Tag: cosmology

Amplituhedron

Physicists have discovered a jewel-like geometric object that dramatically simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality. “This is completely new and very much simpler than anything that has been done before” Interactions that were previously calculated with mathematical formulas 1000s of terms long can now be described by computing the volume of the corresponding jewel-like “amplituhedron,” which yields an equivalent 1-term expression.

this is remarkable. usually these theories are only accessible to the most mathematically gifted (cf string theory / ed witten)

No Heat Death?

gravity saves the day. or rather, the future of the cosmos.

The Fang/Dyson idea (for the lack of a better name) says that rather than an inexorable sinking towards heat death, the universe is biased toward a slow and steady march towards increasing differences over time. Gravity will continue to accentuate the uneven clumping of matter, and create ever more uneven energy potential, constantly building up order, even while local areas run down. But over the very long term, the universe as a whole is running up.

Conformal cyclic cosmology

Our cosmos was “bruised” in collisions with other universes. Now astronomers have found the first evidence of these impacts in the cosmic microwave background. Conformal cyclic cosmology (CCC) posits the existence of an aeon preceding our Big Bang ‘B’, whose conformal infinity ‘I’ is identified, conformally, with ‘B’, now regarded as a spacelike 3-surface. Black-hole encounters, within bound galactic clusters in that previous aeon, would have the observable effect, in our CMB sky, of families of concentric circles over which the temperature variance is anomalously low, the center of each such family representing the point of ‘I’ at which the cluster converges.

or perhaps it was a 4D star?

The Universe formed from the debris ejected when a 4-dimensional star collapsed into a black hole — a scenario that would help to explain why the cosmos seems to be so uniform in all directions.

2022-02-26: Sabine Hossenfelder offers comments:

If the previous eon leaves information imprinted in the next one, then it isn’t obvious that the cycles repeat in the same way. Instead, I would think, they will generally end up with larger and larger fluctuations that will pass on larger and larger fluctuations to the next eon because that’s a positive feedback. If that was so, then Penrose would have to explain why we are in a universe that’s special for not having these huge fluctuations.

Black Hole Inflation

A small change to the theory of gravity implies that our universe inherited its arrow of time from the black hole in which it was born. Our own Universe may be the interior of a black hole existing in another universe.

2019-01-02:

If complexity does underlie spatial volume in black holes, Susskind envisions consequences for our understanding of cosmology in general. “It’s not only black hole interiors that grow with time. The space of cosmology grows with time. I think it’s a very, very interesting question whether the cosmological growth of space is connected to the growth of some kind of complexity. And whether the cosmic clock, the evolution of the universe, is connected with the evolution of complexity. There, I don’t know the answer.”