Kind: captions
Language: en
In 1928, a young man shuffled onto a
stage in Germany to present a lecture
[music] on his recent work. He had a
slightly unusual presentation style.
Physicist Eugene Vner described the
lecture as detached, almost like a
recitation of a technical text. He said
the man spoke without giving any sign
[music] of enjoying his own lecture. But
the work this strange, unassuming man
presented was about to send some of the
most famous quantum physicists of the
20th century spiraling.
After the lecture, Verer Heisenberg
described the man's theory as the
saddest chapter in modern physics.
Heisenberg also wrote to Neils Bore and
said, "I find the present situation
quite absurd." And on that account,
almost out of despair, I have taken up
another field. Legend has it that Wolf
Gang Pie even announced that he was
abandoning quantum physics and then he
started writing a utopian novel. What
had the young man said to disrupt the
world of quantum mechanics so
profoundly? Well, he had been working on
a problem that physicists are still
tackling today. The unification of
Einstein's relativity and quantum
mechanics. And his work had revealed
something troubling. A particle unlike
any seen in the world. A particle with
negative energy.
In 1905, Albert Einstein published his
special theory of relativity. It was
based on the simple idea that for anyone
moving with constant speed, the laws of
physics should be the same. And this
includes any measurement of the speed of
light. So it doesn't matter how you're
moving relative to a beam of light, you
should measure its speed [music] to be
300 million meters/s. This means that
things that we ordinarily think of as
fixed like time and space [music] have
to transform so that the speed of light
is always measured to have the same
value. In making this discovery,
Einstein realized that space and time
are not really separate dimensions at
all. They're linked in a
four-dimensional fabric called
spacetime.
When Einstein applied this idea to an
object emitting light, he found
something peculiar. When an object loses
energy by emitting photons, its mass
must also decrease. And the change in
the object's mass is equal to the energy
of the photons emitted divided by the
speed of light squared. In other words,
he found that energy must be equal to
MC^². [music]
E= MC².
Mass and energy are but different
manifestations of the same thing.
>> So a particle's total energy comes from
its momentum and its rest mass giving a
new relationship between energy and
momentum.
Now if we take the square root of both
sides we get an expression for the
energy of a particle in terms of its
mass and momentum. And if we plot energy
versus momentum in a single dimension,
we get this curve where mc^ squ the rest
mass energy of the object is the lowest
possible value for energy. But really
when we took the square root, we should
have put a plus minus out front which
would give us two curves. One for
positive energies and another for
negative energies. But we don't observe
things that have energy less than zero.
I mean what would that even mean? So in
classical physics the solution is
simple. You just ignore the negative
energy solutions. They can't physically
represent anything. Right, [music]
Casper? Well, sure that sounds right.
But around the same time that Einstein
was coming up with his special theory of
relativity, physicists began observing
some strange phenomena in atomic physics
that were overthrowing all of these
classical assumptions. First of all,
they noticed that when looking at the
energy levels of subatomic particles
like electrons, they weren't continuous
at all. They were discrete. And they
also didn't just behave as particles,
but as waves. So if you would take
electrons and fire them through two
narrow slits, [music] then they would
create interference patterns just like
light does. What they were discovering
was the new field of quantum mechanics.
And in 1926, Irwin Shinger formalized
this field by coming up with his now
famous wave equation, which describes
how quantum mechanical systems evolve
over time.
This was the most radical new theory of
the 20th century and and would remain
so. This is not a bit like Newton or a
bit like Maxwell. This was radically
new. The equation solution called the
wave function s does not describe a
particle with a precise position and
momentum as classical laws would. But
instead the modulus squar can give us
the probability of finding the particle
in a specific location at a specific
time. Deriving the Schroinger equation
is actually surprisingly simple. Just
start by writing down the total energy,
which for a free particle is just its
kinetic energy, a half mv^ 2. And we can
rewrite it in terms of momentum. Mass
time velocity. So kinetic energy [music]
is just momentum squared / 2 m. Now
we're going to make this quantum. And to
do that, we need two things. [music] The
first is the wave function sigh which
describes how particles act as waves at
quantum scales. And the second is
something called a quantum operator.
