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

[geordief]

 

 

Well, Newtonian gravity was suspect when it couldn't account for the precession of Mercury. That was part of the motivation behind GR.

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

[koti]

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

[geordief]

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.

 

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

[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.

[StringJunky]

I'm nor afraid of taking blows so theres hope

 

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.

I think is quite straight forward but it would have been, perhaps, clearer to say: Is spacetime real or is it just a model? Or, getting down to the nitty-gritty: what does real mean?

Edited August 25, 2016 by StringJunky

[koti]

I think is quite straight forward but it would have been, perhaps, clearer to say: Is spacetime real or is it just a model? Or, getting down to the nitty-gritty: what does real mean?

 

What would be your simplified answer to the question: "Is spacetime real or is it just a model?"

[StringJunky]

 

What would be your simplified answer to the question: "Is spacetime real or is it just a model?"

It's a model with measurable parameters; the parameters are the 'real' bits. Those parameters can be reassembled to create new relationships and make another model should the earlier one fail in some area. So, I suppose, one could say the data is real but the concepts that are made from them are just human artifacts.

Edited August 25, 2016 by StringJunky

[koti]

It's a model with measurable parameters; the parameters are the 'real' bits. Those parameters can be reassembled to create new relationships and make another model should the earlier one fail in some area. So, I suppose, one could say the data is real but the concepts that are made from them are just human artifacts.

 

<Sigh>...

Down the rabbit hole again:

 

A parameter is a characteristic that defines a system. Equations including parameters are a model of spacetime. Spacetime "reacts with mass and velocity" therefore is tangible to me for that single reason.

 

Edit:

Ofcourse I am prepared to have my view on this destroyed. Actually, I would love to see a simple, coherent explanation which would undermine my view.

Edited August 25, 2016 by koti

[studiot]

 

String Junky

Spacetime is a model.

 

A model can still be a physical entity.

 

Just because something is a model does not prevent it being an entity.

[michel123456]

 

A model can still be a physical entity.

 

Just because something is a model does not prevent it being an entity.

A model can represent a physical entity.

[koti]

 

A model can still be a physical entity.

 

Just because something is a model does not prevent it being an entity.

 

Yes. I even wrote that myself in this thread couple days ago. While trying to simplify things in my mind in order to answer "the question", I'm having seconds thoughts on this though. I'm afraid that the only conclusion I can come up for now is that I do not have enough knowledge to answer better than I already did.

 

A model can represent a physical entity.

Obviously yes.

[geordief]

A model can represent a physical entity.

That is how I see it . I use the terms "model" and "the modeled" (rather than "reality")

 

"The modeled" is something we accept almost as as an article of faith and the model allows us to "see" what it looks like.

 

But the "modeled" will always be one step ahead of the model

[studiot]

That is how I see it . I use the terms "model" and "the modeled" (rather than "reality")

 

"The modeled" is something we accept almost as as an article of faith and the model allows us to "see" what it looks like.

 

But the "modeled" will always be one step ahead of the model

 

Why so?

 

Go to the Hydraulics Reasearch Station at Wallingford and look at all the modelling they do for design purposes.

 

Both physical models and theoretical ones are used.

[geordief]

 

Why so?

 

Go to the Hydraulics Reasearch Station at Wallingford and look at all the modelling they do for design purposes.

 

Both physical models and theoretical ones are used.

I was referring to the model that will hopefully replace GR etc. Perhaps your models are models that apply to defined areas in physics that are practically set in stone.

 

Even so ,if the top model is subject to continuous refinement then maybe the "sub-models" as it were may also be revised even if no actual improvement is noted.

[studiot]

I was referring to the model that will hopefully replace GR etc. Perhaps your models are models that apply to defined areas in physics that are practically set in stone.

 

Even so ,if the top model is subject to continuous refinement then maybe the "sub-models" as it were may also be revised even if no actual improvement is noted.

 

 

 

It is easy to find counter examples if a proposal is either to narrowly constrained or to general.

 

The trick is to find a happy medium between those two extremes.

 

Your definition of the term model is far too restrictive, yet your comment that the modeled will always be one step ahead of the model is demonstrably false, because it is too general by the use of the word always.

