The Creation of the Universe

[Duckie]

Two things-

1- The reason the expanding universe is causing galaxies to all get farther from eachother is the same reason a baloon inflates and two dots on it get farther away, right?

2- If there was no time before the Big Bang, the universe, time could be said to both exist and not exist at that point, right? An eternal frozen point in time both exists as a moment and not exists by the definition of time (imply continous motion through whatever semi-dimension time occupies), if I am thinking correctly. (Or maybe I just read too much "Zen" type wisdom.)

[Lord Zentei]

Anyone ever heard of a 'steady-state universe'? The universe simply 'is', it didnt start and it cant stop, ever.

I know it's probably be discredited, i kind of heard from some fringe sources.

I however found it interesting so i used it in a story, sort of as a background, to explain an FTL system.

The Family Universe theory sounds like it would make sense. Reminds me of the Marvel universe, how one universe 'blew up' and created ours, and eventually this one will blow up and make the next, etc, etc onto infinity.

The steady state model of the universe was devised by Hermann Bondi, Thomas Gold and Fred Hoyle in the 1940s in order to provide an alternative explanation for the observed redshift of remote galaxies. The incentive for this theory was the so-called "perfect cosmological principle" which asserts that just as we do not occupy a preferred location in space, we do not occupy a preferred location in time. In such a universe the Hubble parameter and mean density remain constant with time, and the velocity-distance relation dr/dt = H0*r which with intergration leads to r(t) ~ exp(H0*t), and the volume of an arbitrary region increases exponentially with time. This means that r -> 0 only when t -> -infinity: a Steady State universe is infinitely old, and no Big Bang ever took place since that would violate the "perfect cosmological principle". In this universe matter has to be created at a rate of dM/dt =D(dV/dt) = 3*D*H0*V, where V is volume, D is mean density and dM/dt is the rate of matter creation. This would have to take place at a rate of ca. 6e-28 kg/m^3 per Gigayear, or one hydrogen atom per cubic kilometer per year. The SS model was a contender until the discovery of the Cosmic Background Radiation in 1965, which was impossible to reconcile into it (various other problems had emerged by then that suggested that the perfect cosmological principle was in fact not true, but the CMB was the clincher).

[Lord Zentei]

Two things-

1- The reason the expanding universe is causing galaxies to all get farther from eachother is the same reason a baloon inflates and two dots on it get farther away, right?

Uh, not quite. The baloon is an analogy that explains that there is no "center" to the universe from which all things are expanding.

2- If there was no time before the Big Bang, the universe, time could be said to both exist and not exist at that point, right? An eternal frozen point in time both exists as a moment and not exists by the definition of time (imply continous motion through whatever semi-dimension time occupies), if I am thinking correctly. (Or maybe I just read too much "Zen" type wisdom.)

The Big Bang singularity itself, like all singularities is not exactly a part of the universe per se: it is a hole in the universe, a point where "everything becones infinite" or more accutately undefined. You can still have an arbitrary number of points leading to that singularity, though, in a manner that Zeno could not understand or accept. Think of an open interval on the number line.

[Surlethe]

Two things-

1- The reason the expanding universe is causing galaxies to all get farther from eachother is the same reason a baloon inflates and two dots on it get farther away, right?

Yes, I believe.

2- If there was no time before the Big Bang, the universe, time could be said to both exist and not exist at that point, right? An eternal frozen point in time both exists as a moment and not exists by the definition of time (imply continous motion through whatever semi-dimension time occupies), if I am thinking correctly. (Or maybe I just read too much "Zen" type wisdom.)

No; the way to think about time approaching the point of the Big Bang is to think of it as a one-sided limit: however close you approach, you will never get there, like the behavior of the x-values of f(x) = ln x as x -> 0.

[Lord Zentei]

Yes i too wonder, what caused the matter that made the Big Bang to exist. Of course i beleive one thing, but i realize i cant prove it or state it as absolute truth. I beleive in a higher power (God) too, but like i said i cant and dont try to prove it as i have no evidence.

As I understand inflation theory, the expansion of spacetime qualifies as negative energy, sort of like an explosion losing energy as it expands. The original mass/energy condensed from this energy loss and became matter ( at least some of it, some became energy )

The Cosmological Constant (or Dark Energy, whatever is causing it), is thought to have a posetive energy density but a negative pressure. Since the pressure of a thing increases it's gravity, a negative pressure causes repulsion. Moreover, the Dark Energy is constant throughout space, i.e. it's density does not diminish as 1/r^3 as mass density does. Thus we get a constant accelleration and an exponential rate of increase for the scale factor.

[Firefox]

Two things-

1- The reason the expanding universe is causing galaxies to all get farther from eachother is the same reason a baloon inflates and two dots on it get farther away, right?

Uh, not quite. The baloon is an analogy that explains that there is no "center" to the universe from which all things are expanding.

If the rubber/latex of the balloon is taken to be space itself, the analogy would work in that way. As the balloon expands (as space does), the dots (galaxies) seem to move farther apart, when that's not necessarily the case.

[Lord Zentei]

Two things-

1- The reason the expanding universe is causing galaxies to all get farther from eachother is the same reason a baloon inflates and two dots on it get farther away, right?

Uh, not quite. The baloon is an analogy that explains that there is no "center" to the universe from which all things are expanding.

If the rubber/latex of the balloon is taken to be space itself, the analogy would work in that way. As the balloon expands (as space does), the dots (galaxies) seem to move farther apart, when that's not necessarily the case.

Yes, I know that. That wasn't what I was driving at though I see now that I misunderstood MRDOD's post somewhat.

Although an additional point should be made that the density of the "dots" affects the rate at which the balloon can be inflated: matter is not merely passive.

[18-Till-I-Die]

snip--

( Even ) More speculative version : Given time, an intelligent species may invent technology that manipulates spacetime in a fashion that produces baby universes, either on purpose or as a side effect. Given time ( and a tree of universes has unlimited time ) this small increase will act as a selcetion pressure for life bearing universes.

Oh, that gives me some ideas. Sorry to go off-topic, but that is REALLY interesting and it's given me an idea. I'm thinking 'Sliders' here.

[ClaysGhost]

The steady state theory is a reasonable example of Planck's quip to the effect that new theories achieve greater acceptance only as their opponents die off.

In the case of the steady state theory, the great Fred Hoyle has gone, but Bondi's still around and Gold is actively making a fool of himself.

The survivors still maintain that the Big Bang theory is seriously wrong, and are still working with models based on the perfect cosmological principle.

[Lord of the Abyss]

The steady state theory is a reasonable example of Planck's quip to the effect that new theories achieve greater acceptance only as their opponents die off.

Was that "Funeral by funeral, science advances." ?

[Lord Zentei]

The steady state theory is a reasonable example of Planck's quip to the effect that new theories achieve greater acceptance only as their opponents die off.

In the case of the steady state theory, the great Fred Hoyle has gone, but Bondi's still around and Gold is actively making a fool of himself.

The survivors still maintain that the Big Bang theory is seriously wrong, and are still working with models based on the perfect cosmological principle.

Ugh. "Solar sailing violates the laws of physics" indeed. More likely that Gold has become senile or something.

Though I imagine that most of those who formerly supported the SS have in fact converted to the BB, it's just those who had made the SS their life's work that are reluctant to let it go. Not surprising, but still bad mojo.