
Every Black Hole Contains a New Universe - robg
http://www.insidescience.org/?q=content/every-black-hole-contains-new-universe/566
======
cft
In Einstein's theory of general relativity, Riemann tensor is assumed to be
symmetric, due to great simplification of the theory compared to the one with
non-symmetric Riemann tensor, and an absolute lack of experimental evidence to
the contrary for 100 years since it was discoveried. Torsion, which is the
cause of asymmetry of the Riemann tensor is set to zero. I do not know why
this author is so excited about torsion tensor, the idea that torsion could be
non-zero has been around for at least 90 years, but got zero traction.
Disclaimer : I have a phd in string theory.

~~~
taliesinb
I _don't_ have a PhD in string theory, but would like to make the point that
many times in the history of science ideas that were originally regarded as
uninteresting lie dormant for a long time only to usefully surface much later
in the context of new evidence.

In this case, the researcher seems to be excited _specifically_ because of the
potential of torsion to explain dark energy -- a recently discovered phenomena
(although of course, oddly presaged by Einstein's cosmological constant hack).

~~~
cft
The classical theory of gravity with torsion certainly does not explain dark
matter. The author is trying to build some quantum theory of gravity, where
torsion is required, speculating that it would explain dark matter. I should
add here that the attempts to build a quantum theory of gravity without
torsion failed in the last 100 years (string theory is the best candidate),
and the author is trying to add even more complexity by adding torsion tensor.

~~~
DeepDuh
I'm trying to follow you as a (very interested) layman, so excuse me if I'm
being stupid. Couldn't the failure to build quantum gravity be BECAUSE torsion
has been excluded (which is I believe what the author suggests)? Maybe this is
something that has to be looked into.

I'm thinking that a marriage of physics, mathematics and CS might be necessary
to overcome our limits in understanding these structures. Something like an
IBM Watson for physicists, where a computer is fed with all informations we
have and solves an optimisation problem to come up with a unified theory
explaining all the phenomenons with the least complex solution (i.e. the least
universal constants). Another requirement would be to have 42 as an error code
for all possible failures in the calculation ;).

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taliesinb
Of course headlines have to be catchy, but this universe-in-a-black-hole
concept is hardly a new one. Rather, the novel part here seems to be the idea
that the connection in GR might might possess non-zero torsion, contrary to
what is normally assumed.

In the whole black-holes-create-universes vein, last century the theoretical
physicist Lee Smolin presented the quite delicious idea (described in his book
The Life Of the Cosmos) that entire universes might be subject to the process
of natural selection.

This would work if singularity formation involves the transmission of physical
constants to the 'daughter' universe with slight modification, quite a thing
to suppose given we don't really know what physical constants 'mean'.

If it occurred, this natural selection would optimize these constants for the
production of black holes, which luckily for us co-incides with the production
of life-bearing stars. Of course, all very unfalsifiable, but kinda epic.

~~~
dalke
One SF short story takes this further. The best form of interstellar travel
generates black holes, so the universe is optimized for producing the type of
life which does interstellar travel via that process. No need for coincidences
here, and even more un-falsifiable.

~~~
ctkrohn
What's the name of the short story? Sounds like it could be interesting.

~~~
Zaak
"What Continues... and What Fails..." by David Brin, perhaps?

~~~
dalke
That's the one - thanks!

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cwzwarich
Will theories like this ever produce any new testable predictions, or is this
the modern equivalent of counting angels on the head of a pin?

~~~
eli_gottlieb
Funny thing: the Talmudic sages actually came to a conclusion on how many
angels could dance on the head of a pin. I think it was about 16 or so.

~~~
Groxx
Well, it's obvious in retrospect, but I'd imagine that took some pretty
awesome reasoning powers.

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einhverfr
I am not a physicist but I have a question about this. If matter is being
sucked into a new universe from an old one, I can understand that the mass of
the new universe would count on the old universe's balance sheet if you will,
showing that the sum of matter and energy is still constant, but wouldn't the
new universe be only partially logically self-contained in this regard?
Wouldn't the sum of matter and energy be increasing?

And if our universe is on the inside of a black hole, shouldn't the amount of
energy and matter be increasing here as well? If not, why not? Why don't we
get to suck in fading stars from our parent universe and get an increasing
amount of m or e?

~~~
powertower
I'm not sure that the extra matter ever "enters" the black hole in a
traditional sense...

As matter approaches it (pass the Schwarzschild radius) and increases in
velocity, time slows down more and more for it.

