so welcome my name is bob jacobs and i'm
here from the physics department to
introduce joel
as you've seen from the movie how many
of you actually read this book
okay i'm going to try really hard not to
give away any clear plot points
but this movie involves a certain amount
of dispute between scientists and the
vatican
and i won't tell you who wins
but but one of the key parts of it is
scientific research that's done at a
place called cern
building something that is going to be
used to do detriment to the vatican and
joel will tell you more about this
um we take this in a very light-hearted
spirit you know scientists have
been uh in conflict with other cultures
even in this campus forever do you know
who this campus is named for
bishop berkeley you know what he's
famous for
proving that the calculus was wrong
so we got even with that although it
took 180 years
to finally do it uh he also was a
philosopher but that doesn't count
tonight
um
so we view this in a certain
light-hearted way uh as part of that we
have brought t-shirts because we're
going to adapt you to our culture
and and because i'm a physicist i
probably can't throw these that far
it's really tough to get a spiral out of
a t-shirt
i got two more to go
there's no way i can hit you that far
away
okay that's it for that if you brought a
car if you got a car and you brought it
maria is the person to give it to she's
waving a card right here
and
joel is his actually works in this joel
works in the production of anti-hydrogen
he has for a while
this is an ongoing project it's one a
wonderful piece of science
he has to leave tomorrow morning to go
to cern which is in switzerland to work
on it so thank you we thank him in
advance for spending his evening with us
telling us all about it
[Applause]
well thank you very much i'm sorry about
us getting started late i've we've set
up a large number well a few demos here
and they've taken a little bit of time
to get running i think i'm a little bit
too
loud at the moment so
no
okay
sounds too loud up here anyway
okay
um
as bob just mentioned the book angels
and demons movie angels and demons is
based on this book by dan brown
and the most i'm going to give away of
the plot in a big way
is that the plot is that a secret
society called the illuminati
steal about a quarter of a gram of
anti-matter from the cern physics
laboratory in geneva switzerland for use
in a plot to blow up the vatican
and fortunately for us sony pictures has
been kind enough to provide us with a
clip which explains all of the physics
behind this
which i'm going to play for you this hot
this is quite quiet so i'm going to turn
the volume up
where is that camera number 86 it's
wireless a2 was stolen it could be
anywhere inside the vatican that
canister contains an extremely
combustible substance called antimatter
we need to locate it immediately or
evacuate vatican city i'm quite familiar
with incendiaries veteran i've never
heard of antimatter being used as such
well it's never been generated in
significant quantities before
it's a way of studying the origins of
the universe
to try to isolate what some people call
the god particle but there are
implications for energy research
what we call it isn't important it's
what gives all matter mass the thing
without which we could not exist you're
talking about the moment of creation yes
and where i am
the antimatter is suspended there
in an airtight nanocomposite shell with
electromagnets on each end
but if it were to fall out of suspension
and come in contact with matter say the
bottom of the canister then the two
opposing forces would annihilate one
another violently what might cause it to
fall out of suspension the battery going
dead
which it will
in six hours what kind of annihilation
how violent a cataclysmic event
a blinding explosion equivalent to about
five kilotons
vatican city
will be consumed by light
not that
[Music]
i hope you understood that
because to tell you the truth i haven't
a clue what they were talking about
all right that's not really true i do
understand some of this stuff
a physicist a nobel prize-winning
physicist named leon lederman
decided to call a particle known to
physics as the higgs boson he decided to
call it the god particle
well actually he didn't his publisher
did
he wanted to call it the god damn
particle
which got censored
um but you have to agree that they have
different implications nonetheless the
god particle got taken up by the media
physicists hate it we refuse to
acknowledge it but there it is
the higgs particle or the higgs boson
was proposed by peter higgs and others
back in the 60s and higgs is the only as
yet unobserved particle in the standard
model of particle physics it's a very
important particle because it's this
particle which is thought to give mass
for all of the other particles we've got
electrons protons neutrons and so on and
so forth but we don't have any
fundamental understanding of where their
mass comes from comes from in fact they
all scale off of this higgs particle and
if we could discover the higgs particle
we would be able to predict
what the mass of all of these particles
are so it's a very important particle
and at this point
detection of the higgs is probably the
goal of particle physics
the search for the higgs actually began
began at some level here in berkeley
with the discovery of the accelerator by
or the cyclotron the invention i should
say the cyclotron by e.o lawrence back
in 1931 the very first accelerator that
was built here was four and a half
inches on a side about this big and
could accelerate particles up to about
80 kilovolts
not very much
but pretty soon we went over to the 1937
inch cell
cyclotron which could get particles up
to 8 million electron volts actually
many of you have seen this device
because it's currently sitting up at the
lawrence hall of science in the parking
lot who's seen this thing here
many of you have
it doesn't look like very much nowadays
but it was a truly important device in
the history of physics
after the 37-inch cyclotron there were a
number of others
but before i go to some of the others
let's just talk for a moment about how
much 8 million volts is which was what
what the 37 inch
cyclotron could get us to
8 million volts is about 70
000 times the voltage in 120 volt outlet
to give you some sense of scale
to go to perhaps a higher scale it's 16
times the voltage on the pacific
intertie which is one of the three main
inter ties that brings power from the
oregon and washington
reservoirs down to los angeles to be
