Thank you very much for that introduction.
It is a great pleasure to be here and continue
perhaps where Bernard left off this morning.
I am going to overlap a little bit with some
of things he has said but I think that will
be alright.
So I am going to talk about cosmology and
in particular I am going to talk about the
first force arguments. But we will first of
all we will have to just skip a bit through
the history of how things developed. So here,
as you saw, is a picture of the medieval universe
which is based on the ideas of Ptolemy in the
Roman world. The earth was at the centre with
concentric spheres revolving around that and
on the outside there was a sphere that enclosed
the stars and beyond all that there was the
celestial sphere and that was the dwelling
place of god. And it was a finite system and
everything was very well in its place. Now
Newton, skipping a lot of time, had very different
ideas. He said the universe must be infinite
and his reasons were as much theological as
anything else. He thought that god has to
fill the universe and god is infinite so you
have an infinite universe. He felt that matter
is in principle spread out everywhere but
then it clumps together to form stars and
planets which is not so very different from
the point of view that has been developed
over the years since then. And, one might
as well add, that Aristotle denied that physically
infinite things could exist. So Newton and
Aristotle are certainly in disagreement on
that issue.
So during the 19th and early 20th centuries
it became recognised that the earth is very
old. Now this is the earth to start off with,
Geology was the key science, people looked
at layers of rock and decided that you just
had to have a very old earth; people debated
about this. But never the less other scientist
thought the universe was still infinitely
old and just came about at some time, and
this was discussed a little bit this morning,
and it became recognised that nebulae were
galaxies just like ours. I won’t talk about
the ‘steady-state universe’, this was
proposed in the 1950s by people who did not
really like the idea that anything changed
time overall. It was based on a philosophical
principle that thing were always the same
and it was a philosophical assumption.
Well, there are two particularly important
developments in cosmology in the 20th century.
And one has been referred to in passing; Einstein’s
theory of general relativity. Now for those of you
who are not physicists this is a theory of
space and time and it relates the properties
of space and time. So space and time have
properties and it relates these to the density
of matter, energy and momentum anywhere in
space; which are the sources of what Einstein
developed as a curvature theory of space and
time. So you can have a universe that is sort
of curved around on itself but it does not
have to be. Now at the same time Hubble, who you heard about
this morning, analysed data concerning how
fast galaxies and stars were moving from us,
mainly galaxies, and he found that the further
away a galaxy was the faster it was moving
away from us. So this he put together as a
constant, though it is not necessarily constant,
it is now called a Hubble parameter; and that
tells you the rate of expansion of the universe.
How fast it is expanding, if you look at things
that are a particular distance away. And after
that in the 1960s, as you saw, there was the
discovery of the Cosmic Microwave Background.
Now this is another picture of the expanding
universe. Because if the universe is expanding
you can do some calculations. You find out that it looks as if
at some point, it looks like in a finite distance
in the past it was all at one very small point
or something like that. And after that everything
has just been getting bigger and bigger and
bigger. So this point where it all started
is referred to as the Big Bang and it is basically
space that has been expanding as the years
have gone by. This is a picture of a finite
spherical universe. We don’t know whether
the universe is finite or infinite, we maybe
never will know whether the universe we live
in is if it is finite or infinite but as far
as this pictorial representation is concerned
we are just thinking of it for convenience
as something that might be finite. And it
is the space itself that I expanding, it is
not really true that a galaxy many light years
away is moving away from us particularly.
It is just the space between us and it is
getting bigger all the time. And what we now
think of a cosmic microwave background, this
is very low energy radiation, at the beginning
of the universe it was very high energy radiation
because energies were higher then and all
the distances were smaller, wavelengths were
smaller and this was a very hot period in
the universe.
Here is a cartoon. Einstein in 1929 began
to convince himself that people were understanding
his theory, he said: ‘People slowly accustomed
themselves to the idea that the physical states
of space itself were the final physical reality’.
Here is some people in New York getting, accustoming
themselves to that idea, and since then quantum
fields have been introduced and I think they
would have been even more puzzled if they
had had to get that as well. Now here is the
history of the universe in one slide, the
big bang followed by everything else. I am
going to take you through this, briefly, so
that you can understand the picture that is
being presented. So start off at the start
of the universe, a big question there, we will talk about that later,
but this is something that people argue about
quite a lot, we don’t really know what has
happened. Then immediately after that it is
supposed that a process called inflation started.
