Thursday, 22 June 2017

Dwarf galaxies: gravity is not entropic

A lonely galactic islandDoes space-time emerge from a network of quantum bits? That’s the theory behind emergent gravity, an idea most recently proposed by Erik Verlinde, a theoretical physicist at the University of Amsterdam. His theory does away with the need for dark matter — unseen particles that appear to affect the behaviour of galaxies and other large-scale structures in the universe. But a recent test of emergent gravity shows that it doesn’t appear to do as good a job of describing the motions of astronomical objects as its theoretical rival.

Left: Dwarf galaxies such as DDO 190, shown here, behave as though they’re filled with unseen dark matter.



THIS ARTICLE IS FROM THE BLOG ‘VERITAS’ Which is “cosmology from a Conservative view

Verlinde has already joined the community of fraudulent pseudoscientists who keep on "working" on something they must know to be complete rubbish

In the text Researchers Check Space-Time to See if It’s Made of Quantum Bits, the Quanta Magazine describes a fresh paper by Kris Pardo (Princeton U.) which tested some 2016 dark matter "application" of Erik Verlinde's completely wrong "entropic gravity" meme. Verlinde has irrationally linked his "entropic gravity" meme with some phenomenological, parameter-free fit for the behaviour of galaxies. What a surprise, when this formula is compared to dwarf galaxies which are, you know, a bit smaller, it doesn't seem to work.

ENTROPIC = Thermodynamics. (on a macroscopic scale) a function of thermodynamic variables, as temperature, pressure, or composition, that is a measure of the energy that is not available for work during a thermodynamic process. A closed system evolves toward a state of maximum entropy.

The maximum circular velocities are observed to reach up to 280 km/s but the predicted ones are at most 165 km/s. So it doesn't work, the model is falsified. This moment of the death of the model is where the discussion of the model should end and this is indeed where my discussion of the model ends.

But what I want to discuss is how much this branch of physics has been filled with garbage in a recent decade or two. I don't actually believe that Erik Verlinde believes that his formulae have any reason to produce nontrivially good predictions.

What he did was just to find some approximate fit for some data about a class of galaxies – which is only good up to a factor of a few (perhaps two, perhaps ten). It's not so shocking that such a rough fit may exist because by construction, all the galaxies in his class were qualitatively similar to each other. That's why only one or a small number of parameters describes the important enough characteristics of each galaxy and everything important we observe must be roughly a function of it. When you think about it, the functional dependence simply has to be close enough to a linear or power law function for such a limited class of similar objects.

3A33FBB700000578-3920096-image-a-1_1478696727082And this fit was "justified" by some extremely sloppy arguments as being connected with his older "entropic gravity" meme. It claims that gravity is an entropic force – resulting from the desire of physical systems to increase their entropy. This is obviously wrong because the gravitational motion would be unavoidably irreversible; and because all the quantum interference phenomena (e.g. with neutrons in the gravitational field) would be rendered impossible if there were a high entropy underlying the gravitational potential even in the absence of the event horizons.

So his original meme is wrong and it contradicts absolutely basic observed facts about the gravitational force between the celestial bodies, such as the fact that planetary orbits are approximately elliptical. But the idea of this Verlinde-style of work is not to care and increase the ambitions. While his theory has no chance to correctly deduce even the Kepler laws, he just remains silent about it and starts to claim that it can do everything and it may even replace dark matter if not dark matter and dark energy.

An even stinker package of bogus claims and would-be equations is offered to "justify" this ambitious claim in the eyes of the truly gullible people, if I avoid the scientific term "imbeciles" for a while. Astrophysicists at Princeton feel the urge to spend their time with this junk. Needless to say, the "theory" is based on wrong assumptions, stupidities, and deception about connections between all these wrong claims and the actual, observed, correct claims. It has no reason to predict anything else correctly and it doesn't.

Verlinde's statement after his newest theory was basically killed is truly Smolinesque:

This is interesting and good work. [But] emergent gravity hasn’t been developed to the point where it can make specific predictions about all dwarf galaxies. I think more work needs to be done on both the observational and the theory side.

Holy cow. It's not too interesting work. It's just a straightforward paper showing that Mr Verlinde's "theory" contradicts well-known dwarf galaxy data. But even if it were interesting, it is absolutely ludicrous for Mr Verlinde to present himself as some kind of a superior judge of Pardo's work. He is just a student who tried a very stupid thing and was demolished by his professor who has showed him the actual correct data.

By the way, the excuse involving the word "predictions" is cute, too. Verlinde emits fog whose purpose is to create the impression that the falsification of his delusions doesn't matter because his theory hasn't been developed to predict properties of "all dwarf galaxies". But a key point of Pardo's paper is that it doesn't matter. One may predict certain things statistically and the predicted speeds are generally too low. The mean value of the distribution is low and so are the extremes. One doesn't need to predict and test every single individual dwarf galaxy. Verlinde just wants the imbeciles to think that a test hasn't really been done yet – except that it has. And he suggests that some fix or loophole exists – except that it doesn't.

121216_verlinde_1But what I hate most about this piece of crackpot work and hundreds of others is this Smolinesque sentence:

I think more work needs to be done on both the observational and the theory side.

Promises and begging for others to support this kind of junk in the future, perhaps even more so than so far.

Should more work be done on both sides? No, on the contrary, less work or no work should be done on this "theory" because it was killed; it is, on the contrary, the promising ideas (those that have predicted something to agree with something else we know) that deserve more work and elaboration in the future. Further research will surely kill it even more, but Mr Verlinde will care even less.

If Mr Verlinde were pursuing the scientific method, he would understand that his theory doesn't work, he would abandon it, stop working on it, stop trying to make others work on it, and, last but not least, he would stop receive funding that is justified by this garbage. He should be the first man who points out that the value of this garbage is zero. But sadly enough, he doesn't have the integrity for that and the people around him don't have the intelligence to behave in the way that would actually be compatible with the rules of the scientific method.

And it's not just Smolin and Verlinde. The field has gotten crowded by dozens of sociologically high-profile fraudsters who pompously keep on working on various kinds of crack pottery that have been known to be absolutely wrong, worthless piece of junk for many years and sometimes decades. Entropic gravity, loop quantum gravity, spin foam, causal dynamical triangulation and dozens of other cousins like that, Bohmian theory, many world theory and a dozen of other "interpretations", various nonsensical claims about reversibility of the macroscopic phenomena, Boltzmann brains, and the list would go on and on and on.

Lots of these people are keeping themselves influential by some connections with the media or other politically powerful interests. Imagine what it does to the students who are deciding about their research specialization. Many if not most of them are exposed to a department where a high-profile fraudster like that overshadows all the meaningful and credible research. Many of these students join this bogus research and they quickly learn what really matters in their kind of "science". And they are very different skills from those that their honest classmates need. In particular, they learn to do the P.R. and they learn to say "how much they care about testing" and also they learn to talk about "future work" whenever they are proved wrong in a test, which happens after every single test, and so on. There is an intense struggle going on between genuine science and bogus science and genuine science is losing the battle.

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