so I Googled what is the universe expanding into.

[MolaKule]

Originally Posted By: d00df00d


..."Dark matter" is basically defined as "whatever is causing the apparent gravitational effects that we don't think observable matter can account for." By that definition, it sure does seem to exist -- not merely as a matter of making the math work, but as a matter of accounting for what we see. Where the mathematical "proof" comes in is defining or speculating about the OTHER features it must have. Those other features are the ones that largely (entirely?) have yet to be demonstrated...



I tend to lean toward the MACHO and RAMBO hypothesis.

The theory of Stellar development says that old stars will die and produce black dwarfs, neutron stars, and black holes, white dwarfs and very faint red dwarfs, and then there are "brown dwarfs" or failed stars that just didn't have enough mass or the right mix of gases to fusion and to "light-up." These objects would constitute "real" dark matter.

All of the above are non-luminous. It is not invisible in the sense of being 'transparent.'

MACHO's or "Massive Compact Halo Objects," and "Robust Association of Massive Baryonic Objects"

https://en.wikipedia.org/wiki/Massive_compact_halo_object

https://en.wikipedia.org/wiki/Robust_associations_of_massive_baryonic_objects

These may be objects such as is defined in 1, and exist in the Halo's of Galaxies.

 

[Garak]

Originally Posted By: Al
Calculus won't cut it in this area

Sure it will, although with a few top ups in other areas. Simple differentiation isn't enough, of course, but some are some rather weighty integrals, along with differential equations, toss in some multivariate calculus, some linear algebra, some analysis, some probability, and non-Euclidian geometry, and you're on your way.

Schmoe: My view on how we've advanced so rapidly is due to collaboration. As communications improved (radio, as you point out) things went nuts.

Mola: As for that class we were discussing, is it a coincidence that they have a physicist teach the chem class?

 

[kschachn]

Originally Posted By: HosteenJorje
"Nothing" is the absence of a real something. We are fortunate that reason won out over of medieval superstition and ignorance and the concept of zero (0) was preserved. The idea of zero was once declared heretical and the work of the devil. It's easier to be naughty than nice.

There are different nothings however. The space between matter (galaxies, planets, even specks of dust) is often looked at as nothing, but even if there is nothing there it is at least empty space. Like that article showed it might not even be empty, but at least it has the framework of space established.

What the universe is expanding into is not even nothing, since "it" isn't even "it" yet. That's not even nothing.

Of course my use of the word "into" isn't correct since there isn't anything for it to expand into.

 

[Wolf359]

Originally Posted By: kschachn
Originally Posted By: HosteenJorje
"Nothing" is the absence of a real something. We are fortunate that reason won out over of medieval superstition and ignorance and the concept of zero (0) was preserved. The idea of zero was once declared heretical and the work of the devil. It's easier to be naughty than nice.

There are different nothings however. The space between matter (galaxies, planets, even specks of dust) is often looked at as nothing, but even if there is nothing there it is at least empty space. Like that article showed it might not even be empty, but at least it has the framework of space established.

What the universe is expanding into is not even nothing, since "it" isn't even "it" yet. That's not even nothing.

Of course my use of the word "into" isn't correct since there isn't anything for it to expand into.


And it's really not nothing, there's hydrogen in the space between stars. Not a lot, but then again the whole theory of a ramscoop is that you scoop up the floating hydrogen in space and use that for fuel to power a spaceship between the stars.

 

[MolaKule]

Originally Posted By: Garak
Originally Posted By: Al
Calculus won't cut it in this area

Sure it will, although with a few top ups in other areas. Simple differentiation isn't enough, of course, but some are some rather weighty integrals, along with differential equations, toss in some multivariate calculus, some linear algebra, some analysis, some probability, and non-Euclidian geometry, and you're on your way.

Schmoe: My view on how we've advanced so rapidly is due to collaboration. As communications improved (radio, as you point out) things went nuts.

Mola: As for that class we were discussing, is it a coincidence that they have a physicist teach the chem class?

Well, it helps.

I have three PG degrees:

Physics

Physical Chemistry

Aerospace Science and Engineering.

You have to have taken a load of Math and Physics Courses before you can even think about taking a Physical Chemistry course.

I was one of those who couldn't decide what he wanted to do when he didn't grow up.

