The Cyclical Universe

[kmMango]

There's been a lot of speculation about the end of the universe. Whether it'll just keep expanding forever or eventually collapse back on itself, or whether our universe is only one iteration of a cycle of expansion and decay.

This possibility interests me the most, due to its possible implications and the fact that it's far less depressing than everything just running down into darkness.

I know many people here know more about physics than I ever will, so tell me what you think about the possibility of a Cyclical Universe. Is it possible? Is there any evidence for it?

[kerbiloid]

It's a multidimensional asynchronous cyclical fractal.

Edited August 12, 2015 by kerbiloid

[SargeRho]

As far as I understand it, a universe dominated by matter and dark matter could go through cycles, but not one dominated by dark energy. Our universe is dominated by dark energy, and thus will continue to expand at an accelerating pace, or even "rip" open.

[Thomassino]

Its expansion rate is accelerating. So either will it start to slow down or it will just expand forever. But don't be depressed! All the energy and matter will remain, it will just transform into new forms. Something ends, something begins...

[peadar1987]

From a probability perspective, I think there is likely to be multiple or cyclical universes. This universe does seem "fine-tuned" to life to some degree (i.e. gravity is not a repulsive force, unequal amounts of matter and antimatter etc.), so I like to think it's just one of many configurations. Makes it less unlikely that intelligent life would arise in *some* universe, if there are lots of them out there. Obviously in the universe where matter repels matter and everything settles to the lowest-density state, there won't be any intelligent beings to lament the fact that their universe isn't "fine tuned" to life.

[ZetaX]

It's a multidimensional asynchronous cyclical fractal.

What is that even supposed to mean¿

[AcidSludge]

What is that even supposed to mean¿

[PB666]

There's been a lot of speculation about the end of the universe. Whether it'll just keep expanding forever or eventually collapse back on itself, or whether our universe is only one iteration of a cycle of expansion and decay.

This possibility interests me the most, due to its possible implications and the fact that it's far less depressing than everything just running down into darkness.

I know many people here know more about physics than I ever will, so tell me what you think about the possibility of a Cyclical Universe. Is it possible? Is there any evidence for it?

No evidence. They look out, they see a universe that is younger and moving away in every direction. that's it. no center, no edge. The universe has apparently accelerated in expansion, this is attributed to dark energy, but we don't know what it is.

[Ravenchant]

From what I've heard, the most likely scenario is an eventual heat death. Star-forming material will eventually run out, but that's projected to happen a few trillion years from now at the soonest, so don't worry.

[kmMango]

I have heard that there is a theory regarding the uncertainty principle, where after the universe has undergone heat death, after an exceedingly long time (10^10^56 years) the background fluctuations could create another Big Bang.

- - - Updated - - -

What is that even supposed to mean¿

He described the universe as an infinite repeating pattern that exists across multiple dimensions. He was trolling, but it actually makes sense:P

[ZetaX]

but it actually makes sense:P

I strongly doubt that.

[kmMango]

I strongly doubt that.

I'm saying he isn't just throwing random words together, even if he is just messing with us. Or maybe he was, and was just very lucky:P

My god, this is the most advanced trolling ever. Throw some gibberish at us, and let us derail the thread debating it.

Either way, back on topic!

Edited August 12, 2015 by kmMango

[GeneralVeers]

Its expansion rate is accelerating.

Is that what's actually happening, or is that merely what we see.....?

In case you're not familiar: general relativity predicts that the passage of time slows down in a gravity well; the "deeper" you are in the gravity well, the slower time goes. This has been verified experimentally; a clock on the surface of Earth does in fact run slower than one in orbit--the effect is enough to throw off GPS satellites if they don't compensate for the error.

So, we humans, standing on Earth (or using satellites orbiting it) are deeper in our particular gravity well than the rest of the universe is. If our local gravity well were to get stronger, events in the universe around us would appear to accelerate.

So what if the gravity well around Earth or in the Solar System is getting stronger? The Sun capturing comets or asteroids passing by the outer rim of the system? The Moon slowly spiralling in towards Earth? The Earth (and all the other planets) spiraling in towards the Sun?

