Does Dark Energy.....

[peter]

.....Mean that the Universe will expand ad infinitum? I saw in a program the other day that scientists mapping the Universe were surprised to discover that the rate of expansion of the Universe, rather than decelerating [what they had been intending to measure] was in fact found to be accelerating. Now they did not go so far as to say this in the program [Horizon; How Big is the Universe], but it seems to me that the logical extrapolation from this is that the model in cosmology where the Universe expands then contracts into a 'big crunch' must be jettisoned. Is this right, or am I missing something here?

Another thing they said [and they interviewed the cosmologists responsible for this discovery] was that space, rather than being non-Euclidean in nature was in fact Euclidean - and this effectively confirms that our Universe is itself infinite! Damn - that's a lot of confirmation coming out of one Horizon program! Anybody up to speed on these two points who can tell me if my ears 'heard aright'?

[wayfriend]

Well, yes, the universe might expand forever, until the density becomes zero, and all matter disintegrates.

If there's a theory that suggests that there is a contraction ahead, even if expansion is now accelerating, I don't know of it. But I suppose it's possible since dark matter must itself eventually ionize or otherwise dissipate.

[peter]

The weird thing about dark energy (as I understood from the programme) is that as the Universe expands it doesn't disipate - rather it increases (and though again, the scientists didn't say so, this clearly runs contra to the LoCoE!)

Curiouser and curiouser!

[Vraith]

The weird thing about dark energy (as I understood from the programme) is that as the Universe expands it doesn't disipate - rather it increases (and though again, the scientists didn't say so, this clearly runs contra to the LoCoE!)

Curiouser and curiouser!

Yea, it seems to always increase according to most I've seen. But only guesses as to why---which is certainly related to the fact that at present we don't know what it is. [[I'm not sure how, or even if, this is always connected to the apparent fact that even the emptiest space has non-zero energy, as several of us delved into in "nothing is unstable" convo.]

I've seen at least some speculation that the expansionary force can...and in the past DID...flip direction, and be contractionary---I think was said about 8 billion years ago? but don't quote me---
[[[edit here to say, cuz above seems opposite what I meant---it didn't flip to contractionary then...it WAS contractionary before that, then flipped to expansion---and it COULD flip back. Maybe. Hard to tell, cuz we still don't know what it is ]]

I'd wager we won't learn much about what it is until we know what dark matter actually is...though I'm also pretty sure I've seen at least a couple people say that the two darks don't necessarily relate/interact. At least not directly. [[as in dark energy isn't necessarily associated with a dark photon/electromagnetism or dark gluon carrying dark strong nuclear, etc. They MAY be related, but they may be totally separate. Even if totally separate, though, I suspect solving one deeply mysterious thing will expand our potential vision/approaches for solving another.]]

Related---I've seen a couple versions of "Big Rip."
In one, all of space, everywhere, and every particle no matter how small and how strongly bound, is torn to shreds in the fullness of time.
In the other, it has limits on the scale of objects it affects? Or on strength?, don't recall exactly. Anyway galaxies and maybe some clusters of galaxies, [those with giant black holes] and all things smaller within their grasp, will manage to cling together...but the spaces between will be torn asunder, so a bunch of universes made up of single or small groups of galaxies survive...I think something similar [but I'm not sure dark energy was the cause] is part of the nature of things described in Brin's later Startide novels.

[Zarathustra]

Michio Kaku speculates in THE PHYSICS OF THE FUTURE that if we can somehow harness dark energy, it would enable nearly "magical" power like anti-gravity, ushering in an new era of physics and technology.

[Mighara Sovmadhi]

There is a theory out there, let's call it "conspansion theory," for contraction+expansion. Basically, this idea is that there are three Venn spheres at the "core" of reality, but instead of being an abstract diagram they are the primitive embedding of set-theory in physical spacetime, and as they manage their internal Venn logic, the spheres variously compress and push outwards on the information/matter in their purview. From some perspectives the outward push will be more noticeable, while from others the condensation will be. (This is all from Christopher Langan, or my interpretation of him.)

[peter]

We're into the area where maths takes over from [mental] pictures ..and hence the point where my [and most lay people's] ability to follow breaks down [and why of course one physicist said that to attempt to understand theoretical physics without a grounding in math was like trying to understand music if born congenitally deaf].

[Vraith]

Fun with dark energy, string, and everything.

And it happens to include a comment related to what several of us were discussing elsewhere...math, formal systems, and my constant distinctions between/take on the inherent gap/space in our kinds of knowledge. [[if string is correct, then our universe is in the swamps, not the landscapes, and is logically inconsistent, someone says.]]

More in it than just that, though.

https://www.quantamagazine.org/dark-ene ... -20180809/

[peter]

Interesting! We know of only one type of universe that exists empirically - that of our own (a de-Sitter universe where dark energy is a stable positive constant). Does this at least not provide a good 'fixed point' to start from - a place from which that which is possible or otherwise can be extrapolated. If this ...... let's call it knowledge.........tells us that string theory is wrong - then it's simply wrong and we discard it?

[Vraith]

.......tells us that string theory is wrong - then it's simply wrong and we discard it?

The thing about string that ties me up [ ] is that even if it is wrong---
and I think it very likely is wrong---
it is one hell of a fruitful/profligate garden to play in...a HUGE crop of physics and math tools, in multiple fields, have come out of it.

