koti

Thanks. Neither was I being sarcastic ,by the way.

 

Actually far the greatest part of what I would consider to have learned on this forum is where I have been disabused of pre conceptions and this may require a few blows to the head from time to time

I'm nor afraid of taking blows so theres hope

But it's about a purely scientific concept, isn't it? It can't be beyond the scope of science because Einstein's mentor, Minkowski, conceived it. Einstein curved it in GR as a way of describing gravity. Spacetime is a model.

I'm sory but I have to disagree. We cant seem to even formulate properly the flawed question of this thread so how can we talk about a purely scientific concept.

So Reativity's "flaws" are of a different nature to Newtonianism's?

 

They just apply to the lack of applicability to the quantum domain and otherwise no flaws at all are apparent in the area it actually covers-whereas Newtonian physics was wrong in a more direct way

 

+1

You are having a laugh or you think I am wasting my time and learning nothing?

I'm having a laugh. I don't think you are wasrimg your time nor do I think you are not learning. Just a joke, thats all.

No, he's having problems getting his head around the way science works, just like you are; it's not easy.

I dont know about geordief but you are partially right about me. Maybe not that Im having problems with how science works because the scientific method is pretty straight forward but Im having difficulties in applying it due to the lack od knowlesge and tools (especially math)

However, we are discussing a philosophical issue here which in many ways is beyond the scope of science.

 

I'm sorry but this is a science forum; assertions like "it smells bad" are not adequate reasons for rejection, scientifically speaking.

 

You quoted my comments where I referred to the first and main phenomenon that disproves determinism, but made no reference to it ??

 

 

Again you quoted my reference to the Block Universe, without reference to my observation of the logical consequence of its construction, but did pick out the " equal footing" concept from one of the links.

In fact the footing is not quite equal since there is a factor of the speed of light needed to modify the time axis to 'equalise'. this footing.

Did you also pick this part out?

I used a colloquialism to short cut my thoughts on the clockwork universe concept. I apologise if I offended you or bent the forum rules.

I will need more time to examine the "Growing Block Universe" concept.

Also ,is it possible that we are restricted in our understanding of the universe because we are a part of it and can never look at it from the outside.?

 

Is there some kind of principle involved with that ?

Yes, I think the principle is called "going in circles on an internet forum"

If GR is right then other models that work will look just like it.

Could you elaborate on this statement?

"I guess what I'm trying to complain about is why do people debate whether stuff happens for a reason when clearly I think it's not needed "

 

This was sarcasm, nothing else.

 

 

 

Strange is right

The 'clockwork universe' idea goes back a long way, and held sway in scientific and philosophical circles from the renaissance right up to the late victorian times.

 

https://en.wikipedia.org/wiki/Clockwork_universe

 

The block universe is a much newer idea

 

https://en.wikipedia.org/wiki/Growing_block_universe

 

 

The former is falsified by radioactivity as we know it.

 

The latter suggests the intriguing thought that both determinism and chance are false since they both rely on change.

 

 

^ Block Universe (or Eternalism) is a well-established scientific view based on the theory of relativity and of space-time as an unchanging four-dimensional "block". I posted quite a lengthy post on it some time ago, which may be a good starting point: http://www.scienceforums.net/topic/89861-is-it-the-universe-created-alone-yes-or-not-only-yes-or-not/page-12#entry925429.

 

You may also want to explore these clips taken from an episode of "Through The Wormhole": http://www.sciencechannel.com/tv-shows/through-the-wormhole/playlist-can-time-go-backwards/

 

Wife keeps telling me to watch a movie with her so I havent had much time to either dig into these in detail nor I will have time to answer in detail so here's a very short summary of the concepts you guys gave me to check out studiot & Memammal :

 

- The 'clockwork universe' idea seems very crude. From what I read on the wiki it smells really bad to me.

- The wiki on the 'Block Universe' concept smells a lot better. I didn't get rid of my discomfort (the analogy from the movie) by reading about this concept but it does seem interesting. Especially the idea that the block universe might resolve the information paradox in black holes by treating time on equal rights with space seems especialy interesting. That concept which states that time is on equal rights with space is intuitively comfortable to me. Back when I was an early teenager and had no idea what GR or QM are this concept felt comfortable to me.

- The cutout from the Morgan Freeman episode Memammal posted does a great job at explaining the complexity of time and its fantastic relativistic implications. It is clear to me or at least I hope I'm right it is clear to me that Einstein's "everyone's now" from that episode does not explain my problem with the analogy from the movie. I'm thinking now something that I havent realised before...maybe my problem with this is of a religious nature not physical nature. Meaning that maybe my problem is with that hiker guy believing in the rock fullfilling its purpose and believing that his own existence inevitably brought him to the tragic moment of being trapped.

 

 

 

Oh boy...going in circles became drowning in quick sand.

Don't you get the feeling we're going in cicrcles trying to answer "this" "question"

We can't even formulate the question properly.

I think I already answered best I can but I answered a question which I formulated myself it seems.

 

I was called away whilst adding to post 121 so Koti didn't see my last comment.

