
Zombie physics: Baffling results that won't die - Oatseller
http://www.nature.com/news/zombie-physics-6-baffling-results-that-just-won-t-die-1.18685
======
rubidium
One not on the list: possible influence of solar neutrinos on nuclear decay
rates. I'm not sure of the current state of this research, but last I heard 4
years ago it was still an un-resolved question.

[http://news.stanford.edu/news/2010/august/sun-082310.html](http://news.stanford.edu/news/2010/august/sun-082310.html)

~~~
_rpd
Here's a recent summary ...

> Concerning the variability of beta-decay measurements

> (Submitted on 20 Oct 2015)

> Many experiments have been carried out to study the beta-decay rates of a
> variety of nuclides, and many - but not all - of these experiments yield
> evidence of variability of these rates. While there is as yet no accepted
> theory to explain patterns in the results, a number of conjectures have been
> proposed. We discuss three prominent conjectures (which are not mutually
> exclusive) - that variability of beta-decay rates may be due to (a)
> environmental influences, (b) solar neutrinos, and (c) cosmic neutrinos. We
> find evidence in support of each of these conjectures.

[http://arxiv.org/abs/1510.05996](http://arxiv.org/abs/1510.05996)

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biswaroop
Can someone explain why the CMB map in the first image is so suggestively
annotated? The original looks far more isotropic:
[http://bit.ly/1MBURTA](http://bit.ly/1MBURTA)

~~~
rubidium
To demonstrate the strange fluctuations. They just used a different colormap
than "the original" (which, by the way, is just one more popular colormap
chosen to represent the data).

Don't worry though, this isn't just an artifact of the colormap. There's been
work done to show that the hot and cold spots are statistically anomalous,
thus this Nature article.

~~~
biswaroop
Hmm. The official source says "In this image the anomalous regions have been
enhanced with red and blue shading to make them more clearly visible."
([http://bit.ly/1MBXXHg](http://bit.ly/1MBXXHg))

That sounds a bit more than a different colormap :)

Also, can't we explain the dipolar variation with some motion in some
direction we haven't accounted for (in our local cluster for instance)? I
imagine that quadrupole and octopole variations are harder to explain through
motion.

~~~
contravariant
>Also, can't we explain the dipolar variation with some motion in some
direction we haven't accounted for (in our local cluster for instance)? I
imagine that quadrupole and octopole variations are harder to explain through
motion.

As far as I know that shouldn't be the case. There's no standard frame of
reference with respect to which you can move, so for nearly all intents and
purposes the earth might as well be standing still. There's also not really
any way to 'move' with respect to the CMB; it's always the same time (i.e.
distance) away. And at the time of it's creation particles were (presumably)
moving in random directions at random speed, with no specific average (or if
you want to be precise, with a Lorentz invariant speed distribution).

Searching for 'CMB Lorentz violation' does turn up a few results, but most of
those seem to be pure conjecture, I couldn't find any experimental evidence
either way.

~~~
biswaroop
> There's no standard frame of reference with respect to which you can move

But a Doppler shift from the Earth's motion would create a dipolar pattern in
the CMB wavelengths. I mean there is an obvious dipole in the CMB due to the
solar system's motion
([http://ned.ipac.caltech.edu/level5/March05/Scott/Scott2.html](http://ned.ipac.caltech.edu/level5/March05/Scott/Scott2.html)).
I just wondered if we're neglecting the motion of some local cluster.

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pavel_lishin
Hypothetically, if there are sentient critters composed of dark matter, would
black holes be a total mystery to them? Since we only really interact with
dark matter gravitationally, would they just see inexplicable gravitational
point-masses with absolutely nothing there to cause them?

~~~
biswaroop
They would still 'see' gravitationally active stars turning into black holes.
They would infer a form of anomalous radiation from seeing the stars
collapsing, and they would guess that there are other fields that interact
with this other form of matter.

~~~
pavel_lishin
That's assuming that there are DM stars in the same place that our stars are
(which is probably a safe assumption to make, if DM stars exist at all.)

~~~
ars
A particle that interacts only with gravity can not make a star.

~~~
pavel_lishin
I'm hypothesizing that dark matter can interact with itself, just as our
matter can interact with itself.

~~~
ars
It's more complicated than that. Think about it from an energy point of view -
if it interacts with something it makes (transforms) energy.

Where does that energy go? Normal particles get hot and make blackbody
radiation, i.e. photons.

Dark matter can't. Does it have a temperature? Can temperature flow between
the particles? Without blackbody radiation you are going to have some
violations of the laws of thermodynamics.

Unless dark matter has some other particle to act as an equivalent. So you are
hypothesizing an entire family of dark matter particles, and a whole set of
new forces.

Two entire universes each with entire sets of particles, that only interact
via gravity. We could have a second sun and a second earth, that overlap us
and never know it, we would just think that the gravitational constant is
different (because our perceived mass is higher).

Sounds like a wonderful setting for a science fiction/horror story.

~~~
pavel_lishin
There was a story on HN not too long ago about a proposed Dark QCD - implying
different kinds of Dark Matter, Dark Chemistry, etc., a whole "parallel
universe" of Dark Matter.

And yup, my friends and I have been brainstorming story ideas all morning!

------
gepoch
I was relieved to find nature.com and real physics here. My immediate
assumption was that this was going to be clickbait about perpetual motion and
such.

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cozzyd
I remain pretty convinced by the argument in
[http://arxiv.org/abs/1210.5501](http://arxiv.org/abs/1210.5501) that DAMA is
not seeing dark matter.

------
beamatronic
We are seven billion intelligent beings, with significant resources,
intelligence, and motivation, and we still don't fully understand "reality".

That is just humbling.

~~~
api
Why should it be easy for us to understand the system that (we assume) gave
rise to us? In fact, there are numerous arguments via things like Godel's
theorem that it _should be hard by definition_ to understand one's
"container."

~~~
Lambdanaut
I'm curious to hear about those arguments.

My intuition tells me that what makes it hard is that if you are part of the
system trying to understand the full system, you must change the system in
order to observe it. In effect, you can never have a perfect model of the
system because the system will always be affected by the model you build.

~~~
api
I'd suggest googling Godel's incompleteness theorem for starters. It proves
that within any given system of rules there exist valid theorems that cannot
be reached by only logical 'graph traversal' of the state space represented by
that system. All systems of rules have 'islands of unreachable truth' within
them. (My attempt at a summary.)

A lot of people maybe read _too much_ into it, but it's a very interesting and
profound theorem. Among other things it more or less proved that attempts to
logically deduce all possible theorems of mathematics from axioms -- which
were popular at the time -- are futile because this is impossible. It's
related in some ways to the Church-Turing thesis, which also proved such
efforts impossible by showing that the halting problem is not solvable... you
could never enumerate all the theorems of mathematics because it's impossible
to tell if you're done.

~~~
escherplex
Pragmatic implications of Godel's theorem are that by extension it is possible
to derive ambiguities in any formal system. And as to the possibility of
formulating a 'general theory of everything' it's good to remember that the
one thing a knife can't cut is itself. Attempt 'Gnothi Seauton' as the old
Greeks put it. Meaning understand self before seriously attempting to employ
received cognitive analytical functionalities to understand other stuff. But
then Kantean musings about what it is that's doing the understanding crop up,
which can go on forever.

