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Is Dark Matter a Glimpse of a Deeper Level of Reality?
Scientific American ^ | 6/11/12 | George Musser

Posted on 06/13/2012 11:11:54 AM PDT by LibWhacker

Two years ago several of my Sci Am colleagues and I had an intense email exchange over a period of weeks, trying to figure out what to make of a new paper by string theorist Erik Verlinde. I don’t think I’ve ever been so flummoxed by physicists’ reactions to a paper. Mathematically it could hardly have been simpler—the level of middle-school algebra for the most part. Logically and physically, it was a head-hurter. I couldn’t decide whether it was profound or trite. The theorists we consulted said they couldn’t follow it, which we took as a polite way of saying that their colleague had gone off the deep end. Some physics bloggers came out and called Verlinde a crackpot.

For those who know Verlinde, that label hardly fits. He is a brilliant theorist, and the amount of discussion his paper provoked suggested that most of his colleagues saw something in it. The whole story caught the eye of New Scientist and the New York Times, but ultimately we at Sci Am opted for watchful waiting. I caught up with Verlinde this spring during a workshop at the Kavli Institute for Theoretical Physics. He has doubled-down on his original paper, and his colleagues’ reaction hasn’t changed. One told me: “There are a lot of ideas he’s bringing together in an interesting way, but it’s a little hard for us to decipher, so I’m withholding judgment.” All he has really done, though, is take a general sentiment among string theorists and follow it to its logical conclusion.

String theorists and other would-be unifiers of physics face a basic problem. The theories they seek to unify, quantum field theory and Einstein’s general theory of relativity, are well-grounded and well-tested, yet mutually incompatible. Reconciling them will demand that some deeply held intuition must give way. One such intuition is that the world exists within space and time. Participants at the Kavli workshop were inclined to think that space and time are not fundamental, but emergent. The universe we seeing playing out in space and time may be just the surface level, where we float like little boats while leviathans stir in the deep.

Black holes provide the strongest argument for this point of view. The laws of gravity predict that these cosmic vacuum cleaners obey versions of the laws of thermodynamics, which is strange, because thermodynamics is the branch of physics that describes composite systems, such as gases made up of molecules. A black hole sure doesn’t look like a composite system. It just looks like a warped region of space that you would do well to stay away from. For it to be composite, space itself must be.

In that case, black holes represent a new phase of matter. Outside the hole, the universe’s “degrees of freedom”—all that its most fundamental building blocks are capable of—are in a low-energy state, forming what you might think of as a crystal, with a fixed, regular arrangement we perceive as the spacetime continuum. But inside the hole, conditions become so extreme that the continuum breaks apart. “You can make spacetime melt,” Verlinde told me. “This is really where spacetime ends. To understand what goes on, you need to use these underlying degrees of freedom.” Those degrees of freedom cannot be thought of as existing in one place or another. They transcend space. Their true venue is a ginormous abstract realm of possibilities—in the jargon, a “phase space” commensurate with their almost unimaginably rich repertoire of behaviors.

Verlinde’s 2010 paper applied this reasoning to the laws of gravity themselves. Instead of being a fundamental force of nature, as almost all physicists since Newton have thought, gravity may be an “entropic force”—a product of some finer-scale dynamics, much as the pressure force in a gas arises from collective molecular motions. At Kavli he went further and argued that the notion of emergent spacetime transforms our entire conception of the universe. “If you realize there’s much more phase space than we usually assume—much more—you will think about cosmology differently,” he argued.

For starters, dark matter may be a glimpse into the depths. To account for anomalous motions within galaxies and larger systems, astronomers think our universe must be filled with some invisible material that outweighs ordinary matter by a factor of five to one. They have never detected the material directly, though, and for something that is supposed to be so overwhelmingly dominant, dark matter has a puzzlingly subtle effect. The anomalous motions occur only in the unfashionable outskirts of galaxies. Stars and gas clouds out there move faster than they should, but don’t do anything truly wacky—it is as if the gravitational field of the visible galaxy were simply being amplified.

