[MUSIC PLAYING]
SPEAKER: Hi everyone and
thank you for coming.
Today, authors Jorge
Cham and Daniel Whiteson
will be telling us
everything they do not
know about their new
book, "We Have No Idea."
Jorge Cham is the creator
of the popular online comic,
"Piled Higher And Deeper,"
also known as "PhD Comics."
He earned his PhD in
robotics at Stanford.
Daniel Whiteson is a professor
of experimental particle
physics at the University
of California, Irvine,
and a fellow of the
American Physical Society.
He conducts research using the
Large Hadron Collider at CERN.
Please take a moment to
silence your cell phones
and anything else
that will beep.
And then join me in
welcoming Daniel and Jorge.
[APPLAUSE]
JORGE CHAM: Hello.
AUDIENCE: Hello.
JORGE CHAM: How's it going?
OK.
It doesn't sound very excited.
AUDIENCE: Woo.
JORGE CHAM: OK.
Now.
All right.
Not much better.
But we'll take what we can get.
Well, first of all, thank you
to Google for inviting us here
today.
We are very excited.
And I would tell you
exactly how excited I am.
But Google probably already
knows everything about me.
So there's no
reason to tell you.
Cool.
Well, my name is Jorge
Cham, as was mentioned.
I'm a cartoonist.
And this is professor Daniel
Whiteson, from the University
of California, at Irvine.
And together, we're
the co-authors
of this book called "We
Have No Idea," which
is about all the things we
don't know about the universe.
Now, today, I'm going to talk
to you a little bit about how
our collaboration started,
how we got together and wrote
this book.
And then Daniel will take over.
And he'll talk to you actually
about what's in the book.
Now, I'm a cartoonist.
And to me, being a
cartoonist, a cartoonist
is about taking a blank page
and filling it with an idea.
And so the idea we want to
draw out for all of you here
today is this idea
that there are still
big gaps in our knowledge
of the universe.
Now in addition to
being a cartoonist,
I also happened to
have a PhD in robotics.
Now, you might be
wondering, what
does having a PhD
in robotics have
to do with being a cartoonist?
Well, I can tell you
that my parents are also
very concerned about
that whole life plan.
But I have a PhD in
robotics, from Stanford
actually, just down the street.
And, in fact, my
research there focused
on making robots that could run.
They could run and walk
like animals can in nature.
And in particular, I focused
on making robots that
could run like cockroaches.
Yeah.
So here is a quick movie of
what these robots look like.
[VIDEO PLAYBACK]
[LAUGHTER]
JORGE CHAM: Yeah.
So I like to show this movie
at all my presentations
for two reasons.
First of all, I feel like this
movie really kind of represents
what getting a PhD feels like.
[LAUGHTER]
Some of you might
know the feeling.
You feel like you're running
frantically the whole time,
but you're not getting anywhere.
Meanwhile, there are some more
intelligent beings stamping you
down.
No.
But I also like to show
it because it's really
kind of the only way that--
it's really the
only way that anyone
will look at my research.
Gotcha.
Because it seemed a little bit
more popular than the research
I spent years working on as
part of my actual career.
A little bit more
popular has been
what I was doing when
I should've been doing
research, when I
was procrastinating,
which was to make these comic
strips called "Piled Higher
and Deeper," or "PhD Comics."
And these are comics
that I just started
writing as a graduate student.
It was my first
year at Stanford.
And I guess I kind
of wrote about what
it was like to start
in a PhD program
and find a place in a lab, all
the begging you have to do.
I also kind of wrote
about what it's
like to be a teaching
assistant, dealing
with those annoying
undergraduates.
We don't have any here
today, do we, any interns?
No.
Oh.
All right.
I'm sure you're cool.
You're here.
You must be cool.
Actually, the comics
were also about learning
about grad student etiquette.
Well, you should never
ask a grad student
how is your research going.
So I just kind of kept
drawing these comics.
And then one day, I decided
to take my procrastination
to the next level.
And I started posting these on
a free web server on campus.
And as most things like
these happen on the internet,
somebody read it on
campus and liked it.
And then they told
their friends that they
knew in other universities
about this web site.
And then they told their
friends and their lab mates.
And those people told other
people in other universities.
And so slowly over the years,
these comics kind of spread
out into the world,
kind of like a virus.
To the point where about 6
or 7 million people a year
come to the "PhD
Comics" web site,
which is an incredibly
small number
if you think about
the fact that there
are about 7 billion
people on this planet.
So there's about a 0.1% chance
that you've ever heard of me
before I walked into this room.
But it just so happened that
one of those millions of people
who went to the web
site was a professor
at the University of
California at Irvine,
who saw these comics.
And he decided to
email me one day.
Out of the blue, I
just get this email
in my inbox saying, hey, Jorge.
I've see your comics online.
I think they're pretty good.
Can I commission you?
Can I pay you to write some
comics about the Higgs boson?
Now, this was a few
years ago, where
there was a lot of attention
in the media being paid
to this discovery, that people
were searching for the Higgs
boson.
And Daniel, the
professor, didn't
think that people were doing
a good job of explaining
what this interesting and
complex phenomenon was
and how people were
looking for it.
So he decided to contact me
and offer to commission me,
to make something that
explained what it was.
And so I thought what?
You want to pay me?
What is that?
I don't understand.
I just put things on
the internet for free.
So I said yes.
And so I went down
and I interviewed him.
And we had a conversation
over lunch at the cafeteria.
And instead of taking notes,
I kind of brought my recorder.
And I recorded our conversation.
And then when I went home
to draw these comments,
I decided to experiment
a little bit.
And so I took the audio
from the recordings
and I recorded myself
drawing the comics.
And I kind of put
those things together.
And we made a video in
addition to the comics.
And we decided to
take this video
and we posted it
on this web site.
You may have heard of it.
It's called YouTube.
And so now, I'll just play
for you guys one or two
minutes, a clip, a one or two
minute clip from this video,
just so you kind of get a sense
of hour collaboration started.
So here's a clip from the video.
[VIDEO PLAYBACK]
- One of the things people
predict is the Higgs boson.
The idea is that Higgs
boson is the particle that
is responsible for giving
mass to the other particles.
So anything that is
going to have mass,
it means it has stuff to it.
It's not actually stuff.
Earlier I was saying
the electron has mass,
but it has no volume.
How can that be?
It turns out mass
is probably just
characteristic of a particle,
the way like charge is.
Like, some particles have
charge, like electrons.
Some particles don't.
It's just a different
kind of charge.
So you can think of mass as
sort of gravitational charge.
And when two things both have
mass, they attract each other.
Interestingly, you
can't have negative mass
or repulsive gravity.
All right.
So the collision happens.
It lasts for like 10 to
the negative 23 seconds.
And you get one measurement.
So if you say, well,
I'm going to plot
the mass, the total
energy, of this guy.
I'm going to add
this guy and this guy
together and add
the total energy,
this axis here is
number of collisions.
In your individual experiment,
you get one measurement,
right here.
Do another one, you get
another measurement.
You do another one.
Eventually, you
build up your data.
And the data looks
like this, for example.
And then you have two theories
that predict the data.
One says, well, I'm going to
predict there's no Higgs boson.
So the data should
fall along this line.
And the other is
I'm going to predict
that plus a Higgs boson.
And the problem is the
difference between these two
theories is very small.
And so it's very
hard to distinguish
these two with our data because
the predicted effect is tiny.
If the predicted
effect were huge,
it would be very easy
to tell the difference
between with Higgs boson
or not with Higgs boson.
But the predicted
effect is tiny,
and so it's really hard to see.
What you need is a
huge amount of data.
You need to take a bajilliion
collisions before you
can see the difference.
That's why we run this thing
40 million times a second,
all day, all year, to
get a lot of collisions,
to tell small differences
between theories.
It's like when you take
a picture of the sky.
If you just take a picture,
you get a little bit of light.
But the longer you leave the
telescope looking at the sky,
the more you can see
farther away things.
[END PLAYBACK]
JORGE CHAM: I like it.
Cool.
That was the video.
And so we posted this online.
And then it just so happened
that a few months later, they
actually discovered
the Higgs boson.
And so when they
discovered this,
there was a huge
amount of attention
paid on this from the media
and the popular press.
And this video
sort of went viral.
Millions of people
watched this video.
And a lot of people
were pointing
to the video as the
clearest and easiest
to understand
explanation of what
this kind of complex
phenomenon was,
and how people were
looking for it,
and especially why they
were looking for it.
So I thought that
was pretty cool,
that the clearest and
easiest to understand
explanation didn't come from
"The New York Times" media
department.
