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- Author: Max Tobin
- Reel, BBC Reel’s Existential Crises series
53 minutes ago
Imagine this situation: It’s the day of an important job interview, but you haven’t woken up yet, so you quickly get dressed, grab something to eat, and rush to the bus stop.
However, since you don’t arrive in time, you have no choice but to walk.
You look at your watch as you turn the corner and hit an unsuspecting pedestrian. Disgusted, you insult him and continue on your way.
You end up arriving at your meeting sweaty and agitated and soon realize that the person you’re talking to is the pedestrian you just hurled a barrage of expletives at.
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Yes, sometimes we feel like the universe is not on our side.
But luckily there are many ways. Because of our parents’ excessive affection, many of us live with the false impression that we are special for one reason or another.
It is a completely unique blend of atoms and personal stories that come together to form this precious person we call “I.”
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 where identical versions of you live happily, feeling that they, and only they, are the real you.
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Our guide through the multiverse: Swedish-American Max Tegmark, professor at MIT and one of the founders of the Institute for Fundamental Questions.
I am of course referring to the multiverse, a theory according to which our universe is nothing other than one of many infinite universes of infinite variety.
It may sound crazy, but this theory has solid scientific basis.
In the early 1980s, researchers decided to measure the afterglow of the Big Bang (formation of the universe) and made the surprising discovery that radiation levels at opposite ends of the observable universe were identical.
This discovery led to a theory called “cosmic inflation,” which states that after the Big Bang, spacetime 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 in the 13.8 billion years that have passed since the Big Bang” said the famous physicist and cosmologist Max Tegmark told the BBC.
“If this is our universe and space is bigger, then by definition there are other universes full of galaxies and other interesting things that are just as real as ours.”
“The people there would call it their universe.”
If there were other worlds, what would they look like?
Stage 1: Cosmic Inflation
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Seremos multidões?
“Level I multiverses are just other regions of space that are the same size as our universe,” explains Max Tegmark.
“The only difference is that the particles originated in slightly different places there than here, so Britain could have lost the Second World War instead of winning it; My name may not be Max Tegmark, but Max Shmerkark…”
“Even if it is unlikely that there is a copy of me with different characteristics, that probability is not zero, because here I exist in this form. So if you roll the dice an infinite number of times, 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 that mean for you?
Well, odds are 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 an astronaut.
The fact is that there are infinite possibilities at this level, infinite atom-by-atom reconstructions, limited only by their conformity to the physical laws of our universe.
What if there were no limits to this?
Stage 2: eternal chaotic inflation
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Worlds in which we could be made of music.
“The Level 2 Multiverse is still an infinite space, like the Level 1 Multiverse, but it is much more diverse,” explains Tegmark.
“If you go very far into space, you get to regions where not only history developed differently, but where you also learn different things in physics class.
“In fact, we have learned that even what we think of as empty space is probably a substance that can freeze, melt and take many different shapes.
“The inflation process that we believe created this vast cosmic space was so violent that it created an infinite amount of every kind of space.
At level 2, all physical laws are thrown out the window.
Maybe gravity works differently in another universe. Maybe we are made of sound, or maybe we are flat spheres, or maybe strange floating balls of energy that exist in 12 dimensions.
Not only are all conceivable universes possible, but also all unimaginable universes, as long as they can be imagined, which is impossible by definition.
Level 3: the quantum multiverse
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Each version does what it wants, ignoring the existence of the other.
“While the parallel universes of levels 1 and 2 are very, very far away in our own space, the multiverse of level 3 is somehow here, in the so-called quantum Hilbert space,” explains Max Tegmark.
“We know that elementary particles can be in two places at the same time.
“But I consist of elementary particles. So if they can be in two places at once, so can I.”
“So one version of me could be here talking to you, while another version of me is getting 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 into parallel branches.”
“But those 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 exists that corresponds to a mathematical structure – that can be described by mathematics – not only mathematically, but also physically,” explains the physicist.
“We could therefore have a universe in which time flows not continuously but discretely, like in a video game, or even universes in which time simply does not exist.
To clarify things, Tegmark points out that “it is not that the Tier 4 Multiverse exists in space and time, but that space and time exists 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 makes life possible.”
“So we live in an oasis, and the whole reality is like a giant version of the Sahara desert, with occasional oases here and there.
But what then?
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Not everything is so smooth.
Multiverses are predictions based on very sound scientific theories, so at least for now it looks like they are 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 does not mean 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 in reality the opposite is true: we give meaning to our universe,” says Tegmark.
“It is thanks to us, small minorities of our universe who have the complexity to experience things, that our universe can become self-aware.
Who knows, maybe if we finally accept that we’re just big apes sitting on a rock, traveling at 68,000 miles per hour across a potentially infinite expanse, we can stop taking everything so seriously.
*This article is adapted from the video by Max Tobin and Dill Steele for BBC Reel.