The Weird Force (Un)known as Dark Energy
Wherever you are in the universe, everything looks like it’s moving away from everything else. Moreover, physicists have found that for the last 7 billion years or so this galactic expansion has been accelerating.
This would be possible only if something is pushing the galaxies apart, adding energy to them. Scientists are calling this something “dark energy,” a force that is real but eludes detection. Dark energy appears strong enough to push the entire universe – yet its source is unknown, its location is unknown and its physics are highly speculative.
There are several theories for the identity of dark energy: it may be energy generated by ghostly subatomic particles that appear out of nothing before annihilating; it may be associated with the recently confirmed Higgs Field, which gives certain kinds of matter mass; or it may be explained by string theory by which extra invisible dimensions of space get compressed into sizes much smaller than atoms.
One of the most speculative ideas for the mechanism of an accelerating cosmic expansion is called quintessence, a relative of the Higgs field that permeates the cosmos. Perhaps some clever lifeform 5 billion years ago figured out how to activate that field, speculates astrophysicist Caleb Scharf.
How? “Beats me,” he says, “but it’s a thought-provoking idea, and it echoes some of the thinking of cosmologist Freeman Dyson’s famous 1979 paper “Time Without End,” where he looked at life’s ability in the far, far future to act on an astrophysical scale in an open universe that need not evolve into a state of permanent quiescence. Where life and communication can continue for ever."
Once we start proposing that life could be part of the solution to cosmic mysteries, Scharf concludes, “there’s no end to the fun possibilities. Dark-matter life, for instance, is a pretty exotic idea, but it’s still conceivable that we might recognize what it is, even capturing it in our labs one day (or being captured by it). We can take a tumble down a different rabbit hole by considering that we don’t recognize advanced life because it forms an integral and unsuspicious part of what we’ve considered to be the natural world.”
The amount of dark energy in the Universe is astoundingly small compared to the theoretically large range it could be (it has been measured to be about one-hundred-millionth of an erg per cubic centimeter). Almost all physicists agree that if the amount of dark energy in the universe were slightly different, life could never have emerged. We happen to live in a universe with a small dark energy value, allowing for expansion rather than contraction, and for the emergence of life. Some theorists believe it’s an example of fine-tuning that demands the existence of a multiverse to explain it.
Once in a multiverse, however, we don't have to limit ourselves to our own universe; we can also involve what lies beyond. Let's just assume that the universes in this multiverse, in addition to being separate from each other, could also exist within each other. It would then become possible that dark energy is simply the "gravity" of another, larger universe that surrounds us; a force that's pulling from outside instead of pushing from within.