This suddenly means that because of quantum
fields in the universe, the universe started
to expand very, very quickly and then it stopped
when it was a certain size. So this is like
10-35 seconds after the start of it is, that
is a pretty short time but that is what was
worked out, then it stops. Now at this point
I have to say there are arguments about inflation,
not everybody accepts it, there are good reasons
to believe in it but also the theory has not
yet been fully made to work to everybody’s
satisfaction. There is a fellow called Paul
Steinhart in Princeton who is very sceptical
and he has made his view clear that 
the theory, he thinks, has not yet been brought to a proper
mathematical state, it’s a bit out of control.
Anyway just take a note that this is commonly believed
and maybe true but there is still work to
be done. And it stops when the universe we can
observe is ten meters in diameter, so it would fit in this room. Then particles:
quarks, gluons and various things start to
form. This is not fully understood but that
is when the matter that we know about begins to form and after
that, after three seconds, all the protons
are now formed so it is believed, and they can
stay as protons, they can become neutrons
and they can form matter. Now, it is
believed that this is really the main source
of protons in the universe. Now in our bodies
there are lots of protons, they make up water
for example, H20, so the protons that we are largely
made of probably date from three seconds after
the start of the universe. Then after 400,000
years we have got stable light atoms, now
before then photons were bouncing around all
over the place but after that the photons
stop being absorbed and bouncing around they
sort of propagated through space. And it is
these high energy photons which have lost
their wavelength as the universe expanded
and now  are looked at as microwaves. That
is how much the universe has expanded since
those early days when everything was very
hot. 400 million years, quite a skip forward,
hot heavy stars form. Now these first stars
are very important because they went through
their hydrogen fuel very quickly and then
they exploded but in that process a lot of
nuclear reactions occurred and these nuclear
reactions generated heavier elements and I mean 
heavier than let us
say Lithium. So carbon, oxygen all the elements
that we are made of got formed by these heavy
stars in the main at this rather early stage.
And the universe became full of debris from
these exploding first generation stars.
Then 1000 million years things start to condense
into galaxies, the sort of picture that Newton
was trying to portray, but he did not know
about galaxies. We can observe back to this
point except that the cosmic microwave background we
can observe back further. So that is why the
cosmic microwave background is so important;
it gets us back further than we can observe
with our telescopes – even radio telescopes.
Many millions of years, we get more and more
happening; smaller stars, planets, heavier
elements, planets like the earth and so on.
8.7 billion years, I’m sorry about the structure
there, our solar system forms so we work it
out and finally we are here today.
So that is the history of the universe in
a nutshell and that is what you need to have
in mind for what I am going to be discussing
next. So having got that picture we are going
to have a bit more of a theological discussion
and I am going to introduce you to what is
commonly called the Kalam argument for the
existence of god. It is Islamic and it means
the scholar's argument and it dates from the
period I have indicated, 9th to 11th centuries
AD. The simplest form says that anything that
comes into being must have a cause and the
universe has come into being so it must have a cause
and this we may naturally identify as god.
So that is the simple form of the argument
and you can generalise it a bit more you can
say, well causes are a very important general
thing, the state of any physical system surely
needs to have a cause and you may need to
use a more general form of the argument at
some point but that is the basic argument
and it means that you do have to believe in
causes. This is something that our fist speaker
stressed as a very important part of the way
we think and the way indeed that we operate
science. Now this, not surprisingly, has been
contested, not everybody likes this conclusion
but amazingly I think it can be said but most
people agree that the basic big bang has a
cause. The argument is in fact accepted but
what should be the cause? If you do not like
the idea of god causing the big bang, our
universe, then you have got to have a physical
system that existed before that, prior existence
for the physical system. And so the question
is could this go back indefinitely? If it
could go back indefinitely in time you might
be able to say there never was any point where
you could talk about a first cause and you
could try and avoid thinking about a creator.
Now this is an argument that is widely acknowledged
as having some weight. Stephen Hawking, who
is not particularly sympathetic towards normal
Christian belief or any other as far as I
know, says: ‘ A point of creation would
be a place where science broke down. One would
have to appeal to religion and to the hand
of God’. This is not something that he is
particularly keen on.