When velocity approaches C, time approaches zero.

Though in another thought, I'd guess that due to the forces involved, the
matter is ripped apart on a sub-quantum scale to the point that it literally
disintegrates into its energy component and basically adds energy to the black
hole (which can be interpreted as mass). But again, it never enters it.

~~~
evanb
This is a well-understood problem in GR. To an outside observer, things never
appear to cross the Schwarzschild radius (R_S), giving the impression that
time stops for in-falling matter when it gets to R_S. This, however, is an
illusion forced on a distant observer.

The stuff that is actually falling into the black hole never notices R_S
because the velocity they measure is not greater than c, and crossing the
event horizon is a completely benign event. It's the later extreme tidal
forces / spaghettification that destroys in-falling matter.

So it is fair to say that stuff enters a black hole.

------
Natsu
So what happens to those universes when Hawking radiation causes the black
hole to evaporate?

And if we're in a black hole, what evidence, if any, do we have for the
effects of evaporation?

~~~
lloeki
Interpreting various equations from my limited knowledge of such a discussed
area, I've come up with this:

Hawking radiation makes a black hole lose mass, hence diminishing its
Schwarzchild radius. The Schwarzchild radius came up because it's a
singularity (in the mathematical sense) in a solution to Einstein filed
equations. The same way matter collapses onto itself up to creating such a
singularity and being encompassed into the now existing event horizon, as soon
as there is not enough mass to sustain the singularity, the event horizon
vanishes, hence the remaining matter "pops" back into our sight.

You could view it otherwise with a thought experiment: take particles out of
the black hole one by one. Each time it will reduce the mass and maybe the
radius. At some point the mass/radius ratio may not be small enough to hold
light and the bubble bursts in plain sight as the event horizon breaks down.
In such a thought experiment, the worst case would be that the black hole
would require every single particle but one to evaporate (unless you assume a
single particle could be a black hole in itself).

An interesting back of the envelope calculation is computing the mass
contained in a Schwartzchild radius of Planck length (the size at which
quantum effects take over).

    
    
        l_P = sqrt(hG/c^3)
        r_s = 2Gm/c^2
    

hence m = sqrt(hc/4G) = 1.0882546265651108e-08 kg which is a bit more than
1e22 electrons sitting at a position 1e-15 smaller than a single one of them.

~~~
astrodust
Is there anything to preclude there being an ultra-massive particle that might
be able to cause a singularity by itself?

The particles we observe today exist in a relatively low-energy environment.
Whatever's going on in the furious intensity that is the inside of a neutron
star that's on the edge of becoming a black-hole could be quite spectacular in
comparison.

------
hkolek
Ok, so if our universe is inside a black hole which is in a "parent" universe
and so on, doesn't there have to be some kind of "root" universe? So where
does that "root" universe come from?

~~~
sigkill
Since there's no concept of space and time "inside" a blackhole, I think it
would be better to think of blackholes as doors to different rooms in a huge
mansion rather than each room having a smaller room contained inside it.

~~~
evanb
Space and time still are well defined inside of a black hole. They only break
down at one point, termed the singularity. But nothing mystical happens and
neither space nor time break down when you pass the event horizon. So there is
indeed a well-formed notion of "inside", as long as you're not in the very
center, where the singularity breaks everything.

~~~
sigkill
A black hole is technically a single point. The part of the hole that we
colloquially refer to is the event horizon. The headline speaks of universes
"inside" a black hole, not an event horizon.

There's a brilliant explanation on reddit by RobotRollCall on this topic. I'll
update my post when I find the link.

~~~
ithkuil
Perhaps you mean this thread:

[http://www.reddit.com/r/askscience/comments/f1lgu/what_would...](http://www.reddit.com/r/askscience/comments/f1lgu/what_would_happen_if_the_event_horizons_of_two/c1cuiyw)

~~~
sigkill
Yes! Exactly that one. Thank you.

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Groxx
So, what happens when black holes collide, and merge into a single one?
Serious question, btw - would we experience it, or does our universe contain
all matter to ever enter our black hole, therefore all it has merged with?

If the latter, how big can black holes get? Can they consume a universe? That
would be a neat end-result - the whole universe goes down the drain, to cause
a new one.

~~~
kylek
interesting notion! who's to say the big bang wasn't caused by a supermassive
blackhole on the other 'side'

~~~
vlisivka
Why you need 'other side'?