This is just a mathematical tool that
extracts information from the wave
function to reveal a specific property
of the particle like its position,
energy or momentum. The operators for
energy and momentum look like this.
By inputting these operators, we can
make each side of the equation act on
the wave function. And that gives us the
Schroinger equation for a free particle.
For particles that aren't free, like
electrons and atoms, you need to factor
in potential energy too, which gives you
the full Schroinger equation.
But there are some places where it
doesn't produce the right prediction.
For example, take the element gold. The
Schrodinger equation suggests that it
should be a silver gray color just like
all the other metals, but it's not. I
mean, it's gold. And for mercury, the
Schrodinger equation predicts that it
should be a solid at room temperature,
but it's a liquid. So, what is wrong?
Well, I'll give you a hint. Because both
gold and mercury are heavy elements.
They have a high number of protons in
their nuclei, which attract orbiting
electrons more strongly. So if you're
thinking in a classical sense, the
electrons would be bound tighter [music]
in and they'd be whizzing around at
higher speeds than in other elements.
And for electrons in some orbits, those
speeds start to get a little too close
to the speed of light. So let's go back
to the Schroinger equation. There we had
the kinetic energy was p ^2 over 2mm.
But for particles moving at relativistic
speeds close to the speed of light, that
equation isn't the right one. The
correct equation is the energy momentum
relation from special relativity.
>> Shreddinger's equation is not consistent
with the theory of relativity. So it's
technically it's not right.
>> So the solution seems simple enough.
Just start with the relativistic energy
momentum relation and use that to derive
a new wave equation.
Well, this is exactly what a physicist
named Oscar Klein did in 1926. He subbed
in the same energy and momentum
operators that Schroinger used and found
this equation.
Klein's work was pretty well received by
a number of his colleagues. In fact, it
turned out that two other physicists,
Walter Gordon and Vladimir Faulk, had
independently arrived at the same
equation in that same year. It became
known as the Klein Gordon equation,
which was a bit of a burn for Faulk.
But that's often how it goes. You do all
the hard work and then no one notices.
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Klein, Gordon, and Faulk.
The Klein Gordon Faulk equation even
made its way over to one of the fathers
of quantum physics, Neils Boore, who
must have been impressed because at the
1927 Solve conference, Boore was
chatting to a promising young physicist
about what he was working on. The young
man said, "I'm trying to get a
relativistic theory of the electron."
Boore replied, "But Klein has already
solved this problem." The young man
disagreed. So, who was this bold
25-year-old?
He was Paul Drack, a man who Boore would
later give the nickname the strangest
man because he was truly one of a kind.
The
>> first time I went to Princeton, I met a
a couple who invited [music]
Durac and his wife and Dak uh for the
whole meal which lasted 3 hours. Didn't
say a single word.
Not one word. He wasn't sulky. He wasn't
angry. He just saw no reason to speak.
>> That's crazy. Durac was a man of so few
words that his colleagues invented a
special unit, a dra, equivalent to
speaking one word per hour. Legend also
has it that he liked to relax by
climbing trees in three-piece suits. And
that wasn't his only strange hobby. As a
student, Dra had attended seminars on
Einstein's theory of relativity, and
he'd kind of fallen in love with it. He
was impressed by the elegance and beauty
of its mathematics. To Dak, this got to
the core of what a good theory must do.
He once said, "It is more important to
have beauty in one's equations than to
have them fit experiment."
>> Do you know why the rock was so drawn to
relativity?
>> Einstein went in there and did it all,
not all but almost all by deductive
reasoning that made a huge impression on
Dra, right? He realized that [music] uh
that it was advanced mathematics was
really important to understanding the
[music] way that nature works. So the
rock found a new hobby obsessively
updating classical equations with
[music] Einstein's theory of relativity
so that they would now work for
relativistic scenarios as well that are
those approaching [music] the speed of
light. He later said this was like a
game for him. And so it's maybe not too
much of a surprise then that he was one
of the people trying to unite quantum
physics and [music] relativity because a
theory that would cover both of these
would be truly beautiful in his eyes.
