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Language: en
I mean wasn't the Higgs called the god
particle at some point it was by a guy
trying to sell popular science books
yeah yeah but by me I am because when I
was hearing it I thought it would I mean
that would solve a lot of the unify a
lot of our ideas of physics as well as
my notion but maybe you can speak to
that was it as big of a leap is it as a
god particle is it a Jesus particle
which which you know what's the big
contribution of pigs in terms of this
unification power yeah I mean to
understand that I really helps know the
history a little bit so when the what we
call electroweak theory was put together
which is where you unify
electromagnetism with the weak force and
the Higgs is involved in all of that so
that theory which was written in the mid
seventies predicted the existence of
four new particles the w+ boson the w-
boson the Z boson and the Higgs boson so
there were these four particles that
came with the theory that were predicted
by the theory in 1983-84 the W's and the
z particles were discovered at an
accelerator at CERN called the super
proton synchrotron which was a seven
kilometer particle collider so three of
the bits of this theory had already been
found so people are pretty confident
from the 80s that the Higgs must exist
because it was a part of this family of
particles that this theoretical
structure only works if the Higgs is
there so what then happens so you this
question why is the LHC the size it is
yes well actually the tunnel that the
LHC is in was not built for the LHC it
was built for a previous accelerator
called the large electron positron
Collider so that that was bit began
operation in the late 80s early 90s they
basically did that's when they dug the
27 kilometer tunnel they put his
accelerator into it the collider that
fires electrons and anti electrons at
each other electrons and positrons so
the purpose of that machine was well it
was actually to look for the Higgs that
was one of the things it was trying to
do it didn't man I didn't have enough
energy to do it in the end but the main
thing it was it studied the W and the Z
particles at very high precision so it
made loads of these things previously
can you make a few of
and the previous accelerator so you can
study these really really precisely and
by studying their properties you could
really test this electroweak theory that
had been invented in the seventies and
really make sure that it worked so
actually by 1999 when this machine
turned off people knew well ok you never
know until you until you find the thing
but people were really confident this
electroweak theory was right and the the
Higgs almost the Higgs or something very
like the Higgs had to exist because
otherwise the whole thing doesn't work
it'd be really weird if you could
discover and these particles they all
behave exactly just theory tells you
they should but somehow this key piece
of the picture is not there so in a way
it depends how you look at it the
discovery of the Higgs on its own is
it's awfully a huge achievement in many
both experimenting and theoretically on
the other hand it's this it's like
having a jigsaw puzzle where every piece
has been filled in you've this beautiful
image there's one gap and you kind of
know that that piece must be there
something right
so yeah so the discovery in itself
although it's important is not so
interesting it's like a confirmation of
the obvious yes at that point but what
makes it interesting is not that it just
completes a standard model which is a
theory that we've known had the basic
layout offs for 40 years or more now um
it's that the Higgs actually is a is a
unique particle is very different to any
of the other particles understand a
model and it's a theoretically very
troublesome particle there are a lot of
nasty things to do with the Higgs but
also opportunities so that we basically
don't really understand how such an
object can exist in the form that it
does so there are lots of reasons for
thinking that the Higgs must come with a
bunch of other particles or that it's
perhaps made of other things so it's not
a fundamental particle that it's made of
smaller things I can talk about that if
you like a bit that's that's still a
notion so yeah so the Higgs might not be
a fundamental particle that there may be
some in my oh man so that that is an
idea it's not you know it's not been
demonstrated to be true but I mean
there's all of these ideas basically
come from the
that it's a this is this is a problem
motivated a lot of development in
physics in the last 30 years or so and
there's this basic fact that the higgs
field which is this field that's
everywhere in the universe this is the
thing that gives mass to the particles
and the higgs field is different from
ever all the other fields in that let's
say you take the electromagnetic field
which is you know if we actually were to
measure the electric field in this room
we would measure all kinds of stuff
going on because there's light there's
going to be microwaves and radio waves
and stuff but let's say we could go to a
really really remote part of empty space
and shield it and put a big box around
it and then measure the electromagnetic
field in that box the field will be
almost zero apart from some little
quantum fluctuations but basically it
goes to naught the Higgs field has a
value everywhere so it's a bit like the
hole it's like the entire of space has
got this energy stored in the Higgs
field which is not zero it's it's finite
it's got some it's a bit like having the
the temperature of space raised to you
know some background temperature and
it's that energy that gives mass it's
the particles so the reason that
electrons and quarks have mass is
through the interaction with this energy
that's stored in the Higgs field now it
turns out that the precise value of this
energy has has to be very carefully
tuned if you want a universe where
interesting stuff can happen so if you
push the Higgs field down it has a
tendency to collapse to what there's a
tenon if you do you're sort of naive
calculations there are basically two
possible likely configurations for the
Higgs field which is either it's zero
everywhere in which case you have a
universe which is just particles with no
mass that can't form atoms and just fly
by at the speed of light or it explodes
