
Entropy and Symmetry - squidproquo
https://www.nature.com/articles/s41598-019-46765-w
======
credit_guy
This is either quackery or a Nobel prize worthy breakthrough. I'm inclined to
go with the first.

Basically they say they can explain the galaxy rotation speed problem using
some novel concepts of entropy and information instead of traditional
explanation involving dark matter. If they are right, this will bag them a
Nobel prize with 100% certainty.

But I'm afraid they aren't right.

* neither author is an astrophysicist

* one's interests are [1] :"Current interests include flexgrid & elastic optical networking technologies (subsystems & devices) & architectures, converged wireless-wireline access networks (5G), theory of information & entropy, cryptography & security."

* the other author describes his interests as follows [2]: "My own interest is accurate ion beam analysis (including RBS and PIXE) using a 2MV Tandem"

* 5G networks and ion beams don't have much in common with cosmology

* the second author is also considered a Biblical scholar [3]. Here's one little glimpse into how he understands the world: "The Kingdom is about the return of the glory of God. Which widgets you have in your pocket is hardly relevant to that."

[1]
[https://www.researchgate.net/profile/Michael_Parker12](https://www.researchgate.net/profile/Michael_Parker12)

[2]
[https://www.researchgate.net/profile/Chris_Jeynes](https://www.researchgate.net/profile/Chris_Jeynes)

[3]
[https://www.churchtimes.co.uk/articles/2018/8-june/features/...](https://www.churchtimes.co.uk/articles/2018/8-june/features/interviews/interview-
chris-jeynes-material-scientist-and-biblical-scholar)

~~~
FiatLuxDave
Judging a paper by the background of the authors is a sure sign that you were
not able to read the paper and understand it. There is no actual astrophysics
in this paper, only Lagrangian mechanics, geometrical algebra and information
theory. Anyone who works with ion beams uses Lagrangian mechanics. Anyone who
works with rf networks uses information theory. So, I'm not sure why their
backgrounds would be a problem here. And seriously, holding someone's
mainstream religious beliefs against them? That's just plain uncivil. I
apologize if this is harsh, but I think that responding here is better than
just downvoting you.

All that said, I agree with a part of your assessment, but for other reasons.
The crux of the paper is a transformation from Lagrangian mechanics (in other
words, the motion of particles with no frictional forces) into a form of
'entropic mechanics' used for calculating the entropy of a certain
configuration of particles. They defined this transformation using a
coordinate system which matched the spiral/helical shape that they were
focusing on (see Eq 9a). In a way, this is a bit of a cheat, because had they
used a fixed cartesian coordinate system I suspect the model would produce
highest entropy when particles aligned with the x,y,z axes.

However, the interesting part of the paper is where they make an independent
prediction of the energy to change B-DNA to p-DNA. This is the only non-
tautology prediction in the paper, and it is interesting that their model
gives a prediction close to the measured value. This means that their
alternate 'entropic mechanics' means of calculation might be useful because it
could simplify complex calculations.

The galactic stuff is basically a tautology. First, they are only calculating
shape, and not doing anything with the velocity distribution (which is where
the dark matter problem comes from). They say that most of the entropy is in
the SBH in the galactic center, but then when they try to calculate the
temperature of the remaining galaxy, they make a stability assumption that
just happens to give the galaxy a thermodynamic structure which matches their
spiral form (section right before eq 27a). Amazingly, this give a maximum
entropy when the galaxy has a spiral structure!

So, from reading the paper only once, my assessment is a) this method could be
useful for calculating entropy for particles in fixed geometries, b) the
galaxy stuff is crap.

~~~
credit_guy
> Judging a paper by the background of the authors is a sure sign that you
> were not able to read the paper and understand it.

Reading a paper requires some effort. The more familiar you are with the
topic, the less effort you invest, but the effort is there.

It's valuable then to apply some heuristics to decide if a paper is worth
reading or even skimming. One such heuristic is if the paper makes it to the
front page of HN, or, say, if it's published in Nature. Based on this, a lot
of people could waste some time they better spend doing something else.

If someone comes and points out some red flags, that's a service to the
community. That service comes at a risk to one's own karma, as it's threading
the boundary of what the HN community thinks is good discourse (for example
the charity principle). Pointing out red flags without pointing out actual
errors in the papers can be easily equated with ad-hominem attacks (believe
me, I thought ten times before deciding about quoting the second author's
thoughts on God).

I still decided that this is a good case to put my karma at risk: the claim
that some new information-entropy force can explain the missing mass in the
Universe is too important to ignore.

That said, your more informed analysis obviously adds much more value than my
superficial one, so thank you for that.

~~~
FiatLuxDave
I appreciate your measured response to my harsh criticism.

I agree with you that some claims are too important to ignore. I can tell that
you believe that you were adding value, and I cannot fault you for that.
However, the red flags which you see as a useful heuristic, I tend to see as
anti-useful. Perhaps we may just disagree on that.

~~~
credit_guy
> I tend to see as anti-useful

I hope to be able to change your view.

Consider hypotheses A and B below:

A: A CS researcher who specializes in 5G networks, and who does not describes
his interests as including astrophysics, makes a breakthrough discovery that
provides a correct alternative to dark matter B: non-A

Which one is more probable? I would say B easily by a factor of 100.

Let's consider 2 other hypotheses: C: someone who can read a paper and point
to its conceptual flaws lists some red flags about its authors D: that person
actually can't read the paper

I guess D is about 100 times more likely than C, isn't it?

Considering that we all engage in probabilistic inference like that, why is it
wrong to communicate its conclusions?

You may have 2 answers to that:

1\. it's against the old adage to critique the work, not the person; I'm
pretty sure that's the answer

2\. the uneducated masses should refrain from criticizing the ivory tower. And
considering that they can't really understand the math, that means they
shouldn't even try to use lateral heuristics, even if they try to give them
the mathematically sounding label of "probabilistic inference". If there was
no Markov Chain Monte Carlo or variational Bayes involved, it's not
probabilistic inference :)

------
squidproquo
Here is a link to a news article that less technical:
[https://www.newsweek.com/milky-way-dark-matter-
kepler-145323...](https://www.newsweek.com/milky-way-dark-matter-
kepler-1453239)