used in air conditioning down there so 8
million volts is much much bigger than
you find on even the highest common
system that you um
that's commonly available so it's really
remarkable that you could get to that
kind of voltages in such a small system
but it wasn't enough physicists are
greedy so then they went to the 184 inch
cyclotron which was built in 1942
you can still see parts of this at least
you can still see the building that
houses this thing as you go out of here
if you look up at the lawrence berkeley
national lab you can see this dome at
the top
um
and the 184 inch cyclotron was built
inside of that
the final cyclotron or the i should say
the final big accelerator built here at
berkeley was the bevertron in 1954. this
was 100
meters in diameter and could get up to
about 6 billion electron volts
unfortunately this was the end of the
line here in berkeley
and the reason is that well 100 feet is
really very large right
and people realize that sticking large
accelerators on a very steep hillside
in a fire zone
a few hundred meters from a major
earthquake fault
really wasn't such a great idea
now in building these sorts of
accelerators they had to change the
shape the original ones were just solid
disks but you couldn't build a solid
disk which was 100 meters in diameter so
these accelerators became donut shaped
and what would happen is you'd have
particles that were going around and
around inside of these accelerators and
every time they would pass a certain
place in the accelerator they get a
little kick so they'd go around faster
and faster and faster and faster
well
once the af left berkeley it went to
lots of other places the biggest
accelerator in the world at the moment
is the tevatron which has a ring which
is 3.9 miles in circumference and can
get up to
just about
a trillion
volts or something like that but
very shortly perhaps later this year the
accelerator called the large hadron
collider at cern should come online this
is in geneva switzerland and you can
can't see it too well on this photograph
but you can see there's this huge ring
going all the way around it's 17 miles
around to give you some idea of the
scale of this device there are no roads
that go straight across so if you take a
bicycle you have to wander around a
little bit but it takes about 30 minutes
to bicycle from one side of the ring to
the other
now cern itself is a huge institution
there are about 10 000 people associated
with it at the moment
from about 500 universities and about 80
countries if you take a look at my badge
over here my badge is
91 666
let's not wonder about why i'm 666
but
the implication of this is that there's
been almost 100 000 people associated
with this laboratory over the years
now
there are 20 official member countries
these are the big the closest members in
there unfortunately the united states is
not actually a member of the cern
laboratory despite us giving them about
a billion dollars
in recent years this means that we don't
have full privileges at the laboratory
one of the privileges for instance that
we do not have is we are not actually
allowed to fly our flag in front of the
laboratory
but anyway
um
the uh
this laboratory has the 17-mile tunnel
and inside of that tunnel there's this
huge accelerator this accelerator and
the detectors associated with this tel
accelerator cost about 10 billion
dollars
which is really a huge amount of money
no matter how you look at it but
physicists really do expect to be able
to detect this higgs particle or the god
particle if you insist at the lhc
because of that pain parts of angels and
demons were filmed at the lhc and at the
atlas detector here's one of these
detectors which is used for figuring out
what happens inside of this accelerator
to give you some idea of the scale of
this project when this thing is fully
operational the amount of information
that will be generated by this
this detector will be about equivalent
to the total worldwide
telecommunications traffic
and all of that is coming out of one
little space
which is a really astonishing thing well
anyway um the cast was at this place and
you know tom hanks and eyelet zur
were photographed and everybody was very
happy to be seen with stars and things
like that not me i wasn't there at the
time that they filmed this but
um
really what do all of these big
accelerators have to do with using atoms
to matter to blow up the vatican
well the answer is not very much
past the bevetron the last big
accelerator that was built here at the
berkeley labs
to understand anti-matter as it's
actually used in angels and demons we
need to consider charges and particles
to go go way back to the beginning in
fact to benjamin franklin who postulated
that there were negative and positive
charges
and we now know that these charges
franklin's charges are typically carried
by electrons and protons electrons are
negatively charged
and protons are positively charged put
them together in a really crude and sort
of embarrassingly simple model and you
have a hydrogen atom
add a few more protons and electrons and
some neutrons as well
and you can build up our entire periodic
table of normal matter
the anti-electron or the positron
was a prediction by a famous physicist
named iraq who in 1928 had a problem
with his mathematics it blew up and to
solve this problem in his mathematics he
invented a positive electron it seems
like a hoax
but in fact it turned out to be a
correct and this positive electron the
positron as it's now called is simply
the charge
swapping of an electron so take an
electron and change its charge from
negative to positive and you'll get a
positive electron or a positron aside
from the change in sign
positrons are believed to be otherwise
identical to electrons
well this wasn't just a phony thing very
quickly thereafter they were discovered
four years later by a guy named carl
anderson who discovered them in cosmic
rays and here's a photograph of a
positron
one of his originally detected positrons
going through his apparatus
where what are positrons from cosmic
rays what are cosmic rays well the top
of our atmosphere is constantly
bombarded by highly energetic particles
most of these particles come from
outside of the solar system they come
from other stars perhaps even other
galaxies
and they move so fast that when these
particles come in and hit and say an
oxygen molecule at the top of that
atmosphere they split the nucleus of
that oxygen molecule
in fact not only do they split the
nucleus they split the things that are
