How quickly is the Universe disappearing from our reach? | by Ethan Siegel | Starts With A Bang! | Mar, 2024
Because of dark energy, distant objects speed away from us faster and faster as time goes on. How long before every galaxy is out of reach?
For nearly all of the 20th century, the biggest question over the expanding Universe had to do with understanding what its fate would be. The Universe, if it’s expanding, had to be a race between two seemingly irresistible factors:
- the initial expansion rate, which worked to drive everything existing within the fabric of space mutually apart,
- and the force of gravitation, which fights against the expansion, and works to pull everything back together again.
Ever since the 1920s and 1930s, when the expanding Universe became well-established both theoretically and observationally, the primary quest of cosmology was to measure the present expansion rate as well as how it changed over time. Those two pieces of information, together, would allow us to infer the ultimate fate of the Unvierse.
Even after the Big Bang became established as our Universe’s beginning, scientists worked to improve these measurements, endeavoring to learn whether our cosmic expansion would eventually reverse and recollapse, whether it would coast…