Consequently, some astronomers and physicists suspect there may be no dark matter after all. If you notice the floorboards in your house are sagging, as if there is too much weight on them, you might conclude there is an 800-pound gorilla in the room with you. You see no gorilla, so it must be invisible. You hear no gorilla, so it must be silent. You smell no gorilla, so it must be odorless. After a while, the gorilla seems so improbably stealthy that you begin to think there must be some other explanation for the sagging floorboards—the house has settled, say. Likewise, perhaps the laws of gravity and motion which led astronomers to deduce dark matter are wrong. “I think dark matter will be a sign of another type of physics,” Verlinde said.

The leading alternative to dark matter is known as MOND, for Modified Newtonian Dynamics. Verlinde has reinterpreted MOND not just as a tweak to the laws of physics, but as evidence for a vast substratum. He derived the MOND formula by assuming dark matter is not a novel type of particle but the vibrations of some underlying degrees of freedom—specifically, vibrations produced by random thermal fluctuations. Such fluctuations are muted and become conspicuous only where the average thermal energy is low, such as in the outskirts of galaxies. Astoundingly, Verlinde even derived the five-to-one ratio. “I started seeing this as a manifestation of this larger phase space,” he said.

MOND is super-iffy, as cosmologist Sean Carroll has detailed in a series of blog posts over the years, most recently this one. I’m inclined to agree, but one thing gives me pause. MOND manages to account for a wide range of anomalous galactic motions with one simple formula. Even if MOND doesn’t overturn the laws of physics, it has shown that dark matter behaves in a simple way. All the complicated dynamics of dark matter must somehow settle down into a very regular pattern. Dark-matter modelers tell me they have yet to explain this.

Verlinde bucks conventional wisdom not only on dark matter, but also on much of the rest of cosmology. For instance, he has reintroduced elements of the steady-state theory that most cosmologists thought they had ruled out in the 1960s. In his model, all matter—ordinary as well as dark—consists of vibrations of the underlying degrees of freedom and so is being created and destroyed all the time. In fact, the same degrees of freedom also explain dark energy, thereby unifying all the components of the universe. What differentiates these components is how fast they respond: ordinary matter is the surface chop, dark matter the languid but powerful deep currents, and dark energy the quiet bulk of the sea. As for another leading cosmological theory, cosmic inflation, he doesn’t think much of that, either.

The grander his claims become, the less plausible they seem. Still, Verlinde has captured theorists’ sense that cosmological mysteries signal a new era of physics. The impulse to explain dark matter and dark energy as signatures of a deeper reality, rather than a bolt-on to current theories, arises not only in string theory but also in alternatives such as loop quantum gravity and causal set theory. And if Verlinde is wrong and spacetime really is a root-level feature of our world, what other intuition will have to give way? What other thing that we thought we knew for sure is wrong?


TOPICS: Astronomy; Science
KEYWORDS: dark; deep; matter; reality; stringtheory
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To: LibWhacker

Sheldon Cooper disproved this theory in 1998.


41 posted on 06/13/2012 1:02:18 PM PDT by Doc Savage ("I've shot people I like a lot more,...for a lot less!" Raylan Givins)
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To: Errant

Funny you should mention EM force...

http://www.amazon.com/Pushing-Gravity-Perspectives-Theory-Gravitation/dp/0968368972


42 posted on 06/13/2012 1:07:49 PM PDT by cuban leaf (Were doomed! Details at eleven.)
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To: evets

I’m waiting for someone to explain that guy’s hair.


43 posted on 06/13/2012 1:10:42 PM PDT by MWestMom (The heart of the wise inclines to the right, But the heart of the fool to the left. Ecclesiastes10:2)
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To: davius
Now, why do people park in driveways and drive on parkways?

Why do you only use your emergency brake when the car is not running, and safely parked ?

44 posted on 06/13/2012 1:12:18 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: davius

uno mas.

Why , when you ask someone how FAR away something is, they tell you how long it takes to get there?


45 posted on 06/13/2012 1:14:20 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: 3rdcoastislander
Michael Crichton said so in Timeline.

He wrote that book? Dang, I must be in the wrong timeline.

See Ya ( maybe ).