inside the nucleus and you get a shower
of different particles that come out
in this depiction this
proton is turning into a pi several
different types of pions and these pions
themselves which are very strange sort
of particle
are themselves
hit other nuclei and they split or they
spontaneously split all by themselves
into yet more particles and the net
result is that we get a shower of
particles coming down from every proton
that hits the upper our upper atmosphere
here's a depiction of such a shower one
proton comes in and it creates initially
maybe two or three other particles and
each of these particles split again
creating more and more particles so that
we wind up with an enormous number of
particles
here down here at um
down here at ground level in fact as you
sit there out in the atmosphere there
are some of these cosmic rays coming
down and going right through you
particularly a type of particle called
called a muon and there are
approximately a thousand muons per
second coming down and hitting you going
right through you at the moment from
these cosmic ray showers
now
there are also naturally occurring
sources of positrons um
there's an isotope of potassium
potassium 40 which is very commonly
found in things like bananas and um
this is a rare but not that rare isotope
about one atom in every 10 000 of
potassium is potassium 40 and potassium
40 emits positrons it emits antimatters
so
as a result of eating this banana
over the course of time that this banana
and its constituents its potassium stays
in me
um
i will experience
approximately
1 000 or so positrons inside me which
suddenly go out now of course
if you have more bananas in you you'll
get more positrons
oh
where's the sound here then begin to
talk about the christmas tree i hope
that means that everyone is glad to see
the lady and the tutti frutti hat
well anyway
um
nowadays we have natural we can make
artificial sources of potassium in fact
i have to stop eating this banana
it's only about 500 of positrons will be
emitted inside of me um
one of the most potent
artificial sources
of positrons that we can make and by the
way we make these by transmutation of
elements inside of other accelerators
but one of the most potent ones is an
isotope called sodium 22 and i was
actually able to borrow a sample of
sodium 22 and it's inside here inside
this bubble chamber
emitting
positrons
which
unfortunately
i'm not really seeing at the moment
but what we were going to show you is
some tracks of positrons coming out of
this device
um
this is all set up right
well
it's about as working as well it's
supposed to i see all sorts of other
things coming in here actually you guys
can take a look at what's coming in here
perhaps
if we could have the camera on the
auxiliary video
is this working
are you seeing this camera over here
it's camera three yeah
okay most of what you see there are not
particles but every now and then you
should be able to see a streak that goes
through this image and those streaks are
mostly cosmic rays but our sodium source
of positrons
is
this thing over here and if you look
really closely at least before the
lecture
when this was working an hour ago
you could see that there were positrons
being emitted by that source and you
could see the tracks left behind from
those positrons as they go through
but unfortunately i'm just not seeing
them at the moment if you want to come
up after the lecture this may be working
by that point sometimes it takes a while
for this to get going i apologize for
that but we're just going to have to
move on
okay
the artificial generation of positrons
has become quite important lately in the
medical profession because we can use
positron emission tomography to learn a
great deal
about what goes on inside people
especially sick people
um what happens is that you are forced
by your doctor to
drink or
breathe or you have injected into you
some radioactive isotope that emits
positrons and those that radioactive
isotope is absorbed in various organs
inside of your body depending on whether
or not that particular isotope has some
particular metabolic activity for the
particular isotope that you're
i'm not saying this very clearly if for
instance you ingested something like
iodine it would go straight to your
thyroid right and if it was radioactive
you could see your thyroid lit up like
this well in this case you can't see
this very well but there's a person over
here who was
forced i think to have some radioactive
substance that emits positron injected
into his veins and you can see that they
all concentrated inside of this person's
stomach something's actually wrong with
this person
and it's a very it proves this proves to
be a very powerful diagnostic technique
for doctors
well that's positrons what about
antiprotons
just like there are anti-electrons there
are anti-protons if you take a proton
which is positively charged and swap its
charge
so that it's negative rather than
positive
you'll get an anti-proton and just like
with
electrons and positrons aside from the
change in sign anti-protons are thought
to be otherwise identical to positrons
and i'm sorry to protons
so
it turns out that the very first
anti-protons were discovered here in
berkeley at the bevetron that
accelerator that i showed you a few
minutes ago
they're made in a process which is quite
analogous to the way positrons are made
in cosmic rays you take
a beam of protons and slam them into a
metal
and after
after this collision some a very small
number of anti-protons will come off of
that metal
the first
ones were made as i said in berkeley in
1955 by segre and chamberlain segre is
the short one chamberlain is the tall
one in this picture and they received
the nobel prize for this work
now just like today publishing is very
important but
unlike that today they didn't have the
world wide web to publish their results
so there's a really neat photograph of
how they publish their results at least
within the local berkeley community it's
a photograph of a
blackboard which shows that on october
6th at 4 30 pm they had detected 38
negative particles of the appropriate
mass in other words 38 anti-protons just
at this moment
now
if matter then is just made of negative
electrons and positive protons negative
electrons and positive protons an
antimatter is made of positive electrons
and negative protons positrons and
antiprotons over here
and they're just basically swapping the
charge
why would we care about all of this
what's so different about antimatter
compared to matter
well the answer is that if you allow
