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You might be unkillable, impossible to delete  out of existence – if one of the most exciting 00:00
ideas about physics, quantum immortality, is  true. To test this idea, we will put a nuclear 00:07
bomb in your living room. But more on that  later. This is real science happening around   00:13
one of the most successful theories of physics. 00:19
To understand why, we need to tell you a story.  00:21
The story of the smallest parts in the universe, 00:25
atoms and fundamental particles. 00:29
With everyday objects things intuitively  make sense – if you kick a marble ten 00:32
times with the same force and at the same  angle, it always lands in the same spot. 00:37
But if you kick an electron ten times exactly the same way, it shows up in different places. 00:42
On the most fundamental  level of reality, randomness is the rule. 00:48
The story that solves this is called quantum  mechanics. Simplified it goes something like this: 00:54
A particle like an electron is not like a tiny  marble but like a shapeshifter – a diffuse thing 01:01
we call a wave, that ebbs and flows. But to make  it much weirder: It’s not a wave of matter or energy, 01:06
but a wave of probability – an immaterial  essence that has values between 0% and 100%. 01:13
What does this even mean? 01:21
Quantum mechanics doesn't really  tell us much about the electron. 01:24
It only tells us how this entity that  we call an electron behaves on average. 01:27
Say you shoot an electron gun at your  apartment. You shoot it 100 times – 01:34
80 times the electron shows up in your living  room, and 20 times in your kitchen. 01:39
So the probability wave of our electron is 80%  in the living room and 20% in the kitchen. 01:44
What is deeply annoying is that this story of probability waves works insanely well in reality. 01:51
It's not just some brainchild that only works on paper. 01:58
Scientists have tested it in countless  experiments and it works every single time. 02:01
It explains how a lot of real things  work, from information passing through 02:06
microchips to the atoms fusing in the center of  stars. And yet how can this story make sense? 02:10
All of our other scientific stories give us a mental picture of the things they are describing – 02:18
a sphere of iron at the center of  earth, an elastic fabric of space. 02:23
But a wave of probability? What’s that even supposed to look like? 02:27
Quantum mechanics doesn’t tell us  anything about the electron itself – 02:32
what it looks like, how it moves, or how it tastes. 02:36
But if our story doesn’t describe the electrons  themselves, what does it describe 02:40
and how does it potentially make you immortal? 02:45
What Is the Quantum Story Really About? 02:48
Scientists have been debating this for a  century. They’ve come up with tons of ideas 02:52
we can’t cover here, but there are two popular  schools of thought. We’ll call them 02:56
linguists and literary critics. 03:00
They are screaming and arguing over what the quantum story really means. 03:03
The position of the linguists is “shut up and  calculate”. They basically claim that quantum 03:08
mechanics is not a story about reality, but  just a kind of grammar for the theoretical 03:13
language of the universe. With this language  we can predict experiments. Nothing else. 03:19
If there is no story, there is no point in asking what the story says about the electron. 03:25
Whether electrons are tiny marbles or  clouds, waves of negative charge or Detective 03:30
Pikachu is missing the point. Quantum mechanics  doesn’t enable you to visualize any electrons. 03:35
All you can do is to run experiments.  And physics is all about experiments, 03:41
not about creating mental pictures for us.  So shut up, stop imagining fairy tales, 03:46
and just use the probability wave to calculate  things. Follow the grammar, ignore the plot. 03:51
“Nooooo!” scream the literary critics: Read  between the lines, there’s a hidden meaning here! 03:58
They are “many-worldians” and they  are convinced that quantum mechanics 04:05
is a story about reality. And they want to interpret the story. 04:09
The many-worlds interpretation of quantum mechanics is not the same as the multiverse by the way, 04:14
which is a whole different can of worms,  but we’ll get to that another time. 04:19
The many-worldians think that the universe  is an infinitely complex quantum state, 04:23
where all physically possible outcomes  coexist simultaneously. If the probability 04:27
wave of your electron is split 80% to 20%  between your living room and the kitchen, 04:32
that means that the electron is split in  a similar way. That there are 5 versions 04:37
of the electron – 4 of them are going to  the living room, and 1 to the kitchen. 04:41
But it isn’t just the electron that  splits. You are observing the electron, 04:46
so there are five versions of you, too! 04:51
Four of them see the electron in  the living room, and one in the kitchen. 04:54
Each of these different versions of you and the electron are equally real, equally true. 04:58
And all of them exist at this moment, in your house. But they can’t communicate 05:03
or interact in any way, so they are totally  invisible to each other. Which means that, 05:08
whoever “you” are right now, you  are just one of your versions, 05:13
experiencing just one thing – either seeing the  electron in the living room, or in the kitchen. 05:17
Many-worlds means that all physically possible  worlds are coexisting right here, right now, 05:23
but independently of each other, like the  branches of a tree. And there are a lot of them. 05:28
Every possible quantum process  means there are other possible worlds. 05:34
A radioactive atom decays? Another world exists  where it didn’t. A cosmic ray hits one of your cells? 05:38
Another world exists where the ray just passed through. 05:45
Each second, bazillions upon bazillions of new worlds exist on top of each other. 05:49
