[♪♪♪]
[♪♪♪]
ROBERT LAWRENCE KUHN:
Whenever it likes, the universe
 strikes me with wonder,
 shocks me with awe.
 The cosmos needs only a moment
 to subvert my thoughts
 and rivet my intention, a
flash disruption of daily life.
 I do not have
 mystical experiences.
 For me, all it takes is the
 actual, factual reality
of the universe, its beginning,
 its size, its structure,
 its future, its far future,
 its fields and particles,
 its laws and regularities.
 This is the realm
 of contemporary
 scientific cosmology.
[♪♪♪]
How to make sense of cosmology.
 How to see the big picture of
 the puzzle of the universe,
 piece together all
 the new discoveries;
 how to seek the fundamental
 nature of the cosmos.
 I hear of an emerging way
 of thinking called:
 philosophy of cosmology.
What is philosophy of cosmology?
 I'm Robert Lawrence Kuhn,
 and Closer to Truth
 is my journey to find out.
[♪♪♪]
[♪♪♪]
 Philosophy, I know,
 is the search
 for the fundamental
 nature of things.
 That's why philosophy of
 cosmology intrigues me.
 Can philosophy
 of cosmology elucidate
 the fundamental nature
 of the cosmos?
When I find, at a conference of
 cosmologists and philosophers,
 will be held in Crete, Greece,
 I decide to attend.
 The idyllic shores distance me
 from my usual urban habitats,
 clearing my head,
 honing my quest.
 To begin, I seek out
 a philosopher of science
 at Rutgers, who co-leads
 a major project
on the philosophy of cosmology,
 Barry Loewer.
Barry, I've been fascinated by
cosmology my whole life,
and I also love philosophy.
I was really intrigued when
I saw you were involved
with the concept of a subfield:
philosophy of cosmology.
Plato and Aristotle, and the
whole tradition in philosophy
have been interested in issues
in philosophy of cosmology,
from Leibnitz and so on.
But cosmology, itself, developed
enormously from 1915 or so on
with the advent of Einstein's
Theory of General Relativity
and all of the incredible
observational results
that cosmologists have
obtained from Hubble onward.
So, cosmology itself,
has changed a lot
and there hasn't really been,
within philosophy of science,
a philosophy of
cosmology subfield
that's been so well delineated
until fairly recently.
So what are the
general big categories?
So, for the philosophy of
cosmology, first is the question
of what is the nature
of space and time?
Then there are the
contents of space and time.
What is there in space and time?
Is matter, in some sense,
and there's a question:
What is matter?
Well, does matter consist of
certain kinds of particles,
protons, neutrons, neutrinos,
electrons; what are these?
Well, the usual view within
physics is that these are
certain kinds of excitations
of fields
so that the basic thing
that exists are fields.
Well, not quite basic,
because this is all described
by quantum mechanics,
and the basic object
in quantum mechanics
is what's called
the quantum mechanical
wave function, or state.
Then, there's the question
of what else there might be,
and one view is that in addition
to there being space and time,
and there being the stuff
that occupies
space and time,
there are also laws
which, in some way, govern
or evolve, or develop,
or describe the patterns and
regularities in the universe.
I, myself, am especially
interested in a philosophy
of science question,
or a question of metaphysics:
What is the nature
of a law of physics?
That's a different question from
what are the laws of physics.
That's a question
for physicists.
And how does this apply, then,
to the understanding
of the progress that
cosmologists are making today?
I'm not completely sure that
an answer to the philosophy
question will be of much
help to the physicist question.
Philosophers have to look at
what physicists are doing
to understand what laws
of physics there are
in order to say something about
what the laws of physics are,
but I'm not sure that physicists
have to know
what philosophers say about
what laws of physics are.
And, in fact, I've found in
my own conversations
with physicists that they're
incredibly confused and all over
the place when they try to deal
with the philosophical question.
Some physicists say
we don't need philosophy,
or the only philosophers we need
are those who can keep
all the rest of the philosophers
off our backs.
[laughter] 
Well, I think
there's something to that.
I'm a philosopher of physics
who knows some physics,
but I'm not an expert
in the way a physicist
or a cosmologist would be
about some of the issues
that arise in integrating
cosmology,
but I am an expert on how
to understand the structure
of concepts and their
relationship to each other
and philosophers get used to
asking certain kind of questions
and thinking clearly
about certain issues.
And I can think of some places
where, in fact,
I'm fairly confident that
physicists have, you know,
chasing their own tails
because they've been
conceptually confused
about certain issues.
The big issue in the history
of recent philosophy of physics
has been the problem of
understanding and interpreting
what quantum mechanics
is really about.
[♪♪♪]
KUHN: To populate
 the philosophy of cosmology,
 Barry, as a philosopher,
 offers three big categories:
 the nature of space and time;
 the content of space and time,
 namely, energy and matter;
 the laws or regularities
 that describe how things
actually happen in the universe.