matter to touch antimatter
it blows up it annihilates
and
when it annihilates all of the matter
all of the mass
turns into
energy via einstein's famous equation e
is equal to m c squared
you get an enormous amount of energy out
of this process in the angels and demons
book about a quarter of a gram of
anti-matter is stolen from cern this is
equivalent to 10 grains of rice
and yet
if you took 10 grains of antimatter rice
and allowed it to touch normal matter it
would cause an explosion that would be
the 10 kiloton
tnt explosion for comparison the bond
that blue dot was blown up over
hiroshima was 15 kilotons
now that 15 kiloton weapon contains 64
kilograms
of uranium inside of it
so the fact of the matter is that you
get an equivalent size explosion out of
these grains of rice even though they
weigh about 250 000 times less
as was used to blow up hiroshima it's
truly an enormous explosion and this
would deal enormous damage to the
vatican if it was used if we start at
the piazza san petro and go outwards
just to get some idea of what vatican
city looks like
and then if underneath the obelisk in
the middle of the plaza i was to allow
those 10 grains of rice to blow up i
would get a circle of devastation
about this big
in other words everything within this
range
would be gone
and there would be very very significant
damage well beyond that point
so you really could in principle do a
lot of damage to the vatican if you were
to blow up some anti-matter there but
we actually shouldn't fear for the
vatican
and the reason is that the economics
associated with anti-matter production
are utterly
and completely infeasible
why is this well anti-protons are still
made the same way they were made back in
the bevitron here in berkeley by
crashing very energetic protons into a
metal
and only a very small fraction of the
protons turn into antiprotons about one
in a million
this fraction results from fundamental
physics not technology and is not likely
to change all that much
to make a one gram of antimatter would
require the entire world's energy
production for about a hundred years
now what do i mean by that
everybody would have to stop cooking
driving their cars lighting their houses
using the internet
absolutely all of the uses of energy in
our society would be have to be funneled
over to cern or some equivalent
accelerator for a whole hundred years
for a century to make a mere one gram of
antimatter
and that's looking at it on the bright
side
in actual fact accelerators like the
bevertron have what is called a wall
plug efficiency they don't manage to
take all of the electricity that you put
into them and put them into the
particles at best they're about 10
deficiency so our 100 years has now
become a thousand years
and things get worse than that if you
take a large number of antiprotons and
put them into a small space they don't
like it
you can exit exactly the same effect by
trying to put a large number of
electrons into a small space
and in a moment if this actually starts
to work
i'm over one for my demos so far today
all right i'm going to cheat
in a moment
oh this is pathetic
what happens
as you've all seen in the sim this is a
van de graaff generator i'm sure you've
all seen this before what happens if you
put too many of them into a small space
is they like to spark they're going to
repel each other they don't like to be
all gathered together and in fact all of
these antiprotons are going to vanish
our ability to trap anti-protons into
one small space is rather limited
and when you include that factor in our
thousand years becomes about a million
years
so unfortunately or fortunately
depending on your point of view we're
never going to be able to generate the
one gram of antimatter that would be
equivalent to make a substantial weapon
in many ways this is a real shame
because we could get to the stars on
about this much antimatter this much
anti-matter would take a hundred
kilogram space probe and accelerate it
to about the tenth the speed of light
which would be more than sufficient for
sending a probe to the nearest stars if
you wanted to go to a near star yourself
you'd probably need a spaceship that was
say on the size of 747 and we could get
that to go to a tenth of the speed of
light with about a thousand kilograms of
antimatter
so it's a real shame really for at least
space exploration that anti-matter fuel
isn't a practical thing
but
the facts of economics dictate that it
is
so
why should we study antimatter if aside
from the science swaps and this
minor fact that it blows up
anti-matter is thought to be identical
to matter why bother doing this at all
well there are many reasons to study
antimatter one of them is that we don't
know how anti-matter interacts with
gravity
it's certainly well known that apples
are attracted towards earth's
and everybody believes that anti-apples
would be attracted towards anti-earths
but it's an open question
about what would happen to an anti-apple
would it fall down towards earth
some physicists have speculated that in
fact an anti-apple would fall up
and go away from earth the betting is
against it but it's a possibility it's
something that people want to think
about and we have absolutely no
experimental evidence on this question
there's an experiment at cern that's
trying to look into this question it's
not my experiment it's another one
and the way they propose to do it is to
fire very slow anti-protons anti-protons
that are moving at about 100 meters per
second which is about the slowest that
we can get them down a one millimeter
tube the protons will be um
deflected downwards by earth's gravity
they're going to fall
presumably the protons are the
anti-protons
and they would fall by a distance of
about half a millimeter
this is a large distance as physics
experiments go it would be easy enough
for us to detect that they had fall fall
in such a large distance so this sounds
like a great experiment but there's a
catch
because inside of this tube there are
electrons in the walls of the tube
they're always going to be electrons and
if for some reason one of those
electrons went from the top tube down to
the bottom tube
that would create an electric field
which was pointing
vertically and this electric field would
be due to the charge imbalance between
these two plates
unfortunately that electric field would
also push on our anti-protons
and it turns out that it would deflect
them by a distance that is more than the
distance of gravity in down this one
millimeter tube instead of falling by
