Parallel Worlds Probably Exist. Here’s Why

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Shared March 6, 2020

The most elegant interpretation of quantum mechanics is the universe is constantly splitting
A portion of this video was sponsored by Norton. Get up to 60% off the first year (annually billed) here: or use promo code VERITASIUM

Special thanks to:
Prof. Sean Carroll
His book, a major source for this video is 'Something Deeply Hidden: Quantum Worlds and The Emergence of Spacetime'

I learned quantum mechanics the traditional 'Copenhagen Interpretation' way. We can use the Schrödinger equation to solve for and evolve wave functions. Then we invoke wave-particle duality, in essence things we detect as particles can behave as waves when they aren't interacting with anything. But when there is a measurement, the wave function collapses leaving us with a definite particle detection. If we repeat the experiment many times, we find the statistics of these results mirror the amplitude of the wave function squared. Hence the Born rule came into being, saying the wave function should be interpreted statistically, that our universe at the most fundamental scale is probabilistic rather than deterministic. This did not sit well with scientists like Einstein and Schrödinger who believed there must be more going on, perhaps 'hidden variables'.

In the 1950's Hugh Everett proposed the Many Worlds interpretation of quantum mechanics. It is so logical in hindsight but with a bias towards the classical world, experiments and measurements to guide their thinking, it's understandable why the founders of quantum theory didn't come up with it. Rather than proposing different dynamics for measurement, Everett suggests that measurement is something that happens naturally in the course of quantum particles interacting with each other. The conclusion is inescapable. There is nothing special about measurement, it is just the observer becoming entangled with a wave function in a superposition. Since one observer can experience only their own branch, it appears as if the other possibilities have disappeared but in reality there is no reason why they could not still exist and just fail to interact with the other branches. This is caused by environmental decoherence.

Schrodinger's cat animation by Iván Tello
Wave functions, double slit and entanglement animation by Jonny Hyman
Filming of opening sequence by Casey Rentz

Special thanks to Mithuna Y, Raquel Nuno and Dianna Cowern for feedback on the script

Music from "Experimental 1" "Serene Story 2" "Seaweed" "Colorful Animation 4"

Fayaz P. A.

There's a version of me out there that understood the whole video.

4 weeks ago | [YT] | 6,538


So you're telling me there's a version where Rick didn't turn himself into a pickle?

not funny.

1 week ago | [YT] | 551


Most unbelievable part of this video:

You're using Norton360 and loving it. The probability of that is way beyond the scope of my comprehension.

3 weeks ago | [YT] | 469


I'm not lazy, my energy is just stored in a different world.

5 days ago | [YT] | 48

Isaak van Daalen

Anyone else feel like the more sense we try to make of the universe, the less sense the universe makes?

1 week ago | [YT] | 97


Meanwhile, in a parallel universe:
"Parallel universes probably don't exist and here's why"

4 weeks ago | [YT] | 5,397

Lauren Doe

I love Bohr's response to Einstein's statement: Don't tell God what to do with His dice.

2 weeks ago | [YT] | 287

XtreeM FaiL

Plot twist:
The cat suffocated.

1 week ago | [YT] | 39

Kristaps Judeiks

Oh, there's a version of me that appreciates Norton Security. Disgusting!

Otherwise, very cool video, lots to think about.

3 weeks ago | [YT] | 210

Universal Noodles

There is a version of me out there who’s brain didn’t melt

1 day ago (edited) | [YT] | 3

J. Paul Walker

I feel like I'm in a quantum state of knowing what he's talking about and following along and also being completely and utterly lost.

4 weeks ago | [YT] | 1,021

Fardin .F

Youtube in 2030: Top 10 universes by military power etc

6 days ago | [YT] | 19

Jhordan E.d.rodrigez

Then, if this is true, doesn't that mean that at some point there was a point of origin where everything was linear, and there was no "parallel world"?

2 days ago | [YT] | 4


So you are telling me that there's a version where everything you said is wrong

3 days ago | [YT] | 9

Adrian Bik

... and here I am trying to understand quantum mechanics at 1 AM

2 weeks ago | [YT] | 13


Elsewhere in a parallel universe:
Hey Michael, Veritasium here

4 weeks ago | [YT] | 2,627

Ana Mao

This just reminds me of a really scary and interesting movie : Coherence, in which people parallel worlds meet each other and get lost .... Still can't get over this movie ...

2 weeks ago | [YT] | 53


The collapse of the wave function is just simulation rendering when we observe stuff.

1 week ago | [YT] | 26

David T

Why does this happen:
Whenever we throw a pencil at a paper without spinning it at its longest axis , at such an angle that the graphite touches the paper , the pencil makes two dots. Please make a video which explains this

2 hours ago | [YT] | 0

Christofer Cervantes

So in another universe, Epstein still didn’t kill himself?

1 day ago | [YT] | 1