How Does Mass Distort Spacetime?

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Discussion Overview

The discussion revolves around the concept of how mass distorts spacetime, particularly in relation to gravity. Participants explore analogies, interpretations, and the implications of general relativity on the understanding of spacetime and gravity.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants question the adequacy of the bowling ball analogy for explaining how mass distorts spacetime, suggesting it lacks the necessary nuances.
  • One participant argues that humans may not be capable of visualizing the warping of 4D spacetime, comparing it to how stick figures cannot comprehend a sphere.
  • Another participant expresses skepticism about equating gravity with spacetime, proposing that mass does not simply deform spacetime but that gravity constitutes spacetime itself.
  • There is a suggestion that the perception of warped spacetime arises from the propagation of the gravitational field rather than a direct deformation of spacetime by mass.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between gravity and spacetime, with no consensus reached on the interpretation of mass's role in distorting spacetime.

Contextual Notes

Participants reference analogies and interpretations that may depend on individual understanding of general relativity and the nature of spacetime, indicating potential limitations in their explanations.

jlorino
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ok if gravity is mass distorting spacetime then how does mass distort it like a bowling ball on a rubber membrane?
i would think it would need something to pull it down :confused:
 
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jlorino said:
ok if gravity is mass distorting spacetime then how does mass distort it like a bowling ball on a rubber membrane?
i would think it would need something to pull it down :confused:

LOL, it's an analogy so it's lacking the precise nuances you're looking for. I personally don't believe we humans are equipped to visualize (in 3D) the warping of 4D spacetime. The same way stick figures can't comprehend a sphere...they can glance it with a series of circles that grow, then shrink, but they can't think or visualize in 3D.

The bowling ball analogy uses gravity (the ball pulling the membrane down) to define gravity. Don't get caught up in the analogy, just revel in the evidence that supports the theory. :D
 
ok but what are the factors that warp spacetime?
 
I personally think that it's a mistake to interpret gravity as being identical to spacetime, and thus mass as deforming spacetime just as the analogous case where a bowling ball bends a rubber sheet. I think then we're basically talking about container space (a legacy of Newtonian physics) and one thing that general relativity shows, I believe, is that spacetime does not contain massive objects.

Remember that the gravitational field couples universally since it is generated, and effects, massive objects. Every object we can empirically experience has mass (mass-energy) so every object generates, and is influenced by, a gravitational force. Because of this, we can then use the gravitational field to define relative distances and relative acceleration. These relative distances and relative accelerations come in the form of the metric.

So gravity is not identical with spacetime. Gravity constitutes spacetime. What we perceive to be spacetime is a phenomenological manifestation of the gravitational field.

So why do we "perceive" spacetime to be warped? Because that is the way the gravitational field propagates.
 
o ok i get it now
i was just reading "The Elegant Universe" by Brian Greene
and had a question

thanx
 

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