half a millimeter they would actually
the way i set it up go up by almost 10
millimeters
which would completely swamp out the
effect that we were trying to measure
because it's absolutely impossible to
have the two sides of these tubes be so
well balanced that there's that there
isn't even a one electron difference
between the top and the bottom of the
tube
so what could you do about this
well the reason the anti-proton is
deflected by the electric field is
because it's charged
neutral antimatter would not be
deflected by the electric field and it
could be used to measure the effects of
gravity on antimatter
what do i mean by neutral antimatter
well just like we can make a hydrogen
atom by taking a proton and having an
electron go around it we can also make
antihydrogen atoms by taking an
antiproton in the center and having a
positron go around the outside this net
object as a whole is electrically
neutral and won't be affected by the
electric fields that we could have
gotten in our trap so we can use
anti-hydrogen atoms to measure gravity
there are yet more reasons to study
anti-hydrogen atoms one of the things
that we would like to do with them is to
look at the spectrum of anti-hydrogen if
you take a look at any gas
and you run an electrical current
through it or some other way of running
well basically run an electric current
through it it's going to glow
here's for instance mercury glass
glowing and over here is neon glass gas
glowing and you can see that they glow
with different colors
well we would like to measure the colors
at which hydrogen and antihydrogen glow
and determine whether or not these
colors are identical
now what does this essentially mean
measuring the colors
of that these things would glow at is in
some loose sense equivalent to measuring
how much time it takes of an electron to
circle around the hydrogen of the proton
in the hydrogen atom and measuring how
much time or with what frequency
a positron circulates around the
antiproton in an antihydrogen atom
um
the
the rate or the frequency that they
rotate around that is going to determine
the color and it could so happen that
they rotate at different frequencies in
other words it could happen that this
positron goes around just a little bit
faster
than the electron goes around if that
was the case the color emitted by these
atoms would change the antihydrogen
would become more blue
well actually these both emit in the
ultraviolet and it would become more
ultravioletly but i can't put
ultraviolet up on the screen so we'll
just have to accept this analogy over
here
now is this likely to happen
well no according to one of the grand
theories of physics there's something
called cpt symmetry which i'll get into
in a minute and see
symmetry is really one of the deepest
things that we know and according to cpt
symmetry the spectra of hydrogen and
hydrogen have to be the same they could
only be different if cpt symmetry is
unbroken is broken now this is very very
unlikely
it really is but it is worth studying
because proof that cpt could be broken
would really revolutionize physics it
would surely be rewarded by a nobel
prize
so what then
is cpt
well i'm sorry why why should we use
antihydrogen for look to look for cpt
violations well it turns out that one of
the things that we can do most
accurately
is to compare the rate at which these
electrons circle that proton and this
positron circles the anti-proton it
turns out that we can compare these so
accurately that we could detect a
difference of one part in one followed
by 18 zeros
that's really an astonishing fact in
reality these electrons go around
crudely speaking about a quadrillion
times per second
imagine that a quadrillion it's a number
that it's hard to even imagine how large
that number is
if it was if one this positron was to go
around just a little bit faster so that
after a thousand seconds it had gotten
ahead by one full revolution remember
it's going around a quadrillion times
per second and i'm saying if we could if
this thing got ahead by one revolution
in a thousand seconds that's something
that in principle we could measure so
this is an incredibly sensitive test of
whether or not they're going around at
the same speed
now
what exactly is the cpt symmetry that
says that this can't possibly happen
well each letter in cpt stands for
something that can be flipped
c stands for charge conjugation p stands
for something called parity conjugation
and t stands for time reversal
now consider the result of an experiment
in which one of these things is flipped
let's say i have an experiment over here
and i conduct an identical almost
experiment over here except i take
everything say the charge in one of
these experiments and flip the charge so
over here i had only minus charges over
here i had positive charges
under some circumstances the results of
that experiment will be identical
and let me go into this in just a little
bit more detail for instance let's take
the c charge conjugation
that says that the signs of all the
charges are inverted positive charges
become negative negative charges become
positive now let me do an experiment
let's say i have two positive particles
two protons and i have my fingers on
these two protons and then i suddenly
let them go what are they going to do
everybody knows this they're going to
repel each other they're going to go
flying apart right
now
let's say instead i took these two
positive particles and flipped their
signs so that they both became negative
particles
i have my fingers on them and then i let
them go what's going to happen
exactly the same thing
in other words flipping the sign of the
charge at least in this experiment
results in the same net result
what about time reversal well i've got a
really neat demonstration that will show
you time reversal over here
you've probably all seen versions of
this these are just two balls which are
free to bounce back and forth this one's
particularly amusing because the balls
are different this ball weighs three
times the amount that this ball weighs
now what i'd like to do is to let this
light ball go keeping the heavy ball
stationary and i want you guys to watch
the pattern
all right if you're a physicist this is
absolutely amazing because what happens
after every other collision the heavy
ball is stationary
let me start that up again
so here we go
i'm letting this one go stationary
stationary stationary stationary
that's really kind of neat
at least if you're a physicist
this is an example of a collision
collisions are really important in