It didn't come from some
professional company
or animators.
It came from actually
one of the scientists who
worked on the project, who
decided to take the initiative,
and commissioned an
artist to work with them,
to create something that
explained this to the public.
So I thought that
was pretty cool.
So since then, we've worked
on a couple of other projects
together.
But our last project is this
book called "We Have No Idea."
And now to talk to you about
the ideas inside of "We Have
No Idea" is Daniel Whiteson.
[APPLAUSE]
DANIEL WHITESON:
Hello, everyone.
And thanks Jorge.
So before I get started,
I have to correct
Jorge's story a little bit.
He's overly modest when
he tells that anecdote.
If any of you have
been in academia,
you know that Jorge is
not just a cartoonist.
He's sort of a celebrity.
I go around and I visit
lots of physics labs.
And on almost every
single wall, there
is one of Jorge's cartoons
because he's really
captured the suffering
of the graduate students.
So he's really super-well-known.
And when I was
thinking about how
to explain physics
using cartoons,
I thought, well,
who could possibly
have both the artistic skills
and the technical understanding
to communicate these
difficult topics?
And so my wife, who is also
a huge fan of "PhD Comics,"
said why don't you email Jorge
Cham and ask him to do it?
And I thought sure, yeah.
And then I'll write
an email to Brad Pitt
and ask him to make a
movie about me also,
like just as likely
to be successful.
But Brad hasn't gotten
back to me about the movie.
But I had the great pleasure
of working with Jorge
on this project.
Yeah.
You're Brad Pitt
in this scenario.
JORGE CHAM: I like it.
DANIEL WHITESON: Yeah.
So our book is called
"We Have No Idea."
And instead of being
another science book that
explains what science
has figured out,
the focus of this book is
about what we don't know,
all the things that we don't
know about the universe.
So if you come to hear
a talk from an author,
you expect them to be an expert
on the topic, a real authority.
So you might be
wondering, well, like,
what's this guy's expertise?
Like, not having
ideas or something?
And so it doesn't
sound so great to claim
that I'm an expert in our
level of cosmic ignorance.
But that's sort
of the situation.
And you might wonder,
well, why write a book
about the things we don't know?
And it's not that I want
to celebrate our ignorance.
There's plenty of
that going on already.
It's that I want to convince
you that in science, ignorance
is opportunity.
It's an opportunity
to make discoveries.
Because when you know
what you don't know,
then you know where to look and
how to answer these questions.
And so what I want
to do, and what
we hope to do in this
book, is to introduce you
to our staggering cosmic
level of ignorance,
to prepare you for all
the awesome discoveries
that we think are coming
around the corner.
OK.
Because it's when you can
confront your ignorance,
then you know how to
look for the answers.
You know how to begin
your exploration.
In the end, it's really
about the exploration.
And when I was a kid, I
thought the age of exploration
sounded like a lot of fun.
I mean all you had to do to
discover something new back
then was jump in a ship,
sail across the ocean,
and land on a new beach.
You could be the first person
to ever walk on a beach,
or eat a new kind of
fruit, or something.
These were amazing
firsts in human history.
And I wanted one.
Imagine like the first person
to ever see the Grand Canyon.
There was the first person
that got to do that.
Or the first person to
ever eat chocolate, right.
That was an experience.
Or the first person to ever
eat chocolate while looking
at the Grand Canyon, right.
These are all important
first in human history.
And I wanted to be
the first person
to know something, or do
something, or see something.
But as you're reading about
the age of exploration,
this happened
hundreds of years ago.
There aren't anymore new
continents to discover
or islands to land on and
name after your poodle.
And thanks to Google
Earth, for example,
it's very difficult
to say that there's
anything left to explore.
And the more you
look around you,
the more you get the
feeling, like, well, not only
have we explored and mapped
the surface of the Earth,
we've also really started
to master technical things
and the way things work.
I mean we have amazing things.
Airplanes that can
fly over oceans.
You can download all
of human knowledge
into a little device
that fits in your pocket.
You can make a billion
dollars off of a single idea.
I mean it's truly a crazy
modern world we live.
It's an age of wonders.
So you might get the sense
that scientists mostly
figured things out.
That we just have a few
little details to wrap up.
And then, we're basically done
understanding the universe.
Well, the point I want
to make to you today,
and the point in our book,
is that exactly the opposite
is true.
That, in fact, we're
at the beginning
of a new age of exploration.
An era of exploration
that I hope
will reveal staggering, crazy
ideas about the universe,
that currently we
have no idea about.
So what do I mean
age of exploration?
Like, how is it possible
to explore things
where we had such a deep
understanding of the universe?
Well, the kind of
exploration I'm talking about
is the kind where we ask
big questions, really
big, fat, juicy, basic,
ancient, deep questions.
The kind of questions
that everybody
wants to know the answer to,
the really big, fat questions.
The questions which,
if you knew the answer,
it would change the way
you felt about your place
in the universe and
the human situation.
These kind of big questions.
So let's be concrete about it.
What kind of questions
am I talking about?
Well, you went down
the hallway and asked
a random person, what are
the most important questions
in life?
They might say things like this.
Well, why are we here?
That's a big one.
What happens after we die,
also an important question.
If I knew the answer
to that question,
it might change the
way I live my life
or treat people, these kind
of really deep, big questions.
Another popular one is what
is it like to be a bat?
This is a question people
think about sometimes.
And the interesting thing
about these questions
is that while they
are deep questions
and important questions, they're
also philosophy questions.
Which means that you can spend a
lot of time thinking about them
and arguing about them, and not
necessarily make any progress.
Even if you smoke banana
peels for 20 years,
and you go down to the
philosophy department,
you might not figure it out.
And you might think
this last one,
what is it like to be a bat, you
might think that's just a joke.
It's actually the title of the
most widely cited philosophy
paper of all time.
People are still arguing about
what it's like to be a bat.
And I think they're never
going to figure it out.
And that's the problem
with philosophy questions.
They're important.
They're deep.
I don't mean to
dismiss philosophy.
But they don't have
objective answers.
The cool thing to
me is that there
are other questions, questions
just as deep, just as ancient,
just as important.
But these are science
questions, questions like this.
What is everything made out of?
How did the universe begin?
The universe has
one true history.
It began in a certain
way, and no other way.
And if you knew that story,
here's how the universe began,
here's what came before
the big bang, here's
what caused the big bang,
you would feel differently
about our lives, and the way
we live it, and the future.
These are important
questions, at the same level.
The cool thing is these
questions have answers.
There is a true, factual
answer to these questions.
And we can discover it.
If we do the right
experiment, and put together
the right pieces and the
clues, we could actually
learn the answer.
After which, no matter how
many banana peels you smoke,
no reasonable people
can disagree anymore
about the answers.
Unfortunately, we can't
include, like, the US government
in the list of reasonable
people anymore because they
don't listen to science.
But people who listen to science
and accept objective truths
can actually agree
on the answers
to big, deep, and
ancient questions.
To me, that's incredible.
And that's the
kind of exploration
that I'm talking about.
So let's zoom in on
one of these questions.
This one here is the one that
I spend my professional life
working on.
What is the universe
made out of?
And this is really a basic
and a reasonable question.
I mean if you wake up as, like,
a conscious being in the world.
You look around you and you
ask, what am I made out of?
What is he made out of?
How is everything put together?
What are the rules?
What is the most basic
element of matter?
How does this whole thing work?
It's an ancient question,
a basic question.
And I think a reasonable one
to want to know the answer to.
I remember, as a kid, smashing
rocks together, and seeing
them break into smaller
rocks, and wondering
how long can you do this for?
Can you just keep getting
smaller and smaller rocks?
At some point, is
it no longer rock?
And I imagined that
people have been
doing this for a long time.
I don't think I'm
the first person
to ever smash rocks together.
I think it's an old question.
It's the kind of question people
have been asking themselves
since people have
been asking questions.
And if particle physicists
were superheroes,
this would be their origin
story, something like this.
This is the dawn of
particle physics here.
And it's an important question.
But it's a difficult
question to tackle.
What is everything made out of?
It's a big question.
How do you approach that?
Well, in science,
our strategy, when
we are tackling something
very big and very difficult,
is try the dumbest thing first.
Just do the simplest,
most obvious thing first.
If that doesn't work, try
the second dumbest thing,
or extrapolate from
it a little bit.
So what's the simplest approach
to answering this question,
what is everything made out of?
Well, you might just try a list.
Look around you and literally
say, what's in the universe?
So your list might look
something like this.
The universe has me.
It has you.
It has this rock,
the other rock,
that other rock over there.
