What causes the warping of space-time?

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Discussion Overview

The discussion revolves around the causes of the warping of space-time as described by Einstein's General Relativity (GR). Participants explore the relationship between mass, energy, and the curvature of space-time, questioning the underlying mechanisms that lead to this phenomenon. The conversation touches on theoretical implications, the nature of action and reaction in gravitational interactions, and the potential insights from a future theory of quantum gravity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants note that GR describes the effects of gravity but does not explain the fundamental causes behind the warping of space-time.
  • There is a suggestion that the presence of energy, whether in the form of mass or photons, is responsible for the curvature of space-time, yet the specific mechanism remains unclear.
  • One participant questions whether matter and energy in space can be seen as both the cause and effect of space-time curvature.
  • Another participant emphasizes that GR treats all objects equally, indicating that smaller objects also contribute to space-time curvature and affect larger objects, challenging the notion of a "largest" object having a special role.
  • There is a discussion about the concept of "first action," with some participants arguing that all objects affect space-time simultaneously, thus negating the idea of a singular initiating action.
  • The role of time in shaping space-time is debated, with one participant proposing that time may have a non-abstract effect related to gravity.
  • Some participants express confusion regarding the deterministic nature of GR and the implications of forces acting simultaneously between objects.
  • One participant argues that large masses are simply collections of smaller masses, suggesting that the curvature of space-time is a cumulative effect rather than a result of a singular action.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of action and the causes of space-time warping, with no consensus reached on the fundamental mechanisms involved. The discussion remains unresolved regarding the specifics of how mass and energy interact with space-time.

Contextual Notes

Participants highlight the limitations of GR in explaining the underlying causes of space-time curvature, indicating a need for further theoretical development, such as a theory of quantum gravity, to address these questions.

TheAlkemist
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Einstein's GR describes gravity as the geometrical "warping" of the "fabric" of space-time. This model is often depicted with a larger object sunk into a flat net creating a well that causes a centrifugal like pullon a neighboring smaller object.

Curvature at every point in spacetime is also caused by whatever matter is present.

This seems to make sense so far.

But my question is; what causes the larger (or largest) object to warp space-time? :confused:
 
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No answers?
 
You know, that's a really good question. If you find the answer you might get a Nobel for it.

Technically, the cause of the warping or curving spacetime is the presence of energy either in the form of photons or mass (through E=mc2). But we don't know what it is about energy that causes this curvature.

General relativity describes the effects but not the causes. So we have a very good description of what happens but no physical explanation for the mechanisms behind this.

I am hoping that when we find a theory of quantum gravity we will know more about the mechanisms for mass causing curvature in spacetime. If you really want to know the answer, you'll have to wait, or work on the problem yourself and become famous if you figure it out.
 
inflector said:
You know, that's a really good question. If you find the answer you might get a Nobel for it.

Technically, the cause of the warping or curving spacetime is the presence of energy either in the form of photons or mass (through E=mc2). But we don't know what it is about energy that causes this curvature.

General relativity describes the effects but not the causes. So we have a very good description of what happens but no physical explanation for the mechanisms behind this.

I am hoping that when we find a theory of quantum gravity we will know more about the mechanisms for mass causing curvature in spacetime. If you really want to know the answer, you'll have to wait, or work on the problem yourself and become famous if you figure it out.
Thanks for the response Inflector. I guess this would distill to the question of the "ultimate cause/mechanism" since "proximal causes/mechanisms" are also described by GR.

OK, so if matter = energy and GR's model has matter (or energy) in space (and not out acting in) then it appears that the matter/energy in space is both, simultaneously, the cause and the effect?:confused:

How would a quantum gravity theory solve this?
 
TheAlkemist said:
But my question is; what causes the larger (or largest) object to warp space-time?

GR doesn't give a special role to the largest object. Every object is treated the same. Smaller objects also cause spacetime curvature, and this curvature has an effect on the motion of larger objects. If only the large object acted on the small object, then in the Newtonian limit the Earth would make a gravitational force on the moon, but the moon wouldn't make one on the earth, violating Newton's third law.