And string might not be wrong in the phlogiston way, it might just be wrong in a Newtonian gravity way. Here's another Quanta thing about stuff that might be underneath the string, and reconcile it with other issues.....

I love this article, BTW, I keep re-reading it, almost understand almost 10% of it...and it seems to imply things about that gap/space I'm always on about.


https://www.quantamagazine.org/the-octo ... -20180720/

[peter]

The "shut up and calculate" approach served physics well in the first half of the C20 and to a pure 'intrumentalist' any model will be judged only on it's utility and never be even thought of in terms of rightness or otherwise. But does Newtonian theory truly differ from relativity in the way phlogiston does from oxygen. Sure relativity covers all the bases of Newtonian and then some - but beyond that (in terms of being real/true descriptions of reality) the connection surley ends? It is in no sense 'nested inside' relativity in terms of its method of operation, action at a distance and the bending of space-time being as different as chalk and cheese?

(I think I've just seen the flaw in this, but no matter - I'll leave the post as it stands for interest in how it be argued against )

I'll try the math link, if only to read it in the manner of one of the more abtruse passages of Finnegans Wake - as an exercise in meditation! )

[Vraith]

(I think I've just seen the flaw in this, but no matter - I'll leave the post as it stands for interest in how it be argued against )

Don't know what one you saw, but the most obvious to me is similar to this:
Go pick any average 6 year old and ask him to tell you everything about a car, and everything about a unicorn.
Both will be wrong...but one will be far less wrong.
The other a perfect example of " not EVEN 'not even wrong.'"

One thing, that's really just a comment, in that article that's messing with my head is the idea that there are number systems that "exist" in which one cannot do simple math, add/subract/multiply/divide. [[but somehow, apparently, they are still useful??? for something???

[peter]

Not very far into the article (where my understanding is just about still holding up!) is the interesting sentence that even at this level the fundamental split between quantum dynamics and the special theory of relatively is manifest; the first we are told is provided by the math of complex numbers while quartonion numbers underlie the second. I wonder what significance is inherent in this observation could I but know it?

Number systems that eschew concepts such as smallness and largeness - Wow! (Curiouser and curiouser to bring a shrinking Alice metaphor into the picture - nice since Dodgson was also a mathematician. )

Great article again V! I predict that when the solution to the standard model is eventually found (and I'm betting it will be via the blackboard and not via the smashing of atoms) that - as with the structure of DNA - we will once again slap our foreheads and say " How could it have been other!"

[samrw3]

Also posted in "Random News section"....

Interesting read about dark matter hurricane. Maybe we will obtain some
answers about dark matter.

www.msn.com/en-us/news/technology/scien ... ocid=ientp

"As our solar system speeds through the outer reaches of the Milky Way . it flies through dark matter at around 230 kilometres per second (around 143 miles per second). A study published Nov. 7 and lead by researchers at University of Zaragoza suggests that the dark matter present in the stream may be traveling at double that speed...giving us a much better chance of detecting dark matter"
......
Because the S1 stellar stream travels directly through the solar system, the dark matter hurricane is likely to cross the path of various detectors spread across the globe set up to detect these hypothetical particles. The study concedes that the current iterations of WIMP detectors will likely not see dark matter from the S1 stream. However, those are geared to detect "axionic dark matter", based on a hypothetical particle known as a axion.

[Skyweir]

As dark matter is theorized to make up around 85 percent of the matter in the universe, detection of the particle or particles that make it up would fundamentally change how we look at the universe. So, really, there's no cause for concern when you hear the term "dark matter hurricane" -- in fact, its a good thing.

[peter]

"When will it be, this thing of which we speak? Will it be such as to lay low the mountains of the Earth and cast them into the tumultuous firmament?"



(My white gold dollars to anyone who can from their own memory!!!! identify the (nearly) quote. )

[Cord Hurn]

"When will it be, this thing of which we speak? Will it be such as to lay low the mountains of the Earth and cast them into the tumultuous firmament?"



(My white gold dollars to anyone who can from their own memory!!!! identify the (nearly) quote. )

Is that a quote from Anele?

[Skyweir]

I honestly have no clue .. but if Cord isnt right, which is highly unlikely.. Id like a hint

[Vraith]

Is it really appropriate to say it will "slam into" us [or anything?]
I mean...
A rock can slam into your windshield...
Sunlight not so much...
You can slam a zombie into the wall...
Not really a thing for a ghost...

[peter]

On that, once while traveling to Sri Lanka I got sidelined to Abu Dhabi in mid July and determined to make the most of my 24 hours in a new country headed toward the exit of the hotel I'd been allocated. The fellow at the reception desk looked at me with a mixture of pity and condescension as I crossed the foyer and said "You don't want to go out there." I noticed that the street outside was all but empty - unusual for midday I thought - but proceeded with a knowing smile that said " I'm British you know; I hope I can stand a bit of sun on my head". I stepped through the doors crisply attired and thirty seconds later returned through the same looking like the proverbial guy who crawls out of the desert. The sheer force of the sun that day was incredible! I feel I can say without in any sense of hyperbole that the moment I stepped outside it slammed into me like a sledgehammer!

On the clue front .....mmmmmm........

TSP'sB

(And if I'm correct there are two of them!)

(Gosh, that last bit's good, though I say it myself! )