Dark Matter and Wave Particle Duality

[chasmanian]

thank you for your excellent reply nFA.

guessing this has been posted before, but just in case:

https://www.forbes.com/sites/startswith ... 38292036f8

[notFritzArgelander]

Yes, I recall posting that when SWaB didn't require a paid subscription.

One thing missing among the things that we know is that the evidence is pretty good that there are at least two components to DM. There seems to be a superfluid and a normal fluid and self interaction by a non gravitational force seems indicated. So it is likely that there are several things (particles-fields) involved.

[chasmanian]

thank you nFA.

I get a kick out of the word smatter.
and how we have a smatter of knowledge about Dark Matter, compared to normal matter.

and maybe could coin a term Dark Smatter.

[notFritzArgelander]

Now to deal with the second piece of the OP.

could Dark Energy too?

this is from this article:

“This was actually Einstein’s idea,” Upadhye says. “If you put in a substance with a negative pressure into the equations of general relativity you get this accelerating expansion of universe.”

https://www.symmetrymagazine.org/articl ... y-particle

First of all Upadhye is playing somewhat fast and loose with the history and misrepresents what Einstein's original idea was. After coming up with the equations of GR Einstein was appalled that there was no static solution. Einstein wanted a closed static universe and GR doesn't permit that. GR only gives collapsing or expanding universes as solutions depending on whether the kinetic energy of the constituents is less than or greater than the gravitational attraction. A perfectly balanced static state is not a solution that is stable. It either runs away to collapse or expand. Nothing "in between" is allowed. So in order to make a static closed universe possible Einstein added the cosmological constant term. Einstein's motivation had nothing to do with an accelerating universe and everything to do with a closed static universe.

Today we know the universe is barely open and accelerating and is also not closed (within observational errors).

So far all the data we have is consistent with Dark Energy not being a particle. It looks more like an energy cost of having space.

The CAST experiment has so far found no evidence of any particles that could be interpreted as evidence for Dark Energy.

Lastly, having a chameleon particle with all these fancy adjustable properties seems to be getting unhealthily ahead of ourselves with a model that has more free parameters in it than the current observations could possibly support.

[chasmanian]

thank you nFA.

this looks interesting.
I think we get 5 free articles per month. maybe I'll repost next week:

https://www.forbes.com/sites/startswith ... d109201268

[notFritzArgelander]

thank you nFA.

this looks interesting.
I think we get 5 free articles per month. maybe I'll repost next week:

https://www.forbes.com/sites/startswith ... d109201268

Well I've reached my limit and couldn't read the article. The title IIRC was "where does dark energy come from?" I don't know what the article says but my answer is we have no clue. IMO the only hint at explaining (and it is only a hint) is in this Perimeter Institute talk by Fay Dowker. There is a hint that dark energy is a consequence of the atomicity of space time.



The relevant bits start at about 50 minutes in.

[chasmanian]

thank you nFA.
that video looks fascinating.

the title of the article is Where Does The "Energy" For Dark Energy Come From?
and I will repost it next month.

[chasmanian]

well, I went to the Ethan article on Forbes, and still get the paywall.
darn!!

[notFritzArgelander]

well, I went to the Ethan article on Forbes, and still get the paywall.
darn!!

Yeah, it's dismal.... I was able to read it and it's mistaken IMO and others. There's a common misconception that conservation of energy doesn't work in GR. Schroedinger started the error off by making unreasonable mathematical demands. Modern treatments have expressed energy conservation quite well in GR. Landau and Lifschitz did it right.

https://en.m.wikipedia.org/wiki/Stress% ... eudotensor

[chasmanian]

thank you nFA.
it would be nice if we could read some free articles every month.

and super fascinating all you wrote.

[chasmanian]

nFA,

would you possibly please have any thoughts about this:

how would e=mc^2 apply to Dark Matter?
can we speculate about that at all?

also, all of the normal regular matter and energy in the Universe, were created in the Big Bang (I think).
regular matter and energy can be transformed into each other.

