Whether we live in a universe that is just one of many, inside a multiverse, is a question that has long troubled astronomers. And, after asking that, another question that is even more perplexing follows: would those other universes contain life of their own?
Now new research has shown that if that multiverse exists it could be filled with many examples of different alien life.
Scientists used vast computer simulations to predict that other parts of the multiverse would be far more hospitable to life than we had previously thought.
But it also causes major problems for the idea of the multiverse. In fact, the strangeness of our own universe might better be explained by an undiscovered natural law, they said.
The idea of the multiverse comes about because in physics terms, our universe is very lucky to exist at all.
Current theories predict there should be much more dark energy inside of our own universe than there is. That is a problem because adding more dark energy would lead it to expand so quickly that any matter would be diluted before it could form the stars or planets that we need to live.
In response to that, some have suggested that we might in fact be living inside of a multiverse. There are in fact lots of different universes – many of which will have more dark energy and so could not host life – and we simply live inside one that worked out in the right way.
But the new study suggests that we might have been overstating how lucky we are. It might actually be possible for stars and planets to form even if there is much more dark energy.
“We asked ourselves how much dark energy can there be before life is impossible?” said Pascal Elahi, a research fellow at the University of Western Australia. ”Our simulations showed that the accelerated expansion driven by dark energy has hardly any impact on the birth of stars, and hence places for life to arise. Even increasing dark energy many hundreds of times might not be enough to make a dead universe.”
It is still true that our universe could be very special. But it does not need to be quite so special, the researchers showed.
“The multiverse was previously thought to explain the observed value of dark energy as a lottery – we have a lucky ticket and live in the Universe that forms beautiful galaxies which permit life as we know it,” said Luke Barnes, a John Templeton research fellow at Western Sydney University.
“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. This is a problem for the multiverse; a puzzle remains.”
That puzzling fact might suggest that the multiverse theory is not true in the first place. The study does not rule out the idea but does suggest that the small amount of dark energy in our universe would be better explained by a law of nature that we do not yet know about.
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