If life is rare in our universe, it might be more common in alternate ones.
According to scientists, life is possible because a triad of alpha particles unite to fuse into carbon. But there are some problems with that theory—fusing two alpha particles leads to a very unstable isotope (beryllium-8), which makes the abundance of carbon in the universe seem odd and improbable.
In the 1950s, astronomer Fred Hoyle suggested that to resolve this problem, the fusion of three alpha particles must create carbon-12 with more energy than it needs. This “resonance” between the collective alpha particle energies and the excited state of carbon-12, which later decays to a ground state, is very sensitive—if you change it just slightly, the creation of carbon isn’t possible. Some experts insist that this fact is evidence of the multiverse’s existence: since the chances of this critical value arising are so low, other universes with other such fundamental constants must exist, too. Only those universes that are appropriately fined-tuned would give birth to life.
Now, cosmologists are taking this idea to the next level.
Here’s Jacob Aron, reporting for New Scientist:
But now Adams and his colleague Evan Grohs have argued that if other universes have different fundamental constants anyway, it’s possible to create a universe in which beryllium-8 is stable, thus making it easy to form carbon and the heavier elements.
For this to happen would require a change in the binding energy of beryllium-8 of less than 0.1 MeV – something that the pair’s calculations show should be possible by slightly altering the strength of the strong force, which is responsible for holding nuclei together.
Simulating how stars might burn in such a universe, they found that the stable beryllium-8 would produce an abundance of carbon, meaning life as we know it could potentially arise. “There are many more working universes than most people realise,” says Adams.
Such universes would actually make more sense, mathematically speaking. Life could arise more effortlessly, without needing to work in that very specific carbon resonance, whatever it may be.
Of course, we don’t have definitive proof that alternate universes are out there—and it’s possible that we never will. But scientists are scrutinizing astrophysical minutiae to figure out their likelihood, and this is a big step in that direction.