 

A model may be a pattern (in the sense used by pattern makers) or a copy.

So it may lead or lag

 

It is, however, instructive to consider the following.

 

It is possible to make a real physical model for that of the abstract characteristics of something else, or something totally abstract.

 

For example analog computers are real physical models of mechanical systems or abstract mathematical constructs.

[geordief]

 

 

 

It is easy to find counter examples if a proposal is either to narrowly constrained or to general.

 

The trick is to find a happy medium between those two extremes.

 

Your definition of the term model is far too restrictive, yet your comment that the modeled will always be one step ahead of the model is demonstrably false, because it is too general by the use of the word always.

 

A model may be a pattern (in the sense used by pattern makers) or a copy.

So it may lead or lag

 

It is, however, instructive to consider the following.

 

It is possible to make a real physical model for that of the abstract characteristics of something else, or something totally abstract.

 

For example analog computers are real physical models of mechanical systems or abstract mathematical constructs.

You haven't addressed my point that I was mainly talking about the top model (eg a TOE)

 

I only went into models in general as an after thought (and I am quite unschooled in models ).

 

GR and similar theories have a particular place (pride of place) in the scheme of models . They are ideally "top models" and all the other models are beneath them in the hierarchy.

 

This top model will ,arguably but not provably be forever one step behind what is being modeled as nobody can say that we will be able to model the physical universe completely .

[Memammal]

The theoretical physicist in this clip from "Through The Wormhole" is seemingly convinced that space-time is a very real model...http://www.sciencechannel.com/tv-shows/through-the-wormhole/building-a-wormhole/

 

@ koti, this is from the same show than the link that I gave in the other thread.

[koti]

The theoretical physicist in this clip from "Through The Wormhole" is seemingly convinced that space-time is a very real model...http://www.sciencechannel.com/tv-shows/through-the-wormhole/building-a-wormhole/

 

@ koti, this is from the same show than the link that I gave in the other thread.

Its always nice to hear that youre not alone

[swansont]

The theoretical physicist in this clip from "Through The Wormhole" is seemingly convinced that space-time is a very real model...http://www.sciencechannel.com/tv-shows/through-the-wormhole/building-a-wormhole/

Nobody has claimed that the model doesn't exist. There's nothing in that clip that suggests spacetime is an actual physical thing.

[StringJunky]

...physical thing.

What is a physical thing to a physicist?

[swansont]

What is a physical thing to a physicist?

Good question. Probably depends on the physicist, but without thinking about it too much, if it produces or makes a (non-virtual) photon go away, it's probably a physical thing (that test is limited to things which interacts electromagnetically).

[koti]

Good question. Probably depends on the physicist, but without thinking about it too much, if it produces or makes a (non-virtual) photon go away, it's probably a physical thing (that test is limited to things which interacts electromagnetically).

Why a photon? Couldnt "it" produce, attract or repel an electron which hass mass and still be "it" ? Why is the test limited to electromagnetism?

[swansont]

Why a photon? Couldnt "it" produce, attract or repel an electron which hass mass and still be "it" ? Why is the test limited to electromagnetism?

Because photons interact electromagnetically. If you have something that doesn't interact electromagnetically, a photon won't be absorbed or emitted. But that wouldn't mean the target isn't real, that's a limitation of a photon.

[koti]

Because photons interact electromagnetically. If you have something that doesn't interact electromagnetically, a photon won't be absorbed or emitted. But that wouldn't mean the target isn't real, that's a limitation of a photon.

ok, those are facts which I fail to see how exactly correlate with the subject of this thread.

Hypothesising, (because that is what I have to do in order to find out what you mean) you went the alley of trying to define "realness" of spacetime by Interacting or not interacting electromagnetically? Why?

[swansont]

ok, those are facts which I fail to see how exactly correlate with the subject of this thread.

Hypothesising, (because that is what I have to do in order to find out what you mean) you went the alley of trying to define "realness" of spacetime by Interacting or not interacting electromagnetically? Why?

I was answering a question about "physicalness", in general. Updating the "hit it with a hammer" criterion. Not specifically about spacetime.