And this approach,
using a list, is
going have a lot of problems.
Problem number one
is the universe
has a lot of rocks in it.
So your list is going
to be super-duper long.
And you guys like thinking
about lists and organizations.
You might also
wonder, like, well,
is the list exclusive
or inclusive?
Because if it's
inclusive, then I
had to have all the
things in the list also.
And is the list on the list?
There's lots of problems there.
The other problem
with a list approach
is that the universe has
more than just rocks in it.
For example, as you
look around you,
you discover the universe
is full of all sorts
of crazy, interesting things.
There's rocks.
But there's also air.
And there's water.
And there's fire.
And there's blueberries
and iPhones.
And the more you look
around, the more you're
sort of impressed and staggered
by the incredible complexity
of the world we live in.
For example, there's puppies,
and bicycles, and strangely
muscular fellows who become
governor of California.
The world is really full
of interesting stuff.
And that's one of the things
that makes it a nice world
to live in.
You wouldn't want to live in
a world that's just rocks,
for example.
And it also highlights what's
a problem with this approach,
is that the list isn't
really an answer.
If you ask me, what is the
world made out of, Daniel?
And I literally gave you
a list that had everything
in the universe on it.
That wouldn't really feel like
an answer to your question.
It's like asking a teenager,
where are you going?
And they say out.
OK.
Well, it's an answer.
But it's not really an
answer to the question.
It's not a satisfying answer.
So what kind of satisfying
answer would you like?
You'd like something
that reveals
something about the world.
Something that explains all
this incredible complexity
in terms of something simpler.
You want to peel back
a layer of reality
and reveal the simpler
set of building blocks
that explain all
of this complexity.
So how do we do that?
Well, we have this dumb list.
So let's try the
second-most dumb approach,
which is organize our list.
So we categorize things.
And we say, well, this stuff
over here is all rock-like.
And this stuff over
here is plant-like.
And you can argue whether Arnold
belongs in the rock category
or the living thing category.
Everything belongs in
a category somewhere.
We're scientists about it.
And you start to
notice patterns.
So you make a list.
You organize it.
You notice patterns.
You ask questions
about those patterns
because those patterns
are your clues.
They're the roadmaps that tell
you what's going on underneath.
Why are there so many
rock-like things?
Why are these
things all similar?
There must be some
pattern there.
OK.
So we've done that.
And fast forward a few hundred
years or a few thousand years,
depending whether you
give the Greeks any credit
for this kind of stuff.
And you get to the periodic
table of the elements.
And you guys might be
thinking, we're smart people.
He's a particle physicist.
Why are we talking about
high school chemistry?
The periodic table is
high school chemistry.
Well, it is high
school chemistry.
It's also, in my
view, one of the most
staggering achievements in
human intellectual history.
Why?
Because it's taken us from
an almost infinite complexity
of stuff, down to a
hundred building blocks.
From those hundred
building blocks,
you can make anything that
you've ever touched, or tasted,
or driven over, or anything.
Anything any human has
ever interacted with,
has been made out of these
hundred building blocks.
If our goal is to
simplify the universe
or reveal a simpler
nature underneath,
this is a huge step
forward already.
And this is hundreds
of years ago.
So it's sort of incredible.
And it makes you wonder,
like, why is it even possible?
Why is it possible
that we live in it?
Why do we live in
a universe where
it's possible to
describe complexity
in terms of simple stuff?
It means something deep.
It means that all
that complexity
is in the arrangements, not
in the objects themselves.
It reminds me of something else.
It's like the
universe is organized
by the Lego principle.
That out of a few basic building
blocks, you can build anything.
You can use the same
basic building blocks
to build dinosaurs, or
to build the pirates,
or like dinosaur-pirates.
It's incredible that
anything can be made out
of these building blocks.
And to me, it's
interesting because it
seems like if you were a cave
man, a cave woman physicist,
you were asking this
question for the first time,
you might consider
various options.
Maybe the world is not made
out of basic building blocks.
Maybe it's infinitely divisible
into smaller and smaller
pieces, using an
infinitely sharp knife.
It could have been.
Or maybe, instead of having
a simple or a small set
of building blocks, maybe
the number of building blocks
could have mirrored
the number of things.
And you could have,
for example, you know,
cats made out of cat
particles, and cartoonists
made out of cartoon
particles, and llamas made out
of little llamalinos or whatever
you'd call those particles.
That certainly could have been.
And if you're the first
person to ask this question,
you have to consider
every possible idea
because you have no rules
about how the universe works.
But nothing that
you see around you
is a basic building
block of the universe.
And we don't just list the
periodic table of the elements,
and say we're done.
So we don't just list
them and say we're done.
We organize our knowledge.
So we group it into the
periodic table of the elements.
After all, there
are patterns here.
That's why we call it the
periodic table of the elements.
OK.
I can see Jorge's getting bored
because he's playing Tetris
here.
But there are patterns here.
And if our goal is to reveal
one more layer of truth,
to reveal the simpler
structure that underlies it,
we have to look for patterns.
And so, I'm not a chemist.
But I know that in
the periodic table,
these guys over here,
on the right side,
are not very active.
And these guys over here, on
the left, are very active.
In the middle, you have these
metals, and all sorts of stuff.
And there are patterns
in the periodic table.
And these patterns are,
in fact, the clues.
They tell us what's
underneath the periodic table.
And we know now, of course,
because we've taken high school
chemistry, that all the
patterns in the periodic tables
are just emergent phenomena
from the structure of the atom.
They were, in fact, clues
that pointed us down to reveal
what the nature of the atom was.
And the reason that
these guys are noble,
and these guys are not
noble, and the metals are
the way they are is
because of this structure.
It's because the electrons
fill up their orbital shells
and don't like to
play games anymore.
It's because the number
of protons in the atom
determines the
element that you are.
So all the chemical
properties are just
clues that pointed to the
structure of the atom itself.
And so we can look
to those clues
to tell us how to understand
a deeper level of reality,
down below the hula hoop level.
But remember, as we're
exploring the universe,
that nothing that you know is a
building block of the universe.
Nothing you play with, the
chairs you're sitting on,
the llama you rode to
work on, the tornadoes,
none of these things are
basic building blocks
of the universe.
The universe is built
out of deeper, weirder,
strange things, that have
no analog in your life.
Not even strange combinations
of things, like llama tornadoes,
can explain the way
the universe works.
We like to use intuitive
ideas, like particles, which
are little spinning balls,
or waves, which we know about
from things, or maybe light
is a particle and a wave.
In reality, the basic building
blocks of the universe
are totally alien to us.
We can try to understand
them using these analogies.
But in the end, they
don't really work.
OK.
So let's zoom in a
little bit and understand
the current state of knowledge.
We have the atom, which
has protons and neutrons,
with electrons whizzing
around it, of course.
And inside the proton
and neutron are quarks.
So you have the up quark
and the down quark.
You put two up quarks
and a down quark
together to make a proton, two
down quarks and an up quark
together to make a neutron.
And that means something
sort of astounding.
It means with just these three
particles, up quarks and down
quarks to make your
protons and neutrons,
and then electrons
to complete the atom,
you can build any atom.
Any atom can be built
out of three particles.
And anything can be
built out of atoms,
which means anything
you've ever tasted,
or stepped on, or interacted
with can be made out
of just three particles.
That's incredible
simplification,
from infinite complexity,
down to three particles.
It means the recipe for
building literally anything
is a certain number of up
quarks, a certain number
of down quarks, electrons, mix.
That's literally the
recipe for everything.
In terms of simplification,
that's pretty impressive.
So you might be thinking,
wow, we went from infinity,
to a hundred, to three.
We're like on the verge
of figuring this out.
The trajectory is pretty good.
If these guys had
come next week,
could they be showing us the one
particle that rules them all?
So we're not quite there.
And the point of the
book is to explain to you
the wrinkles in this story
because the wrinkles are
really interesting.
So first of all, one
wrinkle is we don't just
have these three particles.
We found these three particles.
But there are more particles.
The up quark and the down quark
are two examples of quarks.
But there are other quarks.
There's the charm quark, the
strange quark, the top quark,
and the bottom quark.
I'm not making these names up.
I wish somebody had asked me.
I would have come up
with even sillier names.
The electron is an example of
a particle we call the lepton.
And there's six
of those as well.
So we have not just three
particles that make up matter.
We have these 12 particles
that we've discovered.
So what do we do in science
when we're confused,
we don't know what to do?
Well, first, we
just make a list.
Then we organize it.
So now, the current
state of knowledge
is this, a new periodic table.
It's a periodic table of
the fundamental particles.
