While the search for extraterrestrial life here in this universe is complicated enough, the problem becomes even murkier when you account for the multiverse theory—our universe might one of many "universes" that make up a collective multiverse. Theoretical physicists have long assumed that the vast majority of parallel universes would be unable to harbor alien life, but that assumption is being challenged. A research team of scientists from Durham University, Western Sydney University, and the University of Western Australia have now found evidence that upends previously held notions of why the universe formed as it did, and suggests that the conditions to create a habitable universe are much more likely that previously imagined.
Just as Earth is an assumed rarity in our universe—a Goldilocks planet, not too hot, not too cold, and full of liquid water—our universe as a whole was previously considered to be an extreme rarity among potential alternate universes. Why? Dark energy, the strange and baffling invisible force that is driving our universe's expansion. Jaime Salcido, postgraduate student at Durham University told Newsweek:
"The multiverse theory suggests that our universe is only one of many, baby universes being born like bubbles in a bigger multiverse, with a wide range of physical laws and fundamental constants. The existence of life seems to depend on a small number of fine-tuned fundamental physical constants, such as the strength of gravity and the amount of dark energy. The formation of stars and galaxies is the result of a tug-of-war between these values: gravity causing matter to clump together, the dark energy causing the universe to fly apart."
Scientists thought that if there were any less or any more dark energy in a parallel universe than what we find in our own—dark energy makes up about 70 percent of our observable universe—the alternate universe wouldn't have the physical laws that allow galaxies, stars, and planets to form in the first place.
To test this, the Australian research team studied computer models of the formation of the universe (because we can do that now...) using EAGLE (Evolution and Assembly of GaLaxies and their Environments), the most advanced computer simulation of how our universe was formed. They found something surprising.
It seems that celestial bodies like stars and galaxies form even when they amount of dark energy is no where near the amount predicted to be necessary. In one case, the researchers added one hundred times the amount of dark energy to the system, and a functioning, potentially habitable universe still formed. Salcido says:
“Our research shows that even if there was much more dark energy, or even very little, in the universe, then it would only have a minimal effect on star and planet formation, raising the prospect that life could exist throughout the multiverse.”
Inter-dimensional aliens are objectively more awesome than regular aliens, so that's pretty cool.
The findings do cause a bit of a problem though. The multiverse theory was created as a way to explain the amount of dark matter, and the relationship it has with the fundamental formation of the universe. It doesn't work anymore. While the researchers say this doesn't disprove a multiverse, it does mean that our understanding of dark energy was rather flawed:
"It seems that we need a new physical law to understand dark energy. The puzzle remains.”
It wouldn't be fun if it was easy, right?