4 ways to understand the multiverse, according to science – 09/24/2023 – Science

Imagine the following situation: it’s the day of an important job interview, but you slept too much, so you quickly get dressed, grab something to eat and run to the bus stop.

But you can’t make it in time, so you have no choice but to walk.

You check your watch as you turn the corner and collide with an unsuspecting pedestrian. Angry, you curse him and go on your way.

You finally arrive at your appointment, sweaty and agitated, and soon discover that your interviewer is that pedestrian you just launched a barrage of expletives at.

Yes, sometimes it feels like the universe just isn’t on your side.

But luckily, there are many paths to choose from.

Due to our parents’ excessive affection, many of us live under the false impression that we are, for some reason, special.

It’s a totally unique mix of atoms and personal stories that combine to form that precious person we call “self.”

The point 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, under the impression that they, and only they, are the real you.

I am referring, of course, to the multiverse, a theory that holds that our universe is nothing more than one of many infinite universes, of infinite variety.

Now, this may sound pretty crazy, and this theory is actually based on pretty solid science.

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 led to a theory called cosmic inflation, which is the idea 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 referring to all of space, but only to a spherical region from which light has had time to reach us during the 13.8 billion years since our Big Bang” , renowned physicist and cosmologist Max Tegmark explained to the BBC.

“If this is our universe and space is bigger than this, 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.”

So if there are other worlds out there, what would they be like?

Level 1: Cosmic inflation

“The Level I multiverse is just other regions of space, the size of our universe,” says Tegmark.

“The only difference is that the particles there started in slightly different places than here, so the UK could have lost WW2 rather than winning it; my name may not be Max Tegmark, but Max Shmerkark…”

“As unlikely as it is that there is a copy of me with some other characteristic, that probability is not zero, because it happened here that I exist in this form, so if you roll the dice infinitely many times, there will be other copies of me, some very similar and many others who are a little like me, but different.”

What does this mean for you?

Well, probability says that somewhere in the cosmos there is a version of you who didn’t fall asleep on the day of the interview and another who managed to catch the bus. Even the one who never went to the interview, because she was an athlete or astronaut.

The point is that there are infinite possibilities on this plane, infinite reconstructions atom by atom, limited only by their compliance with the physical laws of our universe.

But what if there were no limits to this?

Level 2: Eternal chaotic inflation

“The Level 2 multiverse is still an infinite space, like the Level 1 multiverse, but it is much more diverse,” says Tegmark.

“If you go very far into space, you will reach regions where not only has history developed differently, but you will also learn different things in physics class.”

“That’s because we’ve learned that even what we think of as empty space is probably a substance, which can freeze and melt, and take on many different forms.”

“That process of inflation that we believe created this vast cosmic space was so violent that it created an infinite amount of every type of space.”

At level 2, all physical laws are thrown out the window.

Perhaps in another universe, gravity works differently. Maybe we’re made of sound, or we’re flat balls, or maybe we’re strange, floating balls of energy that exist in 12 dimensions.

Not only is every conceivable universe possible, but every inconceivable universe is possible, if you can imagine it, which you cannot, by definition.

Level 3: Quantum Multiverse

“While the Level 1 and 2 parallel universes are far, far away in our own space, the Level 3 multiverse is here in a sense, in this thing 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 could be here talking to you, while another version of me was taking ice cream out of the freezer and eating it somewhere else.”

“And a quantum censorship effect called ‘decoherence’ has been discovered that explains why these two versions of Max are completely unaware of each other.”

“So it looks like reality is branching off into parallel branches.”

“But those two Maxes, the one eating ice cream right now and the one talking to you, feel like they’re the only ones.”

Level 4: Mathematical Multiverse

“The Level IV multiverse is the most diverse of all.”

“In it, every physical reality that corresponds to a mathematical structure – that can be described with mathematics – exists not only mathematically, but also physically”, says the physicist.

“So you could have a universe where time doesn’t even flow continuously, but discretely, like a computer game; or even have some universes that simply don’t have time.”

To clarify, Tegmark emphasizes that “it’s not that the level 4 multiverse exists in space and time, but rather that space and time exist in some of these level IV universes.”

In our universe, he says, “we have space and time, we have the right kind of elementary particle physics that supports life.”

“So we live in an oasis, and all of reality is like a huge version of the Sahara desert, with an occasional oasis here and there.”

But what then?

Multiverses are predictions based on very well-founded scientific theories, so, at least for now, it seems like this is all here to stay.

And maybe that’s okay.

After all, science is just a tool we use to investigate the world around us.

When we discover something that can trigger existential crises, it’s not that the world has changed, but we simply begin to look at it with new eyes.

“Some people ask me how our universe gives meaning to our lives as conscious beings, but in fact, it’s the opposite: we are the ones who give meaning to our universe,” says Tegmark.

“It is through us, small minority parts of our universe who have the complexity to experience things, that our universe can become aware of itself.”

Who knows, maybe when we finally accept that we’re just great apes sitting on a rock, traveling at 65,000 mph across a potentially infinite expanse, we’ll be able to stop taking everything so seriously.

*This article was adapted from the video made by Max Tobin and Dill Steele for BBC Reel. If you want to watch the original version, Click here.