And what we try to do is place
all these particles in a table
so we can understand
how they fit together.
Maybe get some clues,
which will lead
us to ask questions,
that will reveal an even
deeper layer of the universe.
So we have the up quark and
the down quark, which you know.
These make the
protons and neutrons.
Together with the electron,
they explain everyday matter.
But in this first
column, we also
include this particle
called the neutrino.
Neutrinos are a really strange,
mysterious particle, sometimes
called a subatomic particle.
That's not really
accurate because it's not
inside the atom.
But it's a mysterious particle.
But it's also everywhere.
For example, there are a
hundred billion neutrinos
passing through my fingernail
every second, a hundred
billion, and in your
fingernails as well.
So why are we not, like,
getting beaten down
by all of these neutrinos is
they pass right through us
without even noticing.
We don't notice them.
They don't notice us.
It's like that guy who lives
down the hall from you,
you don't even like
make eye contact.
[LAUGHTER]
Totally just pass right
through each other.
So neutrinos ignore us.
And we ignore them.
There's so many
neutrinos because they're
being produced by the Sun.
But it's a clue that
a lot of the things
that are happening in the
universe all around you,
you're not privy to.
You can't see you.
You can't immediately detect.
The universe is different
from the universe
that you experience.
So we put all these
four in the same column.
And the interesting thing
about the 12 particles
is that they seem to be
copies of each other.
So, for example, the charm
quark and the top quark,
we put them in the same
row as the up quark
because they are
copies of the up quark.
They have exactly the same
properties, the same charge,
the same interactions,
the same spin.
All of these things are
the same except the charm
and the top are heavier
than the up quark.
Why are they there?
Why does the up quark have
these, like, weird two
secret heavy cousins?
Nobody knows.
The charm quark is much
heavier than the up quark.
The top quark is the
heaviest fundamental particle
we've ever discovered.
It's thousands and
thousands of times
heavier than the up quark.
It's like the up quark's
secret fat country cousin that
can't even leave the house.
It's shin-nappingly
fat, this one.
It's also easily offended.
So the fascinating thing
is that not only are there
two copies of the
up quark, there's
two copies of the down quark.
The strange and the bottom
have the same relationship.
They're perfect copies
of the down quark,
all the same properties,
except heavier.
The electron also
has these copies.
There's the muon, which
is just a heavy version
of the electron.
And then the tau, which
is an even heavier version
of the muon.
And there's even three
of these neutrinos.
So we have these really
interesting patterns
that form when you
start to organize
our knowledge of
the periodic table
of the fundamental particles.
What does it mean?
Well, I hope that it
means that there's
something deeper going on.
Currently, we have no idea.
But we have some fun questions.
The patterns give us questions.
And we hope those questions
will lead us to the answers.
OK.
So what questions do we have?
Well, question number one, why
do we have all these particles?
You only need three
to make all of matter.
Why 12?
Are there, in fact, 12?
Are there 24, 24 billion?
According to theorists,
there's no limit
on the number of
particles that you could
have in a fundamental theory.
How many particles are there?
Why do the particles
each have two copies?
To me, this is a really
interesting deep question
because I like
thinking about numbers.
And one of the fundamental
goals of physics
is to explain the whole
universe in a simple equation.
How do you know that when you're
done, when the equation is
simple enough, well, the
standard people often
use is if it could
fit on a T-shirt.
If you can put all of
physics on a single T-shirt,
then you're done.
Imagine we were there.
And you're looking
at that equation.
And there's a
number in it, five.
That means that five is a
deep, important number somehow
in the universe.
So numbers are important.
Now, we look at
this table, and we
see there's three copies
of every particle.
Why three?
If you ask theorists
and mathematicians
what kind of number do you
expect in a fundamental theory?
Oh, they have strong opinions.
Zero, that's an OK number, one.
You can have pi.
Sure pi is a good number.
Nobody says three, unless
they're Catholic also.
[LAUGHTER]
Why is three?
Is the number three somehow
important to the universe?
It seems to me like either
it is or it's a clue.
Than in a thousand years,
or a hundred years,
people are going to
look back and say,
that was such an obvious clue,
that blah blah, blah, blah,
blah, whatever secret
of the universe
hasn't been revealed to us yet.
It's staring them in the face.
If I had been a
physicist then, I totally
would have figured it out.
It's one of those
screaming clues
that we just don't know
what it means right now.
We just know it's a clue.
Another big mystery
about these particles
is the relationship
of the masses.
We know that, in
general, they tend
to have more mass as
you go this direction.
But there's no
pattern to the masses.
The Higgs boson, if you
know anything about it,
explains how the
particles get mass.
But it doesn't tell
you why this one
got a lot of mass and
this one got almost none.
There's no explanation
for that at all.
And the ratios are crazy.
The top quark is
thousands of times
heavier than any of
the other particles.
It's really strange.
But one of my favorite
ones is this one
about the charges
of the particles.
So the electron is charge
minus 1, sort of by definition.
But the quarks have these really
strange fractional charges,
like 2/3, minus 1/3.
How is that even possible,
a fractional charge?
Well, that's just
because of how you define
the charge of the electron.
But the interesting thing
is about the ratios.
These guys add
up, 2/3, 2/3, 1/3,
to make plus 1, a
proton, which perfectly
balances the electron.
Well, that's
convenient because you
need that exact balance
to have neutral atoms,
and to have physics, and
chemistry, and biology,
and silly physics books,
and free lunch in the cafe.
All that stuff rests on
this perfect balance.
But in our theory, that's
a perfect coincidence.
We have two knobs in the theory,
the charge of the electron
and the charge of the quarks.
And if you're at the control
panel of the universe,
you could set those
things to be anything
and you still get a
valid theory of physics.
So why do they
balance perfectly?
Well, either it's
a huge monster,
cosmic-level coincidence,
and not a almost coincidence,
like the Moon and the Sun
being the same size in the sky,
so you get an eclipse, but a
perfect, exact coincidence.
That's strange.
That's a clue.
But in our current theory
we say, no, there's
no relationship, two
arbitrary numbers.
To me, it's possible that
there's a simpler explanation.
That these things are
actually built out
of the same smaller
set of LEGO blocks,
which would explain why
they have a perfect balance
in their charges.
But currently, we have no
idea that explanation is.
And we don't just like
thinking about the particles.
We also like thinking
about how they
talk to each other,
the forces they
feel when they come into play.
And before Jorge was
the favorite cartoonist
for particle physicists,
we had Richard Feynman,
who came up with the
Feynman diagrams, sort
of a cartoony way of
thinking about physics.
And he thought about the
way particles interact
with each other by
drawing these diagrams.
And so the straight lines
are particles moving
and the wiggly
lines are particles
talking to each other.
And we can use his
calculations and this strategy
to predict the results
of experiments.
And if you've ever worked
in an experimental lab,
you know that if you predict
an experimental result,
and you get something like a
factor of 2, you're like, wow,
it worked.
Science, yeah, it's amazing.
Well, we can predict the
results of experiments
and get the results
to agree with a theory
to 10 decimal places.
10 decimal places, it's
incredible precision.
So the theory we have
about how the particles
talk to each other
works super-duper well.
It almost makes you think, if
you're a conspiracy theorist,
that, like, maybe we are
living in a simulation
and we've, like, uncovered the
source code of the universe.
Maybe this is how
the universe does
the calculations to decide what
an electron is supposed to do.
Because this doesn't
happen by random,
that you get this
level of agreement.
By random chance, it
would be like hitting
a golf ball in New York and
getting a hole in one in China.
It just doesn't
happen by chance.
But we don't measure
our particle theory just
by how well does
it work, like does
it predict the experiments?
Remember, we want a
really simple theory.
We want to simplify
the universe.
So let me show you the
current state of the art
in thinking in particle physics.
This is the Lagrange.
And it describes the standard
model of particle physics, OK.
And in my estimation, it doesn't
quite yet fit on a T-shirt.
In fact, only half of the
terms could fit on the screen.
So we're not quite there yet.
We have a lot of questions left
about how these particles talk
to each other.
But that's not the
end of the story.
That's not even the biggest
problem in particle physics.
So first, I want you to
go away with a feeling
like, wow, there are a deep
basic questions about how
particles work
that we don't know.
We're standing-- we've
made a lot of progress.
But we're staring
into the abyss.
And we feel like in
a thousand years,
people will look back and think,
wow, those things were really
obvious, or I wish
they knew this,
or how could they not
have figured that out?
Well, it turns out
all those questions
are a tiny fraction
of the questions
that we have about the universe.
