Archive for October 17th, 2019

“Fuzzy” Dark Matter & Sub Quantum Physical Reality (SQPR)

October 17, 2019

Abstract: An early Quantum universe would have appeared “fuzzy”, and striated, from Quantum self interference… If one adopts one basic consequence of my own SQPR theory: Dark Matter is made of ultra-light, ultra-low momentum particles. A team of physicists at prestigious institutions by adopting this conclusion of SQPR, one gets a drastically different looking model explaining the filament nature of galaxy distributions. (This completely new approach is indirectly rather supportive of SQPR… and very different from the usual LCDM; it should be testable soon, with new telescopes under construction…)

***

According to official, ruling Big Bang theory, Dark Matter was the starting ingredient for coagulating the very first galaxies in the universe. According to that “LCDM” model, shortly after the Big Bang, particles of Dark Matter clumped together in gravitational “halos,” pulling surrounding gas into their cores, which over time cooled and condensed into the first galaxies. [1] 

Thus a curious situation: Dark Matter is considered the backbone to the structure of the universe, while physicists know very little about its nature, because the DM “particles” have so far evaded detection.

Now scientists at MIT, Princeton University, and Cambridge University have admitted the obvious, namely that the early universe, and the very first galaxies, would have looked very different depending upon the exact nature of Dark Matter.  They simulated what early galaxy formation would have looked like if Dark Matter were “fuzzy,” rather than cold or warm. “Fuzzy” here has a precise definition: it means very low momentum DM “particles”. Such “fuzzy” particles are what my own theory, SQPR is full of, as a consequence of my hypothesis that Quantum Mechanics is LOCAL.

Left is the conventional distribution of galaxies prediction of the conventional Big Bang (“LCDM”). Center is that with “warm” dark Matter. Right is the Quantum “fuzzy” DM model (compatible with SQPR).

Light Mechanics, electromagnetism, is local: this is also called Relativity (Poincaré named it thus). QM being a generalization of Light Mechanics, it is natural that it would be local too: this is the fundamental axiom of SQPR

In that most widely accepted scenario, the so-called LCDM (Lambda Cold Dark Matter) model of the early universe Dark Matter is Cold: it is made up of slow-moving particles that, aside from gravitational effects, have no interaction with ordinary matter (SQPR readily explains why DM doesn’t interact but gravitationally). 

In LCDM, Warm Dark Matter is thought to be a slightly lighter and faster version of Cold Dark Matter (it has been heated by galaxies). 

Fuzzy Dark Matter, is, for official physics, a new concept, something entirely different, consisting of ultralight particles, each about 1 octillionth 10^(-27) the mass of an electron (the Cold Dark Matter particle of LCDM are far heavier — about 100 times more massive than an electron). Repeat: the proposed mass for Dark Matter particles in this new simulation is the mass of an electron divided by 1,000,000,000,000,000,000,000,000,000

Now we are talking. This is the sort of numbers my own theory, SQPR considers.

The Millennium Simulation (below) is an example of an over 10 billion particle simulation that tries to reproduce the cosmic web of dark matter upon which exist galaxy clusters, filaments, and voids we see today. The LCDM (Lambda Cold Dark Matter) model of the universe assumes a flat universe now dominated by a cosmological constant Lambda, Einstein’s Cosmological Constant (Dark Energy?). As I said, the cosmological large structure formation is dominated by cold (non-relativistic) dark matter.

A view of the distribution of dark matter in our universe, based on the Millennium Simulation. The simulation is based on our current ideas about the universe’s origin and evolution. It included ten billion particles, and consumed 343,000 cpu-hours (Image: Virgo Consortium)Researchers found that if Dark Matter is cold, then galaxies in the early universe would have formed in nearly spherical halos, with ten times too much mass there. But if the nature of Dark Matter is fuzzy or warm, the early universe would have looked very different, with galaxies forming first in extended, tail-like filaments. In a fuzzy universe, these filaments would have appeared striated, like star-lit strings on a harp… As observed.  

As new telescopes come online, with the ability to see further back into the early universe, scientists may be able to deduce, from the pattern of galaxy formation, whether the nature of dark matter, which today makes up nearly 85 percent of the matter in the universe, is fuzzy as opposed to cold or warm.

“The first galaxies in the early universe may illuminate what type of dark matter we have today,” says Mark Vogelsberger, associate professor of physics in MIT’s Kavli Institute for Astrophysics and Space Research. “Either we see this filament pattern, and fuzzy dark matter is plausible, or we don’t, and we can rule that model out. We now have a blueprint for how to do this.” [2]

Fuzzy Quantum Waves:

While dark matter has yet to be directly detected, the hypothesis that describes dark matter as cold has proven successful at describing the large-scale structure of the observable universe. As a result, models of galaxy formation are based on the assumption that dark matter is cold.