physics there's all sorts of ways
collisions come up in
in physics and this is one of the
important this is one particular case
and it's possible for us to understand
how this actually happens we can apply
the standard equations of conservation
of momentum and conservation of energy
and we can solve for this system and
we'll get the right answer and it will
predict indeed that one of those balls
will be stationary after every collision
but there's a much better way to do this
and the better way proceeds by taking a
movie of that and i've got a movie over
here
and you can see this movie
it slowed down a little bit
you can see that time is advancing on
that clock over there
okay a movie of what you just saw in
real time
now let's say
i take that same movie and run it
backwards in time
on the top is the original movie you can
see this clock is counting up in time
and on the bottom i've just time
reversed this thing the clock is
counting backwards the movie's running
backwards
and what i want you to see
is that when you do this
it looks exactly the same
everybody see that
the time reversed version
of this experiment is exactly the same
as the original version
and this is an example of t symmetry
time reversal in physics i take an
experiment
and somehow or other i get time to run
backwards
and i get exactly the same result
the last
letter in cpt symmetry is something
called parity parity is a little bit
more complicated could i have the lights
back on here please
but parody is best explained by gloves
two bicycling gloves in this particular
example
one of them
is a right-handed glove the other one
is a left-handed glove
now let's think about these two gloves
for a minute
is there any way that i can
twist and turn this left-handed glove
and turn it into a right-handed glove
all right
there's no way by simply moving it
around
and twisting it and turning it that i
can turn my right-handed glove into a
left-hand glove but as somebody in the
audience did say
to take a more worn-out glove of mine
if you take a right-handed glove and you
turn it inside out
it becomes a left-handed glove something
that i've used on occasion when i've
taken two right-handed gloves to a bike
ride
so
this is an example of a parity
transformation
actually a better way of considering
parity a more physics way of considering
a parity transformation is to imagine
looking at these two gloves
and then just looking at one of them but
looking at it through a mirror
what's going to happen
if i take a look at this glove through a
mirror well it's the same thing that
always happens when you look at
something through a mirror your right
hand turns into your left hand this
left-handed glove is going to turn into
a right-handed glove if i look at it in
a mirror and that's the parity
transformation if i take an ex
take an experiment and turn everything
that's right-handed into everything
that's left-handed wait what do i mean
by something that's right-handed in
something that's left-handed well there
are gloves
but maybe something that's got a little
more physi what's a little more familiar
to you is sugar molecules those of you
are chemists or study chemistry or
biology know that there are right-handed
sugar molecules and left-handed sugar
molecules right
so the experiment consists of taking
an experiment over here and taking
everything that's right-handed and
making it left-handed
and taking everything that was
left-handed over here and making it
right-handed and running that experiment
and when you run that experiment
the results at least under certain
circumstances will be identical
it doesn't matter that you did this
parity transformation actually parity
transformations are discussed in the
movie itself
they don't actually use this world but
there's a big discussion of it because
in the movie a big thing is made out of
the logo for the illuminati and this
logo for the illuminati is what's called
an ambigram that's a that's a real term
not invented by the book or the movie
the thing that's special about an
ambiguam is that if you rotate it
by 180 degrees it turns back into itself
now in the book and presumably in the
movie there's big mystical moments about
this sort of thing
it's actually rather mundane from a
physicist's point of view we would call
this a parody conservating rotational
symmetry and representation in the so3
rotation group but never mind
it's rather boring
a more interesting parity transformation
would be a mirror reflection
here i've taken the illuminati logo and
merv reflected it i'm just looking at it
as if it was through a mirror and you
can see that there's no way for me to
rotate this
and get that
okay this is a fundamentally different
object
than these guys over here this would be
a mirror image the transformation that
takes this one over to this one is
something that violates parity
actually you can have mirror images that
don't violate parity this is for the
movie buffs out there
here is a logo that appeared in a movie
some years ago back in 1985 actually and
it's a mirror ambigum you can see that
if i was to reflect this through a
mirror i would get exactly the same
thing anybody know what that what movie
this comes from
back to the future this is a delorean
motor corporation logo
anyway let's get back to cpt
so
what is it about cpt as i said each
letter stands for something that can be
flipped
charge parity and time and if we take
some experiment
and we turn all the flip all of the
signs minus becomes plus
we
flip all the parity
um left-handed becomes right-handed and
we turn time from going forwards to
being playing backwards then the
experiment that we do will be identical
now physicists really believe that this
is true that if you flip all of these
three things and you have to as it turns
out flip all of these three things if
you just flip one of them or if you flip
some combination of two of them you
won't get exactly the same thing
happening but the cpt theorem says that
if you flip all of these things you will
wind up back with exactly the same thing
happening
on the other hand yes
that's above my pay grade
entropy and time reversal and all of
that are very complicated questions i'd
be happy to discuss it with you
afterwards but those are really really
hard deep philosophical questions within
physics but it does apply to big systems
as well as small systems
okay
why should we really bother if everybody
believes in the cpt theorem it doesn't
seem like there'd be much point to
investigating this question of whether
anti-hydrogen breaks the cpt theorem but