Now what I am going to have to do to consider
this in more detail is take you through what
I believe are the most important ideas that
have been put out by cosmologists in recent
years concerning the possible pre-existence
of the universe, which I will try to refer
to as a cosmos. So as we said this morning
lets think of the Big Bang structure as a
universe and something more general as the
cosmos. This will get a little bit technical
but this does get into the popular scientific
press. You will certainly read about yet another
idea that somebody has had that might get around
the first cause argument I will try and give
you a non-mathematical outline of what the
cosmologist have been saying in recent years.
First of all, two things to mention; there
is a theorem and it is call the Borde-Guth-Vilenkin
theorem which dates from 2003, so that is
relatively recent, a fairly recent development.
And it basically says if things have always
be expanding there must have been a beginning
even if your cosmos is more complicated than
a simple universe. They do a mathematical
calculation that if the Hubble parameter, averaged
over all past times is positive, in other
words, things have always expanded, then the
cosmos must have had a beginning. Nobody has
really got around this. It is to do with the
speed of light. Now there are thermodynamic
issues which I will not say any more about
but it is difficult to have an infinitely
long expanding universe with things happening
all the time without having the universe
just run down and look featureless. There are
problems with an infinite age to an infinite
universe says Aron Wall. An infinite number
of causal event in a finite universe but to
digest this properly you have to digest his
paper which I must say I haven’t yet fully
done.
Now, what are the options? Well, we have just
mentioned a simple Big Bang, we don’t ask
what happened before, nothing happened before,
well in that case the Kalam argument would
presumably apply. If you believe in a general
principle of causation something other than
physics must have caused it and you may naturally
say this was a creator of some kind; god presumably.
But people have argued that perhaps the universe
oscillates. In other words, it gets bigger until it reaches
a maximum size and then it contracts down again, that
is called a big crunch, it keeps ongoing like
that indefinitely, it has been doing this indefinitely.
So no beginning to anything it
is just the way things are. Now this has been
analysed in more detail and it has been found
that you can’t really set up easily a stable
set of oscillations which keep ongoing in
exactly the same way. Two things happen: one
is that the universe eventually goes into
permanent expansion. Well, our universe, it
looks as if it it's expanding permanently this
is again a modern development, people have
analysed the properties of galaxies and supernovae and things like that
and we now believe that our universe will
expand forever. So if it were an oscillating
universe that means we are in the first phase
when this is happening. What amazing luck,
that is pretty probable and there is no particular
reason for this so that makes you suspect
that this just isn’t the right model. And
on top of that, you find that if you trace it back in time,
these oscillations get faster and faster and
it actually had to have had a beginning. This will not
get us off the hook and it is probably not
the right model anyway.
Now, let’s talk about something which certainly
remains a popular idea, so called ‘eternal
inflation’. Now the idea is that this inflation
process is in fact the basic thing that is happening
everywhere in the cosmos. There is a field
which makes everything expand violently but
every now and then there is a sort of pop
and a sort of normal universe materialises; these
are called island universes or pocket universes.
Within this, ordinary space like our own
occurs and our own universe is one of these. There are lots of them. How many is a good question, but the idea
of this doesn't determine this necessarily.
Now, the thing is that the BGV theorem which
I mentioned actually implies that this must
have had a beginning, you know, violent expansion it
must have started, so whether or not you believe
in a multiverse or this kind of eternal inflation
scenario it looks as if the mathematics implies
that it started at some point in time. Now
the opposite extreme is to suppose that somehow
or other the universe had an eternally uneventful past,
it was just sort of sitting there for an indefinite amount of time and then it decided to expand and you can
put flesh on the bones of that argument. Now, people look at this and there are problems there too. It's
very difficult, it seems, to make this sort of model give you a stable universe, I mean something that
was stable for an infinite amount of time,
that's a long time to be stable. So if there's
any kind of instability at all that will
happen; it could contract to a point and collapse
or it could have already done something like expand, why should it have waited for an infinite amount of time
before doing something now? So these ideas, there is a general feeling, as far as I am aware, that
it is very difficult to make them really work.
Now Hawking and Hartle produced a famous model
and that's mentioned in Hawking’s first book
so we have to, at least, consider what he is saying.
