# Curvature of Spacetime

1. Oct 13, 2006

### heliocentricprose

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

2. Oct 14, 2006

### FunkyDwarf

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 dont see why the dark energy would be caused due to curved spacetime, as energy as well as matter can affect it.

3. Oct 14, 2006

### pmb_phy

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

4. Oct 14, 2006

### George Jones

Staff Emeritus
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.

5. Oct 14, 2006

### Daverz

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

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