Because the particles
I've introduced you to,
and the everyday matter
that you're familiar with,
and everything that
makes up me, and you,
and hamsters, and stars,
and dust, and planets
only accounts for a tiny
fraction of the universe.
All of that effort
understanding matter
only explains a little sliver
of what the universe is actually
made out of.
So all that great
progress, divided by 20.
So it turns out that
only 5% of the universe
is this kind of stuff.
So we've measured very
precisely the fraction of stuff
in the universe that's
our kind of stuff.
And that's 5%.
The rest of it is a big mystery.
The rest of the stuff
in the universe,
we don't really have any idea
what this kind of stuff is.
So it's an incredible
moment in physics,
a moment I call precision
ignorance, when we've measured
very precisely
that we don't know
very much about the universe.
And that's exciting
because it means
we have a lot of things
left to discover.
So how is it possible
that we could
know that we know very
little about the universe?
How does that exactly work?
Well, let me tell you
a little bit about it.
The first part of the story
begins with galaxies spinning.
So somebody sent their grad
student out to look at galaxies
and understand how they spin.
And if you want to
think about galaxies,
a good model is to think
about a marry-go-round,
with a bunch of ping
pong balls on it.
What happens if you spin
that merry-go-round?
Well, the ping pong
balls are going
to fly all out unless there's
some force holding them in.
So in the case of galaxies,
that force is gravity.
It keeps all the
stars from flying out
of the edge of the galaxy.
So you can do something
interesting, which
is measure how fast
the galaxy is spinning
and then count up all
the stars and ask,
is there enough gravity to
keep all the stars in based
on how fast they're spinning?
So somebody sent their
grad student off.
Make sure this works, make
these two measurements,
make sure they agree.
And what they discovered is that
the galaxies are spinning much,
much faster than they
should be able to.
Galaxies spinning that fast
should be throwing their stars
out into space all
the time because there
isn't nearly enough gravity
to hold them in when
they're spinning that quickly.
This is a really perplexing
result. For a long time,
people don't understand
it and thought,
well, maybe you mismeasured
how the galaxies are spinning,
or you miscounted the stars,
or something is crazy.
And then eventually
people thought, well,
maybe there's something
else in those galaxies.
Maybe there's some sort
of new invisible thing,
because we don't see it, that
has a lot of gravity to it.
So you need something that's
invisible and has gravity.
So they called it--
they don't what it was--
but they called it dark matter.
And literally, dark matter
is the name of the theory.
It's also a summary of
what we know about it.
It's dark and it has matter.
And that's basically
what we know.
That's the idea.
It also was the problem
it was trying to solve,
like there must be some
sort of dark mattery stuff
to explain all of this.
So it was a big mystery
for a long time.
But if you postulate
the existence
of a huge amount of invisible
matter in these galaxies,
it explains why they're
spinning so fast.
But to understand how
dark matter is dark,
we have to spend
a moment thinking
about how particles interact.
So we say dark matter is dark
because it doesn't give off
light.
It doesn't reflect light,
the way planets and stars do.
That means it doesn't feel
electromagnetism, which
is one of the four fundamental
forces responsible-- the one
responsible for light.
There's also gravity, which
anything that has mass
will feel gravity.
It will attract itself.
Then there's the
weak nuclear force
and the strong
nuclear force, which
are responsible for holding
the nucleus together
and also radioactive decay.
So when we talk
about dark matter,
we know that dark matter
fuels gravity because that's
how it was discovered.
It basically explains
the extra gravity
we need for the
galaxies to rotate.
We know it doesn't
feel electromagnetism.
Because if it did, then
we would have seen it.
It doesn't feel the weak force.
And it doesn't feel
the strong force.
And as far as we
know, dark matter
doesn't feel any other
kind of force at all.
We've been trying to
interact with dark matter
in lots of ways.
But it never seems to respond,
even to our Facebook requests.
All we know about dark matter
is that it feels gravity.
It's sort of defined
to be the thing that
gives the extra gravity.
And so 5% of the universe
is the stuff we know,
that we still have a
lot of questions about.
The fascinating thing
about dark matter
is that you need a
lot of it to explain
how the galaxies are spinning.
It's not like, oh,
you need 1% or 2%.
It's a little bit
of a correction.
It's a mammoth correction.
You have to multiply the amount
of matter in all the stars
by a factor of five
to get enough gravity
to explain how rapidly
these galaxies are spinning.
It's a crazy idea.
When we think of a new physics
theory, we like simplicity.
Think of the simplest theory
that explains your data.
Well, if your theory
requires an immense amount
of invisible matter, that
permeates the universe,
that nobody's ever
discovered before, well, then
maybe you go back and
check your calculations
before you get that published.
And it took people a
long time to accept
the idea of dark matter.
In fact, it wasn't until
people found other ways
to see dark matter that they
really became convinced it
was a thing and not a mistake.
One really cool way
to see dark matter
is to see it acting
as a lens in the sky.
So dark matter is
invisible, which
means light passes through it.
But it has mass.
So it bends space.
And it can bend light as
well, acting like a lens.
So imagine there's a huge
blob of invisible dark matter
between you and some
far, far away galaxy.
What happens to photons
leaving that galaxy?
Well, a photon zooming
off in one direction
will get bent towards you
by this blob of dark matter.
A photon zooming off
in another direction
also gets bent towards you.
So what happens if you
look out in the sky in two
different directions?
You see the same galaxy
at two places in the sky.
It looks just like a lens is
acting somewhere in the sky.
In fact, it's more
than just duplication.
It actually gets
distorted, all sorts
of interesting optical
effects, just like you
would expect from a lens.
You can Google-image
search it later.
It's pretty awesome.
It's called
gravitational lensing.
And when people saw
this, they thought, well,
there must be some invisible
stuff out there that
really does have gravity to it.
It's pretty spectacular
discoveries.
And the last bit came
from a collision.
Now, I'm a particle physicist.
So when I want to
solve a problem
or understand something,
I smash stuff together.
That's like my modus operandi.
Collide particles together,
look to understand
what's inside them.
If you want to
understand galaxies,
that approach
doesn't really work.
You can't say, like,
go to the government
and say I want funding to
build a galaxy collider.
Even these days, we don't have
enough funding for science.
So we can't use all the science
funding on a galaxy collider.
So an astrophysicist has
a different approach.
Instead of building a collider,
they just look out into space
and hope to find this
experiment already happening.
And fortunately, they found one.
So the Bullet Cluster
is a mammoth cluster
of two-- a mammoth collision
of two clusters of galaxies.
So a cluster of galaxies has
both normal matter and dark
matter in it.
So what happens when these two
things slammed into each other?
Well, the normal matter
smashed into itself,
just like you'd expect
when two planets collide
in science fiction movies.
Boom, boom.
Everybody runs away.
But the dark matter passes
right through the normal matter.
It's invisible.
It's also untouchable,
the way neutrinos are.
And it passes through
the normal matter.
It also passes through itself.
So it just passed through
itself to the other side.
So you get dark
matter on either side.
And in the middle, you
have these big explosions
from normal matter.
That's really cool
because it means
that the normal matter was
separated from the dark matter.
And you can use
gravitational lensing
to see directly that
the dark matter is there
and the normal matter
is still in the center.
So this is a way you
can separate the two.
You see that dark matter
really is its own thing.
It's not just a weird
miscalculation of gravity
or a new theory of
gravity for normal matter.
It's its own new kind
of invisible stuff.
So the Bullet Cluster
really was the nail
in the coffin for all
the other theories that
tried to explain dark matter.
It convinced people that dark
matter really is a thing.
It's really out there.
So what is dark matter?
We know that it's dark.
We know that it's matter.
We know there's a lot of it.
That mostly sums
up what we think.
We don't know what it is.
We know there's more of it
than our kind of matter.
Now, we're particle physics.
So our work is this.
So our natural inclination
is to explain the unknown
in terms of the known.
So, for example, one of
the favorite theories
about what is dark matter
is, well, maybe dark matter
is made out of particles,
just like we're
made out of particles.
And the favorite theory is
called a weakly interacting
massive particle, WIMP.
That's one of the
favorite theories.
Another one is, well, maybe
it's these big blobs of matter
out into space.
It's called a massive
astrophysical compact halo
object.
That theory is called the MACHO.
So even in science, we have
the WIMPs versus the MACHOs.
These are two ideas.
But they're sort
of extrapolations
from what we know.
And it's dangerous
to extrapolate
to a quarter of the universe
from a tiny, probably atypical
sliver that you've been
studying for hundreds of years.
So we should keep that in mind.
And the other thing
to remember is
that dark matter isn't
out there in the universe.
Dark matter is everywhere.
Dark matter is
here in this room.