 

[MolaKule]

Quote:
You have to have taken a load of Math and Physics Courses before you can even think about taking a Physical Chemistry course.


Should have read, "You have to have taken a load of Math, Chemistry, and Physics Courses before you can even think about taking a Physical Chemistry course."

 

[Yah-Tah-Hey]

"When was Roswell?" June of 1947 but the so called Roswell Myth started in 1980. The ranch foreman who found the "wreckage" southeast of Corona,NM in 1947 describe what he found as, "bright wreckage made up of rubber strips,tinfoil,a rather tough paper, and sticks." Does that sound like what an interstellar spacecraft would be made of? Or does that sound like the remains of a weather balloon array carrying radar targets? Keep in mind Ockham's Razor in making your choice.

 

[Al]

Originally Posted By: d00df00d

"Dark matter" is basically defined as "whatever is causing the apparent gravitational effects that we don't think observable matter can account for." By that definition, it sure does seem to exist -- not merely as a matter of making the math work, but as a matter of accounting for what we see. Where the mathematical "proof" comes in is defining or speculating about the OTHER features it must have. Those other features are the ones that largely (entirely?) have yet to be demonstrated.

Exactly..and you can say the same about antimatter and positrons theorized by Dirac. The math said it had to be...and sure enough, he was right.

 

[MolaKule]

Originally Posted By: d00df00d

...AFAIK, this is a slight but significant misrepresentation of the case for dark matter.

"Dark matter" is basically defined as "whatever is causing the apparent gravitational effects that we don't think observable matter can account for." By that definition, it sure does seem to exist -- not merely as a matter of making the math work, but as a matter of accounting for what we see. Where the mathematical "proof" comes in is defining or speculating about the OTHER features it must have. Those other features are the ones that largely (entirely?) have yet to be demonstrated.


That's a very good synopsis of the current state of cosmology science.


Here is a paper by Feng of UCIC that describes current DM candidates:


https://arxiv.org/pdf/1003.0904.pdf


"...Current data imply that dark matter is five times more
prevalent than normal matter and accounts for about a quarter of the Universe. More
precisely, these data constrain the energy densities of the Universe in baryons, non-baryonic
dark matter (DM), and dark energy; to be...



...Despite this progress, all of the evidence for dark matter noted above is based on its
gravitational interactions. Given the universality of gravity, this evidence does little to
pinpoint what dark matter is. At the same time, the identity of dark matter has far-reaching implications: in astrophysics, the properties of dark matter determine how structure forms and impact the past and future evolution of the Universe; and in particle physics, dark
matter is the leading empirical evidence for new particles, and there are striking hints that
it may be linked to attempts to understand electroweak symmetry breaking, the leading
puzzle in the field today..."

 

[Garak]

Originally Posted By: MolaKule
Should have read, "You have to have taken a load of Math, Chemistry, and Physics Courses before you can even think about taking a Physical Chemistry course."

Physical Chem I and II at the U of R don't have too much in the way of prerequisites, but it looks like most of quantum chemistry is a separate course. Even that one's not too bad, thought he calendar is misleading. It says Calculus I, but the physics prerequisites themselves have multivariate calculus as a prerequisite, so you get hit in the back pocket, I guess.

I think I already mentioned to you about another physicist I know who had his PhD in physics and his law degree and MD. He didn't know what he wanted to be, either. For the record, he works mostly doing research on automobile safety throughout history, including actual testing and analysis (i.e. things like that old Impala versus the new Impala on YouTube for the insurance people in the States), so he's not teaching physics nor involved in a "direct" physics field, and not practicing law or medicine, either.

 

[MolaKule]

Originally Posted By: KrisZ


This is a very good point. Math can be used to model just about anything, real and fictional. The real things are not a problem because we can do the math and then go out and prove or disprove it through experimentation...



Along that same vein, Physicist Larry Abbott said essentially, "Lets get our house (our cosmological physical constants) in order before we embark on new unified models."

Physicist Larry Abbott stated: “…If we discount the possibility that the vanishingly small value of the cosmological constant is accidental, we must accept that it has profound implications for physics.

