- Author, Max Tobin
- Role, BBC Reel series “Existential Crises”
Imagine the following situation: It’s the day of an important job interview, but you haven’t woken up, so you quickly get dressed, grab something to eat, and rush to the bus stop.
But since you don’t arrive in time, you have no choice but to walk.
You check your watch as you turn the corner and hit an unsuspecting pedestrian. Disgusted, you insult him and continue on your way.
You finally arrive at your meeting, sweaty and agitated, and you soon discover that your interlocutor is that pedestrian at whom you have just hurled a volley of expletives.
Yes, sometimes we feel like the universe is not on our side.
But fortunately, there are many paths to take. Because of our parents’ excessive affection, many of us live with the false impression that they are, for one reason or another, special.
It’s a totally unique blend of atoms and personal stories that combine to form this precious person we call “me.”
The fact is that the world of contemporary physics tells us exactly the opposite.
It tells us that somewhere in the vast cosmos there are other worlds in which identical versions of you live happily, feeling like they, and only they, are the real you.
I am of course referring to the multiverse, a theory according to which our universe is nothing more than one of many infinite universes, of infinite variety.
It may sound crazy, but this theory has solid scientific foundations.
In the early 1980s, researchers decided to measure the afterglow of the Big Bang (origin of the universe) and made the surprising discovery that radiation levels were identical at opposite ends of the observable universe.
This discovery gave rise to a theory called cosmic inflation, which states that after the Big Bang, space-time expanded at breakneck speed, creating a uniform and potentially infinite cosmic plane.
“When we talk about our universe in astrophysics, we are not talking about all of space, but about a spherical region from which light has had time to reach us over the 13.8 billion years that have passed since the Big Bang,” famous physicist and cosmologist Max Tegmark told the BBC.
“If this is our universe and space is bigger than that, then by definition there are other universes too, full of galaxies and other interesting things that are just as real as ours.
“The people there would call it their universe.”
If there are other worlds, what would they look like?
Level 1: Cosmic Inflation
“Level I multiverses are just other regions of space, the same size as our universe,” explains Max Tegmark.
“The only difference is that the particles there started in slightly different places than here, so the UK could have lost World War II instead of winning it; my name might not be Max Tegmark , but Max Shmerkark…”
“Even though it is unlikely that there is a copy of me with any other characteristic, that probability is not zero, because this is where I exist in this form, so if you roll the dice an infinity Sometimes there will be other copies of me, some very similar and many others that look a bit like me, but are different.
What does this mean to you ?
Well, probability says that somewhere in the cosmos, there is a version of you who didn’t fall asleep on interview day and another who managed to catch the bus. Even the one who never showed up for the interview because she was an athlete or astronaut.
The fact is that there are an infinity of possibilities on this plane, an infinity of atom-by-atom reconstructions, limited only by their conformity to the physical laws of our universe.
What if there were no limits to this?
Level 2: eternal chaotic inflation
“The level 2 multiverse is still infinite space, like the level 1 multiverse, but it is much more diverse,” explains Tegmark.
“If you go very far into space, you will reach regions where not only did history develop differently, but where you also learn different things in physics class.
“Indeed, we have learned that even what we think of as empty space is probably a substance, which can freeze, melt, and take many different forms.
“The inflation process that we believe created this vast cosmic space was so violent that it created an infinite amount of each type of space.
At level 2, all physical laws are thrown out the window.
Maybe in another universe gravity works differently. Perhaps we are made of sound, or we are flat balls, or perhaps strange floating balls of energy that exist in 12 dimensions.
Not only are all conceivable universes possible, but also all inconceivable universes, if you can imagine them, which is impossible, by definition.
Level 3: the quantum multiverse
“While the level 1 and 2 parallel universes are very, very far away in our own space, the level 3 multiverse is somehow here, in what is called quantum Hilbert space,” explains Max Tegmark.
“We know that elementary particles can be in two places at once.
“But I’m made of elementary particles, so if they can be in two places at once, so can I.”
“So one version of me might be here talking to you, while another version of me is taking ice cream out of the freezer and eating it somewhere else.”
“We discovered a quantum censorship effect called ‘decoherence’ which explains why these two versions of Max don’t know each other at all.”
“So it seems that reality branches out into parallel branches.”
“But these two Maxes, the one eating ice cream and the one talking to you, feel like they’re the only ones.”
Level 4: the mathematical multiverse
“The Tier IV multiverse is the most diverse of all.
“In this multiverse, every physical reality that corresponds to a mathematical structure – that can be described by mathematics – exists not only mathematically, but also physically,” explains the physicist.
“We could therefore have a universe where time does not flow continuously, but in a discrete manner, like in a video game, or even universes which simply have no time.
To clarify things, Tegmark points out that “it’s not that the Tier 4 multiverse exists in space and time, but that space and time exist in some of these Tier IV universes.”
In our universe, he says, “we have space and time, we have the right kind of elementary particle physics that allows life.”
“So we live in an oasis, and the whole of reality is like a huge version of the Sahara Desert, with an occasional oasis here and there.
But then what?
Multiverses are predictions based on very well-founded scientific theories, so, for now at least, it looks like it’s here to stay.
And maybe that’s a good thing.
After all, science is just a tool we use to study the world around us.
When we discover something that can trigger existential crises, it is not that the world has changed, but that we have simply begun to look at it with new eyes.
“Some people ask me how our universe gives meaning to our lives as conscious beings, but it’s actually the opposite: we give meaning to our universe,” says Tegmark.
“It is thanks to us, small minority parts of our universe who have the complexity to experience things, that our universe can become conscious of itself.
Who knows, maybe when we finally accept that we’re just big monkeys sitting on a rock, traveling at 68,000 mph across a potentially infinite expanse, we can stop taking everything so seriously.
*This article is adapted from the video made by Max Tobin and Dill Steele for BBC Reel.