Thread: pulsating universe

I thought of that a while ago. Lemaitre was a priest before a scientist. Expansion of the universe implies it was once smaller. Big Bang implies a creation. The public is comfortable with that thought. It is familiar, enabling them to swallow the idea of the expansion of the universe more readily.

Of course, I also think that each "pulse" of the universe is "simultaneous" (the universe is outide of time). I've toyed with the idea that the only reason the pulses restart is because the system is imbalanced--it requires sufficient "awareness" to continue.

Well, what the website described, as far as I can see, is nonsense. Even if there was some reason for the universe to repeatedly stop growing for a while, it would not be infinitely old. The whole reason we believe there was a Big Bang is that we observe that all galaxies are flying away from us; then we just extrapolate backwards in time.

What you described is actually an extremely well known cosmological theory. If there is a high amount of mass in the universe, this would be true. However, by current estimates, there is not enough, by a factor of around 100; the universe will continue expanding forever, and fizzle out.

Personally I believe that there are many universes though.

I've never understood how the cyclical universe hypothesis dealt with entropy. Either the laws of thermodynamics break down at the big bang, or there's an external area outside our universe, giving us more energy. Neither option is very satisfying.

That's an interesting point... a singularity is a singularity, I don't see how the singularity at the end of time could have any less entropy than that at the start, violating the second law of thermodynamics...

Then again I haven't studied entropy.

Originally Posted by drewmandan

I've never understood how the cyclical universe hypothesis dealt with entropy. Either the laws of thermodynamics break down at the big bang, or there's an external area outside our universe, giving us more energy. Neither option is very satisfying.

Energy is never lost. It is lost as thermal energy, and dissipates through the universe. It doesn't leave the universe--the universe is a closed system (for this argument. Just as you said, it doesn't make sense for energy to come in from an outside source, it also doesn't make sense for it to leave to an outside place.). The universe has the same amount of stuff (energy and matter) as it had in the first place.

Everything in the universe is cyclic, so why not the universe itself too? As above, so below..

Originally Posted by Abra

Energy is never lost. It is lost as thermal energy, and dissipates through the universe. It doesn't leave the universe--the universe is a closed system (for this argument. Just as you said, it doesn't make sense for energy to come in from an outside source, it also doesn't make sense for it to leave to an outside place.). The universe has the same amount of stuff (energy and matter) as it had in the first place.

That's a violation of the 2nd law of thermodynamics. Here are two versions, both of which don't allow what you just described:

"Heat generally cannot spontaneously flow from a material at lower temperature to a material at higher temperature."

"It is impossible to convert heat completely into work in a cyclic process."

The background radiation is almost completely unusable, at least according to thermodynamics.

Hmmm... I remember that at the Big Bang though spacetime was infinitely wrapped up, before expanding. If a very large quantity of the mass in the universe had formed a singularity, spacetime would be very warped to the extent that it could suck in radiation... I don't know if this solves the thermodynamics problem though.

Everything in the universe is cyclic, so why not the universe itself too? As above, so below..

Really? Okay, explain how the following things are cyclic:

- A ruler.
- Radioactive decay.
- Computational linguistics.
- y = ax + b
- Ringo Starr.
- Adjectives.
- Ham.

Originally Posted by Xei

Hmmm... I remember that at the Big Bang though spacetime was infinitely wrapped up, before expanding. If a very large quantity of the mass in the universe had formed a singularity, spacetime would be very warped to the extent that it could suck in radiation... I don't know if this solves the thermodynamics problem though.

Indeed, one can imagine that if the spacetime metric itself shrinks to a Planck length, thermodynamics might not work the same way. But then again, the radiation is radiating out at the speed of light. It's like an unstoppable force meeting an immovable object. What wins? We may never know. But we do know for sure that our current understanding of thermodynamics would have to be wrong for the radiation to be 're-integrated' into the singularity.

well, id think that the idea that the universe is "pulsating" would explain where all the matter came from (Kinda)

Originally Posted by Xei

What you described is actually an extremely well known cosmological theory. If there is a high amount of mass in the universe, this would be true. However, by current estimates, there is not enough, by a factor of around 100;

but all the matter in the universe had to have been on top of each other at some point (as described by the big bang). So how did it all get there? Because it was all pulled in by gravity.

where else could it have come from?

i dont know, im a man of ignorance with a willingness to learn

well, id think that the idea that the universe is "pulsating" would explain where all the matter came from (Kinda)

Not really.

but all the matter in the universe had to have been on top of each other at some point (as described by the big bang).

No

i dont know, im a man of ignorance with a willingness to learn

Well, you're dealing with advance ideas that needs advance understanding of mathematics.

Saying that I think the most popular view is something called inflationary cosmology, which is kind of like the universe was kind of like alot of bubbles, were one of the bubbles that was inflated and grew into our universe.

