# Schrödinger's Cat [Music Video]

We will all come back
at the end of time.
As a brain in a vat,
floating around,
and purely mind.
I'm just back from the future
and I'm here to report
we'll be assimilated,
we'll all join the Borg.
We'll be collectively stupid,
if you like that or not.
Resistance is futile,
we might as well get started now.
so shut up
and leave me alone.
But we are all connected
(the cat is alive)
we will never die.
Like Schrödinger's cat
and still alive.
We are all connected
(the cat is alive)
we will never die.
Like Schrödinger's cat
and still alive.
We will never forget,
and we will never lie.
All our hate,
our fear and doubt
will be far behind.
But I'm not a computer and I'm not a machine,
I am not any other,
let me be me.
If the only pill that you have left is the blue and not the red,
it might not be so bad to be somebody's pet.
But we are all connected
(the cat is alive)
we will never die.
Like Schrödinger's cat
and still alive.
We are all connected
(the cat is alive)
we will never die.
Like Schrödinger's cat
and still alive.
Since you ask, the cat is doing fine.
Somewhere in the multiverse, it's still alive.
Think that is bad? If you trust our math,
the future is as fixed
as is the past.
We are all connected
(the cat is alive)
we will never die.
Like Schrödinger's cat
and still alive.
We are all connected
(the cat is alive)
we will never die.
Like Schrödinger's cat
and still alive.
In quantum mechanics, particles don't have to decide what they want to do.
At least not until you measure them.
They can go both, left and right.
They can have spin up and spin down.
They are in what we call a "superposition" of states.
An object in such a superposition can do many things at the same time.
If cats were quantum objects, they could be both dead and alive,
at least until you measure them.
Then they suddenly have to decide, what to do.
This might seem strange.
I'm sure you have heard that quantum mechanics is often referred to as "spooky" or "counterintuitive."
But countless experiments have confirmed
that small particles - electrons and even molecules -
indeed behave this way.
And it's not what makes quantum mechanics so strange.
It's that we never observe any of this in daily life.
How can it possibly be,
that we are made of small particles that can be in superpositions
and yet we never see anything in a superposition?
The dead-and-alive cat is a "Gedankenexperiment"
- a thought experiment -
imagined by Erwin Schrödinger.
He took a truly quantum process - the decay of an atom -
and tried to magnify it to macroscopic scales
that are observable with the eye.
The decay of an atom is fundamentally random.
We cannot predict exactly when an atom is going to decay,
we can only predict that it will decay with a certain probability
in a certain amount of time.
So, suppose we take an atom
that has decayed with 50% probability.
Before we observe it, it has both decayed and hasn't.
It's in a superposition.
Now, Schrödinger says,
let's take the atom and put it in a box together with a cat
and a trigger mechanism.
When the atom decays, it hits a detector
and a poison is released that kills the cat.
Now if the atom has decayed with 50% probability,
the cat is both dead and alive.
It seems absurd, doesn't it?
And it is absurd.
It wasn't well understood in Schrödinger's days,
but quantum superpositions are very fragile.
They get destroyed easily.
Especially in warm environments, like on Earth,
everything interacts constantly with something else:
with air, with light, with the box.
The smaller a particle is, the easier it is to isolate it,
and the longer quantum superpositions can survive.
This works for electrons and atoms, but not for cats.
The process that causes these quantum-typical superpositions to get destroyed
is called "decoherence."
Thanks to decoherence,
Schrödinger's cat is either dead or alive, but not both.