Durac didn't see the beauty in Klein,
Gordon, and Fox relativistic update of
the Schrodinger equation. And he wasn't
alone. Fellow physicist Wolf Gang Pi,
after reading Klein's paper, wrote him a
letter wishing his physics a speedy
recovery. Pali was known for being
pretty savage. And actually, the Klein
Gordon equation is useful in some cases,
but he and Drack were both concerned
with one particular feature of the
equation, and that's because the Klein
Gordon equation contains this term.
That's a second order time derivative.
So the wave function is being
differentiated twice with respect to
time. Now remember the shinger equation
also contains a second order derivative
but that's with space [music] not with
time. Time is just first order. So why
is this such a problem? Well think of a
very simple second order time
derivative. [music]
Something like d ^2 y over dt ^2 is
equal to 3. Now to figure out what y is
the function that satisfies this
equation we just have to integrate it
twice.
But notice to find the solution we now
have two integration constants C and D.
And the problem is that we can only find
that if we know both Y at a given time
and if we know the first derivative of Y
at a given time. This makes sense
physically if you think about say
throwing a ball in the air. If you want
to predict the ball's future motion,
well then you need to know where you
threw it from. that's its position and
how hard you threw it. That's its
velocity. Or in other words, you need to
know both the position and the first
derivative of the position.
Similarly, to predict a quantum systems
future state using the Klein Gordon
equation, you'd need the initial wave
function and the initial first
derivative of the wave function.
Now, the beauty of the Schroinger
equation was that if you knew only the
wave function of a system at a given
time, you could use it to determine all
the future states of that system. But in
the Klein Gordon equation, the wave
function no longer told the whole story.
And this introduced a further problem.
The probability of finding a particle in
a given area could no longer be simply
described by the modulus of the wave
function as it was for the Shteringer
equation. For the Klein Gordon equation,
a new equation was needed to describe
the probability using the wave function,
which takes a while to derive. So we
won't get into that here, but it looks
like this. And the problem with that
equation is that unlike the simple
modulus of the wave function, it can
have negative solutions, negative
probabilities.
How can the chance of something
happening be less than zero? As Dur put
it, that of course is physically
nonsense.
So Direct did what Direct does best and
he set out to find his own solution that
contained no second order time
derivatives. First he rewrote the
relativistic energy momentum
relationship like this which is a linear
equation. So no squaring e that is no
squaring the energy operator which is
what gave rise to that second order time
derivative in the Klein Gordon equation.
Now he just had to solve this equation
and find the coefficients alpha x alpha
y alpha z and beta and he would have a
solution.
To do this we can start by squaring both
sides of the equation. Next, we can
expand the momentum on the left hand
side into its three dimensions and then
expand the right hand side to end up
with this long equation. It might look
pretty complicated, but there is a trick
we can use.
Notice that all these terms on the right
hand side are multiplied by PMC cubed,
but on the left hand side there are no
terms containing PMC cubed. So that
tells us that when you multiply these
coefficients together, like the alpha*
beta and beta* alphas, all of that must
be zero. And similarly notice that these
terms are multiplied by two different
momenta like px and p y * c ^ 2 which
also don't have a counterpart on the
left hand side. So these alpha * alpha
terms must also be equal to zero. And
that just leaves this top row. These
terms do match on both sides which tells
us that alpha x^2 must be equal to 1 and
so must alpha y^2 alpha z^2 and beta
squ. So Drack now had a set of
simultaneous equations for alpha x,
alpha y, alphaz, and beta that he just
needed to solve. That sounds easy,
right? But it's not that
straightforward. To see why, let's do
some examples. So say alpha x is 1 and
beta= -1. Well, then we get 1^2, which
is 1 equ= - 1 2, which is also 1. So
that satisfies the top equation. But if
we fill it in here, we get 1 * -1, which
is just -1 + -1 * 1, which is again -1
for a total of -2. So that doesn't work.
