I Dark energy is intrinsic to the space itself

[PainterGuy]

Hi,

I was reading the following 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/starts...t-which-would-lead-to-a-revolution-in-physics

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? Could you please help me with it? Thanks, in advance?

 

[anorlunda]

But then the question is where does the extra new space come from? What creates it?

The whole universe is expanding. That means that its volume increases. But there is nothing outside the universe, so the volume doesn't "come from" anything.

 

[Bandersnatch]

But then the question is where does the extra new space come from? What creates it?

Space is not a material thing that needs to be created. It's just a bit more general notion of distance between objects. When you separate two things, one way or another, you don't create anything in-between them. Yet, there is now 'more' space.
With dark energy, what confounds is our everyday intuition that stationary things don't start moving apart unless there's some unbalanced force involved. But it doesn't have to be true. It might just be that it is natural for things to accelerate apart, and the faster the more distant they are. But it is such a very, very, very tiny effect that it gets swamped by local forces. So we have no common-sense reason to think that it is a natural state of affairs to see distant objects accelerate away. And yet, on large enough scales, that's exactly what is observed.
Once we grant that, we can turn the question on its head, and instead of asking where does the thing 'pushing' objects apart come from, we can ask why certain things don't accelerate apart - like they should be doing. And that's much easier to answer with more palatable intuitions - it's because this system is bound by gravity, this system is bound by electromagnetic forces, this system is bound by... etc.

 

[PeterDonis]

I was reading the following article.

That article is a pop science article, and is not a good source if you actually want to learn the science.

How come the density of dark energy remains constant?

We assume it is constant in our models because we have no evidence to suggest that it isn't, and it being constant is the simplest possibility. But it is not the only possibility; one can construct models in which there is a scalar field that acts like "dark energy" in its effects (causing accelerated expansion of the universe) but does not have a constant density everywhere.

 

[PainterGuy]

Space is not a material thing that needs to be created. It's just a bit more general notion of distance between objects. When you separate two things, one way or another, you don't create anything in-between them. Yet, there is now 'more' space.

Thank you.

But if the space is discrete and made up of infinitesimally small particles or whatever, then more space would mean more discrete particles. I was thinking more along these lines earlier. Could you please guide me?

 

[PeterDonis]

if the space is discrete and made up of infinitesimally small particles or whatever

This is personal speculation and is off limits here.