All of this is also true in the rubber sheet metaphor.
 
bcrowell said:
GR doesn't give a special role to the largest object. Every object is treated the same. Smaller objects also cause spacetime curvature, and this curvature has an effect on the motion of larger objects. If only the large object acted on the small object, then in the Newtonian limit the Earth would make a gravitational force on the moon, but the moon wouldn't make one on the earth, violating Newton's third law.

All of this is also true in the rubber sheet metaphor.
Thanks. I realize this. Action = reaction. In essence, the action/reaction of all objects embedded in this "spacetime" are correlated. I get that. But, this still doesn't answer the question; what causes the first action?
I remember reading Hawking's "A Brief History of Time" where he said that the universe is shaped like a "puckered pea". :confused: So what shapes it?
 
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TheAlkemist said:
Thanks. I realize this. Action = reaction. In essence, the action/reaction of all objects embedded in this "spacetime" are correlated. I get that. But, this still doesn't answer the question; what causes the first action?
I remember reading Hawking's "A Brief History of Time" where he said that the universe is shaped like a "puckered pea". :confused: So what shapes it?

Speaking from a complete layman's point of view, but could it be "time" that shapes it?
 
TheAlkemist said:
ut, this still doesn't answer the question; what causes the first action?

What do you mean by "first" action? All objects affecting spacetime do so simultaneously. There is no "first".

Rephrase please.
 
Time Machine said:
Speaking from a complete layman's point of view, but could it be "time" that shapes it?
responding from a complete layman's point of view, only if you mean that in th same metaphorical sense as saying that love shapes beauty. Both, also, abstract concepts.

DaveC426913 said:
What do you mean by "first" action? All objects affecting spacetime do so simultaneously. There is no "first".

Rephrase please.
By first I mean first. So are you saying that "action" just spontaneously happened? :confused:
Isn't GR a deterministic theory? I'm confused.
 
  • #10
TheAlkemist said:
responding from a complete layman's point of view, only if you mean that in th same metaphorical sense as saying that love shapes beauty. Both, also, abstract concepts.

Is the universe an abstract concept? Is time an abstract concept? Time is non-abstract as a measurement. Time is non-abstract as an event. Nothing would happen without time. As it is now being proved that time is reactant to gravity, there is every reason to hypothesise that time may have a non-abstract effect especially where gravity is concerned.
 
  • #11
Time Machine said:
Is the universe an abstract concept? Is time an abstract concept? Time is non-abstract as a measurement. Time is non-abstract as an event. Nothing would happen without time. As it is now being proved that time is reactant to gravity, there is every reason to hypothesise that time may have a non-abstract effect especially where gravity is concerned.
Yes and yes.

An abstract concept = A mental construct. Not concrete reality or an object.
Mental concepts are constructed (with 2 or more objects). Concepts are derived from the relationships between objects.
In science, the relationship between objects are recorded by measurement. Measurements are used to determine (and express) the QUANTITY of an OBJECT. Eg., that brick is 10 KG. How many seconds is the bricks?:confused:

You can't use time as a measurement for concrete objects. Only as an abstract concept for measuring relationships.

"Time is a non-abstract event" :confused:

I don't understand what this means. In physics, isn't an event something that needs to be defined--qualified and quantified?
 
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  • #12
TheAlkemist said:
By first I mean first. So are you saying that "action" just spontaneously happened? :confused:
Isn't GR a deterministic theory? I'm confused.
If A makes a force on B, B simultaneously makes a force on A. Neither one happens first, and neither one causes the other. What causes the forces to exist (in Newtonian gravity) is that A has a certain mass, B has a certain mass, and A and B are in a certain position relative to one another.
 
  • #13
TheAlkemist said:
By first I mean first. So are you saying that "action" just spontaneously happened?

What action?

It sounds like you're supposing that, at some point in time, there's a large mass floating somewhere that is not causing a dent in spacetime, and then it somehow acts to make a dent.

