without a point of reference.

Re: Is Spacetime Real?

#92

Post by mycall »

karmakaze wrote: post #79
blablabla123 wrote: post #38

Earlier quoted context omitted.

Theory is indeed separated into several disciplines, speaking about mathematization: Phenomenology, Model building, Mathematical Physics. FWIW I think Phenomenology is where a lot is going on, it's about looking what is there and how it compares to the models. The fully formalized ("axiomatic") mathematical descriptions oftentimes lag behind the theoretical models ("postulated") in use that are used to compare with r…

> Atoms are as real as it can get Well put, and also not any specific degree of real, if you accept that the simulation hypothesis can't be disproven. The specific 'real' discovered properties of atoms or spacetime are actually artifacts of simulation.

Is simulation time continuous or discrete? If there is only 1x forward speed for simulation time, perhaps relativity could continue to work, as that fixed single speed would be discrete (speed of light).

I'm not sure how to postulate this idea further, but I've had it for years.

Re: Is Spacetime Real?

#93

Post by sdwr »

mycall wrote: post #92
karmakaze wrote: post #79

Earlier quoted context omitted.

> Atoms are as real as it can get Well put, and also not any specific degree of real, if you accept that the simulation hypothesis can't be disproven. The specific 'real' discovered properties of atoms or spacetime are actually artifacts of simulation.

Is simulation time continuous or discrete? If there is only 1x forward speed for simulation time, perhaps relativity could continue to work, as that fixed single speed would be discrete (speed of light). I'm not sure how to postulate this idea further, but I've had it for years.

I like to imagine the world as being like a distributed game engine running on a computer outside of time. That would mean that life could have existed before physical space or the earth did. History being built piecemeal and in reverse order, a past being created by collective effort and attention. And somewhere along the way Santa planted dinosaur bones.

Maybe when you close your eyes you fade to black, and existing is a constant choice. Maybe situation and circumstance are handshake deals made in the collective unconscious, an onion growing layer by layer from the kernel.

Just something to think about :)

Re: Is Spacetime Real?

#94

Post by kadoban »

mycall wrote: post #92
karmakaze wrote: post #79

Earlier quoted context omitted.

> Atoms are as real as it can get Well put, and also not any specific degree of real, if you accept that the simulation hypothesis can't be disproven. The specific 'real' discovered properties of atoms or spacetime are actually artifacts of simulation.

Is simulation time continuous or discrete? If there is only 1x forward speed for simulation time, perhaps relativity could continue to work, as that fixed single speed would be discrete (speed of light). I'm not sure how to postulate this idea further, but I've had it for years.

I think if we're in a simulation, it's hard to do more than guess at what its properties are. We could try to use mathematics and computer science and physics to see what it looks like from inside, what seems possible to compute (making the probably good assumption that computation and math are universally true), etc. But if you get right down to it, a sufficently advanced/evil simulation could paper over whatever it wants just by modifying our brains, removing troublemakers from existence and memory, etc. Gives me the creeps thinking about it much.

Re: Is Spacetime Real?

#95

Post by 8note »

sailingparrot wrote: post #52
AnIdiotOnTheNet wrote: post #47

Earlier quoted context omitted.

> So then the Aether was real for a while and stopped being real 200 years ago? Yeah, pretty much. > If we discover a new model that makes better prediction than our current spacetime based model, just like relativity was to Newton's theory, will spacetime stop being real? In so far as Newtonian gravitation is also not-real. We still use that model for a lot of things of course. I don't know much about Aether theory…

I do agree with your point, but I think we are seeing the limit of language: when we don't attach the exact same definition to words, we can misunderstand each others while trying to convey the same thing. The way you use "real" is the way I would use "valid": A theory is valid until proven otherwise. And the way I use "real" (and I think it is the same way the article used it), is whether something has any grounding…

Sabine's version of "real" - that the universe cannot exist without this is a better one imo

Worm holes aren't real until we can't describe phenomenon without them.

Same with the aether. Black holes and chairs are real because we can't make a theory that doesn't include them while still making accurate prediy

Re: Is Spacetime Real?

#96

Post by aeternum »

8note wrote: post #95
sailingparrot wrote: post #52

Earlier quoted context omitted.

