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The excerpt below has been taken from a pop-science article.

Dark energy is thought to be different, though. Rather than being a type of particle, it appears to behave as though it were a type of energy intrinsic to space itself. As space expands, the dark energy density remains constant, rather than decreasing or increasing. As a result, after the Universe has expanded for long enough, dark energy comes to dominate the energy budget of the Universe. As time goes on, it becomes progressively more dominant over the other components, leading to the accelerated expansion we observe today.

Source: https://www.forbes.com/sites/startswithabang/2019/01/31/dark-energy-may-not-be-a-constant-which-would-lead-to-a-revolution-in-physics

Dark energy is the name given to the mysterious force that’s causing the rate of expansion of our universe to accelerate over time, rather than to slow down. The question is how come the density of dark energy remains constant. Yes, if it's intrinsic to the space itself and more space is created when the expansion takes place then it's understandable that its density should remain constant. But then the question is where does the extra new space come from? What creates it?

Another related question is that if the space is discrete, or quantum at fundamental level, and is made up of infinitesimally small particles or whatever, as is speculated, then more space would mean more discrete 'space' particles. The quantum fields such as electromagnetic field, electron fields, etc., also spread through the expanding space. So, when the space expands, what happens to those fields? Do those fields also expand along with the expanding space? Could you please help me with it?

Helpful links:

1: https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy

2: https://math.ucr.edu/home/baez/vacuum.html

3: https://www.scientificamerican.com/article/follow-up-what-is-the-zer/

4: https://www.forbes.com/sites/startswithabang/2020/04/18/ask-ethan-what-is-the-zero-point-energy-of-space

5: https://en.wikipedia.org/wiki/Vacuum_energy

6: What's the difference between "dark energy" and "vacuum energy"?

7: Vacuum energy extraction: What happens to the cosmological constant?

8: https://earthsky.org/space/definition-what-is-dark-energy/

Qmechanic
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PG1995
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  • Does this answer your question? Expansion of the Universe: is new space(time?) being created or does it just get stretched? – John Rennie Feb 24 '22 at 06:59
  • @JohnRennie I'm sorry but it doesn't. I have been through that question where you provided the answer. You said there, "The problem is that spacetime isn't an object and isn't being stretched." As a layman, I understand that Einstein's GR is more of a geometric theory to get to the right answers and I don't see spacetime as a rubber sheet. There was a reason I tried to avoid the word 'spacetime' in my question. This is a 'physical' reality that the space expands and it is also true, as it speculated, that the density of dark energy remains constant. So, I'd need more help. Thank you! – PG1995 Feb 24 '22 at 22:15

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