Now, he says that it's not true that as
you go back to the very beginning in time
there was a point where things were infinite,
that's a so-called singularity. He says
at some time very close to that, before then
it was different, there wasn't any real time
before then, it was something he called imaginary
time. This is a mathematical construction,
imaginary time looks rather like space
but his idea was to sort of round off the start of
the universe so that it was all very tidy and mathematically well defined. But if you really ask what's
going on there, and it's a very ad
hoc assumption, I don’t know that there's
any real reason for believing this other
than mathematical tidiness. You still have
to ask, well causation can only occur in real time,
the imaginary time presumably isn’t like
time it can’t have causes in it, it's just a structure,
so what caused all that to be? That too you
have to ask, surely it needed a cause and so
you still ask the same question as before.
Now, I've put as the sixth suggestion "Everything emerges from a quantum object." That is a completely
general idea because nobody really knows what the quantum object would be, but since we believe in
quantum things and we don't yet know how to quantise gravity, it's quite a plausible notion even though it's
not exactly a theory at present. Indeed,
maybe that's exactly what happened. We still
then need to ask what is the cause of the
quantum object, so again you have the same
question as before.
Now let’s go to a book which came out
by Lawrence Krauss, who is well known for
being sort of antireligious, ‘ A universe from nothing’.
Now most of his book is a description of the
big bang and physics and cosmology and it's
very good he explains these things pretty
clearly and, finally at the end he comes to
why, I think,  he really wanted to write the book. Because he thinks that you could have a universe,
as he puts it, from nothing, not even a question
mark. Now it's not very clear what he's
really proposing but he seems to be saying
that quantum fields can fluctuate into a proto-universe
and then it all takes off and you get a big
bang. If that's what he's saying it's not
nothing, it's clearly something. You need
to have some sort of prior existing space
of some sort, you need to have your quantum fields.
So he has rather misled people. But he seems to
be implying that it is really is really nothing. Now
of course if you really wanted to say that
the universe appeared from absolutely nothing,
you can’t reify nothing, it's just not
there. All you could say is that the universe
hasn’t had a start at some point. That's
what a real philosophical nothing is: that there
just wasn’t anything there before. You
can’t come from nothing because it's not there
to emerge from. So one has to be quite clear
here that if somebody really is saying that the universe
came actually from really nothing, they're
just saying that it had a start in time, that's all
they're saying, there's nothing more that
they can say. It could be that the medieval
philosophers expressed themselves a little
bit badly here because the phrase ex nihilo exists
in classical descriptions of creation. What
it really means is that there wasn’t any
prior existence of material that god created the
universe out of, it just started. But that's by the by. So we haven’t yet found a
way of really making the infinite past history of
the universe idea work and that does appear to
be the current state of thinking on the whole.
I could make a few more comments here now general
relativity is a very flexible mathematical theory
and, I mean we believe in it. It's been tested in various
ways, not completely tested out but as far
as we can tell – all the tests that have been
done – general relativity is probably true with a, you know, it might turn out not to be but it looks to be okay
right now. And it allows you to stretch time, if you want to, or space, you just have a different set of
equations. The usual idea is that you choose whatever space and time description will simplify
you argument and your calculations. So they do this all the time, they say "I'll go to a different frame of
coordinates because this makes that calculation easier or less difficult." Now, so if you really did
have an infinite amount of time going back
into the past, as far as general relativity
is concerned you could just transform that away so that an infinite amount of time became mathematically
transformed into a finite amount of time. Now this is a tricky thing to argue perhaps but it may well be
that it's very difficult to talk about an
infinite past time in a hard and dried way anyway
because you could always re-phrase it as it
were. And then of course there's the old
question of whether it's legitimate to talk
about a physical infinity. Now this is a very, very tricky
point which people have always argued about
but you should remember that mathematics and
physics are not the same thing. In mathematics
you can formulate ideas any way you like
you can say "Well I'll start off with a finite physical
system and I'll just see what happens if it gets
infinitely big." You can do all that mathematically
and the mathematics of infinities has all been
worked out to people’s satisfaction. Whether
you can actually start off with something infinite,
and say that’s the physics, is to say the least
debateable. It may be possible, it may not.
But there is a question there. And what this
really means, I think, is this that if somebody
just sits down in an armchair and says "Oh
it could be infinite", they ought to be
challenged. Infinities are not to be played
around with loosely. You've got to be able
to justify whether the kind of infinity that you're proposing is mathematically sensible and whether it's
physically sensible. If you don't do that
then you haven't really said anything concrete.