 Barry is a philosopher.
 How would a cosmologist,
 the other end of the phrase,
 assess the philosophy
 of cosmology?
 I ask an astrophysicist
 who spent 25 years
with the Hubble Space Telescope,
 and who helped determine
 the expansion rate
 of the universe, Mario Livio.
Mario, if we reflect on
the so-called philosophy
of cosmology in saying: What are
the implications of everything
that we're learning in terms of
human's place in the cosmos,
or the nature of reality --
what can we begin to say?
What we have discovered in the
past century or so is that,
from a physical perspective,
our place in the cosmos
has become smaller and smaller.
You know, where it all started
with Copernicus,
who taught us that we're not
the center of the solar system.
Then we discovered that,
in the Milky Way galaxies,
there are billions
of other solar systems
with planets, roughly like ours.
There are -- we now know about
two trillion other galaxies
than the Milky Way, and now,
we're even talking multiverse,
that maybe even
our entire universe
is just one member of an
ensemble of a huge number
of almost infinite ensemble
of universes.
So, from a physical perspective,
our place has diminished
and diminished.
However, notice that, from
a philosophical perspective,
at the same time what has
happened is that every sentence
I said before actually
represented a human discovery.
When Copernicus found what he
found, a human discovered that.
Then, Harlow Shapely discovered
we're not at the center
of the Milky Way.
Then Hubble discovered
there are other galaxies.
Now, we are talking multiverse.
These are all human discoveries.
In other words, as our universe
expanded, it expanded just
as fast as our intellectual
horizons have expanded.
So, in that sense, we actually
play a central role
in this grand scheme of things.
What are the implications of
the discoveries in cosmology
for traditional religious views,
particularly from the
Judeo-Christian tradition?
I have friends who are
very religious people,
superb scientists, and I
actually asked some of them,
you know, what is their view?
All the people I talked to came
back with the same answer,
which was: I actually believe
that everything that we see
goes by the laws of physics,
but who determined what
the laws of physics are,
that's where they bring
in the deity.
So, to them, God determined
what are the laws of physics,
and then basically everything
follows the laws of physics.
How do you feel about that?
I'm not a religious person,
myself, so to me, you know,
laws of physics are what
the laws of physics are.
It doesn't mean that somebody
had to determine
what those laws are.
So, to you, the laws of physics
might be,
as we call them, brute fact.
Something that's there
that's unexplainable
and that doesn't bother you?
Well, in particular,
if there is a multiverse,
which is essentially infinite,
it could, in principle
be that every combination
of laws of physics is out there
in one of these members
of the multiverse
and then we, of course,
find ourselves
in one of those universes
where the laws of physics
allowed for our existence.
But you still need a series
of meta-laws to generate
a multiverse to come to that
conclusion, so you've just --
You need a certain level
of assumption.
So you've just changed
the level of which
you've asked the question,
but it's the same question?
That's true.
It's the same question,
you know,
how did we get there, yeah.
[♪♪♪]
KUHN: To Mario, humanity's
 comprehending the cosmos
 reveals humanity's minuscule
 place in the cosmos.
 The final step, now taken by
 cosmologists, is a multiverse,
 the remarkable idea that there
 are multiple universes,
 perhaps an infinite number
 of universes.
 A multiverse emerges
 from two kinds of reasons:
as the theoretical consequences
 of our best theories of how
 the universe began, and as a
 natural way of explaining
 what seems to be
 an astonishing fine-tuning
 of the laws of physics to
 allow our kind of universe
 with stars, planets, and life.
 I feel diminished by
 my insignificance
 but, paradoxically, I feel
enlarged by my awareness of it.
 That, I realize, is what
 philosophy of cosmology
 is all about.
 But is this multiverse
 real science?
 And how would the existence
 of a multiverse,
 or its non-existence, inform
 a philosophy of cosmology?
 Attending the conference
 is a cosmologist with whom
 I have long wanted to
 discuss such matters,
the distinguished South African
 expert on space-time
 and general relativity,
 George Ellis.
George, you've been dealing
with cosmological subjects
for more than half a century
and what seem to be some
astonishing ideas have
become mainstream:
inflation theory,
how the universe began,
multiple universes --
so what seems to be emerging
is this sort of a philosophy
of cosmology.
How do we analyze cosmology
in this time
of really dramatic
transformation?
I think we've got to recognize
that we're coming,
at a certain level, to
the limits of what we can see
in the following sense.
We can see anything
which comes towards us
at the speed of light,
and that would be
electromagnetic radiation,
x-rays, ultraviolet, and so on.
But we cannot see
further than that.
Now, we have seen out to the
last scattering surface
where the cosmic microwave
background radiation
was let free by the matter
and come traveling towards us.
That is the furthest matter
that we will ever see
by any electromagnetic
radiation.
