At Aeon, we are asked to consider the “superfluid universe.” Physicist Sabine Hossenfelder offers:
Quantum effects are not just subatomic: they can be expressed across galaxies, and solve the puzzle of dark matter
Most of the matter in the Universe is invisible, composed of some substance that leaves no mark as it breezes through us – and through all of the detectors the scientists have created to catch it. But this dark matter might not consist of unseen particle clouds, as most theorists have assumed. Instead, it might be something even stranger: a superfluid that condensed to puddles billions of years ago, seeding the galaxies we observe today.
This new proposal has vast implications for cosmology and physics. Superfluid dark matter overcomes many of the theoretical problems with the particle clouds. It explains the long-running, increasingly frustrating failure to identify the individual constituents within these clouds. And it offers a concrete scientific path forward, yielding specific predictions that could soon be testable.
Superfluid dark matter has important conceptual implications as well. It suggests that the common picture of the Universe as a mass of individual particles bound together by forces – almost like a tinker toy model – misses much of the richness of nature. Most of the matter in the Universe might be utterly unlike the matter in your body: not composed of atoms, and not even built of particles as we normally understand them, but instead a coherent whole of vast extension. More.
Proposals such a this take us well beyond the usual view of dark matter as collisionless particles that do not emit light.
Rob Sheldon writes to say in response:
In a previous post, I mentioned how the idea of a “second dark matter inflation” was a 4th epicycle on the whole “fine-tuned” Big Bang problem. That is, to avoid the conclusion that the Big Bang is designed, physicists have come up with a series of ad hoc explanations that add epicycles to epicycles.
This discussion is a different way to put lipstick on the pig, let’s call it the 4′ epicycle. Instead of invoking a second magical “inflation” for dark matter, this author thinks we could get by with a semi-magical “superfluidity” for dark matter. In both cases 4 and 4′, the problem is that dark matter should have collected in the center of the galaxy that it helped to form. Since it isn’t concentrated there, then there must be a new property of dark matter that prevents its clumping. Epicycle 4 suggested “inflation”, epicycle 4′ suggests “superfluidity”, in both cases it is an “anti-clumping” artifice.
Unlike an inflation that has never been observed, superfluidity was observed and explained in the 20th century as a quantum property of helium-3. What is weird about this paper, is that quantum phenomena aren’t supposed to be observed over distances of millimeters, and with galaxies she’s talking distances of light-years. For the record, that’s some 18 orders of magnitude bigger. If quantum mechanics had that kind of a range, we’d all be living in Gamow’s world of Mr Tompkins.
Philosophically, physicists have become so convinced of the reality of exotic particular dark matter, despite having never seen it, that they are willing to build entire castles out of their poker cards. A century ago, Ernst Mach argued that we should not accept the existence of atoms unless we had seen them, and Einstein took to heart this radical realism, this anti-metaphysicalism of Mach when he proposed his “Special Theory of Relativity”. Other scientists had done all the math–principally Poincare and Lorentz–but it took Einstein to reject the “classical” metaphysics of Newton and Kant, and accept the results of experiment as “real.”
The point of this article is that physicists are engaging in the exact same behaviors as the turn-of-the-century physicists who added epicycles like the “Fitzgerald-contraction” to keep the Newtonian universe happy in the face of contrary evidence. Being able to reject the status quo, being able to “question everything” is not a common trait, but Einstein had it.
And the common wisdom about “dark matter” is that it is an exotic particle without interactions like a neutrino. But what if it is not exotic at all?What if it is something as ordinary as black comets–which release jets of steam when encountering a star, and thus are repelled by the high star densities of the center of galaxies, and thus, all the attributes of dark matter can be represented by ordinary objects with ordinary physics. Why is this so controversial? Could it be because particle physicists are accorded more esteem, more funding than astronomers?
What I find most fascinating about these conundrums, is their sociological aspects. Like the “New Synthesis” in Darwinism, the intractable problems are neither biological nor mathematical, but always sociological. More so now than ever, because science is now done as a group project, with hundreds or thousands of kibbitzers, willing to start a twitter storm over every perceived political blunder. No wonder science has stalled in the 21st century!
See also: Rob Sheldon on the epicycles of today’s cosmology
Arrow of time points to missing dark matter?
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Big Bang exterminator wanted, will train
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