the fact of the matter is there are
outstanding problems here which do not
seem to agree with the results of the
cpt theorem
we exist because there's almost no
anti-matter in our universe if there was
a lot of antimatter in our universe we
would be blowing up on a regular basis
when we look out into the stars we don't
see any antimatter out there and we can
detect antimatter we could detect
antimatter if it was out there we could
detect it without too much problem
but it wasn't always that way back in
the beginning right after the big bang
the big bang 14 billion years ago should
have produced equal amounts of matter
and anti-matter and if i take
some large amount of matter and combine
it with some large amount of antimatter
the net result is it should all be gone
everything should have annihilated and
yet we know unless this all is a figment
of my imagination that
something was left behind us
so of all of these particles out there
there must have been some sort of
imbalance that resulted in us being left
behind
now how could that have actually
happened
well there's all sorts of ways people
can speculate about it but it seems
likely that it didn't start out exactly
balanced there must have been just a
little bit more matter than anti-matter
in the beginning after the big bang
and nobody actually knows how to explain
this this is an open whole an
embarrassing thing in physics we can't
explain this and maybe this is because
cpt which sort of guarantees cpt and
other theorems guarantee that they
should be exactly balanced maybe they
weren't exactly balanced so it is
worthwhile looking at these deeper
questions
even if we expect that cpt probably is
is um
an okay theorem is a correct theorem
so
cpt and gravity
studies both require anti-hydrogen cpt
probably requires trapped anti-hydrogen
certainly precision gravity studies
require trapped anti-hydrogen as well
have we actually made any anti-hydrogen
the answer to that question is yes the
first anti-hydrogen atoms ever made
possibly the first anti-hydrogen ev
atoms ever made in the history of the
universe were made at lear in 1996 lira
was an accelerator and they made about
nine of them which isn't really that
impressive
99 more were made at the fermi lab but
these anti-matter
atoms were made in a fashion that caused
them to be traveling at about 90 percent
of the speed of light after they were
made
and it's fairly hopeless trying to study
something that's going at 90 percent of
the speed of light because it leaves
your apparatus almost the instant it's
created in the first place
so what physicists would really like to
do is to create slow or trapped
anti-hydrogen and that's been done by
this point at first by the athena
collaboration at cern in 2002 and very
very shortly thereafter by the a-trap
collaboration altogether we've made on
the order of a hundred million million
anti-protons
now 100 million sounds like a lot but
it's really not
if they were tightly packed they would
form a box
that was about 100 nanometers on the
side that's a box which is so small that
we couldn't actually see that box
the whole net result would be that they
would weigh a hundred millionth of a
gram
and if i was to use this as an energy
source it would be sufficient to run
this laser pointer for about one second
so really we haven't made been able to
make very much anti-matter at all
in fact
we've made so little of it that it's
very hard to detect that we've made it
in the first place this is an image of
one of the first anti-hydrogen atoms
slow antihydrogen atoms that was
made and detected what it is is an
annihilation event there was an
anti-hydrogen atom over here which hit
the wall of a trap which generated two
gamma rays going off in opposite
directions and some particles which are
called pions which go off in four more
directions these things were detected by
particle detectors which are these lit
up boxes over here altogether the sort
of apparatus that it takes to detect
that anti-hydrogen was made the sort of
detector that is necessary to detect
that antihydrogen is made costs on the
order of a million dollars
so you can see that if it costs us a
million dollars to make a detector that
can detect anti-hydrogen there's really
no chance that we'll be blowing up the
vatican anytime soon
how do we actually do this well we have
to make an anti-matter trap
and here's the anti-matter trap from
angels and demons
um here's a photograph of it i don't
know
what an our anti-matter trap is going to
look like in the end i mean we have some
prototype traps now but i'm absolutely
certain it's not going to look like that
for one thing
we have to worry about how we would keep
stuff inside of this trap
and
we have to be able to make a bottle of
antimatter in which the anti-matter
actually stays around so what are the
issues associated with getting it to
stay around
well if there was any air inside of that
trap
the anti-matter would annihilate on the
air because eventually the anti-model
would find particles of matter in the
air and they would blow up and that
would be the end of it so we have to be
able to make a trap that has absolutely
no air in it well fine you say some of
you have worked in similar fields you
just take a big pump and you pump all of
the air out that turns out to be not
even close to good enough you have to do
a lot better than using normal vacuum
pumps to get out of the air
one of the things that you have to do is
to cool the trap down inside here
i've got some liquid nitrogen this is at
77 degrees kelvin it's very cold
i'm going to fill up this
this little thing with liquid nitrogen
you can see it's boiling at this moment
and
but it will eventually stop boiling
see if i
can fill up the rest
um
and now i've got a nice little goblin
globule of
of um liquid nitrogen it's really cold
just to show you how cold it is
i'll do a little demonstration
i've got a rose here
we're going to freeze this rose
i'm going to let it sit in there for a
little bit anyway
we're going to have to take our trap our
bottle and
cool it down to temperatures which are
even colder than the temperatures of
liquid nitrogen we have to get that trap
down to temperatures of liquid helium
because it turns out that when we really
cool down our trap all of the gas inside
of that trap just condenses on the walls
of the trap and that's the only way that
we can get a vacuum which is
sufficiently cold
it's sufficiently good so that the
matter doesn't annihilate i think this
is pretty cold by now let's see what
happens with it
rose petals it just