So let's let's try another number. Say
alpha x is 1 and now it's alphaz that
[music] is minus one. Well, in that
case, we get 1 * -1. So again we get -1
+ -1 * 1 again -1. So we again get
[music] minus2. And in fact if you look
at this top equation the only numbers
that satisfy this relation is 1 and
minus1. So all these coefficients have
to be either 1 or minus one. But if you
fill that in then the only two possible
answers you're going to get in these
equations is minus2 or positive2. Now
the two equations that are giving
problems are these two. And that's
because alpha time beta is the same as
beta* alpha. So you're always going to
get minus2 or two. So the only way to
get out of this is to somehow make the
order of multiplication matter. But
where do you find something like that?
Let's think about a really simple
vector. Say one in the x direction and
two in the y direction. If I reflect
this vector along the line y = x and
then reflect it about the x-axis, I get
this. But if I start again and instead
reflect it first about the x-axis and
then along y equals x, I get this, which
is totally different. So the order
matters.
How do we express this mathematically?
We need some way to represent
transformations like reflections as a
single coefficient. Which means we need
matrices.
Matrices are arrays of numbers which
encapsulate these transformations
telling us how to reflect, rotate,
stretch or squish across each dimension.
Mathematically the order we multiply
them matters. Since we multiply the rows
of the first matrix by the columns of
the second,
a matrix that reflects along y equals x
looks like this. And a matrix that
reflects about the x-axis looks like
this.
And if I apply them to that original
vector one by one, you can see how we
end up with different results.
And actually using matrices in quantum
mechanics was not completely out there.
Durac had already seen it done by Verer
Heisenberg, his new, if unlikely,
friend. Durk and Heisenberg were very
different characters. Heisenberg was
charming and outgoing. Durk hated
socializing and small talk. Once the two
were on a cruise ship to a conference
together, and Heisenberg spent a lot of
time dancing with women on board. So,
Durk asked him, "Why do you dance?"
Heisenberg replied, "When there are nice
girls, it is a pleasure." Durac thought
about this for a bit before saying, "How
do you know beforehand that the girls
are nice?" So, they were pretty
different guys, but Heisenberg had a
profound impact on Dra.
>> Do you know what drew him to quantum
mechanics initially?
>> He always said that Heisenberg gave him
his start. He always said that in later
life he used to begin lectures when he
was 70 even 80 years old with the
following words. Quantum mechanics was
discovered by Heisenberg in 1925.
>> As a PhD student, The Rock had closely
followed Heisenberg's work. And a few
years earlier, Heisenberg had found that
for certain properties like position and
momentum, the order of multiplication
matters. So X * P is not the same as P
[music] * X. This was actually the
beginning of Heisenberg's famous
uncertainty principle which says that
there's a limit to how precisely we can
know certain [music] pairs of physical
properties in quantum systems. It turns
out that if the order of multiplication
matters for two properties [music] like
position and momentum, then that means
there's an inherent uncertainty in their
combined measurement. The order we
measure them in will change [music] the
outcome. Heisenberg's mentor Max Bourne
suggested that he could represent this
mathematically by using matrices because
[music] there the order of
multiplication also matters.
This led Heisenberg to a new form of
quantum mechanics which was
mathematically equivalent to
Schroinger's equation but it was based
on matrix algebra.
Durac recognized something similar in
his coefficients where the order of
multiplication clearly mattered. So he
thought matrices might be the solution.
For his coefficients, he tried 2x two
matrices since they're the smallest,
simplest matrices that could make the
order of multiplication matter. He found
that some worked with the equations. In
fact, those reflection matrices we tried
earlier worked well, but he just
couldn't find solutions for all four
coefficients that all worked together.
>> This is not simple. You're direct one of
the smartest people of the 20th century
in physics, right? But it was not easy.
You don't have just to twiddle with bits
of the shred equation. you you'd have to
do something completely radical. His
working is in there and you could see
him really struggling.