I have dark matter in
my hands right now.
It passes right through us.
I can't hold it or contain it.
But it's here with us.
It's not like out
there somewhere.
Maybe dark matter is a
totally new kind of matter.
Maybe it's not even
made out of particles.
Or maybe it's made out of a
whole new kind of particles,
the way we are, many
different kinds of particles.
So maybe there's complex dark
matter physics, and dark matter
chemistry, dark matter biology.
For all we know, there could
be dark matter life right here
in this room with us.
And if you were
dark matter life,
you wouldn't think of
us as normal matter.
We're the little sliver
of 5% you could almost
round away in your
understanding of the universe.
In some dark matter physics
class is a professor saying,
yeah, we understand
96% of the universe
except for this
little weird sliver.
So maybe there are
dark matter tourists.
So 5% of the universe is
explained by the particles
we have some clue about.
27% of the universe
is dark matter.
We know it's there.
We don't know very
much about it.
That still leaves 2/3 of the
universe's budget totally
unaccounted for.
No accounting firm is
going to accept that.
So what is the rest of this pie?
Well, the rest of this
pie is filled by something
called dark energy.
But dark energy is
really science code
for "we are totally
clueless about the rest
of the universe."
Because the truth is,
and until 20 years ago,
we didn't even know that we
were clueless about this part.
Now, don't be confused.
Dark energy and dark
matter have no relationship
other than literally
the word "dark."
OK.
That's the only connection
between the two theories.
So how did people
even figure out
that dark energy was a thing?
Well, people were thinking about
the history of the universe.
So if you know
something about physics,
here's a brief summary of
the history of the universe.
So first, you had the Big Bang.
And all the stuff in the
universe exploded out.
And then interesting
stuff happened.
And people were wondering
what's going to come next?
So is there enough
gravity in the stuff
in the universe for
things to slow down, turn
around, and then come
back into a Big Crunch?
That was one
possible explanation
for the history
of the universe--
the future of the universe.
Another possibility
is that there
wasn't enough stuff in the
initial explosion, not enough
gravity to turn things around.
It would just drift
out gradually,
slowing down, cooling off,
until the universe cools off
and spreads out into
something known affectionately
as the heat death
of the universe.
OK, not a cozy time.
But these were the
two possible theories
that people were considering,
the Big Crunch or the heat
death of the universe.
So they said, well,
let's measure it.
Let's go out and look, see
if things are speeding up
or see how much things
are slowing down.
So it turns out the universe
preferred secret option
C, which is neither
of these ideas.
Which, to me, is like
the best case in science,
when you discover
something that nobody
expected to be the answer.
So they went out and
they measured it.
And they discovered that
actually what's happening
is that it's not
slowing down at all.
It's expanding
faster and faster.
It's accelerating
in its expansion.
That's crazy.
Nobody even thought
about that as an idea
because to accelerate
the size of the universe
requires some sort
of force, which
requires some sort of energy.
And the amount of
energy that would
required, well, maybe
like 2/3 of all the energy
in the universe.
That would be totally crazy.
And, in fact, that's
what's happening.
And we have no idea why.
We know that it's happening.
We measured it.
And we see that the universe
is expanding faster and faster
every year.
We just don't know why.
What could possibly be
responsible for pushing
galaxies away from each other?
I mean galaxies are heavy,
hundreds of billions
of stars in them.
Stars are not tiny objects.
What could be responsible for
pushing all of these galaxies
apart from each other?
We have no idea.
Which means that we have
no idea whether it's
going to turn around, or
whether it's going to continue,
or whether it's
going to increase.
But there's a fascinating
consequence to it.
The space between us
and other galaxies
is growing at faster than
light can traverse that space.
What does that mean?
It means that these galaxies
are going to move out
beyond our visible horizon.
So every year that you
look up at the night sky,
it's going to get darker,
and darker, and darker.
So imagine doing astrophysics
in 10 billion years,
if human civilization
survives the next three years,
or until the next election.
[LAUGHTER]
So imagine in 10
billion years, we're
trying to rebuild
human astrophysics.
And people are looking
up into the sky
and wondering where is
everything or is there
anything out there?
They could be looking up
into a totally black sky,
in which case they would have
no clue about how things work.
All the critical
information that we
learn from looking
at the stars, they
will be totally ignorant of.
Now, before you feel, like, too
great about the fact that we
are living now and we can use
the stars to help us understand
the universe, remember we're 14
billion years into the history
of the universe already.
If we had evolved 10
billion years ago,
and looked up at
the night sky then,
what would it have revealed
to us that's now totally gone
and lost forever?
Well, we have no idea.
So the future of the universe is
something we don't understand.
It's not something
we can predict
because we have no understanding
of the mechanism by which
the universe is expanding.
And it's only recently
that we've even understood
that it is expanding.
So that's why I say we're at
a special moment in physics
because we very recently figured
out exactly how little we know
about the universe, which means
that we have an opportunity
to learn something about it.
So here's a pie
chart to summarize
our knowledge of the universe.
Most of the universe
is something we just
don't understand at all.
We label it dark energy
so we can write grants
about it that sound cool.
But really, we have no
clue what this thing is.
There are some ideas.
People have come up with
theoretical explanations
for what dark energy might be.
And they do calculations.
And they compare
those to what we see.
And they're off
by 10 to the 100.
There's only, like, 10 to the
80 particles in the universe.
So 10 to 100 is a
huge, huge mistake.
27% of the universe
is dark matter.
Something, we know it's there.
We know it's matter.
We don't know really
anything else about it.
Is it one particle?
Is it lots of particles?
Is it something
else, totally weird?
We don't know.
The rest of the universe,
this little corner, this 5%,
the et cetera part of
the universe, that's me,
and you, and ice
cream, and bicycles.
We're really the little
bits of the universe.
And so you might
think, well, how
are we in making progress in
understanding this question
about what is the universe?
Well, it's sort of
like imagine somebody
told you to
understand elephants.
Then you spent 300 years
only studying the tail,
not even realizing there
was more to the story.
And then one day,
finally, somebody
walks around to the front.
Like, excuse me, maybe
you want to, like,
look at the rest
of the elephant.
Well, what are you going
to do in that situation?
How are you going to feel
confident in understanding
the rest of the elephant?
Well, what you're probably
going to do is say,
well, maybe the
rest of the elephant
is made out of tails also.
Or like, I can
describe the elephant
as a linear combination of
tails that I already understand.
Because you're get to cling to
the theories you know, right.
Well, you might think
that's ridiculous.
That's absurd.
It's obviously a
stupid thing to do.
That's exactly the same
argument I made 10 minutes ago
about dark matter.
Maybe dark matter is also
made out of particles
because that's all we know.
So we should be careful in
extrapolating our knowledge
to the rest of the universe.
It's a great tendency in physics
to extrapolate from the known
into the unknown.
But it's also dangerous
when you're extrapolating
from an unrepresentive sliver.
So I don't mean
to be depressing.
What I mean to do
is to encourage
you to think about the kind
of things we might be thinking
about in the future.
Because it's a special
moment of physics
when you realize that you
don't know very little.
It's a chance you
have to reboot.
To throw away everything you
thought you knew and think,
you know what,
maybe we're looking
at a unrepresentative slice.
We need to come up with
some crazy new ideas.
It's those moments when you
know you know very little that
give you the opportunity
to totally, like,
come up with something
completely new, that
could blow your mind.
And in 200 years,
or in 500 years,
children's books
about the universe
will contain facts
that, to us, are crazy,
that we wouldn't even believe.
Imagine giving this
talk to Isaac Newton,
a staggering genius in the
history of human physics.
He had no idea about
any of this stuff.
And it would totally
blow his mind.
How can we take anything
he said seriously?
He had no clue about
the cosmic situation.
The way we think about
primitive cave men
is the way future scientists
will think about us.
At least we know that
we don't know very much
about the universe, which
gives us a heads-up or a way
to get started.
So we know that we don't know
very much about the universe.
However, it is an exciting time
because, at the same time as we
know that we're
clueless, we're also
building awesome new tools to
help us solve these mysteries.
So we have the Large
Hadron Collider.
And it smashes
particles together,
to try to see
what's inside them.
We have the gravitational
wave observatories,
that can see ripples
in space and time
and black holes colliding
billions of years ago,
which is pretty awesome.
We have space
telescopes, which can
help us look back into the
early moments of the universe
and figure out these questions
about how things got started
or what happened
before the Big Bang?
Hopefully, in the future, we'll
have even cooler technologies,
maybe given to us by
our alien friends.
I like to think that this is
an amazing period in physics.
