Second Big Bang: Is this possible?
Sikao
original big bang. Would this create a new universe? How long
would the original universe last? Would it still continue to
expand, or would the new universe's gravity start pulling the
outer boundaries of the old one in?
josX
Who are you asking.
Why don't you come up with some interesting thought's to ponder on...
I guess the answer to your questions could be all yes, no, (long,short),
and everything in between, so hit the road and give us a speculation
/you/ like! If it is illogical, let's find out!
greetz
Jos
--
Sikao
>Sikao wrote:
>> Suppose there's an explosion inside the universe as big as
>> the original big bang. Would this create a new universe?
>> How long would the original universe last? Would it still
>> continue to expand, or would the new universe's gravity
>> start pulling the outer boundaries of the old one in?
>
>Who are you asking.
>
>Why don't you come up with some interesting thought's to
>ponder on...
>
>I guess the answer to your questions could be all yes, no,
>(long,short), and everything in between, so hit the road and
>give us a speculation /you/ like! If it is illogical, let's
>find out!
Well, my initial thoughts are the new universe would possibly
expand at the speed of light, destroying and "burning up" the
universe from the inside out. This means that in order to
survive, intelligent lifeforms would have to travel further out
into space to escape (assuming they can). What I'm not sure
about is whether the old universe would continue to expand or
not. I know there are differing views on whether it will it will
continue to indefinitely expand or not now, but I'm curious to
hear people's opinions and reasoning as to whether the scenario
that I present would affect it either way.
º¿º
> Suppose there's an explosion inside the universe as big as the
> original big bang.
What's there to supply the explosion. The original big bang had all the
material which created the present universe. I suppose you could talk
hypothetically and pretend that only half the matter from the original
explosion is expanding outwards and half was left...
>Would this create a new universe?
no.. all it would do is send out a lot of debris throughout the current
universe. You must remember that time and space didn't exist until the big
bang happened now the new explosion is happening within it.
> How long
> would the original universe last?
I suppose there are two theories that you can possible count..one is that
the universe keeps expanding till it dies out or secondly, that it reaches a
point where it starts to implode upon itself..I favour the second as it
means the universe recycles itself to the point just before the big bang
then explodes all over again to start a new universe...
> Would it still continue to
> expand, or would the new universe's gravity start pulling the
> outer boundaries of the old one in?
as above..
Mark Folsom
news:9bsoec$tn2$1...@slb3.atl.mindspring.net...
The boundary of the explosion could be moving toward you at the speed of
light right now. When it arrives, you will be obliterated.
Mark Folsom
josX
Great :-). Ok, a big bang in an existing Universe, will intelligent
species hypothetically living in the older universe survive, and how.
Have you considdered the vastness of the universe: if there were to
be a big bang in the middle of it, it would take the same time as
the current universe to expand to the same size and to "burn it all
up". But the current universe is not looking like a giant fire-ball,
and the same would probably hold true for the newborn universe. So
it well burn up a good portion of the universe in the middle perhaps,
but much will remain. Especially if you say it must expand with the
speed of light, which is increddibly slow on these scales (2 miljion
years to travel from Andromeda to here if I am correct, and that is
right on the doorstep).
Then about the continued expansion. I am unconvinced of this expansion,
however, asuming expansion, considder please this thought I made up
some time ago (about "indefinitely" exanding):
1. The force of gravity is assumed to near zero if the distance gets
greater, but it still exists, however minute.
2. When two objects fly apart in a big-bang in oposite directions (for
simplicity), their relative speeds are a fixed number, however great.
1+2=3. The force of gravity will eat away at this speed because the two
objects are atracted to eachother, however minute. Given an defined
distance, and an indefinite amount of time, eventually the speed
will has to drop to stand-still, and then reverse, and then continue
to increase until a big crunch.
So "indefinitely expanding" is an impossibility (let me know what you think
about this!!).
Now, will the earlier universe remain to expand, or start to contract? I
guess that would depend. If there suddenly sprang up a new gravity-centre
in the universe due to a new big-bang, that gravity would tuck at the
existing and slow it's speed down faster, possibly returning it if the
speed was already low (in a certain amount of time ofcourse).
Onother problem it this: will the gravity of the new universe be felt
/immidiately/ throughout space, or will it's gravity influence travel
like a wave with the speed of light. If it travels with the speed of
light, the effects on the existing universe would be even less (bar near
the location of the new big-bang).
greetz
Jos
--
Trakar
>Well, my initial thoughts are the new universe would possibly
>expand at the speed of light, destroying and "burning up" the
>universe from the inside out. This means that in order to
>survive, intelligent lifeforms would have to travel further out
>into space to escape (assuming they can). What I'm not sure
>about is whether the old universe would continue to expand or
>not. I know there are differing views on whether it will it will
>continue to indefinitely expand or not now, but I'm curious to
>hear people's opinions and reasoning as to whether the scenario
>that I present would affect it either way.
My immediate response is to think that the new universe would create
it's own space-time, and would thus be completely seperated from from
our universe upon formation.
Paul Morris
There is an article in the current (or recent) issue of New Scientist
which suggests that the big bang was actually a collision between
two 3-d universes (or 3-branes) within a larger 4-d universe.
According to this view, there could be another such collision in
the future, but its approach would be signalled by changes in the
gravitational constant, which do not seem to be occurring presently.
Paul
--
Email: lastname at best dot com. No spam please.
All spam will be complained to sender's ISP.
º¿º
"Paul Morris" <notr...@best.com> wrote in message
news:notreally-220...@morris.vip.best.com...
Chris Hillman
On Sat, 21 Apr 2001, Sikao wrote:
> Suppose there's an explosion inside the universe as big as the
> original big bang. Would this create a new universe? How long would
> the original universe last? Would it still continue to expand, or
> would the new universe's gravity start pulling the outer boundaries of
> the old one in?