I do agree with your point, but I think we are seeing the limit of language: when we don't attach the exact same definition to words, we can misunderstand each others while trying to convey the same thing. The way you use "real" is the way I would use "valid": A theory is valid until proven otherwise. And the way I use "real" (and I think it is the same way the article used it), is whether something has any grounding…

Sabine's version of "real" - that the universe cannot exist without this is a better one imo Worm holes aren't real until we can't describe phenomenon without them. Same with the aether. Black holes and chairs are real because we can't make a theory that doesn't include them while still making accurate prediy

but the universe can exist without chairs

Re: Is Spacetime Real?

#97

Post by chris-orgmenta »

invalidtaxonomy wrote: post #23

This raise a bunch of interesting questions, but the first one that comes to mind is "should approving such cookie popup for your business be considered a clear sign of mental illness?". This is clearly the work of a dangerous and deranged mind that I would not feel comfortable letting my family hang out with.

Come on now, that's facetious and you know it. I'm on your side but hyperbole like that isn't going to get us anywhere. Let's just invoke Hanlon's razor and accept that these decisions are mostly just made without much thought or understanding.

Re: Is Spacetime Real?

#98

Post by kamaal »

jodrellblank wrote: post #51
thisiscorrect wrote: post #19

Earlier quoted context omitted.

You sense spacetime directly too. It's what holds you do this planet we inhabit. I think atomic phenomena may feel somehow more familiar because it takes far less energy to make them dynamic than it does for gravitational phenomena. If we were somehow huge beings made of binary stars or something, gravity would probably be the very familiar force and atomic phenomena almost inconceivably small to you.

Atomic phenomena are almost inconcievably small to me. There's around a hundred trillion atoms in a human body cell, and around a hundred trillion cells in a human body, plus or minus an order of magnitude or two. It's astonishing to me that people in the early 1900s could measure and calculate the charge on an electron, or that Marie Curie had to process tons of pitchblende to purify micrograms of Radium - and could…

As a kid I read the whole Michelson–Morley experiment in a public library. It was a quite a peek into how the science of that era was done.

Basically you start with some base information(axioms and postulates), then you gather some experimental evidence for those axioms and postulates. You establish some rules on which your experimental and observational universe works. Then what follows is volumes and volumes of Math.

If Im not wrong relativity itself was developed over a decade. And I'd assume it took tons and tons iterations, retries and tweaking to make it work.

Where common people like us get lost is looking at Symbol manipulation directly. At that stage Math scares the day light out of us.

The right approach is to start with your own axioms, postulates, truths and symbols and start working from there.

This is really like some newbie seeing a super massive code base and thinking it could be outside their reach to ever work with such a thing. But if you look at it carefully. All there is to it is loops, condition statements, operations, variables and basic abstractions.

Re: Is Spacetime Real?

#99

Post by tobmlt »

Judging by the comments I think there might be a good amount of interest in reading Gavin Bascom’s “On the Inside of a Marble”

As for the actual question of spacetime, I like the author’s conclusion for the time being:

“ But despite all the things that spacetime enables us to predict and know, it isn’t real in the same way that an atom is real. There’s nothing you can do to “detect” spacetime directly; you can only detect the individual quanta of matter and energy that exist within your spacetime.”

For the future, I think ...“it’d be really cool if”.... holography stitched spacetime from entanglement/entropy such that we could measure directly... something quantum... and believe it to be a real measurement of spacetime itself, right here in good ol’ de Sitter (or wherever we are, should experiment find things afresh;). Is there any hope there I wonder.

Re: Is Spacetime Real?

#100

Post by drdeca »

drran wrote: post #81
sailingparrot wrote: post #43

Earlier quoted context omitted.

So then the Aether was real for a while and stopped being real 200 years ago? If we discover a new model that makes better prediction than our current spacetime based model, just like relativity was to Newton's theory, will spacetime stop being real? The article was clearly using "real" with the definition we attach to it in our everyday language, not in deep philosphical sense.

Aether is real again as Higgs field. Speed of light in vacuum is variable again (gravitational waves). Vacuum is no longer an empty space.

> Speed of light in vacuum is variable again (gravitational waves).

Hm? Can you elaborate on this?

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