Before we launch into constructing new unified models, however, we must face the dilemma that the relation implied by the vanishing of the cosmological constant is unnatural. The miraculous cancellations required to produce an acceptably small cosmological constant depend on all the parameters relevant to particle physics. Known and unknown….”

http://pages.erau.edu/~reynodb2/blog/Abbott_CosmologicalConstant_SciAm.pdf
Page 113.

Much of the time we tend to get ahead of ourselves. Too many times big-bang theorists have allowed their theory to determine or interpret the validity of their observations, rather than using the observations to shape the theory. When we allow the theory to take precedence over the observations, then the progress of science is stalled.

 

[MolaKule]

There are rival theories to Dark Matter's existence and one of those theories is the
MOND or MOdified Newtonian Dynamics which is an interesting theory in itself.

Quote:
"...A long-smoldering feud over the existence of mysterious dark matter is heating up. For decades, a few scientists have argued that dark matter—the stuff thought to make up 85% of the matter in the universe—cannot explain a universal pattern in the motions of spiral galaxies such as our own Milky Way. Instead, they propose modifying Newton’s law of motion. Now, a leading theorist argues that dark matter can explain this pattern after all, potentially knocking the pegs out from under the rival theory, modified Newtonian dynamics (MOND).

“This is the most compelling paper I’ve seen in the context of dark matter of why there might be this kind of relation,” says James Bullock, a cosmologist at the University of California (UC), Irvine. The new paper attempts to rebut a refined case for MOND recently put forward by Stacy McGaugh, an astronomer at Case Western Reserve University in Cleveland, Ohio. But McGaugh, a leading advocate of the MOND interpretation, says theorists “have a long way to go to convince me that they’re seriously addressing the problem, let alone solving it...”


http://www.sciencemag.org/news/2017/01/can-dark-matter-vanquish-rival-theory


Here is a PowerPoint presentation that gives quite a bit of background to the Physics of MOND, but says that Dark Matter theory and MOND should exist on equal footing:

www2.mpia-hd.mpg.de/~nielbock/talks/MOND_Seminar.ppt

Another scientist here is try to kill Dark Matter as well:

Quote:
...The latest attempt to explain away dark matter is a much-discussed proposal by Erik Verlinde, a theoretical physicist at the University of Amsterdam who is known for bold and prescient, if sometimes imperfect, ideas. In a dense 51-page paper posted online on Nov. 7, Verlinde casts gravity as a byproduct of quantum interactions and suggests that the extra gravity attributed to dark matter is an effect of “dark energy”—the background energy woven into the space-time fabric of the universe.

Instead of hordes of invisible particles, “dark matter is an interplay between ordinary matter and dark energy,” Verlinde said...


https://www.wired.com/2017/01/case-dark-matter/

https://www.quantamagazine.org/deathblow-dealt-to-dark-matter-disks-20171117/

 

[goodtimes]

We are built to survive in a physical universe where time exists and our brains interpret inputs fro our sensors to form images, sounds, smells. I have heard time described as change of state. It the universe contains all changing states, everything else beyond an expanding universe is timeless. Not detectable to our senses, and eternal. No past, present, or future. Mind boggling, all of it. All IMO.

 

[Schmoe]

Saw an interesting documentary on the future of the universe....they claim that at some point...I mean way out there, that there will not be a universe at all. It will all go "cold." I had presumed that matter would recycle itself and continue on, literally, forever.

 

[d00df00d]

At that point, won't the universe be indistinguishable from a zero state, from which another Big Bang could happen?

 

[Wolf359]

Originally Posted By: d00df00d
At that point, won't the universe be indistinguishable from a zero state, from which another Big Bang could happen?


I don't think it's a zero state, just a uniform temperature where no additional work could be done.

As for whether another big bang could happen, I don't think anything has been established about that. So it's as likely as pigs learning to fly. No data on that speculation. The 2nd big bang were if the universe collapsed, but it looks like that's not going to happen so an expanding universe and the heat death for us.

 

[MolaKule]

Due to the irreversibility of the universal thermodynamic process, the entropy of the Universe would increase until a final thermal equilibrium is reached, resulting in a cold, dark universe which still has matter, but no longer has any energy to do work, such as fusion, gravity, etc.

Irreversible Thermodynamics of the Universe: Constraints from Plank Data, Advances in High Energy Physics Vol. 2014 Article ID 652962.