>> Then Drack had a stroke of genius. He
said, "I suddenly realized that there
was no need to stick to quantities which
can be represented by matrices with just
two rows and columns. Why not go to four
rows and columns
with these four 4x4 matrices? Direct got
these solutions to his simultaneous
equations. A matrix with ones on the
diagonal is mathematically equivalent to
a one. And a whole array of zeros is the
same thing as zero. So all of the
equations were satisfied. Durac had
found coefficients that worked. Now we
can substitute those matrices back into
Durac's linear equation. Then rewrite
the three momenta and alpha coefficients
as vectors. And just as we did with the
Schroinger and Klein Gordon equations,
we can use the energy and momentum
operators to make both sides act on the
wave function. If we substitute those
operators in, we get DAC's final
equation for the relativistic free
electron.
The young man who spent his life looking
for mathematical beauty had found
perhaps his most beautiful equation of
all. People were expecting the solution
to be horrible and it turned out to be a
thing of beauty, right? It was something
you look at and you think that is
absolutely amazing. [music] It's a
pattern that Draq had found deep in
nature. Nothing like that had been seen
in physics at that time.
To see some of that beauty, you only
have to compare it to the Shreddinger
equation, which you can see right here.
Now, the two look very similar, but
there is a lot hidden in the Duck
equation. First of all, it's
relativistic. So, it works at really,
really high speeds because it uses
Einstein's energy momentum relationship,
unlike the Shreddinger equation, which
breaks down there. But what's even more
beautiful is that if you look at this,
the Rux equation isn't just first order
in time derivatives, it's also first
order in spatial derivatives, whereas
the Shreddinger equation was second
order in spatial derivatives. So, you
might wonder, well, why does that
matter? Well, because not only does
going first order and all derivatives to
solve the second order time derivative
problem of the Klein Gordon equation, it
now also treats time and space [music]
symmetrically. And it becomes really
important if you start thinking about
relativity where time and space are not
separate dimensions. [music]
They're intertwined in a
four-dimensional spaceime. And while the
shredding equation had just a single
component wave function, to make [music]
the wave function work with these 4x4
matrices, in the rock's case, you
actually need a wave function that has
four components. So it will look
something like this. S 1, S 2, S [music]
3, and S 4.
The four component wave function means
that the DRA equation describes four
possible states for any quantum system
which reveals something Schrodinger's
single wave function didn't. An electron
at a given energy level actually has two
possible states due to different
orientations of its intrinsic angular
momentum. Spin up and spin down.
This spin creates a tiny magnetic field.
So these two states are like tiny
magnets pointing in opposite directions.
And that has an interesting implication.
Take hydrogen, which has one proton and
one electron. Classically, the electron
whizzes around the proton. But if you
switch to the perspective of the
electron, well, now it's the proton
that's moving. And since it's positively
charged, that moving charge creates a
magnetic field in the electron's frame
of reference. So now you've got this
electron, which has its own mini
magnetic field, interacting with a
larger magnetic field. And that
interaction will be slightly different
for a spin up and a spin down electron.
And as a result, some energy levels of
the electron split into two closely
spaced energy levels. And you can
actually see this if you zoom into the
emission spectrum for a hydrogen atom.
Schroinger's equation didn't predict
that splitting since it just had one
solution for each energy level. But with
Drax's four component solution, the top
two wave functions now described two
different spin states with two slightly
different energies.
>> The Rock admitted himself that he had
never set out to capture spin in his
equation.
>> I started out this work without any
intention at all [music]
of bringing in the spin of the electron.
>> But hold on, because if an electron at a
given energy level only has two possible
spin states, then why do we have a four
component wave function? Why are there
four states and not just two?
>> Well, that's what brings us back to that
1928 lecture at the start, the one that
seemed to drive even the most
wellestablished quantum physicist mad.
Because that strange man presenting his
work was actually Paul Drack sharing his
new equation with the world. It was
Drack's beautiful equation that
Heisenberg called the saddest chapter in
modern physics.
To understand why all those physicists
were losing their minds, we only have to
look at the simple case when a particle
is at rest. This term right here
describes the momentum. So when the
particle doesn't move, this becomes zero
and it drops out, which gives us this.
