If A Multiverse Exists It Could Abound With Life

Could the universe we know be just one of many in a multiverse? Jaime Salcido/simulations by the EAGLE Collaboration

Assuming cosmologists haven't made some huge mistake, this suggests, Lewis said, “Some unknown mechanism has sliced most of it off.” The problem, he continued; “Is we can imagine something that canceled out all of dark energy, but it is hard to explain what would get rid of most and leave this tiny residue.”

Yet if most of the expected dark energy existed, the universe would be lifeless, flying apart so fast that matter would be too diffuse to form stars. Back-of-the-envelope estimates suggested this would happen at only slightly higher dark energy levels than exist.

However, Lewis' modeling, published in the Monthly Notices of the Royal Astronomical Society, concludes a universe could have 50-100 times the dark energy of our own and still allow the multiple generations of stars needed for rocky planets with the elements required for life. It would be a lonely place, with galaxies separating so quickly each once would lose touch with others, but the fundamentals within galactic groups wouldn't change.

A difference of 102 is tiny compared to 10120, so most values of dark energy would still prevent life. The finding creates new puzzles because, Lewis said, “We expect to be close to the maximal acceptable value of dark energy.” As co-author Dr Luke Barnes of Western Sydney University put it; “Our work shows that our ticket seems a little too lucky, so to speak. It’s more special than it needs to be for life.” The fact that there appear to be so many possible values above ours could be a strange quirk, but might also suggest our understanding remains incomplete.

Sadly, however, it's unlikely that anywhere in the multiverse the laws of physics are so different they allow a habitable disk resting on the back of a turtle.

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