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/sci/ - Science & Math

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6127105 No.6127105 [Reply] [Original]

What are /sci/'s thoughts on the cyclic universe? Crack pot nonsense we need to let go, or is there actually some legitimacy to it?

>> No.6127384

bump

>> No.6127818

>implying the universe isn't flat and infinite

>> No.6127862

>>6127818
It isn't flat but it doesn't exist either.

>> No.6127877
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6127877

>>6127862

>it doesn't exist either

Explain?

>> No.6127929

Assuming infinite time, finite matter/energy. Seems like it could be cyclic. But then there's entropy. Anyway, I really hope it isn't.

>> No.6127949
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6127949

>>6127818
>>6127862
>>6127877
>Implying we're perceiving the universe in a correct way.

>> No.6128000

>>6127949
The only way to perceive endless expansion is to realize it never was there to begin with.

>> No.6128301

>>6128000
Wonder how everybody else feels about this

>> No.6128310

How can such a proposal be legitimate if it has no basis in evidence whatsoever? The universe has been measured many times to be essentially flat. And it's expanding. And the rate of expansion seems to be increasing. And there's nowhere near enough mass to close it anyway. So we can't be cyclic.

>> No.6128636

>>6128310

That's how we interpret the information with our current models of understanding. What we interpret to be "flat" now could mean something entirely different in 100 years time.

>> No.6128680

>>6128310
The universe can still have a closed topology and appear flat from measurements on its surface. As for the expansion bit, there exists the idea of conformal rescaling which essentially occurs after heat death. It also has some things to say about how the CMB should look, but no one has found hints of the predicted structure as far as I know.

>> No.6128716

>>6128310
>doesn't understand what "flat" means

You must have failed your differential geometry class even harder than Einstein did.

>> No.6128725

Anything with mass has a gravitational effect on the entire universe that just decreases to .000... the farther it gets away but not nothing. It seems inevitable that the expansion of the universe will run out once the energy that's propelling particles forward is countered by the gravitational pull of the rest of the universe. Even if we were to shoot one particle out of the edge of the universe really fast, it would just create one spike of space that would eventually stop moving and reverse like a ball being thrown into a trampoline.

Space can be expanding faster than a particle moves, but it's still dependent on a particle existing to create the space between itself and another particle. Although the gravitational effects weaken, the reduction of the velocity of any particle are cumulative. Even light does not escape a black hole so while it will continue to move at the speed of light, eventually all massive particles will come together and create something like a mega black hole that will just collapse the space in upon itself drawing in more energy including light until it gets so much energy that for some reason it destabilizes, and creates another big bang.

>> No.6128732 [DELETED] 

>>6128310

>How can such a proposal be legitimate if it has no basis in evidence whatsoever?

A cyclic Universe is predicted by Quantum Loop Cosmology, which has produced several correct observations already.

>> No.6128743

>>6128725
Standard candle measurements show that the rate of expansion is increasing. Hence why dark energy is a thing that cosmologists talk about.

As for the rest, it breaks down even with the exclusion of dark energy when you account for the fact that the metric expansion of space at the edges of the observable universe is faster than the speed of light.

>> No.6128835

>>6128725
everything you said is wrong.

2/10 for making me point it out.

>> No.6128887

>>6128716

Flat + Expanding + Accelerating = my conclusion.

It's a conclusion that's too simple for you to refute. That's what you're really butthurt about.

The preponderance of evidence says there's no cyclic universe. Flatness implies certain things. Combine flatness with expansion, and that implies that along with the suggested range of matter density, the universe would expand forever, albeit slowing as it went. But once the expansion was determined to be accelerating, it's even more assured that the universe cannot cycle.

>> No.6128912

>>6128743
How do we know that observation isn't localized. How do we know it applies to the universe as a whole?

>> No.6128913

>>6128887
Unless you include Penrose's conformal rescaling.

>> No.6128924

>>6128887
I challenge you to write down the math.

>> No.6128942

>>6128912
BECAUSE WHEN WE LOOK BACK IN TIME TO THE EARLY UNIVERSE IT WAS SMALLER, AND THE SAME STUFF THAT WENT ON TO MAKE UP OUR LOCAL UNIVERSE IS THE SAME STUFF THAT WENT ON TO MAKE UP THE REST OF THE UNIVERSE THAT IS BEYOND OUR OBSERVATIONAL LIMIT.

>> No.6128953

if spacetime is curved it probably curves in on itself because fuck you.