to an enormous value what we call the
Planck scale which is the scale of
quantum gravity and at that point if the
Higgs field was that strong even an
electron will become so massive that it
would collapse into a black hole and
then you have a universe made of black
holes and nothing like us so it seems
that the the strength of the Higgs field
is to achieve the value that we see
requires what we call fine-tuning of the
laws of physics you have to fiddle
around with the other fields in the
standard model and their properties to
get it to this right sort of Goldilocks
value that allows atoms to exist this is
deeply fishy people really dislike this
well yeah I guess what so what would be
a so to two explanations one there's a
God that designed this perfectly and two
is there's an infinite number of
alternate universes and we'll just
happen being the one in which life is
possible
yeah complexity so when you say I mean
life any kind of complexity that's not
either complete chaos or black holes
yeah yeah I mean how does that make you
feel what do you make that has such a
fascinating notion that this perfectly
tuned field that's the same everywhere
yeah is there what do you make of that
yeah well you make of that I mean yeah
you laid out two of the possible
explanations is not some well yeah I
mean well someone yeah some cosmic
creator way yeah let's fix that to be at
the right level that's one possibility I
guess it's not a scientifically testable
one but you know theoretically I guess
it's possible sorry to interrupt but
there could also be not a designer but
couldn't there be just I guess I'm not
sure what that would be but as some kind
of force that that some kind of
mechanism by which this this this kind
of field is enforced in order to create
complexity basic basically forces that
pull the universe forwards an
interesting complexity I mean yeah I
mean those ideas I don't really
subscribe to them as I'm saying it
sounds really stupid no I mean yeah and
there are definitely people to make
those kind of arguments you know there's
ideas that I think it's Lise Mullins
idea one I think that you know universes
are born inside black holes and so
universe is that behave like Darwinian
evolution of the universe where
universes give birth to other universes
and of universes where black holes can
form are more likely to give birth to
more universes so you end up with
universes which have similar laws I mean
I don't know whatever but why I talked
to dr. Lee recently understand this
podcast and he's he's a reminder to me
that the physics
community has like so many interesting
characters yeah it's fascinating yeah
anyway so so me as an experimentalist I
tend to sort of think these are
interesting ideas but they're not really
testable so I tend not to think about
very much
so I mean going back to the science of
this there wasn't that there is an
explanation there was a possible
solution to this problem of the Higgs
which doesn't involve multiverses or
creators fiddling about with the laws of
physics if the most popular solution was
something called supersymmetry
which is a theory which is involves a
new type of symmetry of the universe and
in fact it's one of the last types of
symmetries that is possible to have that
we haven't already seen in nature which
is a symmetry between force particles
and matter particles so what we call
fermions which held before the matter
particles and bosons which are force
particles and if you have supersymmetry
then there is a superpartner for every
particle in the standard model and the
without going to the details the effect
of this basically is that you have a
whole bunch of other fields and these
fields cancel out the effect of the
standard model fields and they stabilize
the Higgs field at a nice sensible value
so in supersymmetry you naturally
without any concurring about with the
constants of nature or anything you get
a Higgs field with a nice value which is
one we see so this is one of the written
and supersymmetry has also got lots of
other things going for it it predicts
the existence of a dark matter particle
which would be great it you know it
potentially in suggests that the the
strong force and the electroweak force
unify high-energy so lots of reasons
people thought this was a productive
idea and when the LHC was just before it
was turned on there was a lot of hype I
guess a lot of an expectation that we
would discover these super partners
because and particularly the main reason
was that if if supersymmetry stabilizes
the higgs field at this nice Goldilocks
value these super particles should have
a mass around the energy that we're
probing at the LHC around the energy of
the Higgs so it was kind of thought you
discovered the Higgs you probably
discover superpartners so once you start
creating ripples in this fixed field you
should be able to see these kinds of
you should be yeah super fields would be
there at the very beginning I said we're
probing the vacuum what I mean is really
that you know okay let's say these super
fields exist the vacuum contains super
fields they're they're these super
symmetric fields if we hit them hard
enough we can make them vibrate we see
super particles come flying out that's
the sort of that's the idea I hope
that's the whole of mine but we haven't
but we haven't so so far at least I mean
we've had now a decade of data taking at
the LHC
no signs of super partners have
supersymmetric particles have been found
in fact no signs of any physics any new
particles beyond the standard model have
been found so supersymmetry is not the
only thing that can do this there are
other theories that involve additional
dimensions of space or potentially
involve the Higgs boson being made of
smaller things being made of other
particles that's an interesting you know
I haven't heard that before that's
really that's an issue but could you
maybe linger on that like what what
could be what could Higgs particle be
made of well so the the oldest I think
the original ideas about this was these
theories called Technicolor which were
basically like an analogy with the
strong force so the idea was the Higgs
boson was a bound state of two very
strongly interacting particles that were
a bit like quarks so like quarks but I
guess higher energy things with a super
strong force so not the strong force but
a new force that was very strong and the
