Space time is not phisical object

[menniandscience]

space time fabric is not phisical concept, hence we have to ask, how do mass effect at all it? there can not be an interaction between those two

 

[Dale]

space time fabric is not phisical concept

"Spacetime fabric" is a phrase I generally only see in pop-sci books, not in the scientific literature.

 

[menniandscience]

"Spacetime fabric" is a phrase I generally only see in pop-sci books, not in the scientific literature.

you can drop the fabric, the question remains

 

[menniandscience]

"Spacetime fabric" is a phrase I generally only see in pop-sci books, not in the scientific literature.

maybe just - 'space'

 

[Rap]

space time fabric is not phisical concept, hence we have to ask, how do mass effect at all it? there can not be an interaction between those two

Why do you say that spacetime is not a physical concept?

 

[menniandscience]

Why do you say that spacetime is not a physical concept?

maybe i should have said 'object'. it's not made of anything, it's just space

 

[Rap]

So you meant to say that spacetime is not a physical object, so how can mass affect it?

 

[menniandscience]

So you meant to say that spacetime is not a physical object, so how can mass affect it?

yes, that's my question

 

[Dale]

Why do you think that physical objects are so unique that they are the only things which can be affected by mass? Why shouldn't spacetime also be affected by mass? Why can't there be an interaction between the two?

The evidence is against that claim, so I don't understand what would make you think it is correct.

 

[ZapperZ]

yes, that's my question

Why is it so important TO YOU that you need to clarify that it is not a "physical object"? How does this change the physics? You can call it a cow for all we care. How does it change the physics?

The way you keep having to change what you meant to say seems to indicate that you haven't thought these things through. Are you just making things up as you go along?

Zz.

 

[menniandscience]

Why is it so important TO YOU that you need to clarify that it is not a "physical object"? How does this change the physics? You can call it a cow for all we care. How does it change the physics?

The way you keep having to change what you meant to say seems to indicate that you haven't thought these things through. Are you just making things up as you go along?

Zz.

1.why being cynical (atribute to me bad things). in my language it's easyer for me to articulate, unlike in english - not.
2. there is nothing wrong with keep sharpining the question and make it more accurate
3. i could have continue calling it space time fabric but it might give wrong connotation

as for the question: space is not made of anything. in phisics action and re-action are always on the same substrate. it would be easier to see that as the dualistic view of human, when some people argue that there is soul and body yet it can't be explained how one interact with the other.
space is not 'phisical' but containing the the phisical. so how body make it deform, what is the chain of phisical-causality

 

[Neandethal00]

space time fabric is not phisical concept, hence we have to ask, how do mass effect at all it? there can not be an interaction between those two

Space is physical, Time isn't.
That is why I have difficulty in accepting time as a dimension.

 

[Rap]

Space is physical, Time isn't.
That is why I have difficulty in accepting time as a dimension.

Why does something have to be physical in order for it to be a dimension?

 

[Rap]

as for the question: space is not made of anything.

space is not 'phisical' but containing the the phisical. so how body make it deform, what is the chain of phisical-causality

Why do you say space is not made of anything, not physical? Why do you not say that , since it deforms, then it is made of something, it is physical? Maybe we must say that because we have discovered that it does bend, therefore it is physical?

 

[ZapperZ]

1.why being cynical (atribute to me bad things). in my language it's easyer for me to articulate, unlike in english - not.
2. there is nothing wrong with keep sharpining the question and make it more accurate
3. i could have continue calling it space time fabric but it might give wrong connotation

as for the question: space is not made of anything. in phisics action and re-action are always on the same substrate. it would be easier to see that as the dualistic view of human, when some people argue that there is soul and body yet it can't be explained how one interact with the other.
space is not 'phisical' but containing the the phisical. so how body make it deform, what is the chain of phisical-causality

You didn't answer my question. How would it change or affect the PHYSICS of how we do things? How would such a definition make any difference?

If I call something a boson or a fermion, it makes TREMENDOUS difference in the physics. Calling Pluto to be either a planet or not a planet makes ZERO difference, both to the physics, and to Pluto itself! All you are doing is trying to put labels on things at the superficial level, without any indication that such a label actually has a physical significance. We call such an exercise in the physics forums "a waste of time".

Zz.

 

[menniandscience]

You didn't answer my question. How would it change or affect the PHYSICS of how we do things? How would such a definition make any difference?