So all of this in practice is, as I say,
difficult to deal with unless you're prepared
to think very carefully about a particular
proposal. So general statements: "Oh it
could have been infinite"; are not really
legitimate these days.
So this takes us through what I believe are
the main cosmological theories. There are
some more, for example, there's an idea that the universe might have contracted down to a small point
and then expanded again but time went backwards when it was contracting which is another way of saying
you have two universes both expanding but joined together. You have the same problem again, what
happened to cause the event where, at the point where, these two universes emerged from. So it does appear,
as I say, the Kalam argument holds right now, and
therefore if you believe in a strong principle
of causation an extra physical first cause is implied
because we've dealt with the physical possibilities that
we can think of.
Now, yes, a word of caution from Leon Lederman,
author of ‘The God Particle’ book. So
you can read that, that's his opinion and
I think it's probably an opinion that quite a
lot of people would have if they're not cosmologists.
That we are not in the realm of experimental
science, really. There have been some sort
of ideas that you could try to test it; at
present we don't really know how to test
any of these ideas.
So there is an issue here whether this is
philospohy or science. It might turn into science once
you can propose some good experimental tests.
And I think one should also say that the Kalam
argument is largely directed towards physical
materialists who might not wish to believe
in non-physical causes. Now if you have religious
faith, you’ll believe that god is there
and there's a perfectly good way of thinking
which says that causes everything all the time. I’m not arguing against that, of course the
beginning of time is part of time so you're
not excluding any other theological points
of view by pointing out that it looks as if
the purely physical picture isn’t sufficient
in itself. And I have not said anything against
what you might call spiritual causes if you
believe, for example, that god is able to, you know, interact with people and do things from the heavenly
realms that has nothing to do with what I've been talking about. It's something
that you are perfectly allowed to believe
in if this is part of the faith you have.
So that's again not something to do with this particular argument and if you want to read
what I've said in more detail at length,
last year I published a longer version of
this in the journal Science and Christian
Belief and you can turn to that and read it
at your leisure. But since I've got a few minutes
left I think I'll go on to talk about a few
more things. Well, first of all, final comments about this.
I have said nothing about the nature of the physical
laws and constants. This was alluded to by Bernard
and I'll say a little bit more about this
in a few minutes. So although I've said
here another talk to deal with the subject
in detail I will just reiterate some of the
things that Bernard said this morning.
Now there's always a general caveat,
the science can always change. People have
had these ideas about cosmology which I've
outlined. It could be that next year someone
will have a really brilliant creative, new idea
which will change the situation. You can’t
say that this won’t happen. So this is how
it is right now, this is the state of the
argument. And you must believe in causation,
I've stressed that, so although you can believe in God without believing in a first cause, because even if
the universe were infinite in time, you would still have, could very well ask ‘Why is it here at all?’.
And you can say there should be a general reason
for even an infinite universe to exist and some
sort of creative being is clearly something
to bring onto the table at this point and
say that you believe in God who can create
anything with any structure. I've not, of
course, been able to say anything about the
nature of the first cause from this argument.
You can’t say from the Kalam argument that
there must have been a personal god; it could
have been a deistic god, whatever. In fact
some of the sceptics might well, if you
drove them into the corner, say ‘Well, you know, perhaps there is a distant deistic god’; but their thing
then would be not really wanting to believe
in a personal god.
So now since I was originally asked to say something about multiple universes, I'll spend a few minutes doing
that. But let’s just go through again about
why, one reason why one might want to believe
in this. As Bernard said, you've got to form
a universe for human life because we're here
and that means that it must've been possible for
us to be here and so you ask, "What's on
the shopping list? What would you have to
have to make a universe which is suitable for beings
such as ourselves?" And three space dimensions
are important, if you have more than three
space dimensions than gravitational orbits
of planets around stars won't be stable.
This can be worked out, you can do the calculations in multiple dimensions. Three space dimensions
give stable planets and that seems to be
a good idea so I suppose if you believe
in string theory there may very well be some structures out there with seven space dimensions,
I’m not saying I believe this, but there
could be, but they would not form planets
the way that we have a planet. You have the
various nuclear forces: electromagnetic force,
weak force, gravity. And here is a picture
of all these elementary particles; they also
have anti-particles. I won’t go through
all this. Quarks. It's the up and the
down of the U and the D quarks that make up
matter that is stable, the rest are unstable.
