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Sabine Hossenfelder: Are dark matter and dark energy scientific?


Hossenfelder, the author of Lost in Math: How Beauty Leads Physics Astray, argues that dark matter and dark energy could be wrong but that they are in principle reasonable hypotheses:

It’s not only one prediction that does not fit to observations, it’s many different ones. For dark matter it’s that galaxies rotate too fast, galaxies in clusters move too fast, gravitational lenses bend light too strongly, and neither the cosmic microwave background nor galactic filaments would look like we observe them without dark matter. I explained this in detail in an earlier video.

For dark energy the shooting gun signature is that the expansion of the universe is getting faster, which you can find out by observing how fast supernova in other galaxies speed away from us. The evidence for dark energy is not quite as solid as for dark matter. I explained this too in an earlier video.

So, what’s the scientist to do when they are faced with such a discrepancy between theory and observation? They look for new regularities in the observation and try to find a simple way to explain them. And that’s what dark energy and dark matter are.

Sabine Hossenfelder, “Are dark energy and dark matter scientific?” at BackRe(Action)

Ultimately, of course, they may seem “scientific” principally because they are ideas that appear in a certain form. The question of whether the terms “dark matter” and “dark energy” correspond to anything that actually exists could be a different one.

The Milky Way's halo is displaced dark matter. Dark matter is a supersolid that fills 'empty' space and is displaced by visible matter. The supersolid dark matter displaced by a galaxy, pushing back and exerting pressure toward the galaxy, causes the stars in the outer arms to orbit the galactic center at the rate in which they do. mpc755
As usual, Sabine reports "facts" that are not observations, but inferences. Matter, ordinary matter, doesn't have to have a pressure. Black holes, for example, have no pressure. The mistake is thinking that "dark matter" is a small particle, when in fact, it has to be larger than a pea and smaller than an asteroid (from collision cross-sections calibrated at the Bullet supercluster.) Likewise, "dark energy" is neither dark nor energy, but a pressure. So Sabine is correct that there need be no connection between them, but this mysterious swap of attributed properties does seem more than a coincidence... Robert Sheldon

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