grows it got to be so cold that it just
shattered when i slammed it against the
table
okay
so we have to make our trap little
really really cold and let me tell you
um
this trap of
angels and demons doesn't look cold to
me that looks like it's at room
temperature so it's not realistic in
that way but there's another problem
let's say we can get all of the air out
we still have to keep all of the
antimatter from touching the sides of
our bottle because after all if it
touches the sides of our bottle it's
going to annihilate
so we have to build a bottle which
doesn't actually have any physical sides
how do you build a battle bottle out of
nothing the way you build a bottle out
of nothing is to use electric and
magnetic fields
and here's a picture of our trap
basically what we have is we have a
series of electrodes and we put our
anti-protons
and there's an abbreviation for that in
and over here and our positrons in over
here
and we set up an electrostatic well
which is just basically a valley made
with electric fields and that traps the
particles in in the axial direction it's
a little bit harder to get them trapped
in the radial direction but i can show
you how we do it with this demonstration
over here
assuming this demonstration
works
which
oh yes it is working if you could zoom
in on this at the moment
on this camera i'm sure you guys can't
see this in the back oh
what do i have to do here i have to
put this on auxiliary right
okay
yeah
what you can see here
i hope
is right over here is you can see a beam
of electrons which is being emitted by
an electron gun
and as you can see that beam of
electrons likes to travel in a straight
line
and so it very quickly hits the glass
the sides of the glass over here and
basically electrons get absorbed by the
glass in other words these electrons are
not trapped however i can use these
coils over here to turn on a magnetic
field
and the net result of turning on those
magnetic fields is that that electron
beam will be bent i'm going to turn the
electron beam on slowly and you can see
that i'm starting to bend that electron
beam into a circle
and eventually
i can get the beam to bend back onto
itself
well this is how we can store charged
particles in a trap
without having them touch the sides
basically we apply a strong magnetic
field the particles all want to go out
but the magnetic field bends them around
in a circle and they come back to where
they started
let's go back to my presentation
how do we make antihydrogen
well
once we've got the particles in the trap
like this
we somehow have to mix those particles
together
and we can do that basically by
electrostatically tilting the trap
and when it tilts they just run into
each other and when they collide and
overlap like that they're going to make
some anti-hydrogen
at this point i could go into one of my
normal normal seminar modes and start
doing a lot of technology with you and a
lot of physics with you but i think it's
inappropriate for the audience
so at this point i think i'm going to
leave how we actually do this because it
really does get quite technical very
quickly and just cover in the very few
remaining moments a few other issues
from the book
so
oh
actually i'm a little bit early
anti-hydrogen creation has been very
successful
our next step is to actually trap the
anti-hydrogen atoms that we have not
succeed in doing so we can make
antihydrogen but we can't yet get them
to stay within the bottle and that's
really the next step here
and with that
no not quite with that
we're going to use for those of you who
are experts we're going to use a magnet
the antihydrogen magnetic moment to
trapping in a minimum b field and with
that i'd like to talk about some other
issues within the book according to the
book
cern owns an x-33 space plane
i don't know about this um i know that
they have certainly not sent it to san
francisco to pick me up
they are however willing to send the
shuttle to the airport to pick me up
in the book
cern is a beautiful campus
and there is a beautiful building at
cern
this really is a very very nice building
actually not only is this a very pretty
building it's a great architectural pun
because it's built to look like a
cyclotron
everybody see that
this outer thing
here
is this big magnetic coil and this
center cylinder in the center
is this part of the building out there
so it's a great architectural pun
unfortunately it is not representative
of the way the rest of cern looks
cern actually is rather run down
industrial
here for instance is my beautiful
office in a trailer
do they have indoor skydiving at cern
there's a scene in the book in which
they have indoor skydiving
much to my surprise i talked to a friend
of mine today who does parachute jumping
indoor sky driving is real there's a
facility not far from here where you can
go indoor skydiving and i have a movie
oops
come on i have a movie
showing you indoor skydiving just for
fun it's about 10 seconds
anyway the way that works if i could
have the lights back on is there's a
giant fan
which blows people up and you really can
float on that if you know what you're
doing it costs something like a few
hundred dollars for a half hour session
so it's not a cheap hobby
but you could do it um
and a big point of made of this in the
book that the facility to do this exists
at cern how many think people think that
there actually is a facility to do this
at cern
wait
these are my graduate students
they spent a lot of time at cern
but obviously
they've seen a part of cern that sadly i
have not
anyway
um
i'd like to conclude by thanking a whole
bunch of people in particular roberto
over here really helped me a lot with a
lot of these demonstrations
but lots of other people have helped
with
me with this too and i'm going to
conclude by reading you a poem that was
published in the new yorker back in 1956
commemorating the discovery of the
anti-proton
well up beyond the tropostrada there is
a region stark and stellar where on a
streak of anti-mata live dr edward
anti-teller
remote from fusion's origin he lived
unguest and unawares with all his
anti-kitten kin and kept macassars on
his chairs
one morning idling by the sea he spied a
tin of monstrous girth that brought
three letters aec
outstepped a visitor from earth
then shouting gladly over the sands met
two who in their alien ways were like as
lentils
their right hands clasped and the rest
was gamma rays all right it doesn't scan
very well but never mind that
thank you very much for coming i hope
you've learned something about
antimatter