Higgs was a bound state of these these
objects and the Higgs wouldn't principle
if that was right would be the first in
a series of Technicolor particles
Technicolor I think not being a theorist
but it's not it's basically not done
very well particularly since the LHC
found the Higgs that kind of it rules
out you know a lot of these Technicolor
theories but there are other things that
are a bit like Technicolor so there's a
theory called partial composite nurse
which is an idea that some of my
colleagues that Cambridge have worked on
which is a similar sort of idea that the
Higgs is a bound state of some strongly
interacting particles and that the
standard model particles themselves the
more exotic ones like the top quark are
also sort of mixtures of these composite
particles so it's a kind of
extension to the standard model of which
explains this problem with the Higgs
bosons Goldilocks value but also helps
us understand we have we're in a
situation now again a bit like the
periodic table where we have six quarks
six leptons in this kind of you can
range in this nice table and there you
can see these columns where the patterns
repeat and you're good okay maybe
there's something deeper going on here
is that you know and and so this would
potentially be something this partial
composite loss theory could explain sort
of enlarge this picture that allows us
to see the whole symmetrical pattern and
understand what the ingredients why do
we have wind so one of the big questions
in particle physics is why are there
three copies of the matter particles so
in what we call the first generation
which is what we're made of there's the
electron the electron neutrino the up
quark on the down quark they're the most
common matter particles in the universe
but then there are copies of these four
particles in the second and the third
generations so things like muons and top
quarks and other stuff we don't know why
we see these patterns we have no idea
where it comes from so that's another
big question you know can we find out
the deeper order that explains this
particular tape period table of
particles that we see is it possible
that the the deeper order includes like
almost a single entity so like something
that I guess like string theory dreams
about is this is this part is this
essentially the dream is to discover
something simple beautiful unifying yeah
I mean that is the dream and it I think
for some people for a lot of people it
still is the dream so there's a great
book by Steven Weinberg who is one of
the theoretical physicists who was
instrumental in building the standard
model so he came up with some others
with the electroweak theory the theory
that unified electromagnetism and the
weak force and here at this book I think
it was towards the end of the 80s Early
90s called dreams of a final theory
which is a very lovely quite short book
about this idea of a final unifying
theory that brings everything together
and I think you get a sense reading his
book written at the end of 80s and early
90s that there was this feeling that
such a theory was coming
and that was the time when string theory
had been was was very exciting so string
theory there's been this thing called
the superstring revolution and
theoretical physical very excited they
discovered these theoretical objects
these little vibrating loops of string
that in principle not only was a quantum
theory of gravity but could explain all
the particles in the standard model and
bring it all together and you as you say
you have one object the string and you
can pluck it and the way it vibrates
gives you these different notes each of
which is a different particle so it's a
very lovely idea
but the problem is that well there's a
there's a few people discover the
mathematics is very difficult so people
have spent three decades and more trying
to understand string theory and I think
you know if you spoke to most string
theorists they would probably freely
admit that no one really knows what
string theory is yeah I mean there's
been a lot of work but it's not really
understood and the other problem is that
string theory mostly makes predictions
about physics that occurs at energies
far beyond what we will ever be able to
probe in the laboratory yeah probably
ever by the way so sorry they take a
million tangents but is there room for
complete innovation of how to build a
particle collider that could give us an
order of magnitude increase in in the
kind of energies or do we need to keep
just increasing the size of thing I mean
maybe yeah I mean there are ideas but to
give you a sense of the Gulf that has to
be bridged
so the LHC collides particles at an
energy of what we call fourteen terror'
electron volt so that's basically
equivalent of you accelerated a proton
through 14 trillion volts that gets us
to the energies where the Higgs and
these weak particles live there very
massive the the scale where strings
become manifest is something called the
Planck scale which i think is of the
order 10 to the hang on get this right
is 10 to the 18 Giga electron volts so
about 10 to the 15 tera electron volts
so you're talking you know trillions of
times more energy more the Tenno at 10
to the 15 they tend to the fourteenth
larger
it's a very big number so you know we're
not talking just an order of magnitude
increase in energy we're talking
fourteen orders of magnitude energy
increase so to give you a sense of what
that would look like were you to build a
particle accelerator with today's
technology bigger or smaller and then
our solar system as start the size of
the galaxy the galaxy so you need to put
a particle accelerator that circled the
Milky Way to get to the energies where
you would see strings if they exist so
there's a fundamental problem which is
that most of the predictions of the
unified these unified theories of
quantum theories of gravity only make
statements that are testable are
energies that we will not be able to
probe let and barring some unbelievable
you know completely unexpected
technological or scientific breakthrough
which is almost impossible to imagine
you never never say never but it seems
very unlikely yeah I can just see the
news story Elon Musk decides to build a
particle collider the size of our it
would have to be we'd have to get
together with all our galactic neighbors
to pay for it I think you feel like CERN
on on mega steroids
you