You have to make them in elementary particle accelerators and spot them by what happens as
they quickly decay into other things. But we
have reconstructed this picture by looking
at all sorts of different interactions that
can take place in particle accelerators and
this is what comes off. And the blue symbols on
the right: the gamma is a photon, the g is a
Gluon – that's the strong force, the z and w convey
the weak force. The weak force is responsible,
for example, for radioactive decays of a lot of elements. So uranium takes a long time to decay, well perhaps that's
not a very good example, let’s say carbon
14 takes a long time to decay because it's
the weak force that does this. But it can
act quite quickly but it's not as strong as
the others. And the Higgs particle is a
final piece of the mathematical jigsaw. Now
this, I hope you will be prepared to believe
me, is a mathematically complex and subtle scheme;
this is why it took so long for people to
work it out. I mean it's a very cleverly
ingeniously set up system that enables all
this to happen.
And here is a lot more requirements for a
universe, for human life, some of which
you saw this morning. You must have more matter than antimatter, that probably means that you've got to have
more than just two quarks when you work
it out. The others give you more flexibility
in the forces to generate an asymmetry between
matter and antimatter. The universe must be
long-lived which puts various constraints
on the parameters of the universe, you've
got to have it something like, well let’s say 10 billion years 14, whatever we are occupying
it's got to be that order of magnitude, one
billion years probably wouldn't be enough.
You've got to form galaxies, you've got
to form hydrogen but the right amount of hydrogen.
If everything was hydrogen nothing would
work very well. But if nothing was hydrogen
it wouldn't work either. You've got to
have a suitable amount of helium because the
heavy elements get formed out of helium. All that has got to be got right in the early
stages of the universe, I could put numbers
in here but we don't have time today. You've
got to form heavier elements and stars.
Now that's a tricky one, it's not so easy
as you might think to get exactly a really good amount of carbon to be formed because we're made of carbon
and so on. The first stars must explode properly,
you must have a suitable mixture of stars
some like our sun, others are big and powerful;
organic chemistry. So all of this puts a lot
of constraints on the kind of physics that
you have and again there are possible explanations.
One is the fine tuning is naturally unlikely but God made it happen, that's entirely reasonable
from a believers point of view. And it means that there's purposeful design. It's intellectually a perfectly
good idea but it does mean that, you know, you've got
to give up some of the other ideas perhaps.
Just by luck the only possible universe is
anthropic. Well that's hard to evaluate but
you do require a lot of luck.
Multiverse, okay. Now there could be many, many
universes and then the idea is that they've got to have different properties and we live in
one that's good for us. It's perfectly possible to have one huge cosmos with lots of universes
in that are all the same. Why not? It just
means the constants of nature are always all
the same. That wouldn't solve your poblem of course so you've got to have a particular kind
of multiverse with a lot of variation in
all the physical constants in order to get, you know,
this kind of randomisation process working. And superstrings have been proposed, or m-branes
as was mentioned. Now, the thing about m-brane
theory is that it's not actually a theory
yet. It's so complicated that people think that they ought to be able to work it out but it hasn't been done
yet. So one is jumping the gun a bit by saying that here is a theory that will explain everything
because it's not yet there. But you can have
lots and lots of quantum vacuums. Now quantum
vacuums just means there's sets of parameters
and physical laws of nature and numbers that
do things. 10^500 probably enough but one doesn't really know. But you can model the number of universes
separately, I mean the number of different permutations of superstrings is one thing.
How you actual form a universe is another thing, so you've got two different problems to work out.
Now Penrose, you've heard of Penrose, he
has the following objection to a multiverse;
he says that our universe is unnecessarily
large for our needs. We could live
in a smaller universe, let's say a tenth of the
size, he is probably right I suppose. But then
he works out what he thinks is the likelihood
of a large universe appearing and he says
that most universes are much rarer if they're large than if they're small. In fact
he believes that if the universe were a tenth of the size of ours there'd be hugely many more
of them, in other words we're living in a quite fantastically, unlikely universe. He calculates
this factor as 10^(10^123) which is a preposterously
large number. So if you believe his argument
you have to believe that for no good reason
our universe is much, much larger by far;
a very, very rare event has happened. Well it's a matter of judgement. Now of course we can
always allow God to create universes, many
of them and this was suggested years ago in
Europe, that God could create many universes.