Our Universe has disproportion between (visible) matter and antimatter. Black
holes my contain missed anti-matter. So when black hole will consume all
matter of our Universe, it will bang again, without help of any parent
Universe.

~~~
kylek
I said "other 'side'", not 'other side'! (dimensions are silly :) ) However,
I'm not a physicist and really have no idea what I'm talking about :( reading
about cosmology is only a hobby/daydream of mine.

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zellyn
What the article doesn't mention is that the universe inside the black hole is
_exactly the same as this one_. So if you head over to a black hole, dive in,
and travel to earth, everyone welcomes you "back" and asks how it went.

~~~
gpvos
I don't think that that follows in any way from the article. But the idea is
interesting. Care to explain or give references?

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PaulHoule
The esact mechanism of 'Torsion' may not be right, but there have been
indications for a long time that there may be another universe inside a black
hole -- because if you look at the solution to Einstein's equations, there's a
place on 'the other side' that is flat.

If there is some process like cosmic inflation triggered by high energy
densities (like Andre Linde's chaotic inflation) it's pretty believable that
some kind of 'bang' happens when a black hole formss and the output of that
bang fills the 'other side'.

------
vecter
IANAP but if universes could be born from black holes, would they also
disappear if the black hole were to evaporate via Hawking radiation?

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BigTuna
On a related note, I find it very intriguing that the three properties that
distinguish black holes from one another (mass, charge and spin) are the same
ones that distinguish quarks. That's a beautiful symmetry between some of the
smallest and largest things in existence.

------
Sander_Marechal
What impact would this have on scenarios of the end of our universe?

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charlieflowers
Perhaps this helps explain Fermi's paradox (at least partly) ... some of the
many, many aliens we should have found by now might be living either out in
the parent universe, or inside other black holes in our universe. I'm way out
on a limb here, but it's an interesting speculation. Whadda you think?

~~~
tuxcanfly
Fermi's paradox would still hold for _this_ universe, methinks.

~~~
jeffool
Yeah, but there could be a new parenthetical, "likelihood of an alien living
in another universe, multiplied by all the effects of Fermi's Paradox itself,
and multiplied by the likelihood of that alien's ability to traverse
universes."

~~~
mokus
I think that would be a very small extra factor, especially if you also add
the likelihood of that alien's interest in traveling to specifically this part
of this universe.

And of course, we have no reasonable basis for estimating any of those
numbers. We have a sample size of one universe and we don't even know the rate
of occurrence of life in that one. Still, it can be fun to speculate.

------
andrethegiant
Does this mean that black holes can be inside black holes?

~~~
AsylumWarden
Black hole version of inception! <http://www.imdb.com/title/tt1375666/>

Actually, this is much to complicated for my feeble mind. I am sticking with
the "Parallel Universe Box" from the Futurama series
(<http://futurama.wikia.com/wiki/Parallel_Universe_Box>). It makes my head
hurt less.

------
k3liutZu
So Black Holes are actually closures

------
ygmelnikova
"You're very clever, young man, very clever," said the old lady. "But it's
turtles all the way down!

------
gcb
With my highschool physics i was lost at "since energy can create matter"...

------
twsted
Sheldon Cooper, what do you think? Bazinga?

------
SagelyGuru
Black holes and dark matter are likely to be just artificial constructs to
rescue certain mistaken orthodoxies of astro physics.

Electrostatic force is much much stronger than gravity. It is known to be
ubiquitous both on micro (sub-atomic) scale and on macro (cosmic) scale.

Once you acknowledge its existence, it is no longer necessary to postulate
black holes in the centres of galaxies to hold them together.

~~~
Retric
I hope your kidding, but if your both serious and not trolling:

Like charges repel and opposite charges attract which prevents large scale
accumulation of charge in even a tiny area by cosmic scales. Gravity while
locally weak does not have these issues and you can keep dumping more mass
into the same area more or less indefinitely.

~~~
SagelyGuru
Dumping more and more mass into a black hole until it holds a whole universe
is, apparently, not enough. But, hey, isn't it lucky that there is now also an
unobservable _dark matter and energy_ and just enough of it to make the
'gravity only' sums come out right? Hmmmm.

Does this really sound more plausible to you than that widely separated bodies
in vacuum, large and small, can hold charge?

I hope you are kidding.

~~~
astrodust
Keep reading your high-school textbook on physics and be sure to note the
equations on calculating the force of an electrostatic charge over very large
distances.

If you rubbed the entire galaxy with a cosmic-sized cat you still wouldn't
have the effects you're postulating.

