Is Dark Matter a Glimpse of a Deeper Level of Reality?

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?

Like smaller than 53.025×10(to the minus 36 power) ft...

The fabric of the universe is indeed finely-woven.

Exodus 26 “1 Make the tabernacle with ten curtains of finely twisted linen and blue, purple and scarlet yarn, with cherubim woven into them by a skilled worker. 2 All the curtains are to be the same size —twenty-eight cubits long and four cubits wide. 3 Join five of the curtains together, and do the same with the other five. 4 Make loops of blue material along the edge of the end curtain in one set, and do the same with the end curtain in the other set. 5 Make fifty loops on one curtain and fifty loops on the end curtain of the other set, with the loops opposite each other. 6 Then make fifty gold clasps and use them to fasten the curtains together so that the tabernacle is a unit.

“They even admit they cannot prove it exists and that you need faith that it does.”

I don’t normally comment on threads about religion because I won’t enter a debate where the final argument is the point of a gun, but this is a science thread so here we go.

Scientist’s don’t take anything on faith. you are confusing theory with faith. A theory is just a framework to describe an as yet undiscovered and unproven phenomenon. It is a guess as to what might be behind some measurable effect on the perceived universe. In order to become fact a theory needs to be proven with evidence. Scientist prove a theory by trying to falsify it. Faith by definition is belief without evidence or proof. Faith needs no proof. Faith and reason are opposites. The reason something is taken on faith is that it can not be taken in reason. When a scientist comes upon evidence that proves his theory wrong he throws it out or changes it to fit the new data. With every theory he or she throws out he lessens the pool of possible answers and moves closer to the truth. Scientists don’t have faith that the sun will rise tomorrow, they have a conviction based on the fact that it has risen every day for billions of years.

When faith is confronted by contrary evidence it simply denies that the evidence exists or that existence exists. Or it invalidates man’s reason or his faculties of perception.

I love getting into anything that attempts to bust paradigms in the vein of “Everything you know is wrong”. Two subjects over the last 20 years especially fascinated me. The “gravity may actually push” theory is one. The other is Thomas Gold’s theory that oil is not a fossil fuel, but is abiotic.

And both of these theories are supported by new discoveries (e.g. methane on Titan). They may both be on to something.

I’ve said, since I was a kid, that technology seems to solve our problems just when we think we’ve hit a wall. And since I became a Christian, I believe God planned it that way.

I am not the one who said they have faith instead of proof. It was a leading scientist. Read what I posted in comment #12.

In the article it quotes Sean Carroll, a cosmologist at the University of Chicago, as saying,

"No matter what you do [in devising new theories] you're going to have to believe in dark matter."

The quote above is from an article that was published by SPACE.com in 2007, but tie this into the current up to date information we have that shows they are still searching for evidence to prove their theory that, what they call dark matter exists. Below is an excerpt from Phys.org about the lack of dark matter in Sun's neighborhood,

The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighborhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts. But a new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful.

If you read down through the article you learn they have yet to even be able to detect dark matter in laboratories here on Earth. They cannot detect it anywhere, yet we are told to believe in something not proven, that is what faith is my friend.

despite the fact that it has resisted all attempts to clarify its nature, which remains obscure. All attempts so far to detect dark matter in laboratories on Earth have failed.

So we have a theory that we are told we must believe in. Sorry, but when I am told that I must believe in something we now know has yet to be proved exists, that is faith.

I can offer more proof that God exists then they can give that what they call dark matter exists. Until they prove it exists, it is but a theory, just like evolution.

However, I stand by my assertion that the elusive element they call "Dark Matter", or cosmic glue, is Christ Jesus. Until they admit that fact, they will forever have to have faith in something they will never prove exists in the form they want it to exist.

“Their true venue is a ginormous abstract realm of possibilities”

I suggested before in this forum that scientists are being dragged kicking and screaming toward the concept of a Supreme Being, one both immanent and transcendent. Add the concept of “divine Will” to a “ginormous” (read unbounded) “abstract realm of possibilities”, and you start to get close. You can think of “divine Will” as the path from “abstract realm of possibilities” to a “manifested reality”.

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