In middle ages, the archbishop, or was
it the bishop of Paris, said in a number of
pronouncements said that you should not prevent
God from creating many worlds, perfectly
possible, we mustn’t limit God’s power
in this way. So this has been on the table
for quite a while but you still need general
laws of physics of course and I think one should say that you shouldn’t dumb down God too much because
the mathematics of superstrings is, well formidable, is too difficult for most people. It's probably too difficult
in real detail for anybody, even Ed Whitten who is probably the most brilliant mathematical physicist
alive. I think there are things that he hasn't worked out yet. So this is a big intellectual
requirement to get these superstrings right.
What observational? None really.
There was this idea that there's some feature of the cosmic microwave background might be an indication
of another universe. I think people aren't talking about that so much right now
it's debatable. So with that kind of questionable
assumption we don't have any evidence for any of
this and how could you actually test the ideas? One doesn’t know really. It might happen. One
can always imagine that what is now philosophy
will turn into science when people think of
some good experimental tests.
So why should you believe in these theories?
Well philosophical reasons, you like it. Aesthetic reasons, you like it. Anti-religious reasons, now, the
people who say, who put these theories out, always say that their motivations are a and b. But well I
don’t know. Oh, here's a bit of popular journalism for you. The people who put out this edition
of the Scientific American were clearly completely
convinced by the cosmologists that it was
absolutely definite that there were lots of
parallel universes. Well who knows? I don't think
this was a particularly scientific example
of this normally very reliable journal.
Okay, Max Born, he became a professor of physics
at Edinburgh. He was a well known quantum theorist
and that is what he had to say about things
in general; that a certain amount of common
sense, if you can rely on that, might be a good
idea. So that's just something to think about,
that was his opinion.
Oh, finally, human specialness. This we come back to
Bernard’s points that, you know, we are conscious beings, we have consciousness.
I have and I presume you have too. Physics doesn't know how to deal with this. Complexity, with all respect,
has not actually given us anything other than a pre-requirement perhaps for consciousness, there's
something more coming. So you need an anthropic principle if you think that physics is preparing the
way for something which is non-physical because
why should it do that. If you don't believe
that there's anything special about us then
you could just say "okay that is just the
way it happened." It could have happened
innumerable other ways, no need to explain
anything. But it seems that there is something here
that does need to be explained. And well we could
accept that the universe looks designed and
thus except the theological consequences.
Well, unbelievers would say that it's wishful thinking but, you know, there is evidence, I don’t say it's
proof but it's evidence, that this could
well be the case. There also exists, as Bernard
mentioned, a reluctance to believe in God
from unbelievers. Susskind who wrote a book
on the cosmic landscape, all about superstrings, that's what he said: "The anthropic principle"
he says, "makes many physics very uncomfortable …. The need for supernatural agent, a threatening,
antiscientific idea." Well it's very much,
I would say, a personal and emotional feeling
but it's one that a lot of folk probably
have and you can’t just sweep that under
the carpet while accusing believers of having other motivations. I think that probably most people
have a lot of background dispositions to believe
different things.
Well let me give you my personal views here,
this is just one page of thoughts. I think
I am basically agnostic about a physical multiverse,
I don’t know, maybe there may not be. I'm
reluctant to believe in a very elaborate theory without good observational reasons though,
so I am in fact suspicious of violating Occam’s razor which says you shouldn’t have
more things than you need so extravagantly.
There's also a basic philosophical principle
of science, let’s say, if you have too many universities, especially an infinite number, you can explain anything
you like. Anything you think might exist somewhere will
exist somewhere and does this trivialise science?
You've got rid of nice tidy explanations
for something. You've just said: "Well,
we're in the universe where that one happens." And one should be a little bit wary. I think, of this.
I ... we haven’t talked about the many worlds interpretation of quantum mechanics but I just jotted
down that, for reasons I can justify afterwards, I find that very implausible. So here's a
statement and it's a warning about getting
too intellectual without putting some observational
flesh on your argument. T. H. Huxley in 1890
was speculating about a sort of scholarly
civilised religion of the future, he said: "No longer in contact with fact of any kind. Faith stands
now and forever proudly inaccessible to the
attacks of the infidel." And I think that
cosmologist need to be a little bit careful that their subject doesn't drift too far in that
direction. So thank you very much.