So the philosophy of cosmology
is going to have to get to terms
with that fact that there is
this visual horizon and that's
a limit to what we're ever
going to be able to see.
So what's the implication of
that for cosmological theory?
If one starts positing theories
of what lies beyond the visual
horizon, they're not testable
in the conventional sense.
And so, if you're going to
produce a multiverse theory,
we can't see those
other universes,
we can't interact with them.
Well, the motivation,
why they come to a multiverse,
- is multiple.
- Yes.
And, on the one hand, it seems
to be the forced consequence
of inflation theory, of how
this universe started
and the multiverse,
a natural consequence of that.
There's another motivation
that seems to be driven by
fine-tuning that says: how do
you get fine-tuning and that --
so there seems to be
two independent ways
of getting at the multiverse.
So it's...
Yes. So, the first one
is through inflation,
and I think it's important
to understand
that not all inflationary models
lead to a multiverse.
It's a subset
which lead to them.
Anyhow, the bottom line is that
the fact that we have inflation
makes a multiverse a
possibility but not a necessity.
The second point is that
the philosophical motivation
is for fine-tuning and
particularly the cosmological
constant, and, very briefly,
if the cosmological concept
was very much bigger than it is,
we wouldn't be here because
structures wouldn't have formed,
and so we want to explain why
that should be the case.
That is a philosophical
justification and so,
the question that cosmologists
have to ask themselves is:
If I have a philosophical
justification for a theory,
such as a multiverse,
does that prove it exists?
And this takes us back
to the roots of science.
Does philosophy prove the
stuff about the real world?
And I think we know
the answer to that.
Since the scientific revolution,
we've known that you can have
any theories you like,
but you want to actually
be able to test them.
Right, right.
We need to be careful
with the multiverses,
saying they're very attractive
philosophically
in many kinds of ways,
but once you go on
to say they are an established
part of science,
you've got to produce
some convincing proof,
and for many multiverses,
it's basically not possible
to get that proof.
What you say is on
the surface, true.
What do you do at that point?
You can give up,
which nobody wants to do.
You can try to find other
indications in our world.
You can look for coherence.
Which of the explanations that
you can have, seem to be
the most simple, Occam's Razor,
that you don't have to multiply
entities, and you can
figure out alternatives.
Even if you can't prove them
scientifically
and look which seems
more logical.
Yes.
So Occam's Razor you can use
in many different ways,
and my own view is that
with the multiverse
you are multiplying entities
far beyond [unintelligible].
You're trying to explain
one universe
in terms of billions
of other universes.
A particular point, which
is very important here,
the multiverse literature
is replete
with the word "infinity."
Now, one thing I will say
with total confidence,
is that any theory which talks
about infinities
of physical entities is not
a scientific theory
because there isn't any
possibility whatever of proving
that an infinity
of anything exists.
So what's your current
position on this totality?
I think in particular what we
need to do is look for
other ways of explaining
the values of the constants,
and if you get such
an explanation,
then you don't need any of this
multiverse stuff to explain it.
What I do think is we need
to get more clarity
on the philosophical issues, and
I think it's a complete fallacy
to think that the multiverse
solves the fine-tuning problem
because all of those
problems recur
at the level of the multiverse,
so I can produce for your
multiverse theory in which
no universe is in our life,
or in which many universes
are in our life
and so your question is:
Where do the laws of physics
for the multiverse come from?
Where do the constants from
the multiverse come from?
Why are they tuned so
as to allow life to exist?
And so, the multiverse does not
solve any fundamental issues.
The fundamental options
are pure happenstance,
that just happen to be that way,
and if it's ability, it had no
other option to being that way.
It is high probability, it was
very probably it'll be that way,
which is basically
the multiverse option,
and then, a design or intent
kind of thing that somehow
ever something intended that
it would be that kind of way.
Now, the physicists, by and
large, don't like the last one
because it's taking them outside
the domain of physics,
and their assumption
is that physical causation
is the only causation at work
in the universe.
Now, that is manifestly a false
statement within the universe,
whether it applies to how the
universe came into existence
is a separate kind of issue.
[♪♪♪]
KUHN:
 George questions a multiverse
 with two kinds of arguments.
 First, if a multiverse cannot
 be tested,
 how can it be counted
 as science?
 Second, how could
 a multiverse truly solve
 the fine-tuning problem,
 especially if it is burdened
 with infinities?
 Both questions exemplify
 the probative power
 of philosophy of cosmology.
But what about the deep question
 of how the cosmos
 can develop and unfold?
 The nature of time.
 At the conference is
 a philosopher of science
 at Columbia, the co-director
 of the Philosophy
of Cosmology Project, and expert
 on the foundations of physics,
 David Albert.
David, in order
to understand cosmology
and understanding of
the arrow of time, is critical.