That in the next five years,
or 10 years, or 15 years,
we will make some of
these discoveries,
answer some of these questions.
And it will really
be a turning point
in the history of physics.
I hope that in a hundred years
people think back and think,
wow, I wish I had
been a physicist back
in 2020, when they really
figured out whatever it
is we're about to figure out.
I like to think about the
discovery of quantum mechanics,
all those experiments
people did over
like the course
of 10 years or so.
People just sat down,
and thought about it,
and figured it out.
And it revealed what the true
nature of the universe was.
And I sometimes think, if
I had been around then,
I totally would've
figured it out.
But when you're standing in the
forefront of human knowledge,
not knowing which
direction to go,
any of these possible
crazy ideas could be true.
It's not easy to know
which direction is correct.
So in hindsight, it
might be obvious.
But here we are, not knowing
much about the universe.
So to round out our
tour of silly charts
about the universe,
and to impress on you
how little we understand
about the universe,
this bit here is dark energy.
Most of the universe is
something totally not
understandable to us.
This bit here is dark matter.
It's something-- we're
pretty sure it's matter.
But that's about all we know.
And this little bit is me,
you, and dark chocolate.
And so in our book, we talk
about this one question,
what is the universe
made out of?
Because it's one of these
deep and ancient questions
that we think can be answered
and will be answered.
And when it is,
we'll change the way
we think about the universe.
But there are lots
of these questions
in science, big, deep, ancient
questions, with answers.
Questions like, what
happened before the Big Bang?
Nobody knows the answer
to that question.
Even the early moments of the
Big Bang are still a mystery.
Or even more basic questions,
like what is space?
You might think,
well, that's obvious.
Space is emptiness.
It's just the abstract backdrop
on which things happen.
Well, we know now
that that's not true
because we know that
space can expand.
We know space can bend.
Space can even ripple.
Emptiness cannot ripple.
So space is not just emptiness.
It's a thing that we live in.
It's like as if we
were fish, and we've
been swimming in water
for thousands of years,
not even realizing
that water was a thing.
We just thought it was
the thing we were in.
And then you discover, oh,
it's a dynamical thing,
with properties.
Space is like that.
It might even have
strange phases
that we haven't even explored.
We don't know basic
things about space,
like how many
dimensions are there?
Well, there's three that
we're familiar with.
But string theory
predicts 11 or 26.
And there's lots of ways
that there could be extra,
little curled up
loops of dimensions
that we're not
even familiar with.
So really basic ancient
questions about the universe
have not been answered.
But they have answers, these
answers that can be revealed.
So we talk about all
those in the book.
And the point of our book
and the presentation today
is not to convince you that
science doesn't know anything.
It's to show you that science
will make great discoveries
in the future and to
prepare you for those
by introducing you to our
cosmic level of ignorance.
So thanks very much
for your attention.
[APPLAUSE]
SPEAKER: So we're right up at
the end of our allotted time.
But I think we can take
a couple of questions,
if anyone has any.
And then afterwards,
Daniel and Jorge
have been kind enough
to do a book signing.
DANIEL WHITESON:
And stick around
and answer any other
crazy questions you have.
SPEAKER: Anyone?
No one?
DANIEL WHITESON: No questions?
Oh, here we go.
AUDIENCE: Here are
some questions.
SPEAKER: Just a moment.
AUDIENCE: Hi.
Thanks for giving
us a great talk.
Are there any
questions in this book
that you would have
liked to explore,
but did not manage
to fit in the book?
DANIEL WHITESON: Yeah.
There are a lot of
questions that we
don't have the answer
to, that we also
didn't talk about in the book.
In the book, we tried to
limit ourselves to questions
that we thought people
could understand
without any
scientific background,
like simple, deep questions.
For example, a lot
of people ask us
why didn't you talk about
the mysteries of neutrino
oscillations in the book?
Well, neutrinos are interesting.
But it takes-- it's like a
20-minute explanation for why
they're interesting.
So we tried to focus on things
that were very accessible.
But there are other
things, like the mysteries
of quantum mechanics, that
would take a whole other book.
AUDIENCE: Thank you.
JORGE CHAM: So stay
tuned for our next book.
We still have no idea.
AUDIENCE: Which ones are
your favorites, individually?
DANIEL WHITESON: I think
one of my favorites
is the question
of what is space?
Because it's not a question you
hear a lot of people even ask.
But I think it's a really
deep and important question.
I really liked
writing that chapter
because I like thinking
about what space was.
When I first heard about, like,
space expanding, I was like,
what does that even mean?
It's like I understand
each word individually.
But together, it's like
it doesn't make any sense.
So it's once you liberate
yourself from the idea
that space is an abstract
idea and discover
that it's a physical
thing, that you can think
about how changes and moves.
It's a totally new way of
thinking about the universe.
That was my favorite one.
JORGE CHAM: My
favorite is chapter 13.
If you get the book, it's
a very special chapter.
But no.
There's also a chapter I
really liked about cosmic rays.
And I like it because it's a
very, very specific mystery.
Like Daniel mentioned, we're
being bombarded by particles
all the time.
And especially they are
interesting because they're
super, super-high
energy, like they're
super-duper high energy.
We're being shot at
by these particles.
And nobody really knows
where they're coming from
or what could be making them.
Like, there's no
process in nature,
or astrophysics, or physics that
scientists know about, or could
even imagine, could be producing
these super-high energy
particles.
And so the possibilities
are, like, insane.
Like, there could be
something totally new thing
in the universe nobody
has ever seen before.
Or it could be, like,
aliens shooting at us.
So it's a pretty cool mystery.
AUDIENCE: Hi.
Thank you for the talk.
Wasn't there a theory
that our universe
starts with a Big Bang.
Then it crunches.
And then Big Bang again.
And what happened to that
theory if we're expanding now?
DANIEL WHITESON: Great question.
Yeah.
So there was a theory, the
sort of cyclical universe,
Big Bang, Big Crunch,
Big Bang, Big Crunch.
That theory is less popular
now because of dark energy.
Because we know the universe
is expanding like crazy.
But we don't know what dark
energy holds for the future.
Dark energy, for
example, only turned on
about 5 billion years ago.
So for a long time,
the universe was just
sort of coasting
and slowing down.
And then it turned on.
What's going to
happen in the future?
It might turn around
and make a Big Crunch.
So a Big Crunch is
still a possibility.
In fact, there's a theory of
spacetime called loop quantum
gravity, that says
that maybe all of space
is pixelated on this
tiny, tiny scale.
And it specifically
predicts a Big Crunch.
So the short answer is a Big
Crunch might still happen,
but nowhere in the near future.
So don't worry about it.
And you still have to
pay next year's taxes.
[LAUGHTER]
But we know dark energy
is such a mystery.
We can't predict
what's going to happen
because we don't understand
the mechanism for it at all.
AUDIENCE: Yeah.
Thanks for doing this talk.
This is awesome.
So I think it's
superimportant to have
entertaining, accessible
examples of science,
especially for,
like, young people
to get them interested in
STEM and things like that.
Are there other resources or
organizations that you know of
and that you support,
that you think
are really good to point
to or to support monetarily
or otherwise, things like that?
DANIEL WHITESON: Well, first,
buy 10 copies of the book.
JORGE CHAM: And gave them
to young kids or teenagers.
DANIEL WHITESON:
It's a good question.
I agree that science
communication is important.
And, in fact, it was Goggle
that partially inspired this
because I was reading--
Google put out a science
comic, a technical comic,
about the development
of the Chrome browser.
Scott McCloud did it.
And you know, like,
how to write a browser
is not like going to be the top
selling story on "The New York
Times."
But it was a really
compelling comic.
It was really well done
in terms of communicating
something technical.
So I'm seeing more
and more of this,
like collaborations between
scientists and artists.
And I think not all scientists
are good communicators, which
is fine.
You don't have to be
good at everything.
But the important
thing is to pair up
with somebody who's
a good communicator
and has artistic skills.
And I hope to see more
of that in the future.
In terms of supporting those
causes, it's a good question.
JORGE CHAM: Yeah.
There's a bunch of,
like, YouTube channels
that are really
good at explaining
science and things like that.
And there's a lot of comic
artists online doing it also.
I think that what Daniel
was saying, that I agree
with a lot, is the idea that--
I mean, you guys are the ones
kind of making this technology
and pushing the boundaries of
science and in engineering.
And so I really like the idea
of people in those positions
kind of taking the initiative,
to not just do the research,
but also think
creatively and figure out
new ways to communicate
this stuff out to people.
I mean there's a
lot of examples now.
But tomorrow,
somebody can come up
with a totally different type
of collaboration or a way
to communicate the stuff.
