Dark Energy & Curvature of Spacetime

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Discussion Overview

The discussion revolves around the relationship between dark energy and the curvature of spacetime as described by general relativity. Participants explore concepts of gravitational fields, negative pressure, and the implications of dark energy on the expansion of the universe.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that dark energy, viewed as negative pressure, could be a result of the natural curvature of spacetime.
  • Another participant expresses uncertainty about the concept of negative pressure and argues that dark energy emerged to explain the accelerated expansion of the universe without an obvious energy source.
  • A different participant asserts that dark energy is defined as a positive cosmological constant and questions the idea that it could arise from curved spacetime.
  • Some participants discuss the implications of coordinate changes in general relativity, with conflicting views on whether such changes can produce a gravitational field in flat spacetime.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the nature of dark energy and its relationship to spacetime curvature, with no consensus reached on these points. There are also conflicting interpretations of general relativity related to gravitational fields and coordinate changes.

Contextual Notes

Limitations include varying interpretations of general relativity, the definitions of dark energy, and the assumptions underlying the discussion of gravitational fields in different coordinate systems.

heliocentricprose
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General relativity says that the gravitational "field" is just the warping of space by mass. I like to think of the ball on the trampoline analogy. Is dark energy, basically negative pressure, be caused by the natural curvature of spacetime?

http://www.geocities.com/ixi_dima_ixi/gr.JPG
 
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im not sure what you mean by negative pressure. dark energy came about mainly because the expansion of the universe was accelerating with no obvious energy input, hence the dark energy idea. I don't see why the dark energy would be caused due to curved spacetime, as energy as well as matter can affect it.
 
heliocentricprose said:
General relativity says that the gravitational "field" is just the warping of space by mass. I like to think of the ball on the trampoline analogy. Is dark energy, basically negative pressure, be caused by the natural curvature of spacetime?

http://www.geocities.com/ixi_dima_ixi/gr.JPG
What General Relativity actually says is that the presence of a gravitational field can be produced by a change of coordinates, even in flat spacetime. This is so in a uniform g-field for example.

No. Dark energy is, by definition, a positive cosmological constant matter. Since that sounds weird they decided to call it dark energy. So either dark energy or negative pressure could generate a gravitational field, whether the gravitational field be in flat spacetime or curved spacetime.

Pete
 
pmb_phy said:
What General Relativity actually says is that the presence of a gravitational field can be produced by a change of coordinates, even in flat spacetime. This is so in a uniform g-field for example.

General relativity most certainly does not say this.

In fact, its say the opposite: no change of coordinates can change the non-zero/zero nature of the gravitational field.
 
pmb_phy said:
What General Relativity actually says is that the presence of a gravitational field can be produced by a change of coordinates, even in flat spacetime.

It would be a bizarre universe indeed if changing from [itex]x, y, z[/itex] to [itex]r, \theta, \phi[/itex] in our equations generated a gravitational field!
 

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