Next, we can sub in the energy for this
quantum operator to get this. So now we
know that beta * mc^ 2 must be equal to
the particle's energy. And if we write
out beta and multiply by mc^ squ then we
find two positive solutions and two
negative solutions for the energy. So
negative energy solutions are baked
right into the rock equation.
This idea that a free electron could
have negative energy was impossible for
any of these physicists to accept.
Because think about it, if electrons can
have a negative energy, then that means
that they could continually radiate
positive energy that is emit photons and
drop into lower and lower negative
energy states. There would be no limit
to how far they could fall into the
negative energy abyss. It looked like to
many very smart people and direct was
smart enough to know they had a point
that this equation it got the mass and
the magnetic moment of the electron.
Yes. But on the other hand, it predicts
this ridiculous situation where they
have negative energy values, right?
>> That's nonsense. So Heisenberg said, "I
give up. This is just this is just
ridiculous." So Drack, he had in some
very clear sense had to rescue his
equation. Dra spent 3 years sticking to
his guns. He tried all sorts of ways to
interpret his new equation to explain
where the negative energy was coming
from.
Then in 1931 he proposed something
radical to explain the negative energy
solutions.
A new [music] kind of particle unknown
to experimental physics having the same
mass and opposite charge to an electron.
We may call such a particle an
anti-electron. [music]
We should not expect to find any of them
in nature on account of their rapid rate
of recombination with electrons.
So Drack was proposing that those four
states described in his four component
wave function are a spin up electron, a
spin down electron, a spin up
anti-electron, and a spin down
anti-electron.
>> When Durac said that, people didn't
start running around and say, "Where's
this anti-electron?" They just ignored
it.
>> Yeah.
>> Cut to uh the laboratory at Caltech. In
1932, a Caltech postoc named Carl
Anderson was working on a project trying
to identify the charged particles
produced by cosmic rays. He photographed
the tracks these particles left in a
cloud chamber containing a uniform
magnetic field. Anderson noticed several
instances of a similar track. It looked
a lot like the tracks he'd seen left by
electrons, only it curved in the
opposite direction in the magnetic
field, kind of like the tracks of
positively charged protons. But there
was no way it could be a proton based on
the length of the track. It had traveled
farther in air and therefore it had to
be much lighter. It had to be something
with around the same mass as an electron
but opposite charge, a positive
electron, or as he named it, a posetron.
He actually also tried to rebrand
electrons as negatrons, but that one
didn't quite stick.
Just one year after Durac proposed the
anti-electron, Carl Anderson found it
entirely by accident.
But this alone doesn't get rid of the
negative energy problem. Remember what
we said earlier. If any particles like
these posetrons can have negative
energy, then they could continually
radiate energy and drop into lower and
lower negative energy states.
Fortunately, The Rock proposed a
solution to this problem as well,
although it was a little crazy.
He theorized something called the direct
sea, describing a vacuum as an infinite
sea of electrons occupying all available
negative energy states. And since no two
electrons can occupy the same state,
this prevents observable positive energy
electrons from falling into the negative
energy states. A hole or vacancy in this
sea then becomes a posetron. When an
electron and a posetron meet and
annihilate, [music]
well, that's just an electron falling
back into the sea and filling that hole.
The theory is mathematically sound. Of
course, it's direct we're talking about.
But if you feel like it's hard to come
to terms with the idea that we're
floating on an infinite sea of
electrons, well, you wouldn't be alone.
It's not even that crazy if, I don't
know, several decades later, people find
that exact model in a physical system.
In condensed matter physics you see an
an exact analogy of also having
electrons uh in the conduction band and
safe balance veence band.
>> Yes that's true that's true but but
direct really was you [music] know out
there you see what I mean was people
like you know see really senior people
are saying this is nonsense but it was a
way of direct rectalinear [music]
thinking thinking well maybe this and
then it drove him to antimatter.
Thankfully in 1941 a Swiss physicist
named Ernstuklberg had a clever idea.
