The expansion of our universe is accelerating. Perhaps it’s some mysterious form of dark energy, but last year researchers put forth the radical idea that the accelerated expansion is due to our universe absorbing adjacent baby universes. More recent research has shown that while the idea still might work, it’s much more complicated.
Astronomers first discovered dark energy in 1998, when two independent teams found that distant supernovae were far dimmer than they should be, implying that the expansion of the universe was accelerating. Since then, many other lines of evidence have led to the same conclusion, but the ultimate cause of the accelerated expansion remains a mystery.
Dark Energy Is a Cosmological Constant
The simplest explanation for dark energy – the name given to the accelerated expansion – is what’s known as a cosmological constant. An idea first introduced by Albert Einstein, the equations of general relativity allow us to add simple constants. In essence, in this view the expansion of the universe accelerates because there is a baked-in acceleration.
