well as you know I I'm a semi-tractor
physicist at the moment I'm working on
graphene and graphene transistors and
enjoying that but whenever I have a
holiday or a weekend especially because
a rainy weekend or rainy bank holiday I
tend to start look at reading books
about cosmology I've just been reading
the Proceedings of a bunch of
conferences
well we think about our universe as
consisting of our planet of course going
around the solar system the solar system
being centered on the Sun and the Sun
being a fairly modest star in our galaxy
and the galaxy can contain something
like about if I remember correctly
something like nearly a hundred billion
stars we see that as the Milky Way of
course and then the night sky if we know
where to look and I've got a sharp eyes
and the sky is dark we can see the
another galaxy like ours that's the
Andromeda galaxy and in fact the
Andromeda galaxy and our galaxy which
you call the Milky Way are parts of our
group of galaxies our local Group of
galaxies and then if we look further out
with big telescopes we can see more and
more distant galaxies 30 bottom half and
he'll scooter and arrow 31 that is
scooter okay
going back to when the universe was much
much younger because of course it takes
time for light to get from those very
distant galaxies to us and so we're
seeing our universe at a much earlier
stage but there are ideas with the this
idea of that the universe is now
expanding due to the presence of the
dark energy or if you want to call it
the cosmological constant that that was
Einstein's biggest blunder and I think
we've done some stuff on that already in
60 symbols and so on
the idea of this space expanding and in
particular the very rapid expansion of
space inflation in at the very very
early stages of our universe this idea
of inflation has led to the idea that
other inflation's can happen beyond our
own observable universe so we got other
universes blowing up and there may be an
infinite number of these and they may be
quite different from the universe in
which we live and that means different
in the sense that wealth at extreme
example they may or may not contain
electrons and protons though that's very
hard to imagine maybe they would just
contain dark matter which is very
mysterious to us we have it in our
universe but we don't really know what
it is it's not like it's not protons or
electrons that's for sure
so we got that dark matter you could
imagine universities made after dark
matter or maybe just made out of black
holes which where all the matters could
kind of be compactified and doesn't
really exist as electrons anymore so
that would be a strange universe to us
so cosmologists are suggesting we are
only one of a large and possibly an
infinite number of other universes and
that whole subset is sometimes called
the multiverse though of course the
universe should contain everything but
they yeah yeah but universe but the
multiverse a very clever name that there
are lots of universities out there and
probably at least with you know with our
present understanding of physics and
without experimental techniques like
telescopes we have no possibility at all
of ever knowing anything about these
universes so people then argue hard-core
physicists would then argue I think that
well look if we can ever chance them and
they're outside science because we can't
do any experiments with them but of
course you can't really do very many
experiments with pretty much all of our
universe we can only observe it but we
observing it is sufficient for us to get
information about it so the most recent
discovery being the discovery of dark
energy which is causing the universe
apparently to expand at an
ever-increasing rate
there's a wonderful chapter in the book
I mentioned by Martin Rees where he
describes what he calls in a version
therapy that if you're afraid of big
tarantulas then you start off putting a
little spider right hand and then a
bigger one eventually you know you might
be able to put up with a tarantula on
your hand something like that and but I
think he's quite enamored with the idea
of multiverses in fact I guess he's one
of the big proponents of it and his idea
is that it's quite a valid point that he
makes is that at the time of gala before
Galileo we had a much more restricted
view of the universe before him we you
know there was a whole period for a
couple of thousand years that we thought
that the earth was the center of the
universe and then experimental
observational astronomy started and
people took a more enlightened view and
we had a heliocentric view of the
universe people like Kepler and so on
and Newton built on that but even so at
that period even until large telescopes
were were made when we were no idea of
what galaxies were so we were very much
restricted to something perhaps a bit
bigger than the solar system the solar
system or the nearby stars but
eventually we realized there were other
galaxies beyond us but of course I
already mentioned the point that if we
have with our biggest telescopes we are
we are we simply we're probably if we
make telescopes a bit bigger we'd be
able to probe further back in time
towards nearer to the Big Bang and see
more distant galaxies they're just too
far away at the moment because they too
dim for us to see properly so we could
imagine at the moment that we are
limited we simply can't see those
galaxies because they too dim but they
still exist and they consistent with the
model that we've developed now but of
course at the present time
even if we could suddenly spend tens of
billions of pound by rather wasting and
all these other stupid projects like
wind pop wind turbines for example maybe
I ought to invest it in in big
telescopes and then we could probe probe
deeper but even then even with bigger
telescopes there would be parts of our
universe that we could not observe but
simply because not enough time has
elapsed for the light to travel from
those distant and unobservable galaxies
to reach us by the present time
but if we wait for another 50 years we
will see a few more wait another hundred
years so and again those are part those
are subjects of physics and it's
perfectly reasonable so this is Reese's
idea that you can use this aversion
therapy and probe deeper and deeper and
even think about things you haven't seen
yet well that you know that's that's
probably right but but we could we could
ask questions about you because we know
something about the creation of our
universe we think we understand that