Noted.

 

I don't know if you did either, but it addressed your question.

 

Put another way I am suggesting that the question (as I understand it) asks if there is a 'container' , separable from the contents, which would still be there if our current version of the equations of relativity were changed again?

I understand the question differently - more literally. I much more prefer to try to answer the question as you see it though.

 

Don't forget that

 

1) There is more than one solution to the equations of relativity, we try to pick the most appropriate.

 

2) The equations themselves have chaged several times over the last century.

The equations of relativity have changed m

Someone got called out again while typing?

 

As for the question you stated:

"Is there a separate fabric (like the grid on my avatar) that everything (matter etc) exists in that we can call spacetime?"

I am a physics hobbyist and I'm sure I lack many crucial tools (especially math) to understand this stuff properly therefore my comments I'm sure might be crude to you.

Having that out of the way, the answer I got is pretty straight forward - No.

First of all, spacetime as I understand it, is not separate from anything. Matter, mass and gravity are inevitably and firmly connected and related to spacetime - opposite of separate to me.

Matter doesn't exist within spacetime, it co-exist with it - it cannot exist without it. If I understand correctly, spacetime in large scales always reacts in repeatable ways with mass and velocity (I'm not sure if I'm correct here, are there any repeatable, experimental findings confirming that?)

My crude explanation of relativity above, leads me to assume that spacetime is an entity.

 

 

 

 

Strange is right

The 'clockwork universe' idea goes back a long way, and held sway in scientific and philosophical circles from the renaissance right up to the late victorian times.

 

https://en.wikipedia.org/wiki/Clockwork_universe

 

The block universe is a much newer idea

 

https://en.wikipedia.org/wiki/Growing_block_universe

 

 

The former is falsified by radioactivity as we know it.

 

The latter suggests the intriguing thought that both determinism and chance are false since they both rely on change.

I will need to read up on the "block universe" idea before I can continue this discussiin as I clearly do not have the tools.

 

Your example of what you mean is fine, as is your reasoning about models in general.

Good to hear.

 

However your reasoning starts from the premise that spacetime and relativity (general or special) are synonymous.

No it does not. Spacetime as I see it is an entity in which relativity effects are having their show and that entity plays an active role in the play. These relativity effects are explained by Einstein's equations. These equations are a model.

 

They are not.

I agree.

 

Relativity provides a (mathematical) model of something (our universe) that would still be there if the model were at some time shown to be incorrect or inadequate.

I agree.

 

It is a matter of semantics whether we call that something 'the universe', 'spacetime' or my 'backyard'.

I agree as well. For that reason I'm close to the conclusion that trying to answer this twisted question is beyond me.

I don't think I can come up with a better answer to this (flawed) question than what I wrote above:

 

"Spacetime as I see it is an entity in which relativity effects are having their show and that entity plays an active role in the play. These relativity effects are explained by Einstein's equations. These equations are a model"

Going back to the original question - "Is Space Time a Physical Entity or a Mathematical Model"

It would be nice to establish and agree on some reference points which we can use to cope with finding a potential answer to this twisted question:

 

Reference points:

 

Einstein's General Relativity provides a model of space-time. That model has been confirmed experimentally. That model does not reflect a complete picture of our reality. That model fails at explaining how small scale reality works which QM deals with. GR and QM are not compatible with each other. That incompatibility does not mean that Einstein's model is flawed, it means that it is not complete.

Can we all agree on the above or am I mistaken somewhere?

 

Edit:

Example:

 

A sail boat equipped with a motor has more functionality than a sailboat without a motor installed. This does not mean that a sailboat without a motor is faulty or flawed.

 

 

To support my position. I thought that would be obvious.

 

Noted.

^ Block Universe (or Eternalism) is a well-established scientific view based on the theory of relativity and of space-time as an unchanging four-dimensional "block". I posted quite a lengthy post on it some time ago, which may be a good starting point: http://www.scienceforums.net/topic/89861-is-it-the-universe-created-alone-yes-or-not-only-yes-or-not/page-12#entry925429.

 

You may also want to explore these clips taken from an episode of "Through The Wormhole": http://www.sciencechannel.com/tv-shows/through-the-wormhole/playlist-can-time-go-backwards/

 

Will do, thank you for sharing.

 

 

I'm not sure why the old-fashioned idea of a "clockwork universe" is so counter-intuitive. It seems kind of obvious that if you knew the position and velocities of all particles you predict where they would end up - like a giant game of snooker.

 

To me it doesn't feel right. And it's not just because of QM which states that the universe is not fully deterministic - I felt that way before I knew that.

 

 

Why is it unfair?

"Do you have a model without known flaws that has supplanted GR?"

Obviously you do not believe that I can answer this question positively. If you know the answer to your question which is "no" then what is it exactly that you are trying to achieve by asking it? Thank you for fixing my post properly btw.

 

 

 

 

Do you have a model without known flaws that has supplanted GR?

 

This question is unfair and is an invitation into a quarrel.