“Stop it!”, shout the linguists. “If these  worlds can’t interact with each other, 05:54
we can't check whether they exist! This is  not science. So please shut up and calculate…” 05:59
Wait! There is a way to find out. 06:05
But to do it, you’ll have to die a few hundred times.  And maybe prove that you are immortal! 06:07
The Ultimate Experiment 06:14
All we need are two electron detectors  connected to a nuclear bomb in your living room. 06:17
If the detector in your living room  is activated the nuke explodes. If the one   06:22
in the kitchen is activated you are safe.  Now sit on the nuke and have your brave   06:27
assistant shoot the electron gun. There are  two ways this can go. There is a 20% chance   06:32
the electron lands in the kitchen and  you survive, and an 80% chance you die. 06:37
Ok, let’s shoot! 06:42
Beep. 06:45
Oh, lucky you! The electron landed  in the kitchen. Let’s try once more: 06:46
Beep. 06:52
And once again: 06:53
Beep. 06:55
And another 100 times! 06:55
Beep, Beep, Beep, Beep, Beep, Beep, Beep… 06:58
If there is only one universe, you’ll die fairly soon. 07:01
Sooner rather than later the electron will trigger  the nuke and you’ll be instantly vaporized. 07:05
But if the many worlds interpretation is true,  then every time your assistant shoots the gun, 07:11
there are five versions of you and four  instantly die. Only one of your versions 07:15
is alive and there’s only one thing  you can experience – your survival. 07:21
It doesn’t matter how many times you try. From  your perspective, you will survive every time. 07:26
At first it will seem like luck. But at some  point your “luck” will become near-impossible. 07:32
In a universe with just one reality,  your odds of surviving 100 times in a row  07:37
are about 1 in ten duovigintillion  – a 1 followed by 70 zeroes. 07:43
So if you did the experiment 100 times and you  are still here, the universe just whispered   07:49
its deepest secret to you. Yes, you killed  hundreds of versions of yourself. But you 07:55
now know for sure that the many worlds are true.  Because you are still here experiencing things. 08:01
And that you are kind of immortal! 08:07
Okay, well, all that might be a bit  overwhelming - let’s break it down again. 08:10
The Cosmic Secret 08:15
If every possible quantum process  always happens in some branch, 08:17
then this doesn’t only mean that  there are almost, but not quite, 08:21
infinite versions of you – but there  is always a “you” that gets insanely lucky. 08:24
A tumor starts, but a cosmic ray kills it before  it spreads. A bolt of lightning strikes at you,   08:30
but a quantum fluke makes it miss  by a meter. A washing machine falls   08:36
from a roof, but all its atoms  quantum-tunnel through your body. 08:40
No matter how extremely high the  likelihood is that you will die, 08:44
there may always be a branch in which you survive. 08:48
So should you start wingsuit-flying today?  Well, not so fast. For every version of you that 08:51
survives, bazillions don’t. And all those versions  of you are just as real as you are right now,   08:57
watching this video. So if you care about the  current version of yourself, you should care   09:04
just as much about all the versions still waiting  to be and their loved ones. In other words – if   09:09
you see a washing machine falling, better move  away and save as many of your versions as you can. 09:15
The more universes exist with you in them the  better, your existence makes the universe richer. 09:21
And there is another good reason to move. 09:27
While the many-worlds interpretation of quantum mechanics feels beautiful and elegant, 09:29
that doesn’t make it true. We don’t know if  it’s true and so far no literary critic sat 09:34
on a nuke to risk being wrong. If the “shut  up and calculate” people are right, there is 09:39
just one world. Just one version of you. And if  the washing machine hits you, you are done for. 09:45
But wouldn’t this be nice to know? 09:51
If the many worlds idea is true,  then no matter how unlucky you get, 09:55
you will always know that somewhere, you are lucky. 09:59
Quantum mechanics is an amazing tool to explore  different realities. But what about this reality? 10:07
Ground News, the sponsor of this video,  can help you navigate our media universe, 10:13
where every news outlet has their  own perspective on the world. 10:17
In a nutshell, Ground News is a website and  app designed to make reading the news easier 10:20
and more data-driven. Every day, they  collect articles from around the world 10:25
and break each story down visually. You see  reporting bias, reliability and ownership; 10:29
all backed by three independent  media monitoring organizations. 10:34
Take this story about a new concept for a quantum  computer. Right away you can see that over 90 news 10:38
outlets reported on it. Then, you can see where  these outlets lean politically and how reliable 10:43
they generally are - you can even compare  headlines to see how these potential biases 10:47
might affect framing. Some media outlets frame  it as a major leap forward for IBM as a business, 10:51
and highlight the commercial potential for  quantum computing. Others focus more on the 10:56
science itself, and use precise language  to emphasize the technical challenges that 11:00
were overcome. This way you get to  see how headlines alone can affect 11:04
your perception and decide for yourself if  this finding is the future or just a fad. 11:07
If you’d like to give them a try, go to  ground.news/KIN, or scan the 11:12
QR code on the screen. Using this link saves  you 40% off an unlimited access subscription, 11:16
and directly supports our channel. We  think the people at Ground News do a 11:21
really important job - if you can never  know all quantum versions of yourself, 11:25
better make sure this version  has the full view of the horizon. 11:29