You've talked about something
called a past hypothesis
to give us a really deep
understanding
of what this arrow
of time means.
How does that work?
There's an enormously pervasive
sense of there being
a profound difference between
the past and the future.
And I think it's helpful to
divide this temporal asymmetry
into three broad categories.
First of all, there are a
whole bunch of ordinary physical
processes: ice melting, soup
cooling, smoke dispersing,
so on and so forth, that we see
happen in one direction
but not in the other.
We never see smoke collecting
back into a cigarette.
This is a category
of asymmetries
that's well summarized by
the laws of thermodynamics.
There's another category
of asymmetries,
so-called epistemic asymmetries.
We have a very different kind
of epistemic access;
that is, we have a very
different kind of capacity
to know things about the past
than we do about the future.
If somebody says I'm thinking of
an occasion when an egg dropped
on the floor and splattered in
exactly the shape of Argentina,
as chance would have it,
we know unless they're lying,
they're talking about a past
incident, not a future one.
That's not the kind of thing we
ever know about the future,
and it's perfectly obvious
to everyone that we know
all sorts of things
about the past
that we can never at present
know about the future.
Good.
Third, there's what's
called a causal asymmetry.
That is we make our way
around in the world
with a very profound conviction
to the effect that
what we do now can affect
the future,
but can do absolutely nothing
about the past.
And it has been wondered for a
long time if these asymmetries
have anything to do
with one another,
and if they can be traced
back to some deeper feature
of the structure of the world.
But, in recent years, people
have been able to formulate
more and more precisely the hope
that all of these asymmetries
can be traced back to
very special conditions
that existed at the time of the
Big Bang, that, in particular,
if you suppose that at the time
of the Big Bang,
a quantity called
the Energy of the Universe,
had a very, very small value,
that there's some hope
that we can account for all
of these phenomena,
not merely the thermodynamic
one, which has very directly
and obviously to do
with entropy,
but also the epistemic asymmetry
and also the causal asymmetry.
The epistemic and causal as well
to go back
to the beginning
of the universe?
Yes, that's right.
That's right.
- That is...
- That's not intuitively...
It's not intuitively obvious
at all, but it seems to me
that it's because the initial
entropy of the universe
was so low that we can have
things like records
or photographs of past events
but not future events.
And that, by acting now,
we can affect the future
but not the past.
Okay, so go through that
and define entropy
in the context
of that differentiation.
Entropy, in thermodynamics,
is a measure of how many ways
a certain state
could be realized.
That is, there's a cup of
coffee in front of me now.
There are a lot of particular
arrangements of the atoms in
this cup of coffee which would
still count as a cup of coffee
with the same temperature and
the same volume
and so on and so forth.
What we mean by the entropy
of a particular physical state
is some account of how many
different exact micro-conditions
would be compatible
with that macro condition.
It's been known for a long time
that if the universe started out
in low entropy, that would
give a good account
of why smoke spreads out
but never recollects
into a cigarette,
of why ice melts but never
refreezes in a warm--
Simplistically order
to disorder?
That's right.
Order to disorder.
What's a little bit more
surprising is that
this pattern of going from order
to disorder can also provide
an account why there could
be such a thing as, say,
a record or a photograph
of a past event existing
here in the present,
but not a future one.
What are the implications
for cosmology,
as we looked from the beginning
of the universe into what looks
now its ultimate dispersion,
trillions of years from now.
Well, one of the things that's
inherent in these kinds of
considerations is that there is
this very surprising consequence
that things look -- that look
like very local features
of our lives here on earth,
that I can affect the future
by acting now
but not the past,
that I can remember past
events but not future ones,
if you trace these back
to the deepest level,
you're really talking about
cosmic scale features
of the universe as a whole.
[♪♪♪]
KUHN: Philosophy of cosmology
 seeks deepest levels
 of cosmic reality,
 asking fundamental questions
 about the universe.
 How to characterize and
 integrate the essential
 components of the cosmos,
 space-time, energy, matter,
 laws, regularities.
How to articulate the minuscule
place of humanity in the cosmos
 with humanity's penetrating
 understanding
 of how the cosmos
 actually works.
 How to assess the presumption
of a vast ensemble of universes,
 and whether physical
causation is the only causation.
 How does the quantum world
 and the nature of time
 affect the universe,
 its beginning, evolution,
 structure, and future?
 I find myself at once
 exhilarated and troubled.
 Exhilarated by the ineffable
 majesty of the universe,
 troubled by the radically
 opposed realms
 of its possible meanings.
 Not many working cosmologists
 concern themselves
 with philosophy of cosmology;
 why should they?
 Why distract themselves
 from the hard business
 of teasing out the universe's
 ancient secrets?
 As for me, I must concern
 myself to be...
 closer to truth.
ANNOUNCER:
 For complete interviews
 and for further information,
 please visit closertotruth.com
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