 

 

 

how does this support koti's position? (which seems to be "we can't tell, so let's call it real")

 

This false statement of yours about my position is also unfair and is alao an attempt to get into a quarrel.

 

Would you consider changing your rhetoric with me?

 

 

For example, a better model is that the Sun and the Earth both orbit a common point, the barycentre.

 

And then ... we might consider that they both orbit the centre of the galaxy. But then we have to start thinking about dark matter, otherwise the model is not accurate.

 

But then we have to ask what dark matter is ...

When you are at the stage of asking what dark matter is (or any previous stage for that matter) does it mean that the earth orbiting the sun model has failed? Or even remotely has it become inaccurate?

Very interesting narrative/analogy. Block-Universe Determinism/Eternalism suggests that the accident depicted in the referenced movie would have been unavoidable. The character has indeed, since the day he was born, moved along his "predetermined" or "fixed" personal path through a static environment/universe, experiencing his reality (his life) spacetime-slice at a time, towards that particular (inevitable) spacetime-slice of reality, that directly experienced qualia...the accident and the time that followed it. Similarly he would have no free will in determining his next step...it has already happened...he has just not experienced it yet.

 

Allegedly our brains have highly evolved mitigating mechanisms to alter our sense of reality so that we can cope with our experiences in a "meaningful" (or "chronological") way...i.e. we perceive "our reality" as events unfolding around us (randomly) with the passing of time. Which is why we "instinctively" feel uncomfortable with the notion that it is in fact us who are moving through- and experiencing different slices of our static (deterministic) world line.

 

A deterministic universe does not necessarily imply a supernatural designer/god. Admittedly one could argue in favour of a deistic or pantheistic "god", but a personal and/or involved god would hardly fit such a paradigm.

 

There seem to be quite a few parallels with the other ongoing thread "Is Space-Time a Physical Entity or a Mathematical Model?"

 

PS. The irony of it is that a deterministic block universe could also be compared to a movie...it is a done event, we can rewind or forward, watching any part thereof but nothing will change...

 

I like the irony which you caught. I don't think I can agree with that view on the universe but the irony is sleek When you talk about "slices" are you loosely referencing the holographic universe theory or the multiverse theory or some other theory? I'm not familiar with "Block-Universe Determinism" I will have to put it on my list of stuff to check out. I'm having a real difficulty in coping with: "the accident depicted in the referenced movie would have been unavoidable" It's like drinking freshly squezed lemon juice

I agree totally. But at the time, it was considered a good model. We can build a model of dark should we choose to. It won't be a very good one, but it will be a model nonetheless.

 

But the point is that models that fail can't represent reality. All models fail at some point.

 

You agree that a model of the sun orbiting the earth was flawed. We have a new model now which states that the earth is orbiting the sun. You state that all models fail at some point. I'm sory but Im having difficulties agreeing with that logic.

The question at hand is seriously flawed in my opinion:

"Is Space-Time a Physical Entity or a Mathematical Model" ?

Einstein's equations which deal with spacetime are a MODEL of spacetime. Spacetime is not a model unless Einstein's equations are a model of a model? As far as I know, these equations have been experimentally confirmed numerous times - time dillation, gps time compensation in sattelites, etc. If we agree that Einstein's model is accurate in describing spacetime this should mean that its an accurate model. I realise that its not accurate in describing the quantum world and many other fenomena but that doesnt mean that spacetime is a model nor that spacetime is or is not an entity does it- for the same reason that you do not use scissors to hammer in a nail.

 

 

It only makes sense because of the models we have in place. If we had different models, our interpretation of what we observed would be different.

 

We used to think the sun went around the earth, and interpreted our observations accordingly. This is a problem of growing up and being immersed in models we have embraced because they work well.There was a time when that wasn't the accepted model, and the worldview was different as a result. We could very well develop a model where dark was the phenomenon, and light was the absence of dark.

Model of the sun orbiting the earth was a bad model which did not reflect reality - Can we agree on that? What you wrote about building a model where dark is a phenomenon and light is the absence of dark implies that nothing can be established and used as refference

.

Hypotheticaly...if string theory or some other new theory manages to put QM, GR and gravity gracefuly together proving on its way that spacetime is part of something far greater and far more complex than what we know now, would this mean that spacetime would become "unreal" or "real" all of the sudden? Would mass suddenly stop having an impact on spacetime if that new fantastical theory of everything would become available?

"Dark" is absence of light. Isn't "dark" just a concept which is not dependent on models? How does that correlate with spacetime being or not being real/a model ?

"Reality" as I see it, is much more than what our 170K year old species can currently understand. I think it would be bigheaded to assume that the nature which is 13.7B years old is constructed in such a way that our mere 5 senses have to grasp it all.

I think so, because if we have to use instruments we are creating a 'map of the territory' and a map is not the the territory; to borrow an expression.

I'm not sure if I grasp properly what you ate saying. I would like to dig into this subject deeper, Im stuck at work now and I will have more time to discuss in the evening. As a teaser...I think we deal with issues non detectable by our 5 senses all the time with them being very real.