Observations show the universe appears flat, yet its true size and global shape beyond the observable horizon may remain forever unknown.
Using gravitational waves as a measure of the universe's rate of expansion could solve the biggest headache in physics, the so-called "Hubble tension." ...
An expanding universe complicates this picture just a little bit, because the universe absolutely refuses to be straightforward. Objects are still emitting light, and that light takes time to travel ...
A rare gravitationally lensed supernova called SN 2025wny appears in five separate images due to the gravity of two ...