pretty well now there's a big bang and
we have we had inflation and then
gravity started slowing everything down
and then we realized that the
cosmological constant is there as well
it was nice things biggest blunder after
all he introduced it and then you decide
you didn't want it but now it does look
as if there's that battle something like
it is causing the accelerated expansion
in the universe you always seem to me
like quite a practical scientist you
like you like experiments you like the
hands-on stuff you like evidence why do
these multiverses capture your
imagination so much when these things
that no there's no experiment well I
think if people have been watching these
probes they they know about my obsession
with the fine-structure constant which
is one of the fundamental constants of
nature and of course the fine-structure
constant shall I write it down this is
equal to the square of the charge of the
electron over four PI epsilon naught
this is this bit is pretty boring and I
could combine it with that so I'll just
put that on brackets but it should be
there in the SI units that we employ and
then we got Planck's constant and then
we've got C in the denominator and the
value of this as we know is 137 point O
3 5 9 9 and then I can't remember it
doesn't go on the nines forever but
something like that but to a good
approximation is 1 over 137 that
fine-structure constant is telling us
the ratio between the strength of the
electronic charge and Planck's constant
the other interesting constant who take
the mass of the proton and divide that
by the mass of the electron that gives
me another constant which is 1836 point
1 5 I think dot dot so that's very
important now both of these constants
the vatic up to have chemistry as well
standard in biochemistry and maybe in
life as we understand it
the values of those constants are quite
important now there are some other
constants of course that are very
important as well there's gravity now
it's not the gravity on the surface of
the earth which is just 9.8 times 9.8
meters per second per second it's big G
or Newton's constant which is much more
general in which we can apply not just
gravity on the earth but you know the
gravitational pull between the between
the earth and the moon and and the pole
of the Sun on the earth so big G's
another very important constant and
there are a bunch of other constants and
in the fine-structure constant is the is
the constant relating to electrical
charges electromagnetism but there are
other forces in nature like the weak
interaction so the weak fine-structure
constant as well the weak interaction
fine-structure constant and the things
that hold the strong forces that hold
nuclei together and the quarks and the
gluons and so on things that make the
protons we got the strong force as well
so we've got in addition to that we got
out for week we've got alphas strong
interaction and there are various other
things that parameters that we have to
put into the standard model of particle
physics and then the other one I'd like
to write down so if we look at all of
these the other one is the cosmological
constant which is self is very
interesting and that is the thing that
the astronomers have discovered by
looking at the supernova in very distant
galaxies they from this they deduce that
the universe is beginning to expand away
and getting blackboard more rapidly
expanding as well because this thing
will eventually overpower the
gravitational attraction that's this
that's been tending to hold back the
universe since the time of the Big Bang
so we got a whole suite of constants now
I haven't written them all down but
there's the the the electrical
fine-structure constant let me put an e
on that electromagnet I should put
electromagnetism fine-structure constant
so that's the electromagnetic
fine-structure constant which by the way
it does change with energy and length
scale that's just this low energy value
we've got the proton to electron mass
ratio we've got big G Newton's constant
which determines the strength of gravity
and we've got the cosmological constant
and we've got these other constants for
the strong weak interaction another
parameter
in standing so we got all these and we
know them and and you can you can look
up a standards textbook and look up
their values and there they are you know
universe no of course the fascinating
idea about but the multi-is
well-fastened video I personally the
idea in our universe is why do the
constants have the value values that we
have they have and we don't have we
don't really have a theory for that I
mean we can work out that the proton
electron mass ratio by putting in the
parameters in the standard model but
we've at inferred you know those
parameters a bit if you like that we
just have to deduce them from
measurement most importantly they are
very very important for the existence of
a lot of life for the existence of rocky
planets and stars and so on they've got
our values which are quite critical to
that and then for the synthesis of
larger nuclei atomic nuclei in stars
they're important for that and even the
synthesis of heavy elements in the in
the Big Bang important that it's all
these things like they really determined
that the universe in which we live so
then you can ask the question that if
there are other universes out there are
those values constant and according to
string theory which I don't ask me there
we got string expert here you can go and
talk about but according to string
theory those constants could be
different in a different Big Bang
scenario in another universe and as far
as I can tell what I've read it's
perfectly possible that some of these
particles that we are really important
to us might not even exist in another
universe
there's another there's also very
interesting about the cosmological
consequently which is fascinating we've
only known it's there really for the
last experimentally for the last decade
and some smart theoreticians were
talking about it of course Einstein
dreamt it up but we didn't really know
how big or how small it was and he turns
out of course to be worryingly extremely
worryingly small because if you do a
back-of-the-envelope calculation and
work out what the energy of the vacuum
is this pressure that's pushing the
university and even if it's the
university apart a unit if we sorry I
always say University because if we do a
back-of-the-envelope calculation to
estimate what the strength of the
cosmological constant or perhaps I
should say more strictly the dark energy
