The universe is a vast and mysterious place, the secrets of which we have yet to understand. But what if ours isn’t the only universe? On NASA’s 60th anniversary we ponder the question: What if we are part of a multiverse?
What Is a Multiverse?
Multiverse theory is an umbrella term for a group of hypotheses, including string theory, the Big Bang theory and quantum mechanics, that suggest our universe, though unique, is not the only universe in existence.
Cosmologists put forward the idea that our universe is just one of many, possibly even an infinite number of other universes, and that all of these universes combined compose the entirety of existence.
An example of a multiverse theory is the ‘Many-Worlds Interpretation’. MWI is an interpretation of quantum mechanics which proposes that everything that could have happened, did happen in a multitude of universes.
If it sounds familiar that is because it resembles parallel universes, a familiar trope in comic books, novels, movies and tv series, perhaps most famously depicted by the original Star Trek’s ‘mirror universe’.
British cosmologist and astrophysicist Martin Rees has said, “Our entire universe may be just one element — one atom, as it were — in an infinite ensemble: a cosmic archipelago.”
Multiverse theory has increased in popularity over the last 30 years as physicists try to unravel the complex underlying principles which make our universe function.
Physicists and astrophysicists have been tackling a problem related to dark energy — the mysterious form of energy theorised to exist in all of space and drive the expansion of the universe.
According to current theories about the origin of our universe, there is much less dark energy here than there should be.
This was explained through multiverse theory — other universes have larger amounts of dark energy which inhibits the creation of stars and therefore life — we happened to hit the cosmological lottery with a ‘lucky ticket’.
A joint effort by researchers from British and Australian universities used one of the most realistic computer-generated simulations of the universe to delve deeper into this subject.
Without going into the full science, Dr Pascal Elahi, at the University of Western Australia, puts it simply: “We asked ourselves how much dark energy can there be before life is impossible.”
They discovered that increasing the amount of dark energy in the universe in simulations had a negligible impact on the formation of stars, and subsequently the potential for life.
Dr Elahi stated, “Even increasing dark energy many hundreds of times might not be enough to make a dead universe.”
Finding out that dark matter has less impact on star formation than previously thought proves problematic for multiverse theory.
Dr Luke Barnes, a John Templeton research fellow at Western Sydney University says, “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.”
The suggestion is that some as yet undiscovered natural law could explain a lot of the gaps in current scientific knowledge.
Not everyone agrees with multiverse theories, at least not in this universe.
Although the Many Worlds Interpretation of quantum theory has been around for 60 years or so, it has gone from being ridiculed to being scrutinised, added to, but still ridiculed.
Of course, string theory and Big Bang theory both argue the possibilities of multiple universes.
Some say these theories cannot be science because we can never observe and therefore never prove the existence of other universes.
Others say that there is ‘an over-reliance on mathematics’ in the multiverse theories.
For most of us these theories, and the arguments for and against — though interesting, and mind-boggling at the same time — are of minor importance.
We still have plenty of problems to address here on Earth after all.