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Q & A: dark matter and the origin of the universe

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Most recent answer: 04/06/2014
Q:
Sorry if this is a repeat... I didn't get any indication that my question had been submitted so I am re-submitting it. There is a series of questions I have that led me to believe that dark matter is the original stuff of the universe and that we are one bubble in an ocean of bubble universes floating in an incredibly large expanse of dark matter. This is a culmination of an accumulation of bits of info and ideas that others have done the research on and unfortunately keep floating around in my head like puzzle pieces or a series of clouds, occasionally taking shape or falling into place leading me to a sense of making sense. I have thought about the Big Bang/Rapid Expansion from a singularity and am intuitively not happy with that hypothesis. I believe in the guess that our universe is one in an ocean of bubble universes, but for now let's assume the idea of a singularity is correct. In a singularity what form does the matter take? In high density objects matter takes some hypothetically exotic forms including quark-gluon plasma in neutron stars. In partical accelerators we break up particles into constituent pieces. Can crushing in supermassive black holes or the singularity reduce matter to it's maximum density (not infinite as matter must take up space) breaking apart neutrons and even those constituent parts? Could matter crushed to its maximum density be THE elementary particle(s)? How small could such matter be? Undetectably small? Is it likely to be a neutral particle? Could the densest layer of matter in a black hole or singularity be the hypothetical dark matter? This leads to my question, the idea behind which works for an expanding singularity or an original state of an ocean of dark matter either exisiting as the beginning of the universe or distributed by the bang/expansion. Dark matter, if it is the elementary particle(s), would combine eventually forming the simplest of atomic particles the proton & electron, forming hydrogen... which would eventually lead to the universe we know. My question is... Could hypothesized dark matter be residual matter, not yet combined, from the earliest mega-universe state or the big bang? I have many other questions based on a positive answer to this one and some questions whose answers or just the question may support the idea that dark matter is residual primordial dust. Please don't spare my feelings, I would prefer you burst my bubble-universe-black-hole-recycling-into-dark-matter-mobius-sphere-of-continuous-destruction-creation-hypothesis rather than let me be trapped in a self-made cage of ignorance. I need laser pointers leading me to solutions, support, or refutation so I can get on with other imaginings rather than thinking I have superficially/rudimentarily solved the riddle of where we came from and where we are going. If I have to I will even read a textbook or two... ugh!! Did I hear someone type "more like two hundred"?
- Michael Polidori (age 60?)
Newport News Va
A:

That's a lot of questions! I'll answer some to get you started.

It's unlikely that dark matter (assuming that's the right interpretation of the data) played a key role in the origin of the universe. Dark matter clumps up with the more familiar matter, inside our universe. That's pretty much the opposite of thinking of the universe as floating in some sea of dark matter.

Perhaps what you have in mind is something close to the "eternal inflation" (good search term) picture. There some form of dark energy, in some ways similar to the stuff driving the acceleration of our current expansion, drives an accelerating expansion which sheds countless universes like ours. That's pretty much a standard picture, at least for the time being. There are arguments that even in such a picture there would have to be a singularity at the start, if one ignores quantum gravity. However, the general consensus is that a theory of quantum gravity will replace the singularity with something or other. Some sort of ongoing re-creation cycles are one possibility, discussed in Sean Carroll's From Eternity to Here.

The picture of there being a set of ultimate "elementary particles" may not be right. The stuff that comes out of a high energy collision is not necessarily any more or less fundamental than what went in.

Mike W.


(published on 11/27/2013)

Follow-Up #1: alternatives to dark energy?

Q:
I thought I was following up on my previous question about the origins of Dark Matter... but I think there are some issues with your website or page. Dark Energy is hypothesized to exist. If I understand correctly Dark Energy hypotheses sprang from the idea that the universe is expanding with more distant objects accelerating faster than closer objects. Not only do I dislike the singularity intuitively, the idea of a mysterious Dark Energy seems ludicrous. I see some of the reasoning... if the mysterious & dark gravity can be a property of matter that is mutually attractive, why can't there be a mysterious dark energy that is repulsive? For gravity we have the reality of a falling apple as proof of the mysterious dark force... and tides, escape velocities, gravitational lensing and black holes. What evidence do we have for Dark Energy? I believe that is the increasing Doppler shift of ever more distant objects. But I think there is a simpler explanation for this shifting shift using our first form of Dark Energy, gravity. This only works if our universe is bounded. Something else that must be true is that gravity (which is proved to lense light) can stretch or compress light as well (black hole fully compresses a light wave yielding maximum blue-shift). Compression of light may be related to star color, blue red or yellow? That just come to mind, so I thought I should include it. Back to our thought experiment to cork Dark Energy's well-spring. Let's start at the center of the Earth, where we would be weightless (and crushed and crispied, I know, but this is a thought experiment). As we travel toward the surface we would begin to have increasing weight as more and more of the Earth was trying to pull us back to the center. At the surface we would have maximum weight. The entire planet and all of it's lifeforms would be pulling on every atom in our bodies. In a universe of limited size, at the gravitational center of the universe we would have no universal weight (U-weight). As we traveled outward, we have increasing U-weight until we reached the edge of our bubble. At that point every object in the universe would be pulling on every atom in our bodies. What effect would that U-gravity have on light from a star on the edge of our universe? Would the Doppler shift be shifted a little by all that gravity pulling from one side of the star? If the answer to that question is yes, then wouldn't the light from a star closer to us have less of a Doppler-shift shift? Of course it would... and that would explain the ever-increasing Doppler shift showing more and more distant objects moving away at ever increasing speeds and, I assume, ever increasing accelerations? If this stuff stands up to scrutiny from the field of astrophysics, do I get at least a Nobel nomination? Heck, I would be willing to throw in my ideas on Dark Matter as a combo-package just to get an honorable mention... What say you Answerer Van?
- Michael Polidori (age 60?)
Virginia, USA
A:

If I understand you correctly, your idea is a rather old one- that a special distribution of ordinary mass could have effects that mimic the universal acceleration predicted for dark energy. Recent tests of this idea have shown that it doesn't work: . If I understand the argument correctly, there's not enough density of ordinary attractive mass (including dark matter) to provide for a big enough spatial variation to mimic the whole apparent acceleration.

The dark energy hypotheses doesn't just come out of nowhere. One typical result as things cool down is that they get stuck temporarily in supercooled states with higher energy than the true equilibrium state. Without any further fudging, the general relativistic equations predict that should cause accelerating expansion, i.e. inflation. There's lot's of evidence that such an effect happened very intensely very early in the history of the universe. And there's lots of evidence that it's been happening weakly for the last few billion years. 

Alternate theories are still welcome, and may win in the end. The key thing is to find ways of testing them.

Mike W.


(published on 04/06/2014)

Follow-up on this answer.