– English Lyrics

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Lyrics & Translation

[English]
You might be unkillable, impossible to delete  out of existence – if one of the most exciting
ideas about physics, quantum immortality, is  true. To test this idea, we will put a nuclear
bomb in your living room. But more on that  later. This is real science happening around  
one of the most successful theories of physics.
To understand why, we need to tell you a story. 
The story of the smallest parts in the universe,
atoms and fundamental particles.
With everyday objects things intuitively  make sense – if you kick a marble ten
times with the same force and at the same  angle, it always lands in the same spot.
But if you kick an electron ten times exactly the same way, it shows up in different places.
On the most fundamental  level of reality, randomness is the rule.
The story that solves this is called quantum  mechanics. Simplified it goes something like this:
A particle like an electron is not like a tiny  marble but like a shapeshifter – a diffuse thing
we call a wave, that ebbs and flows. But to make  it much weirder: It’s not a wave of matter or energy,
but a wave of probability – an immaterial  essence that has values between 0% and 100%.
What does this even mean?
Quantum mechanics doesn't really  tell us much about the electron.
It only tells us how this entity that  we call an electron behaves on average.
Say you shoot an electron gun at your  apartment. You shoot it 100 times –
80 times the electron shows up in your living  room, and 20 times in your kitchen.
So the probability wave of our electron is 80%  in the living room and 20% in the kitchen.
What is deeply annoying is that this story of probability waves works insanely well in reality.
It's not just some brainchild that only works on paper.
Scientists have tested it in countless  experiments and it works every single time.
It explains how a lot of real things  work, from information passing through
microchips to the atoms fusing in the center of  stars. And yet how can this story make sense?
All of our other scientific stories give us a mental picture of the things they are describing –
a sphere of iron at the center of  earth, an elastic fabric of space.
But a wave of probability? What’s that even supposed to look like?
Quantum mechanics doesn’t tell us  anything about the electron itself –
what it looks like, how it moves, or how it tastes.
But if our story doesn’t describe the electrons  themselves, what does it describe
and how does it potentially make you immortal?
What Is the Quantum Story Really About?
Scientists have been debating this for a  century. They’ve come up with tons of ideas
we can’t cover here, but there are two popular  schools of thought. We’ll call them
linguists and literary critics.
They are screaming and arguing over what the quantum story really means.
The position of the linguists is “shut up and  calculate”. They basically claim that quantum
mechanics is not a story about reality, but  just a kind of grammar for the theoretical
language of the universe. With this language  we can predict experiments. Nothing else.
If there is no story, there is no point in asking what the story says about the electron.
Whether electrons are tiny marbles or  clouds, waves of negative charge or Detective
Pikachu is missing the point. Quantum mechanics  doesn’t enable you to visualize any electrons.
All you can do is to run experiments.  And physics is all about experiments,
not about creating mental pictures for us.  So shut up, stop imagining fairy tales,
and just use the probability wave to calculate  things. Follow the grammar, ignore the plot.
“Nooooo!” scream the literary critics: Read  between the lines, there’s a hidden meaning here!
They are “many-worldians” and they  are convinced that quantum mechanics
is a story about reality. And they want to interpret the story.
The many-worlds interpretation of quantum mechanics is not the same as the multiverse by the way,
which is a whole different can of worms,  but we’ll get to that another time.
The many-worldians think that the universe  is an infinitely complex quantum state,
where all physically possible outcomes  coexist simultaneously. If the probability
wave of your electron is split 80% to 20%  between your living room and the kitchen,
that means that the electron is split in  a similar way. That there are 5 versions
of the electron – 4 of them are going to  the living room, and 1 to the kitchen.
But it isn’t just the electron that  splits. You are observing the electron,
so there are five versions of you, too!
Four of them see the electron in  the living room, and one in the kitchen.
Each of these different versions of you and the electron are equally real, equally true.
And all of them exist at this moment, in your house. But they can’t communicate
or interact in any way, so they are totally  invisible to each other. Which means that,
whoever “you” are right now, you  are just one of your versions,
experiencing just one thing – either seeing the  electron in the living room, or in the kitchen.
Many-worlds means that all physically possible  worlds are coexisting right here, right now,
but independently of each other, like the  branches of a tree. And there are a lot of them.
Every possible quantum process  means there are other possible worlds.
A radioactive atom decays? Another world exists  where it didn’t. A cosmic ray hits one of your cells?
Another world exists where the ray just passed through.
