-
"Hey, another atom.
I'm hydrogen, nice to meet you.
-
How are you feeling about the jump?"
-
"Hi there, I'm antihydrogen,
your antiatom,
-
and to be honest, I'm feeling
kind of neutral.
-
My positron and antiproton balance out,
just like your electron and proton, right?"
-
"Hey, yeah! You look just like me,
but different somehow."
-
"Whoa, be careful! If we get too close,
we'll disappear in a spark of energy.
-
I'd like to stay in one piece."
-
"Oh wow, sorry."
-
"It's okay. I was just thinking,
-
it's kind of weird for us to be
-
chatting like this before our
jump above CERN."
-
"Why's that?"
-
"Well, for starters, how do we know
we'll both fall?"
-
"Of course we'll fall. It's gravity,
-
you know, the force of attraction
between masses.
-
I even know how fast we should fall.
-
Galileo showed in that tower experiment
-
that all falling objects accelerate
at the same rate, regardless of mass."
-
"That's for bigger objects.
-
It's a different story
for small particles like us.
-
Our mass is so tiny that the gravitational
force we experience is miniscule,
-
and if the particles are charged,
like my antiproton or your proton,
-
then it becomes impossible to detect
-
compared to the much greater
electromagnetic force acting on them."
-
"But that's only for charged particles.
You and I are both neutral.
-
Our charges balance out,
so the electromagnetic force is small
-
and the gravitational force
should be detectable.
-
I know mine's been measured."
-
"Because you're everywhere,
but I'm kind of hard to find."
-
"Why is that, anyway?
-
Shouldn't there have been an equal amount
-
of matter and antimatter created
in the Big Bang?"
-
"You'd think so, but then all of
those particles
-
would have annihilated
each other into energy, remember?
-
And the Universe is obviously
full of matter.
-
No one knows why there is more matter
than antimatter,
-
which is why scientists
are so interested in studying me."
-
"So where do they find you anyway?"
-
"Actually, I was made in that
lab down there.
-
They needed an accelerator to make
my antiproton because it's so heavy,
-
just as heavy as your proton.
-
Getting my positron was easier.
-
It's much lighter, like your electron,
and there are materials
-
that naturally decay by emitting one.
-
Then they just had to put the two together
and they got me.
-
But it's only recently
-
that they've been able to keep me
-
around long enough
to study my properties."
-
"And now they've sent you on this
jump with me. Hey, wait a minute."
-
"That's right. We're reenacting
Galileo's experiment,
-
but with matter and antimatter
instead of two objects made of matter."
-
"So what's going to happen?
-
Are you going to fall
upwards or something?"
-
"Only one way to find out!"