B Big Bang Wasn't the Beginning? Study Proposes Alternative....

[ISamson]

A new paper is proposing a new alternative to the Big Bang.

Silva Neves said his "cosmological model was built from studies in regular black holes," and avoids the need for a singularity in both black holes and the beginning of universal expansion. He notes, however, that this is still purely hypothetical.

"There is no empirical evidence for bouncing cosmologies today," he said. "But there is no evidence for the initial singularity as well."

"The Big Bang as the initial singularity is only a speculation," Silva Neves told Space.com. He said that "there are many observations in cosmology" that support the hypothesis that the universe went through a period of rapid expansion, but that there is no direct evidence that this expansion started with a singularity.

His model includes a concept known as bouncing cosmology.

https://www.space.com/38982-no-big-bang-bouncing-cosmology-theory.html

 

[newjerseyrunner]

I’m confused by what they mean it didn’t have to “start at a singularity.” Does the author think that physicists believe that black holes and the initial seed were actually infinitely dense?

A singularity simply means it’s a place in the math where our current formulations don’t work. We expect this is because of theories are incomplete, not that there are actually infinitely dense things.

There are multiple frameworks that don’t have infinitely dense points at the beginning. LQG has a cyclical model as well.

 

[ISamson]

I’m confused by what they mean it didn’t have to “start at a singularity.”

I think he is saying that it is a continuous, eternal cycle of Big Bang, Big Freeze, Big Bang, Big Freeze...

 

[Mordred]

Again cyclic models have been proposed as well as bounce models.

 

[Orodruin]

Can we please stop linking to sensationalist popular science news and start citing the original paper, https://link.springer.com/article/10.1007/s10714-017-2288-6

The proposition of a cyclic universe is not new. What he has done (according to the abstract) is to draw an analogy to a family of black holes.

Furthermore, a cyclic universe generally has a contraction phase. Given that the universe is currently undergoing accelerated expansion, this seems unlikely.

 

[ISamson]

Furthermore, a cyclic universe generally has a contraction phase. Given that the universe is currently undergoing accelerated expansion, this seems unlikely.

Why does the cyclic model seem unlikely?

 

[newjerseyrunner]

Why does the cyclic model seem unlikely?

Because from our limited understanding of dark energy, it seems to be a constant value. So as space continues to expand, there will be more and more dark energy. The ratio of dark energy to matter (regular and dark) is always climbing so gravity’s effect on the evolution of the universe will slowly deminish, making it impossible to ever start shrinking or even decelerate.

That’s got to be taken with a grain of salt because we have no idea what dark energy really is.

 

[laymanB]

Why does the cyclic model seem unlikely?

And I believe you would have to propose some mechanism for decreasing the entropy so that the contracted universe would once again start in a low entropy state.

 

[Chronos]

Entropy is complicated and there is nothing to suggest it can ever decrease. It is unclear if even black hole evaporation can cause entropy to decrease.

 

[Phys12]

Because from our limited understanding of dark energy, it seems to be a constant value. So as space continues to expand, there will be more and more dark energy. The ratio of dark energy to matter (regular and dark) is always climbing so gravity’s effect on the evolution of the universe will slowly deminish, making it impossible to ever start shrinking or even decelerate.

That’s got to be taken with a grain of salt because we have no idea what dark energy really is.

Because of dark energy, will galaxies move far apart from each other, or will it result in a big rip tearing apart the nucleus of atoms?

 

[PeterDonis]

Because of dark energy, will galaxies move far apart from each other, or will it result in a big rip tearing apart the nucleus of atoms?

A "Big Rip" scenario requires more than just ordinary dark energy. Dark energy, as that term is usually used, refers to something that looks like a cosmological constant. In terms of energy density and pressure, it is something that has a pressure equal to minus its energy density. This will just cause accelerating expansion on cosmological scales; it won't affect bound systems.

A "Big Rip" scenario requires something that has a pressure that is more negative than minus its energy density. A term I have seen used to describe this kind of stuff is "phantom energy". I'm not aware of any evidence that suggests such stuff exists in our universe.