The wave function contains a term that
looks like this where energy is
multiplied by time. So we can see that
if we just change the sign of time when
the energy is negative then we get the
same result because a negative
multiplied by a negative gives us a
positive. Stuckleberg took this and he
suggested that negative energy electrons
traveling backwards in time [music] are
mathematically equivalent to positive
energy anti-electrons that is posetrons
[music] traveling forwards in time. A
few years later around 1948 Richard
Feineman took this idea and used it in
one of the most powerful tools in modern
physics the Fineman diagrams. In his
sketches of particle interactions he
showed antiparticles traveling the
opposite way to particles backwards in
time.
It was a brilliant trick. Negative
energy solutions no longer had to mean
there was negative energy or a direct C.
They simply indicated the presence of an
antiparticle.
We now know that there's a corresponding
antiparticle for every subatomic
particle with the same mass but opposite
charge. So the proton has the
anti-roton, the nutrino has the
antiutrino and so on. According to his
friend Heiserberg, that [music] was the
biggest leap in 20th century physic to
to say there's a whole slew of of
antiarticles corresponding [music] to
particles and DRA got that through this
crazy model. But all is not solved.
[music] This new anti-orld introduces
some big questions about the very nature
of our universe. Because particles and
their antiparticles are equal and
opposite. When they come together, they
annihilate and produce two photons with
energy equivalent to their mass and
kinetic energy. And this process is
reversible. Two photons with the right
energies can produce a matter and
antimatter pair. This is called bright
wheeler pair production.
During the first moments after the big
bang, the universe was hot, dense, and
full of these pairs popping into and out
of existence. [music]
If an equal number of matter and
antimatter particles were created, you
would expect them to all annihilate each
other in this dense environment, leaving
behind only energy. But that didn't
happen. We ended up with a universe full
of matter. [music] If we work backwards
from how much matter and antimatter is
in the universe today, it's actually
estimated that only one [music] particle
per billion of matter needed to survive
this hot, dense era and not get
annihilated. That tiny difference would
give us the makeup of our universe today
where matter dominates. So what allowed
that one particle per billion to escape
annihilation? Why did matter win out
over antimatter?
Well, that's a pretty big question with
some not so simple answers. So, we're
doing an entire second video where we
have some pretty spectacular [music]
stuff happening. We're getting into the
beast. It's absolutely insane. I feel
like I should not be in here. So, you're
making anti-atoms.
>> Yes.
>> It's so cool.
>> Durac is probably less wellknown than
people like Heisenberg or Schrodinger,
[music]
but his contribution to quantum physics
was immense and he was recognized for
it. He shared the 1933 Nobel Prize with
Schroinger for the discovery of new
productive forms of atomic theory.
And perhaps this gave strange quiet
Durac some newfound confidence [music]
because that physicist in the audience
of his 1928 lecture at the start Eugene
Vner actually became a reasonable friend
of Durax and in 1934 introduced Dak to
his sister Majit Vner a woman who would
change Dur's life perhaps more than any
equation or Nobel prize.
They were antiparticles, right? They had
completely different personalities.
[music]
He had almost no empathy, right? And he
knew it. She had buckets of it. He
hardly talked. She couldn't stop
talking. You could just go on like they
are completely different people. But the
marriage did work. My great friend Lilia
Harris Chandra, who knew them, she came
out with a great line. Great line, which
is he gave her status, she gave him a
life. So I guess there is one particle
antiparticle pair that never
annihilated.
Hey, one last thing. In case you didn't
already know, we just launched the
official Veritasium game. It comes with
800 questions and it's the perfect way
to challenge your friends. Every time we
play it at Veritasium, things get a
little bit heated and that is so much
fun. If you want to go check it out,
then head over to our Kickstarter where
you can pre-order your own version. And
right now, we've enabled global
shipping, so no matter where you are in
the world, you can get your own version.
We're coming close to the final few days
of the Kickstarter campaign. So, this is
your last chance to get your hands on
the exclusive launch edition. So, if you
want to support us, head over to
Kickstarter by clicking the link in the
description or scanning [music] this QR
code. I want to thank you for all your
support and most of all, thank you for
watching.