There is no such action.

From the moment the individual atoms coalesced from the BB, each atom had its own tiny dent. Large masses are simply collections of small masses. Large dents are simply a culmination of many small dents.
 
  • #14
Is the universe an abstract concept. Is time an abstract concept?

TheAlkemist said:
Yes and yes.

An abstract concept = A mental construct. Not concrete reality or an object.
Mental concepts are constructed (with 2 or more objects). Concepts are derived from the relationships between objects.
In science, the relationship between objects are recorded by measurement. Measurements are used to determine (and express) the QUANTITY of an OBJECT. Eg., that brick is 10 KG. How many seconds is the bricks?:confused:

You can't use time as a measurement for concrete objects. Only as an abstract concept for measuring relationships.

"Time is a non-abstract event" :confused:

I don't understand what this means. In physics, isn't an event something that needs to be defined--qualified and quantified?
Trying to find seconds in bricks is as confusing as trying to find a weight in time. An abstract concept indeed.
If, however you wanted to know how long the bricks will last, a measurement of time would be appropriate. The measurement is a concept but the passing of time is a physicality.

As I am in layman's terms, please excuse any deviation from actual physics.
Your earlier comment mentioned love and beauty being abstract concepts as well as the universe and time. This rather deviates into the realm of human social interaction, the study of which making physics seem as though childs play. Admittedly I have much to learn in both fields especially where talking to physicists.

An abstract concept = A mental construct. Not concrete reality or an object.
This does not describe the universe as observed by me or not the bits I can observe anyway. My universe is a very much concrete and other carbon based reality of objects.

I believe that the event of time is very much being defined--qualified and quantified. Here are some links that I found really interesting. I am aware that I am off course in that your question is about gravity, however it would seem that time and gravity are linked.

http://www.independent.co.uk/news/s...-bad-news-if-you-own-a-penthouse-2088195.html

http://www.brighthub.com/science/space/articles/58548.aspx#ixzz11ulsv9o7

http://www.astroengine.com/?p=24201
 
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  • #15
...and belongs in Philosophy, if it is going to continue along these lines.
 
  • #16
DaveC426913 said:
...and belongs in Philosophy, if it is going to continue along these lines.

Point taken. What a shame. I was enjoying.
 
  • #17
DaveC426913 said:
What action?

It sounds like you're supposing that, at some point in time, there's a large mass floating somewhere that is not causing a dent in spacetime, and then it somehow acts to make a dent.

There is no such action.

From the moment the individual atoms coalesced from the BB, each atom had its own tiny dent. Large masses are simply collections of small masses. Large dents are simply a culmination of many small dents.
No. I'm not supposing that. And IMO, that's just transferring the (causal) issue to the BB. I'll stop here.
 
  • #18
TheAlkemist said:
No. I'm not supposing that. And IMO, that's just transferring the (causal) issue to the BB. I'll stop here.
Well, yes. That's exactly right. The curvature was formed when the mass came into existence, shortly after the BB. More likely, the curvature was formed when the energy was first formed out of the BB itself, even before it cooled and coalesced into matter.

I am speculating here, but I imagine spacetime started off almost infinitely curved i.e curved back on itself when it was smaller than an atom. As it expanded, it flattened. But the concentrations of energy which ultimately formed matter would have retianed more curvature than the vacuum they occupied, forming puckers in an otherwise constantly flatterning expanding universe.

The point though, is that all the mass that exists today, along with all its curvature, was created from the BB. No more mass, and thus no more curvature, was formed after that.
 
  • #19
Time Machine said:
Is the universe an abstract concept. Is time an abstract concept?

Trying to find seconds in bricks is as confusing as trying to find a weight in time. An abstract concept indeed.
If, however you wanted to know how long the bricks will last, a measurement of time would be appropriate. The measurement is a concept but the passing of time is a physicality.
We experience the passing of time. Like we experience emotions like anger. How do u discern which is physical between the two? As far as I know, in science something is physical when you can touch, see, hear, smell and taste it.