Each second, bazillions upon bazillions of new worlds exist on top of each other.
“Stop it!”, shout the linguists. “If these  worlds can’t interact with each other,
we can't check whether they exist! This is  not science. So please shut up and calculate…”
Wait! There is a way to find out.
But to do it, you’ll have to die a few hundred times.  And maybe prove that you are immortal!
The Ultimate Experiment
All we need are two electron detectors  connected to a nuclear bomb in your living room.
If the detector in your living room  is activated the nuke explodes. If the one  
in the kitchen is activated you are safe.  Now sit on the nuke and have your brave  
assistant shoot the electron gun. There are  two ways this can go. There is a 20% chance  
the electron lands in the kitchen and  you survive, and an 80% chance you die.
Ok, let’s shoot!
Beep.
Oh, lucky you! The electron landed  in the kitchen. Let’s try once more:
Beep.
And once again:
Beep.
And another 100 times!
Beep, Beep, Beep, Beep, Beep, Beep, Beep…
If there is only one universe, you’ll die fairly soon.
Sooner rather than later the electron will trigger  the nuke and you’ll be instantly vaporized.
But if the many worlds interpretation is true,  then every time your assistant shoots the gun,
there are five versions of you and four  instantly die. Only one of your versions
is alive and there’s only one thing  you can experience – your survival.
It doesn’t matter how many times you try. From  your perspective, you will survive every time.
At first it will seem like luck. But at some  point your “luck” will become near-impossible.
In a universe with just one reality,  your odds of surviving 100 times in a row 
are about 1 in ten duovigintillion  – a 1 followed by 70 zeroes.
So if you did the experiment 100 times and you  are still here, the universe just whispered  
its deepest secret to you. Yes, you killed  hundreds of versions of yourself. But you
now know for sure that the many worlds are true.  Because you are still here experiencing things.
And that you are kind of immortal!
Okay, well, all that might be a bit  overwhelming - let’s break it down again.
The Cosmic Secret
If every possible quantum process  always happens in some branch,
then this doesn’t only mean that  there are almost, but not quite,
infinite versions of you – but there  is always a “you” that gets insanely lucky.
A tumor starts, but a cosmic ray kills it before  it spreads. A bolt of lightning strikes at you,  
but a quantum fluke makes it miss  by a meter. A washing machine falls  
from a roof, but all its atoms  quantum-tunnel through your body.
No matter how extremely high the  likelihood is that you will die,
there may always be a branch in which you survive.
So should you start wingsuit-flying today?  Well, not so fast. For every version of you that
survives, bazillions don’t. And all those versions  of you are just as real as you are right now,  
watching this video. So if you care about the  current version of yourself, you should care  
just as much about all the versions still waiting  to be and their loved ones. In other words – if  
you see a washing machine falling, better move  away and save as many of your versions as you can.
The more universes exist with you in them the  better, your existence makes the universe richer.
And there is another good reason to move.
While the many-worlds interpretation of quantum mechanics feels beautiful and elegant,
that doesn’t make it true. We don’t know if  it’s true and so far no literary critic sat
on a nuke to risk being wrong. If the “shut  up and calculate” people are right, there is
just one world. Just one version of you. And if  the washing machine hits you, you are done for.
But wouldn’t this be nice to know?
If the many worlds idea is true,  then no matter how unlucky you get,
you will always know that somewhere, you are lucky.
Quantum mechanics is an amazing tool to explore  different realities. But what about this reality?
Ground News, the sponsor of this video,  can help you navigate our media universe,
where every news outlet has their  own perspective on the world.
In a nutshell, Ground News is a website and  app designed to make reading the news easier
and more data-driven. Every day, they  collect articles from around the world
and break each story down visually. You see  reporting bias, reliability and ownership;
all backed by three independent  media monitoring organizations.
Take this story about a new concept for a quantum  computer. Right away you can see that over 90 news
outlets reported on it. Then, you can see where  these outlets lean politically and how reliable
they generally are - you can even compare  headlines to see how these potential biases
might affect framing. Some media outlets frame  it as a major leap forward for IBM as a business,
and highlight the commercial potential for  quantum computing. Others focus more on the
science itself, and use precise language  to emphasize the technical challenges that
were overcome. This way you get to  see how headlines alone can affect
your perception and decide for yourself if  this finding is the future or just a fad.
If you’d like to give them a try, go to  ground.news/KIN, or scan the
QR code on the screen. Using this link saves  you 40% off an unlimited access subscription,
and directly supports our channel. We  think the people at Ground News do a
really important job - if you can never  know all quantum versions of yourself,
better make sure this version  has the full view of the horizon.