“The problem is, there are some discrepancies between observations and predictions of cold dark matter,” Vogelsberger points out. “For example, if you look at very small galaxies, the inferred distribution of dark matter within these galaxies doesn’t perfectly agree with what theoretical models predict. So there is tension there.” This is a euphemism: According to LCDM, the heavy DM particles should sink towards the core of galaxies, and this is exactly what is not observed. 

Enter, then, alternative theories for dark matter, including warm, and fuzzy, which researchers have proposed in recent years.

“The nature of dark matter is still a mystery,” Fialkov says. “Fuzzy dark matter is motivated by fundamental physics, for instance, string theory, and thus is an interesting dark matter candidate. Cosmic structures hold the key to validating or ruling out such dark matter models.”

Fuzzy dark matter is made up of particles that are so light that they act in a quantum, wave-like fashion, rather than as individual particles. This quantum, fuzzy nature, Mocz says, could have produced early galaxies that look entirely different from what standard models predict for cold dark matter.

“Even though in the late universe these different dark matter scenarios may predict similar shapes for galaxies, the first galaxies would be strikingly different, which will give us a clue about what dark matter is,” Mocz says.

To see how different a cold early universe could be, relative to a fuzzy early universe, the researchers simulated a small, cubic space of the early universe, measuring about 3 million light years across, and ran it forward in time to see how galaxies would form given one of the three dark matter scenarios: cold, warm, and fuzzy.

The team began each simulation by assuming a certain distribution of dark matter, which scientists have some idea of, based on measurements of the cosmic microwave background — “relic radiation” that was emitted by, and was detected just 400,000 years after the alleged Big Bang. Dark matter doesn’t have a constant density, even at these early times. There are tiny perturbations on top of a constant density field. Those perturbations would gather more Dark Matter, nonlinearly.

The researchers were able to use existing algorithms to simulate galaxy formation under scenarios of cold and warm dark matter. But to simulate fuzzy dark matter, with its quantum nature, they needed to bring in the Quantum.

A cosmological map of Interfering Quantum strings:

To the usual simulation of cold dark matter were added two extra equations in order to simulate galaxy formation in a fuzzy dark matter universe. The first, Schrödinger’s equation, describes how a quantum wave evolves in the presence of (potential) energy, while the second, Poisson’s equation, describes how that (self-interfering) quantum wave generates a density field, or distribution of Dark Matter, and how that distribution leads to (uneven) gravity — the force that eventually pulls in matter to form galaxies. They then coupled this simulation to a model that describes the behavior of gas in the universe, and the way it condenses into galaxies in response to gravitational effects.

In all three scenarios, galaxies formed wherever there were over-densities, or large concentrations of gravitationally collapsed Dark Matter. The pattern of this Dark Matter, however, was different, depending on whether it was cold, warm, or fuzzy. 

In a scenario of cold dark matter, galaxies formed in spherical halos, as well as smaller subhalos. Warm Dark Matter produced  first galaxies in tail-like filaments, and no subhalos. This may be due to warm dark matter’s lighter, faster nature, making particles less likely to stick around in smaller, subhalo clumps.

Similar to warm dark matter, fuzzy dark matter formed stars along filaments. But then quantum wave effects took over in shaping the galaxies, which formed more striated filaments, like strings on an invisible harp. This striated pattern is due to constructive interference, an effect that occurs when two waves overlap, similarly to the famous Double Slit experiment. When constructive interference occurs, for instance in waves of light, the points where the crests and troughs of each wave align form darker spots, creating an alternating pattern of bright and dark regions.

In the case of fuzzy dark matter, instead of bright and dark points, it generates an alternating pattern of over-dense and under-dense concentrations of dark matter.

“You would get a lot of gravitational pull at these over-densities, and the gas would follow, and at some point would form galaxies along those over-densities, and not the under-densities. This picture would be replicated throughout the early universe.”Vogelsberger explains.

The team is developing more detailed predictions of what early galaxies may have looked like in a universe dominated by fuzzy dark matter. Their goal is to provide a map for upcoming telescopes, such as the James Webb Space Telescope, that may be able to look far enough back in time to spot the earliest galaxies. If they see filamentary galaxies such as those simulated by Mocz, Fialkov, Vogelsberger, and their colleagues, it could be the first signs that Dark Matter’s nature is fuzzy.

“It’s this observational test we can provide for the nature of dark matter, based on observations of the early universe, which will become feasible in the next couple of years,” Vogelsberger says.

SQPR predicts less “fuzzy” Dark Matter in the earlier universe. However, a lot of the effects described by the MIT team would nevertheless happen, and for the same exact reasons. So the apparition of striated structures would not be surprising… even if LCDM was completely wrong. 

Patrice Ayme

***

***

[1] There is a famous theorem that Newton needed for his celestial mechanics and tried to prove (and may have succeeded to prove; it’s controversial whether he did or not) according to which a ball of mass M acts gravitationally as a point of mass M.

***

[2] Vogelsberger is a co-author of a paper appearing (October 2019) in Physical Review Letters, along with the paper’s lead author, Philip Mocz of Princeton University, and Anastasia Fialkov of Cambridge University and previously the University of Sussex.