Those events aren't hypothetical, either--all three are actually happening. Very slowly to be sure, and the gravitational change is very slight.....but if these effects--or some other effects I forgot to mention (or that we humans don't know about!) are concentrating more mass in and around the Solar System, our perception of time and events outside the Solar System would change.

Oh dear.....I think I just made things more complicated.

[kmMango]

Never considered that, I would think those factors aren't powerful enough to explain what we've observed.

[GeneralVeers]

Keep this in mind: all the other explanations as to why the expansion of the universe is (apparently!) accelerating, are all centered around entirely hypothetical ideas that are logically identical to the gremlin in your refrigerator who runs and hides whenever you open the door.

It's Albert Einstein and his Cosmological Constant, all over again......

[Andersenman]

From what I've heard, the most likely scenario is an eventual heat death. Star-forming material will eventually run out, but that's projected to happen a few trillion years from now at the soonest, so don't worry.

You're funny. With this curious but overall inconsequential blip in carbon chemistry called life in one hand and the very foundation of existence in the other ... I'd rather have a place where something doesn't exist over a place where nothing at all CAN exist.

Is that what's actually happening, or is that merely what we see.....?

[...]

So what if the gravity well around Earth or in the Solar System is getting stronger? The Sun capturing comets or asteroids passing by the outer rim of the system? The Moon slowly spiralling in towards Earth? The Earth (and all the other planets) spiraling in towards the Sun?

Those events aren't hypothetical, either--all three are actually happening.

[...]

Except they aren't. Effectively. It's proven and explained that the Moon's orbit is widening centimetres each year, so whatever mass Sun, Earth and Moon are accumulating from interplanetary matter, it's not enough to compensate or even reverse the effect mentioned.

Saying something about the existence of influences is one thing, failing to provide magnitudes is another. This article mentions estimations of 37-78 kilotons (metric, imperial, short, long ... doesn't matter) of material collected by Earth per year. Here is cited that Earth loses hydrogen and helium at a rate of (calculated and rounded) 96 kilotons per year. (Calculating the effective change in gravitational pull and the resulting change in orbit parameters shall be left as an exercise to the reader.) So unless those estimations are massively wrong and/or I forgot/missed/do not know about any other significant mechanisms of mass transfer from/to Earth, there is no such thing as our gravity wells becoming stronger. Including the Sun's.

Edited August 13, 2015 by Andersenman
spelling, grammar

[GeneralVeers]

Except they aren't. Effectively.

You only disproved one. So, right now, you're batting one out of three.

So unless those estimations are massively wrong and/or I forgot/missed/do not know about any other significant mechanisms of mass transfer from/to Earth

Exactly--what if there's something out there you don't know about?

It's not just the acquisition of mass by our Solar System that could "deepen" our local gravity well. It's not mass, per se, that determines strength of a gravity well, it's density. Acquiring more mass is simply one means by which density can go up. If, for example, a planet shrinks (same mass, less volume) the local gravity well deepens.

Gravitational time dilation is a known and verified phenomenon in science. Dark matter and dark energy are not. I find the possibility of nearby asteroids we haven't yet spotted to be a lot more plausible than a gremlin in the astronomical fridge.

[ZetaX]

I recommend you to do the math and then tell us how that much mass should go unnoticed. And how that really works out anyway, cause it simply won't.

[Andersenman]

You only disproved one. So, right now, you're batting one out of three.

Just because you said the same thing three times doesn't mean I have to disprove the same thing three times. Which by the way I did, come to think of it.

What if? Well, I'm fairly sure IF there was enough matter present and available to increase the weight of said bodies at the required rate, I'm fairly sure both their presence and their effects would be very, very much noticeable.

Edited August 13, 2015 by Andersenman

[Ravenchant]

You're funny. With this curious but overall inconsequential blip in carbon chemistry called life in one hand and the very foundation of existence in the other ... I'd rather have a place where something doesn't exist over a place where nothing at all CAN exist.

Me too, but it's not like we can do anything about it.