If I call something a boson or a fermion, it makes TREMENDOUS difference in the physics. Calling Pluto to be either a planet or not a planet makes ZERO difference, both to the physics, and to Pluto itself! All you are doing is trying to put labels on things at the superficial level, without any indication that such a label actually has a physical significance. We call such an exercise in the physics forums "a waste of time".

Zz.

i ask you: how does mass affect space? [knowing it is does not help]

 

[menniandscience]

Why do you say space is not made of anything, not physical? Why do you not say that , since it deforms, then it is made of something, it is physical? Maybe we must say that because we have discovered that it does bend, therefore it is physical?

then what is the chain of physical causality of mass-> space deforms

 

[JaredJames]

i ask you: how does mass affect space? [knowing it is does not help]

I think you have some basic concepts confused. Perhaps someone here more knowledgeable than myself could point you to some introductory articles that would explain the subject.

I'd also add that just because we can't explain it, doesn't mean it doesn't exist / happen. What matters is if we can observe it.

A simple example is lightning. Nobody is entirely sure what causes it and exactly how it works, but that doesn't stop us observing it.

Isn't the whole "bending of space" (I assume this is the space is a sheet scenario) just a way to describe how mass (gravity) has an effect? It doesn't have to mean it physically does it.

 

[ZapperZ]

i ask you: how does mass affect space? [knowing it is does not help]

You are making for some very strange series of assumptions. You are essentially saying that if "A" causes "B", then A and B must be of the same "type". This is faulty logic. A charge causes the presence of an electric field. But no one here will say that a charge and an electric field are the same "physical object".

So again, back to my question. So what IF space-time is "not a physical object"? How has it changed the physics? This question is not something you have been able to answer.

Zz.

 

[Dale]

i ask you: how does mass affect space? [knowing it is does not help]

By increasing the time-time term of the stress-energy tensor (and potentially other terms also if the mass is moving).

 

[Cleonis]

we have to ask, how do mass effect at all it? there can not be an interaction between those two

Well, the very assertion of relativistic physics is that we do have to attribute physical properties to spacetime.

As an example, here is a quote from a review article called:
http://iopscience.iop.org/0034-4885/63/9/201"
Source: the magazine 'Reports on Progress in Physics' Volume 63, page 1317

[...]
general relativity introduces a finite coupling coefficient between curvature of spacetime, described by the Einstein curvature tensor, and the stress energy tensor which describes the mass–energy which gives rise to the curvature.
[...]
The coupling coefficient $c^4/(8\pi G)$ is an enormous number, of order 10⁴³. This expresses the extremely high stiffness of space which is the reason that the Newtonian law of gravitation is an excellent approximation in normal circumstances,
[...]
The existence of gravitational waves is intuitively obvious as soon as one recognizes that spacetime is an elastic medium.
[...]

That's the way it is with relativistic physics: physical properties are attributed to spacetime.

However, this does not mean that matter and spacetime are the same thing. A difference remains. Matter consists of particles that can be tracked through time. Space has no individual parts that can be tracked through time. The idea of velocity doesn't apply for space.(In the above I haven't considered quantum mechanics. Insights from quantum physics may have a bearing on the above. I don't know enough of quantum physics to say something about that.)

 

[menniandscience]

hear

you proved me that i don't have good criterion for distinguish physical object from non one as 'thought'. i thought that physical means 'made of some kind of particles' (whether it is light or wood). but then i remembered that it said that dark matter is not made of anything we know, so it could be the case for space (eventhough it is still weird for me to think about space as something that change like that. is spacetime elastic and strech like a rubber (stores energy?!?) next to black hole? if the black hole disapper where the extra space go?)
so i need to think and read more.

thanks !

 

[menniandscience]

stiffness of space
physical properties are attributed to spacetime.

can you elaborate on that?

Space has no individual parts that can be tracked through time.

if space has no time how can it changed?

 

[Dale]

is spacetime elastic and strech like a rubber (stores energy?!?)

I don't know about stretching, but it definitely stores energy.

 

[Dale]

Space has no individual parts that can be tracked through time.

if space has no time how can it changed?

If the curvature tensor is changing wrt time then there is a distribution of stress-energy tensor which is changing wrt time.

 

[menniandscience]

I don't know about stretching, but it definitely stores energy.

potential energy?