New JWST lens survey: can it save the expanding Universe?
Observations from within the local Universe limit measurements, producing conflicting Hubble expansion rates (67 vs 73 km/s/Mpc), motivating new methods such as JWST multiply-lensed supernova observations.
Ask Ethan: What does "gravitationally bound" mean in the expanding Universe?
Gravitationally bound systems remain together when mutual gravity overcomes cosmic expansion; only stronger expansion or external influences can separate bound components.
Ask Ethan: Can stars form within the expanding Universe?
Stars formed early because local overdensities and gravitational collapse overcame cosmic expansion despite low mean density and accelerating expansion.
Ask Ethan: Could evolving dark energy lead to a Big Crunch?
Current observations suggest dark energy may be evolving and possibly weakening, which reopens the previously discarded possibility of a future Big Crunch.
Double-detonation supernova may set universal candles alight
The explosions of white dwarfs play a crucial role in astronomy, yet, despite their importance, the long-standing puzzle of the exact mechanism triggering their explosion remains unsolved.