There have been some speculations as to how quantum gravity might affect
the conventional global picture from gtr of a black hole formed by
gravitational collapse. One speculation is that the spacelike
(unavoidable) strong curvature singularity might be partially replaced by
"bubbles" which rapidly expand to form new "baby universes". See for
example the sketch of the proposal of Barrabes and Frolov at the bottom of
page
http://math.ucr.edu/home/baez/RelWWW/history.html
In such a case, the baby universe would behave just like our own (positive
comoslogical constant, initially very dense and hot with rapid and
"decelerating" Hubble expansion; later "decoupling" of matter and radiant
energy, later still much slower but "accelerating" Hubble expansion,
asympotic to de Sitter vacuum). The development of these baby universes
would be entirely independent of the development of the parent universe.
Once you understand what the conformal diagrams on the above cited page
mean, this is pretty obvious from the diagram of the Barrabes and Frolov
scenario.
N.B.: this scenario is just an educated guess; there is as yet no quantum
theory of gravity, so at the moment we can only guess about what the large
scale effects of quantum corrections to gtr at very high energies might
be.
> Well, my initial thoughts are the new universe would possibly
> expand at the speed of light, destroying and "burning up" the
> universe from the inside out.
That can't happen if a baby universe is born inside a black hole.
However, many decades ago, Penrose was worried that generic gravitational
collapse (e.g. not assuming spherical symmetry) in gtr might lead to a
"naked" curvature singularity. Since gtr breaks down near a curvature
singularity, if such a singularity is not "dressed" by an event horizon,
which (by definition) would prevent "signals" from near the singularity
from getting out through the horizon, then gtr could not predict the
effect of gravitational collapse as observed by outside observers. In
particular, Penrose was worried that the formation of such a naked
curvature singularity might sometimes produce (according to gtr) what
Hawking later called a "thunderbolt", a null curvature singularity
propagating at the speed of light and destroying (part of) the universe as
it goes.
As you may know, Penrose formulated the famous Cosmic Censorship
Hypothesis, which conjectures that generic but approximately spherically
symmetrical gravitational collapse always results in an event horizon.
Most workers in gtr believe this is the case (c.f. also Thorne's "hoop
conjecture"), but no-one has yet proven it.
In other work, Penrose and Khan studied colliding gravitational plane
waves, and showed the collision of two "impulsive" plane waves could
result in the formation of a naked singularity. Later many other similar
exact solutions were found involving colliding waves, including colliding
EM waves. Since plane waves are highly idealized (they model transverse
gravitational radiation far from an isolated source, near a given
observer), workers in gtr have generally hoped this is an artifact of the
overidealized symmetry in these models. But again so far no-one has been
able to prove this.
I myself studied gravitational plane waves and gave various explicit
examples of "waves of death" which involve a null singularity which
propagates at the speed of light, progressively destroying a model
spacetime which initially appears to its inhabitants to be good old
Minkowski spacetime. In this model, observers naturally have no clue the
wave is coming until it hits; very rapidly thereafter, they are spindled
and crushed by tidal forces which increase without bound in finite proper
time. However, because by their very nature plane waves idealize away the
source of the radiation, my exact "wave of death" solutions give no hint
how such things might be generated. Nonetheless, they would appear to
lend some credibility to the notion that -if- it were possible to form a
thunderbolt, it would indeed propagate at the speed of light and would
progressively destroy at least some region of spacetime.
> This means that in order to survive, intelligent lifeforms would have
> to travel further out into space to escape (assuming they can).
No help against thunderbolts, because they propagate at the speed of
light! (If they exist.)
However, this naturally leads to an amusing speculation: how can humans
protect themselves against possibly inimical extra-terrestial
civilizations which might be -arbitrarily- more technologically advanced
than we are? The all-too-familiar logic of the Cold War suggests that the
only possible defense is to develop a way of generating a Wave of Death.
Then, if a powerful extra-terrestial threatens us, we can threaten back by
warning them that we will destroy the Universe if they try to destroy us.
> What I'm not sure about is whether the old universe would continue to
> expand or not.
Ah, now that's an interesting point. The Wave of Death mentioned above
propagates on a Minkowski background, if you will, not an FRW background
with positive cosmological constant. I guess that waves of death are
possible in FRW universes, but clearly could only destroy the absolute
future of the event where they are generated. This means that a
sufficiently distant and powerful extraterrestial civilization could
(perhaps as a rather unethical scientific experiment) send a thunderbolt
our way secure in the knowledge that they will have receded under our
cosmological horizon by the time we notice rapidly increasing tidal forces
and generate our Wave of Death in response. So it would seem that we have
in fact no defense whatever against any civilization powerful enough to
generate a thunderbolt. Our only hope is that thunderbolts are either
physically impossible, or else so hard to make that by the time any
civilization can do the trick, our home will lie beyond their cosmological
horizon and they will thus be no threat to us.
Hmm....come to think of it, since a thunderbolt would presumably destroy
some of our absolute future, presumably anyone generating such a thing
would be safe from retaliation of any kind regardless of cosmological
horizons. Hard to be sure since I know of no exact solutions representing
thunderbolts (in the sense of propagating null singularities which only
destroy part of the universe).
> I know there are differing views on whether it will it will continue
> to indefinitely expand or not now,
Actually, in the past two years a strong concensus has emerged that the
universe will continue to expand indefinitely and indeed that the Hubble
expansion is accelerating. See Ned Wright's pages (see the link from the
FAQ; see the link from RWWW; see the link from my home page below).
Chris Hillman
Home Page: http://www.math.washington.edu/~hillman/
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