DANIEL WHITESON: I saw a Higgs
boson dance performance once.
I'm not sure I learned
much about science.
But it was entertaining.
[LAUGHTER]
AUDIENCE: Hello.
Are there any questions that you
cannot conceive of a possible
answer to?
So with dark energy, you
could start making up theories
tomorrow.
And none of them would be
particularly well-founded.
They'd likely be wrong.
But it seems to me, like,
you can conceive of what
the answer might look like.
Are there any questions
where that's not true?
So for me, one maybe
is consciousness.
DANIEL WHITESON: Right.
So that's a very question.
A lot of the times
we can speculate.
But our speculation exceeds
the bounds of science.
So one example is what
happened before the Big Bang?
Well, it may be that all
the information about what
happened before the Big Bang
was destroyed in the Big Bang.
We'll never know.
One popular theory
of the Big Bang
is that the Big Bang
was one of many.
And is an infinite
number of universes
that were all created, but now
are separated from each other,
and are moving away
from each other faster
than the speed of light.
So we will never detect them.
That kind of theory is fun.
But it's basically philosophy
because you can't ever test it.
So, yeah, there are
a lot of questions
like what happened
before the Big Bang,
where we can have
ideas, but it's not
clear we'll ever be
able to test them.
However, science is
always moving forward.
And things that used to
be philosophy questions
are now science questions.
Because we've developed new
technologies, and new ideas,
and new clever ways to
test these subtle theories.
That question you raised,
what is consciousness,
is sort of a
favorite one of mine.
It's one that I think
will actually never
be testable by science because
science assumes consciousness.
And so you can never step
outside of it to probe that.
But that's a whole other topic.
That's a great question.
AUDIENCE: Hi.
Thanks for the great talk.
So I have a question about--
so how do you think
software engineers
can contribute to
perhaps answering
some of these questions?
And also, how do you
see machine learning
coming into the picture?
DANIEL WHITESON: Wow,
a great question.
We're doing a lot of machine
learning these days in particle
physics and in astronomy because
we have larger and larger data
sets and more and
more subtle signals.
So actually, one of the
things I personally research
is how to use machine learning
tools to solve particle physics
problems?
One thing you guys can do is
hire more particle physicists.
For example, [INAUDIBLE]
here is one of my students.
And he now works here at
Google, to make more connections
between these two fields.
Because you guys have a
lot of awesome hammers.
And I'm always frustrated
when I see, for example, like,
oh, Facebook spent $100
million on this tool
to identify somebody's
face in a picture.
It's like so much money is
being spent on what seems
to me like trivial problems.
Like, is there a cat
in this internet video?
So many PhD theses
have been written
on that question, which is
like a great example of, like,
a hard question.
But, like, who cares?
And we have hard questions
where we actually
care about the answer.
What is dark matter?
Is this a Higgs
boson, yes or no?
So just, like,
talk to scientists,
try to get them to explain
their problem to you in terms
of their language and
teach them your language.
And I think you'll find a
lot of interesting overlap.
JORGE CHAM: A cool
project is, do you want
to tell them about CRAYFIS?
DANIEL WHITESON: Yeah.
So, for example, one
project I'm working on
is trying to understand
these cosmic rays
by turning everybody's
smartphone into a particle
detector.
And then if you network all
of these smartphones together,
you can build a
global-sized telescope,
which could look out
into space and see maybe
where these cosmic
rays are coming from.
It's called CRAYFIS, Cosmic
rays found in smartphones.
And we certainly need software
help for that project.
So if you're really
interested, send me an email.
AUDIENCE: Do you think
dark matter is more
important than cats in videos?
DANIEL WHITESON: Do I
think dark matter is more
important than cats in videos?
JORGE CHAM: Maybe the dark
matter is cats in videos.
DANIEL WHITESON: Yeah.
I think cats know
something about dark matter
they're not telling us.
[LAUGHTER]
AUDIENCE: Hi.
It seems like every time
we get closer and closer
in getting an
answer, it was like,
oh, now we have dark matter.
And then it went away.
Oh, now we have dark energy.
Because now you have your
pie chart of 5% is us.
But I wouldn't be surprised,
like 50 years from now,
oh, no, now we have
another dark thing.
So dark power or whatever.
JORGE CHAM: Dark power.
AUDIENCE: Now, we know like--
JORGE CHAM: The dark side.
AUDIENCE: Yeah.
So it was 0.1% of the universe.
And so this is a question that
I don't think I have an answer.
But do you expect that to
continue happening, especially
also the other way around.
So now we have three particles.
But I wouldn't be surprised
that then we have one.
And then, boom, a whole raft
of infinite new particles.
And we have a new table of
fundamental, fundamental,
fundamental particles.
And we will go, like, all the
way to a rabbit hole, upwards
and downwards.
DANIEL WHITESON: I
love your question.
We address this question
specifically in the book.
The question is like,
could there ever
be a theory of
everything or could we
ever understand the universe?
So I hope not because I
like asking questions.
But there are some
arguments that the universe
might have a smallest particle.
So one way to interpret
your question might be,
could we ever drill down and
discover the smallest particle
or is it just going to keep
going forever, smaller,
and smaller, and
smaller particles?
Well, we don't know.
But there are some
arguments that suggest
that the universe has a small--
a distance scale beyond
which you can't measure.
The universe is pixelated
at some smallest level.
But there is an end to this.
The arguments are pretty weak.
They go like this.
If I take all these
numbers that I
found about the universe,
the speed of light,
Planck's constant, Newton's
gravitational constant,
and I multiply them together
in this creative way,
I get a number that
has units of distance.
That's called the Planck length.
What is that number?
Well, it's 10 to the minus 35
meters, really, really small.
Does that mean the
universe is pixelated?
No.
Does it mean if the
universe is pixelated,
it's pixilated at that size?
No.
But what do we do in science
when we don't know what to do?
We do the dumbest thing first.
So that was the dumbest thing.
So it's sort of a
hand-wavy argument
that maybe at that scale,
or somewhere within a factor
of a million of that
scale, the universe
might be pixillated
at the smallest level.
But that scale is
10 to 15 smaller
than what we can currently see.
So we're really far away
from ever seeing that.
I mean you'd have to build like
a solar-system-sized particle
collider to study things
at that small scale.
So I think it's likely that
the universe is pixelated,
though I don't have any
hard evidence for it.
And that eventually, we
could figure that out.
But it's a long way from now.
AUDIENCE: Thank you.
DANIEL WHITESON: A
great question though.
I mean even if we had
a theory of everything,
the questions don't stop
because you guys asked, like,
why is there a three
in that theory?
What does that mean?
Then philosophy takes over.
AUDIENCE: Hey.
Thank you for the talk.
It was awesome.
DANIEL WHITESON: Thank you.
AUDIENCE: A quick question.
Don't you think first person
to see the Grand Canyon would
have lived hundreds
of thousands of years
ago, not a few hundred.
DANIEL WHITESON: Yeah, probably.
I mean 10 or 20
thousands of years ago,
was the migration down
from the Bering Strait.
AUDIENCE: But I have a
science related question too.
What do you think we're
going to figure out
first, dark matter
and dark energy
or a unifying model of
gravity and electromagnetism?
Do we need one for the other?
What do you think?
DANIEL WHITESON: Well,
that's a great question.
We could figure out dark matter
anytime in the next few years.
It's possible.
We're looking for dark
matter very actively.
We're trying to
create it in the lab
by smashing particles together.
We have these big tanks of
heavy water underground, that
are looking for dark matter.
So we could discover it any at
Or we could keep looking for it
and not find it.
So dark matter is
the most likely thing
to be discovered in
the next few years.
But also, it could be decades.
Dark energy, it's
pretty exciting
because it's such
a big question.
And we can make progress on
that really unpredictably.
It could be a long time.
A unifying theory of gravity
and the other forces, people
have been working
on that for decades
and made very little progress.
So I don't expect
that to be wrapped up
anytime soon, unless we
can visit a black hole
and look inside of it.
Because inside a black
hole is all the data
we need to understand
why we don't have
a quantum theory of gravity.
If you've seen the
movie "Interstellar,"
that part of that movie
was actually true.
JORGE CHAM: The rest,
we have no idea.
DANIEL WHITESON:
We have no idea.
Great question.
AUDIENCE: All right.
Well, I think we're going
to wrap up the Q&A now.
And then Daniel
and Jorge will be
signing books and answering
any lingering questions
for the next while.
DANIEL WHITESON:
Thanks everybody.
AUDIENCE: Yeah.
Thank you.
[APPLAUSE]