which is kind of equivalent to it
the back-of-the-envelope calculation
gives us an answer that's the biggest
miscalculation in all of science because
it's not out by a factor of ten or a
factor of a hundred or a thousand which
is ten to the third or ten thousand
which is ten to the fourth that back the
envelope calculation is out by a factor
of 10 to the power 122 value smaller
values may be 10 to the 60 by you doing
slightly different theories but
basically we do not know why it has the
value that it has because of the present
time is actually fairly close to the
density all the rest of the stuff
ordinary matter like us and the dark
matter but it's also just about the
value that it has is just about big
enough for us to observe it at the
present time using our present
technology and that seems to you know
seems so kind of why is it so small and
it's rather strange it's got the value
that it has for us to observe right now
but there we are so nobody really knows
why it has the value it has which brings
me back to the multiverse because in
other universe is within this multiverse
the cosmological constant or the dark
energy could be much bigger so the
universe will rip apart even before
galaxies have time to form even before
stars of time to form so no stars no
planets no galaxies would be no us and
you know that would be a universe which
we would find very hard to think of in
terms of life existing so that's an
interesting
thing that could could be different and
if the fine-structure constant or the
proton electron mass ratio were
different then you know we we wouldn't
have a kind of universe that we've got
if the strong interaction would be too
strong you'd have die protons falling
for example rather than having the types
of atomic nuclei that we have in our
universe so there are lots of
interesting questions why are the
constants so why are the fundamental
constants down at the microscopic level
of fundamental particles down to the
smallest length scales that we can
measure going right up to the strength
of the gravitational constant and the
and the cosmological constant those
could be different and we have no idea
why they have the values they have a
present our universe I can understand
why you have this fascination with these
constants as they apply in our universe
but again a pragmatist like you knowing
that almost by definition we will never
get to observe these multiverses these
other these other ones it just seems
like a philosophical debate hmm I wonder
what it would be like if they have
different numbers and we'll never know
we never see it's almost like just like
it's just like dreaming to me that
doesn't seem your style but I think all
all all physicists have the idea that
there is out there a theory of
everything that if we try harder we may
be well I be I'm not sure this the
multiverse annoyed probably argues this
is not the case but I think a lot of us
part of us these these sort of
hard-headed rationalist reductionist
physicists would would would like to
think that we can get we can understand
better why some of these constants have
the value that they have or at least
that understand more clearly they're all
linked together and in particular
perhaps understand how we can combine
the the strong and the weak and the
electromagnetic interaction with gravity
I mean that's one of the big challenges
of physics physics to get a good theory
of quantum gravity and to see how all
these forces come together and maybe
even see how they link to the
cosmological constant or the dark energy
so I I suppose asking these questions
about
they have the values they have is this
idea reductionism that we can get a much
more thorough idea of how the universe
works and why the constants of the
values that they have but at the same
time thinking about this constants makes
me and knowing that there are these
string models which are addressing these
problems these string modelers are
predicting that other universes could be
could exist we could be we could have
these inflation and inflationary
cosmology that these universes can just
inflate out of vacuum fluctuations I
guess makes us think about other
possible values the of the of the
fundamental constant and of course that
these anti so-called like anthropic
principle as well comes in that why the
universe has the constants that so I
suppose the multiverse I mean there's an
interesting controversy here does them
does mean I'd like to think that the
multiverse if is it sort of removes God
which I'd quite happy to push him in as
much of the way I hate the idea of
metaphysics coming into physics so I'm
rather attracted in multiverse scenario
because it pushes those two things
further apart but I believe there are
people who think I mean there are
philosophers for example who believe
that the multiverse would actually be
some argument for some huge supernatural
being I don't know why they think this
maybe they think that if he's so
supernatural he's gotta have lots of
universes to work with rather you know
it's not enough to do in this universe
though goodness knows it seems if it was
somebody useful around to sort of all
the problems we've got that might be a
good thing so I I don't like metaphysics
at all so I multiverses attract me for
that reason as well I suppose short of
conferences and people writing papers
and talking about it what's next then
what is the holy grail or what's the
what's the big thing that will take the
multiverses to the next well I I don't
really know I mean the observational
problem is serious I mean the string
theory and super strings have been
around for twenty years there are some
really interesting text books by
practitioners you know people who really
know that what they talk about not
amateurs like me in this field who you
know who
is skeptical about all the effort that's
gone into string theory because it
hasn't produced anything tangible there
are so many possible solutions that you
can get out of string theory that that
may not provide the answers that we want
it's a matter of opinion right my
personal opinion is that that the
reality of things requires there to be
some tests that somebody could do in
order to actually show that there isn't
that this thing you've hypothesized
actually has some consequences for other
things but they were precisely the same
then they diverged when this quantum
event occurred so there's sort of all
sorts of universes sitting on top of
each other and they're splitting apart
in differentiating as time goes on