As I am in layman's terms, please excuse any deviation from actual physics.
Your earlier comment mentioned love and beauty being abstract concepts as well as the universe and time. This rather deviates into the realm of human social interaction, the study of which making physics seem as though childs play. Admittedly I have much to learn in both fields especially where talking to physicists.
I don't see how it makes physics seem like child's play. The humanities and social sciences are as important as physics and are certainly not child's play. If you keep the terminologies and definitions in physics objective then I don't think it should deviate.

An abstract concept = A mental construct. Not concrete reality or an object.
This does not describe the universe as observed by me or not the bits I can observe anyway. My universe is a very much concrete and other carbon based reality of objects.
Me too. But through science not mathematics.

I believe that the event of time is very much being defined--qualified and quantified. Here are some links that I found really interesting. I am aware that I am off course in that your question is about gravity, however it would seem that time and gravity are linked.
http://www.independent.co.uk/news/s...-bad-news-if-you-own-a-penthouse-2088195.html

http://www.brighthub.com/science/space/articles/58548.aspx#ixzz11ulsv9o7

http://www.astroengine.com/?p=24201
I'll check out the links. I agree, gravity and time are links but only conceptually using mathematically.
 
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  • #20
DaveC426913 said:
Well, yes. That's exactly right. The curvature was formed when the mass came into existence, shortly after the BB. More likely, the curvature was formed when the energy was first formed out of the BB itself, even before it cooled and coalesced into matter.

I am speculating here, but I imagine spacetime started off almost infinitely curved i.e curved back on itself when it was smaller than an atom. As it expanded, it flattened. But the concentrations of energy which ultimately formed matter would have retianed more curvature than the vacuum they occupied, forming puckers in an otherwise constantly flatterning expanding universe.

The point though, is that all the mass that exists today, along with all its curvature, was created from the BB. No more mass, and thus no more curvature, was formed after that.
The BB caused it. Gotcha.
 
  • #21
TheAlkemist said:
We experience the passing of time. Like we experience emotions like anger. How do u discern which is physical between the two? As far as I know, in science something is physical when you can touch, see, hear, smell and taste it.

I don't see how it makes physics seem like child's play. The humanities and social sciences are as important as physics and are certainly not child's play. If you keep the terminologies and definitions in physics objective then I don't think it should deviate.

Me too. But through science not mathematics.

I'll check out the links. I agree, gravity and time are links but only conceptually using mathematically.

I am over in Philosophy discussing the in's and out's of the universe and time being abstract concepts. I am awaiting the outcome and will be back. How did you find the links?
 
  • #22
P.S. I would like to discuss the social, physics, childplay aspect, but Dave is right. It belongs in Philosophy.
 
  • #23
Time Machine said:
Point taken. What a shame. I was enjoying.

I have a post in the Philosophy section in this realm. In essence I believe that the fundamental forces are constraints which we pay for the potential space we have...it is a matter of conservation.
 
  • #24
Time Machine said:
P.S. I would like to discuss the social, physics, childplay aspect, but Dave is right. It belongs in Philosophy.
Feel free to start a thread and i'll join :smile:

Skaffen said:
I have a post in the Philosophy section in this realm. In essence I believe that the fundamental forces are constraints which we pay for the potential space we have...it is a matter of conservation.
can you pls provide a link to this post? Thanks
 
  • #25
TheAlkemist said:
Feel free to start a thread and i'll join :smile:

can you pls provide a link to this post? Thanks

I would also like link to skaffen's thread.

Hi TheAlkemist. I have an interesting "gravity" related method of time travel going on thread below. It is also time and dimension related, so I think you would be interested.

https://www.physicsforums.com/showthread.php?t=441627
 
  • #26
Time Machine said:
I would also like link to skaffen's thread.

Hi TheAlkemist. I have an interesting "gravity" related method of time travel going on thread below. It is also time and dimension related, so I think you would be interested.

https://www.physicsforums.com/showthread.php?t=441627

will check it out. thanks :smile:
 

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