[ExI] Dark mass = FTL baryons?

John Clark johnkclark at gmail.com
Thu Aug 24 18:32:58 UTC 2017

On Thu, Aug 24, 2017 at 12:00 AM, Stuart LaForge <avant at sollegro.com> wrote:

> ​> ​
> I too share this concern, which is why I take my calculations using the
> Botlzmann distribution with a grain of salt.

​Boltzmann ​
​is useless in finding the speed of particles in a gas in temperatures more
than a hundred thousand degrees or so, you could go a bit higher if the
particles are very heavy and a bit less if the particles are very light.​

> ​> ​
> But that being said, we aretalking about conditions in the first
> microsecond of the big bang. I don't
> ​ ​
> think SR or GR is of much use here either. How can the speed of light in a
> ​ ​
> vacuum be meanigful if there is no vacuum yet, only a superheated
> ​ ​
> quark-gluon plasma that light cannot penetrate?

​Saying the speed of light is the fundamental speed limit in the universe
is true but a bit misleading, it would be better to say that 186,000 miles
a second is the fundamental speed of causation and light is just one of the
things that reaches that limit. The effect gravity has is also limited by
that speed so you could just as easily say light moves at the speed of
gravity. The strong and weak nuclear forces are also limited by that same
fundamental speed limit of causation.

And there was plenty of light a
 after the Big Bang but you couldn't see anything except a super bright
uniform glow because the photons kept being diffused so there was no way to
form a

​> ​
> I don't use the term tachyon for precisely this reason. Space noodles are
> ​ ​
> different from
> ​ ​
> tachyons in a number of ways: They are protected from
> ​ ​
> interacting with observers by event horizons.

​If that's true then they can never effect any of our observations, but we
observe that galaxies hold together even though there is not enough regular
matter in them to produce the required amount of gravity to do so. ​

​> ​
> space-noodles would hardly seem to move at all
> ​ ​
> in the short time they manifest in our causal domain. You don't get much
> ​ ​
> slower than standing still.

​I don't understand, the title of this thread is "​
Dark mass = FTL baryon

​> ​
> This is actually a pretty good explanation although I still don't see why
> matter without chemistry would form intersecting filaments instead of
> clouds. Why isn't dark matter spread uniformly throughout the universe in
> thermal equilibrium. Why is it clumping?

​There is no simple answer to that, you've got to do huge supercomputer
simulations on what would happen if everything started out very hot and
space was expanding and there was one type of matter that was effected by
gravity and electromagnetism (regular matter) and another type of matter
that was 6 times as plentiful that was just effected by gravity (Dark
Matter) and see what happens. In the simulations if you make the Dark
Matter particles very light then they're still moving pretty fast and they
do indeed form a uniform cloud, and in that simulated universe galaxies
never form which is obviously inconsistent with observation.

However if you assume Dark Matter particles are very heavy, from a few
hundred times the mass of the proton all the way up to the mass of a human
cell, then they would form filaments and galaxies of regular matter would
form in that simulated universe, and that is consistent with observation.

> Any particles that massive would have had to freeze out of the
> quark-gluon plasma of the big bang fire ball *before* protons when the
> universe was even younger and hotter.

Physicists have a pretty good understanding of the quark-gluon plasma era
of the universe but they don't understand Dark Matter, so it must have come
into existence well before that, and we know very little about that era.

> So where did all that thermal kinetic energy go? WIMPs don't interact
> with light or matter except gravitationally, so it could not have
> radiated any of the energy away.

Einstein said energy can be converted into matter, M = E/C^2.

> The paper's figure of 54 meters per second doesn't even begin to make sense.
> How are WIMPs able to stay in the galactic halo, where orbital speeds are
> on the order of 150 km/s at such a puny speed? Any WIMPs moving that slow
> should have been gobbled up by central black hole of any galaxy long ago.

Dark Matter particles very rarely fall into the central black hole because
they'd have to be heading directly toward it and all black holes are very
small targets.  For a particle of matter (dark or regular it makes no
difference) in orbit around a black hole (and it will be in orbit unless it
is heading directly toward it) to actually spiral into it the angular
momentum of the particle must be reduced and by a lot because the Black
Hole is so small.  When any sort of matter, dark or regular, gets close to
a black hole it is moving very fast, but to spiral in it's got to slow down
and get rid of most of that angular momentum.  Regular particles can do
that by interacting with other particles, but Dark Matter particles can't
so unless they're precisely aimed at it they never fall in.

 John K Clark

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