Key Vocabulary

Start Practicing
Vocabulary Meanings

universe

/ˈjuːnɪvɜːrs/

B2
  • noun
  • - the totality of everything that exists, including all physical matter and energy, the planets, stars, galaxies, and the contents of space.

quantum

/ˈkwɒntəm/

C1
  • adjective
  • - relating to or denoting phenomena that are governed by the laws of quantum mechanics.
  • noun
  • - a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents.

story

/ˈstɔːri/

A2
  • noun
  • - an account of past events in someone's life or in the development of something.

reality

/riˈæləti/

B2
  • noun
  • - the state of things as they actually exist, as opposed to an idealistic or notional idea of them.

electron

/ɪˈlektrɒn/

B2
  • noun
  • - a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.

experiment

/ɪkˈsperɪmənt/

B1
  • noun
  • - a scientific procedure undertaken to make a discovery, test a hypothesis, or demonstrate a known fact.
  • verb
  • - perform a scientific procedure to test a hypothesis or demonstrate a known fact.

wave

/weɪv/

B1
  • noun
  • - a disturbance that travels through a medium, transporting energy from one place to another.
  • verb
  • - move one's hand to and fro in greeting or as a signal.

world

/wɜːld/

A1
  • noun
  • - the earth and all its inhabitants.

time

/taɪm/

A1
  • noun
  • - the indefinite continued progress of existence and events in the past, present, and future regarded as a whole.

many

/ˈmeni/

A1
  • adjective
  • - a large number of.

thing

/θɪŋ/

A1
  • noun
  • - an object that one need not, cannot, or does not wish to give a specific name to.

scientist

/ˈsaɪəntɪst/

B1
  • noun
  • - a person who is studying or has expert knowledge of one or more of the natural or physical sciences.

universe

/ˈjuːnɪvɜːrs/

B2
  • noun
  • - the totality of everything that exists, including all physical matter and energy, the planets, stars, galaxies, and the contents of space.

idea

/aɪˈdiːə/

A2
  • noun
  • - a thought or suggestion as to a possible course of action.

school

/skuːl/

A1
  • noun
  • - an institution for educating children.

calculate

/ˈkælkjʊleɪt/

B1
  • verb
  • - determine the amount or number of something mathematically.

true

/truː/

A2
  • adjective
  • - in accordance with fact or reality.

interpret

/ɪnˈtɜːrprɪt/

B2
  • verb
  • - explain the meaning of (information, words, or actions).

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