46 posted on 06/13/2012 1:18:45 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: beethovenfan
My head hurts.

I can fix that, if you'll just look here...


47 posted on 06/13/2012 1:21:35 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: davius
for the same reason that time flies like an arrow, but fruit flies like a banana
48 posted on 06/13/2012 1:24:28 PM PDT by from occupied ga (Your government is your most dangerous enemy)
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To: davius
for the same reason that time flies like an arrow, but fruit flies like a banana
49 posted on 06/13/2012 1:24:49 PM PDT by from occupied ga (Your government is your most dangerous enemy)
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To: LibWhacker
Silly me. I thought this was already answered.


50 posted on 06/13/2012 1:25:08 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: OneVike
You are right, they cannot admit He exists,

I don't think that is the problem. Most scientists believe in God.

They are merely trying to understand how he did it.

51 posted on 06/13/2012 1:36:18 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: newheart

I understand what you are sating, but what you fail to realize is thatthe dark matter the scientists are speaking of does not exist. They even admit they cannot prove it exists and that you need faith that it does.

So I am not saying Christ is anything he created, because what they claim exists does not.

taken to the logical conclusion, they are looking for the one thing that holds all things together. They call it dark matter. In truth what they are looking for is Christ as Hebrews 1:1-4 explains. So my analogy was that Christ is the dark matter they are looking for.

I am not saying Christ is a creation, when He is in effect THE Creator.

I hope that clears up the misunderstanding. I have no better way to express that what I say is exactly what you believe. So we are saying the same thing. My original statement was put in a way to open their eyes, not yours.

You could say I did what Paul did when he used the statue to the unknown god to explain the true God to them. Paul was not saying God was a creation as the unknown god was, but instead unknown to them because their eyes and minds were closed to the truth.


52 posted on 06/13/2012 1:38:59 PM PDT by OneVike (I'm just a Christian waiting to go home)
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To: The Cajun
Our space/time reality floating around on and the results of a more basic reality with not necessarily the same laws of physics..........I could go for that.

Even if we thought we were the center of the Universe , and everything was created just for us, what difference would it make?

53 posted on 06/13/2012 1:39:54 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: Errant; cuban leaf
Problem is, to push it depends on some sort of as-yet undetected “ether”.

Like quantum foam. The ground floor of atomic movement? The "ohmmmmmmmmm' that God continuously utters that is the basis for the existence of matter and energy?

54 posted on 06/13/2012 1:44:29 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: UCANSEE2

I would like to think most scientists are like Copernicus and other early scientist who studied the creation to understand the Creator, but alas, I disagree.

By far and large the vast majority do Not believe in the God of the Bible, the One and Only true God. Their god is much too small to create the world in 6 days, let alone create man without some sort of evolution.

If the true God who cannot lie, lied about the number of days and how he created us, then He is not a true God. Their god is much, much too small to be the same as my God.


55 posted on 06/13/2012 1:46:13 PM PDT by OneVike (I'm just a Christian waiting to go home)
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To: BenLurkin
They why are gravity wells like dimples in the fabric of space time?

You should see it from the other side.

56 posted on 06/13/2012 1:46:38 PM PDT by UCANSEE2 (Lame and ill-informed post)
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To: cuban leaf
You recommending? :)

I checked out the reviews and from them, the author must cite evidence that the inverse square law applies to both? Many forces in God's universe share that characteristic. I may have to download it on kindle, sounds interesting.

Thanks,

57 posted on 06/13/2012 2:12:12 PM PDT by Errant
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To: UCANSEE2
The "ohmmmmmmmmm' As in wave frequency, IMO. The continuous nature is certainly just one of the many of God's mysteries yet to be revealed... ;)
58 posted on 06/13/2012 2:18:04 PM PDT by Errant
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To: UCANSEE2
You should see it from the other side.

LOL, Maybe we are!

59 posted on 06/13/2012 2:19:26 PM PDT by Errant
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To: UCANSEE2
They are merely trying to understand how he did it.

I agree that the really smart ones are/were.


60 posted on 06/13/2012 2:23:35 PM PDT by Errant
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