How can gravity grasp on space time?

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Discussion Overview

The discussion revolves around the concept of how gravity interacts with and distorts spacetime, particularly in the context of quantum gravity and general relativity. Participants explore the relationship between matter, energy, and gravitational effects, as well as the underlying principles that govern these phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how gravity distorts spacetime and seeks clarification on the topic.
  • Another participant suggests that gravity is a distortion of spacetime and questions whether the inquiry is about how matter produces gravity or the mathematical representation of gravity as curved spacetime.
  • A participant clarifies that energy is what distorts spacetime and references the stress-energy tensor as a key concept in understanding this relationship.
  • It is noted that, according to general relativity, anything with stress-energy produces gravity, implying that matter's high energy density leads to a significant stress-energy tensor.
  • One participant posits that the fundamental nature of gravity, spacetime, and energy is not fully understood, suggesting that these entities may have been unified in the early universe under extreme conditions.
  • This participant also discusses the implications of spontaneous symmetry breaking and how it relates to the emergence of the characteristics we observe today.
  • There is acknowledgment that while mathematical formulations like the Einstein stress-energy tensor and field equations capture most gravitational phenomena, the behavior of gravity at singularities remains an area of uncertainty.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and uncertainty regarding the nature of gravity and its relationship with spacetime. There is no consensus on the fundamental mechanisms at play, and multiple viewpoints are presented without resolution.

Contextual Notes

The discussion highlights limitations in understanding the fundamental nature of gravity, spacetime, and energy, particularly at singularities, and the dependence on mathematical frameworks to describe observed phenomena.

medgalis
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Hello. This topic might seem stupid, but i got interested in quantum gravity and I didn't understand how gravity grasps and distorts spacetime. So my question is, how can gravity distort spacetime?
 
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Hi medgalis, welcome to PF,

Gravity is distorted spacetime. Your question is a little like asking how can work transfer energy. Work is a transfer of energy. So how is simply by definition.

I am not sure what you really want to ask. Perhaps you want to know how matter can distort space-time, I.e. How can matter produce gravity. Or perhaps you want to understand what physical features of gravitation require the mathematical representation to be curved spacetime.
 
Yes, that's exactly what i wanted to ask, but didn't know how to ask.
 
How can matter produce gravity.
 
Err, energy "distorts" space time.

I think it's this thing that calculates how Stress energy tensor.This is a quote from the wiki page;

"The stress–energy tensor is the source of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity."
 
medgalis said:
How can matter produce gravity.
According to GR, anything with stress-energy produces gravity. So matter produces gravity because it has a high energy density and therefore a "large" stress-energy tensor.
 
How can gravity grasp on space time?...How can matter produce gravity..


nobody really knows HOW such a thing can happen. That's likely because nobody knows exactly what gravity, nor space, nor time, nor even energy is. Sounds crazy, but all those entities apparently were 'unified' really, really early in the universe...at extremely high and unstable energy levels...meaning at those early times all the entities were the same...maybe roughly like a 'quantum foam' if you know that term...

In any case, those early unstable conditions underwent a 'spontaneous symmetry breaking'
and, voila, everything you see around you emerged or developed. So today we see a bunch of characteristics around us and are trying to figure out how they are related. For example, in special relativity Einstein deduced that space and time are not constants as they superficially appear to us...He grabbed relationships from Lorentz and Fitzgerald and Maxwell and with brilliant insights concluded: the speed of light is constant, not space, not time!


But as already noted in prior posts, it turns out we HAVE codified our observations about how most of gravity works...we have math that matches observations...via the Einstein stress energy tensor and field equations, for example...these seem to capture MOST situations... from most of black holes to most of the universe...not bad!

But what happens to gravity space and time at 'singularities' is not yet understood...so the progress continues.
 

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