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The universe is expanding, in theory because of 'dark energy'. Does this mean that this dark energy is causing an increase in the amount of spacetime? I.e., does dark energy cause the creation of spacetime?

Níckolas Alves
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aepryus
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    Note that the dark energy causes the expansion of the universe to speed up. General relativity can describe an expanding universe, including a “hyperbolic” universe which expands forever, whose dark energy content is zero. – rob Jan 16 '23 at 04:03

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This very close to previous question: How is Space-Time produced?

The point of that question is that spacetime is not "produced" because it is not a "thing" - it is just a mathematical object. So the accelerating expansion being driven by the dark energy isn't creating new spacetime.

However there is a sense in which dark energy does create more dark energy because as spacetime expands more dark energy is created. This happens because unlike matter, the density of the dark energy remains constant as spacetime expands. So if you drew some imaginary cube in space and waited a Hubble time for the expansion to double its size then the amount of dark energy inside the cube would have increased by a factor of eight. You'll next be asking doesn't this violate conservation of energy, and the answer is that in an expanding universe energy is not conserved.

John Rennie
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  • Energy is attribute of matter (dark or visible) but not of spacetime. However, the last one cannot exist without matter. Do I understand it right? – JanG Jan 16 '23 at 09:38