I would say no.
About 5 billion years ago, the universe sort of had a 'break' in expansion. Since then it's been expanding ever more rapidly.
Thanks to this is the effect of Gravity and Dark Energy (the energy of the vacuum): gravity has a limited reach (go read Newton), while Dark Energy has an infinite reach. Dark energy is gravity's counter force: it makes object get away from eachother.
First, the DE pulls the objects away, but struggles against gravity. As the objects get further and further apart, the gravity lessens, thus accelerating the objects. That's what's been happening to the universe lately

Originally Posted by ThreeLetterSyndrom

I would say no.
About 5 billion years ago, the universe sort of had a 'break' in expansion. Since then it's been expanding ever more rapidly.
Thanks to this is the effect of Gravity and Dark Energy (the energy of the vacuum): gravity has a limited reach (go read Newton), while Dark Energy has an infinite reach. Dark energy is gravity's counter force: it makes object get away from eachother.
First, the DE pulls the objects away, but struggles against gravity. As the objects get further and further apart, the gravity lessens, thus accelerating the objects. That's what's been happening to the universe lately

It doesn't sound like you know what you're talking about.

Actually I have read about this information in the Scientific American many different times with different articles with new developments.

The science community has been very close to this idea for a little over a year now.

But this article has a tone of flaws and makes ridiculous questions for the big-bang theory which he himself does not own up to in his theory.

Either way, his theory is still using the idea of the big-bang theory.

but all the matter in the universe had to have been on top of each other at some point (as described by the big bang). So how did it all get there? Because it was all pulled in by gravity.

where else could it have come from?

i dont know, im a man of ignorance with a willingness to learn

It was just there. You're saying that mass was created separated by space, then it came together under gravity to form a singularity, then it exploded to make the universe; the first step is completely unnecessary. We might as well just say the singularity exploded to form the universe.

Actually I have read about this information in the Scientific American many different times with different articles with new developments.

Have you read any uni books on cosmology? and not just dumbed down crap they put in Scientific American.

gravity has a limited reach (go read Newton),

I'm pretty sure there have been some recent developement in the theory of gravity.

We might as well just say the singularity exploded to form the universe.

Entropy has to be really low at the time of the big bang, so no explosion.

Originally Posted by Xei

It was just there. You're saying that mass was created separated by space, then it came together under gravity to form a singularity, then it exploded to make the universe; the first step is completely unnecessary. We might as well just say the singularity exploded to form the universe.

Reality does not exist for your perception of necessity.

Yeah that follows directly and is definitely completely related to what I said.

Originally Posted by wendylove

Entropy has to be really low at the time of the big bang, so no explosion.

Agree..

It amazes me however, considering the Universe itself has a well-defined thermodynamic arrow of time. But this doesn't address the question of why the initial state of the universe was that of low entropy? If cosmic expansion were to halt and reverse due to gravity, the temperature of the Universe would once again increase, but its entropy would continue to increase due to the continued growth of perturbations and eventually blackhole formation. Kind of makes you wonder.

Originally Posted by Xei

Yeah that follows directly and is definitely completely related to what I said.

No? I thought you were saying that any conditions that lead to a singularity expanding to create the known universe were unnecessary in a cosmological model since it could have easily have started with the singularity. My point is that Even if we came up with a model that had the universe beginning with the big bang that remained consistent with all observable phenomena, it is still a possibility that the singularity was in fact caused by something else. Reality doesn't necessarily only contain what is 'needed' and may well contain an infinite set of superfluous possibilities.

Oh yes, it's a possibility, of course; something I imagine we'll probably work out in the end through progress in physics, too.

It's just the person who asked the question was saying that the only possible source of a singularity would have been a past universe collapsing, which is not true... it's no less possible that the singularity at the Big Bang was the very beginning. We really don't know where the singularity 'came from' (as far as I know) so it's just guesswork at the moment.

the whole gravity pulling it together thing, thats called the big crunch, its the opposite of the big bang and it takes away a bit of the universe, i read about the big bang and the big crunch when i was about 7 or 8 years old.

I think the problem a lot of people encounter here is that they read about things like "big bang" and "big bounce" while knowing exactly 0% of the math and physics that went into these concepts. So then they come up with completely ridiculous mental images like the big bang being like an explosion, and then they reject these theories based on their own misunderstandings.

Originally Posted by drewmandan

I think the problem a lot of people encounter here is that they read about things like "big bang" and "big bounce" while knowing exactly 0% of the math and physics that went into these concepts. So then they come up with completely ridiculous mental images like the big bang being like an explosion, and then they reject these theories based on their own misunderstandings.

the big bang is actually two extremely small particles colliding, then something happens, to do with electrons etc. i dont know much quantum physics. and within a nanosecond a chunk of universe "appears" (obviously not a scientific description)

and the big crunch is basically just an implosion, probably caused by a black hole or something.

and the big bounce is just a scientific model of what they think the formation of the universe is, its not a thing which happened. here is the model: