Show threadDaniel PomarèdeMar 14, 2024

A timely Nature cover, on the occasion of Albert Einstein 145ᵗʰ birthday.

The issue features a fascinating Review Article by Carla and Franz Kahn: «Letters from Einstein to de Sitter on the nature of the Universe»

https://www.nature.com/articles/257451a0

#universe #Einstein #deSitter #physics #science #nature #cover #naturecover #cosmology #history #philosophy #letters #astronomy #astrophysics #relativity #generalrelativity #astrodon

Letters from Einstein to de Sitter on the nature of the Universe - Nature

The correspondence between Einstein and de Sitter during 1916 and 1918, recently discovered in the archives of the Sterrewacht at Leiden provides a fascinating glimpse of the thinking of the two principal progenitors of modern cosmology.

Nature
ᴄᴏʀʀᴀᴅᴏMar 31, 2023

A team of #researchers led by #KyotoUniversity is exploring '#deSitter #space' to invoke a higher dimension to explain #gravity in the expanding #earlyuniverse. They have developed a concrete method to compute #correlationfunctions among #fluctuations on expanding universe by making use of #holography.

https://phys.org/news/2023-03-believing-exploring-de-sitter-space.html

Seeing is more than believing: Exploring 'de Sitter space' to explain gravity in the expanding early universe

Having more tools helps; having the right tools is better. Utilizing multiple dimensions may simplify difficult problems—not only in science fiction but also in physics—and tie together conflicting theories.

Phys.org
xameerJan 6, 2021
AdS/CFT <->> duality bw pure #quantum gravity g in (2+1)-d anti #deSitter space and extremal #holomorphic CFTs. g has no local degrees of freedom, but when the cosmological constant is negative, there is nontrivial content in theory, due to existence of BTZ #blackhole solutions.
xameerDec 28, 2020
A Lie Algebra is seen to be a special classical limit of the algebra of #Poincaré group, in the limit c → ∞. Technically, the #Galilean group is a celebrated group contraction of the Poincaré group (which, in turn, is a group contraction of the #deSitter group SO(1,4))
xameerDec 28, 2020
A Lie Algebra is seen to be a special classical limit of the algebra of #Poincaré group, in the limit c → ∞. Technically, the #Galilean group is a celebrated group contraction of the Poincaré group (which, in turn, is a group contraction of the #deSitter group SO(1,4))
xameerDec 14, 2020
In two spatial and one time d, general #relativity turns has no propagating gravitational degrees of freedom. In fact, it can be shown that in a vacuum, spacetime will always be locally flat (or #deSitter or anti-de Sitter depending upon the cosmological constant).
xameerDec 14, 2020
In two spatial and one time d, general #relativity turns has no propagating gravitational degrees of freedom. In fact, it can be shown that in a vacuum, spacetime will always be locally flat (or #deSitter or anti-de Sitter depending upon the cosmological constant).