I wonder if Dark Matter can be transformed into something else.

also, the amount of regular matter and energy in the Universe, is a set amount.
they aren't making any more of it. (like real estate.)
but the amount of Dark Energy continues to grow.
am I right about this?
(its been a while, and I forget alot of stuff. and I know you are a reliable source and excellent person to ask this stuff.)

thank you for any thoughts,
Charlie

[notFritzArgelander]

nFA,

would you possibly please have any thoughts about this:

how would e=mc^2 apply to Dark Matter?
can we speculate about that at all?

If it didn't then special and general relativity would be contradicted.

also, all of the normal regular matter and energy in the Universe, were created in the Big Bang (I think).
regular matter and energy can be transformed into each other.

I wonder if Dark Matter can be transformed into something else.

no one has a clue about this. there are speculations but so far.... if there were a definite idea about a transformation then a DM detector would be simple: build a device that encourages the transformation.

also, the amount of regular matter and energy in the Universe, is a set amount.
they aren't making any more of it. (like real estate.)
but the amount of Dark Energy continues to grow.
am I right about this?
(its been a while, and I forget alot of stuff. and I know you are a reliable source and excellent person to ask this stuff.)

yes, under the currently known cosmology the total matter (including dark) and energy is fixed. in comoving coordinates there are conservation numbers that remain constant.

here's a riddle: since the dark energy contribution to total energy in comoving coordinates grows, how come the total mass-energy density is so close to zero? the universe is observed to be flat and has zero energy density. how can that be when the dark energy is growing?

answer me that and you can probably count on an all expense paid trip to Stockholm.

thank you for any thoughts,
Charlie

always welcome....

[chasmanian]

thank you soooo much nFA.
must sleep now.
will reply soon.

[chasmanian]

thank you again nFA.

its fun to think about Dark Matter transforming via e=mc^2.

as for the riddle:
its not that the Dark Energy percentage component of the Universe is increasing,
and the rest of it (Dark Matter and normal matter), is decreasing?

or how about, the density does not change, because spacetime is expanding?
in sync with the growing Dark Energy?

[notFritzArgelander]

thank you again nFA.

its fun to think about Dark Matter transforming via e=mc^2.

as for the riddle:
its not that the Dark Energy percentage component of the Universe is increasing,
and the rest of it (Dark Matter and normal matter), is decreasing?

or how about, the density does not change, because spacetime is expanding?
in sync with the growing Dark Energy?

But look at the problem in a finite comoving volume. DE has constant density. So as the comoving volume increases in size the total DE in that volume increases. The matter and radiation contained in that volume decrease in density and the total energy in the comoving volume remains fixed. So in the same comoving volume matter-radiation stays fixed modulo work done against gravity but the DE total increases.

So how is it that the net energy density has stayed constant and near zero since the Big Bang?

[chasmanian]

trying to understand.

comoving volume factors out the expansion of the
universe.
so how is the comoving volume increasing in size?

and what does modulo mean?
can you say that using a different word or words?

[notFritzArgelander]

Let me try a different tack....

Measurements of the CMB background and recent distant indicators say that the universe is flat. This implies that the total energy density is near zero and always has been. But the matter-energy density is decreasing and the dark energy density is constant. With the universe expanding, matter-energy decreasing and dark energy density constant how is it possible that the total of both seems constant and equal to zero?

[chasmanian]

thank you nFA.
will ponder.

[notFritzArgelander]

thank you nFA.
will ponder.

me too. i don't have an answer, you know.

[chasmanian]

thank you nFA.
will ponder.

me too. i don't have an answer, you know.

excellent, thank you nFA.

brainstorming possible answers.
(really just using my imagination. there is nothing which is physical here.
just free form thinking for fun, and exercise my tired old brain.)

- there is another component, as yet not observed.
its density increases commensurate with the decrease in matter-energy.


- there's an interaction, as yet not observed, between Dark Energy and matter-energy,
which is causing the total flatness.

- something caused by an unobserved property of Dark Matter.

- something to do with Quantum Gravity

- the Flying Spaghetti Monster