[♪♪♪]
[♪♪♪]
ROBERT LAWRENCE KHUN:
 I yearn to know deep reality,
 so I start 
 with what I know for sure,
 the deep structure
 of our universe.
 I say our universe,
 not the universe
 because our universe
is special in at least one way:
 we are in it.
 Is this trivial?
 Patently obvious, of no value?
[♪♪♪]
 This leads to the so-called
 fine-tuning of our universe.
 Here's the claim:
 Conditions that allow
 for complex structures --
 galaxies, stars, planets,
 life, brains, human beings --
 depend on a few
fundamental constants of nature
 lying within 
 tight ranges of values.
 And if these fundamental
 constants were to differ
 only slightly, those complex
 structures wouldn't exist.
 We wouldn't exist.
 That's the claim.
 But is fine-tuning valid?
What's fine-tuning in cosmology?
 I'm Robert Lawrence Kuhn,
 and Closer to Truth
 is my journey to find out.
[♪♪♪]
KUHN: The claimed
 fine-tuning of our universe
 presents a puzzle.
 Why does fine-tuning
 seem meaningful to some,
 irrelevant to others?
 To me, it's maddening.
 Is fine-tuning 
 a real phenomenon?
 If so, it cries out
 for explanation.
 Discoveries in physics
 and cosmology
convinced many scientists that,
 yes, fine-tuning
 is a real phenomenon.
 But recently,
 there has been pushback.
 Is there less fine-tuning
 here than meets the eye?
 When I hear
 of an international conference
 on the physics of fine-tuning,
 I decide to attend.
 This is no celebration
 of fine-tuning.
 The conference is held 
 on the idyllic island of Crete
 in Greece,
 whose coastal splendor
 itself can seem fine-tuned.
 To pose the problem precisely,
 I begin with the co-author
 of a book on fine-tuning:
A Fortunate Universe: 
Life in a Finely Tuned Cosmos,
 Welsh-Australian
 astrophysicist, Geraint Lewis.
KUHN: Geraint, 
you work in cosmology,
what's the value 
of a fine-tuning perspective?
Well, the question really
grows out of the research
that's come over 
the last couple of decades,
and this discovery that we have
an accelerated expansion
of the universe.
We need some other
energy-density in the universe
that gives us
accelerated expansion,
and we know
that can't be matter,
it can't be anything
like normal materials.
Gravity -- it's
the other direction.
Gravity -- it attracts.
So we need something to repel.
So we find that we have
this stuff in the universe; 
we really don't know what it is
so we give it a sexy name, 
like dark energy,
and when we look 
at the sort of energy density
that we have in dark energy,
and compare it to 
our theoretical calculations,
this is where there's
this huge discrepancy.
We have the observed values 
at ten to the 120 times smaller
than the theoretical
expectations that we get.
Now, this is the so-called 
energy density
of an absolute vacuum?
- Yes.
- So there's nothing in it.
There's no molecules in it
theoretically, 
no atoms, nothing?
That's right. 
So if you imagine you've got
an empty box in the universe,
when you add the quantum
mechanical aspects
then you get particles popping
in and out of existence.
All this quantum vacuum stuff.
And you can add up
the energy density
that's in an empty vacuum due
to these quantum fluctuations
and that gives us
this huge amount of energy
per volume of space compared
to what we observe.
So the question is,
is why does our universe have
any of this stuff in it at all?
In the past, matter dominated,
and now it's thinned out, and
now dark energy has taken over.
Because dark energy is the same
in a given volume of space--
- Yes.
- whereas as matter spreads out,
the space grows so that 
the density of matter gets less,
but the density of this energy
doesn't get less.
That's right.
So, it has a higher percentage
of the total; is that right?
Absolutely. Absolutely.
So we're now in an epoch
where this stuff dominates,
and it will now always dominate.
So the question is, is then
why do we have, you know,
10 to the minus 120 
of the amount of dark energy
that theory tells us we should?
And this goes back 
to this notion of the multiverse
whereby we have 
this inflationary epoch,
we've formed all these
little bubbly universes,
and they've all got their own
little laws of physics,
and ours was born
with this just sliver
of dark energy left in there.
So the question that 
we wanted to tackle is well,
what if our universe had been
born with slightly different
dark energy properties?
So we can do this, right?
We simulate chunks 
of the universe on a computer,
and we can put in the matter
density soon after the Big Bang.
The formation of stuff
in the universe is a battle
essentially between cosmic
expansion and gravity
pulling things together,
so we have 
the mathematical framework,
we can just put in 
the amount of dark energy.
And again, at the start, it's
always dormant because matter
with such high density, but
it means that
if you make dark energy
more concentrated at the start,
then it comes to take over 
earlier and earlier
in the history of the universe.
And that's bad for the formation
of things like galaxies.
So, we've got matter pooling
together in the early universe.
That crashes down, maybe
dark matter crashes down,
taking gas with it, 
that gas pools to the center,
forms a galaxy which
is made of stars,
in those stars 
you create the elements
that formed you and I.
If dark energy kicks in earlier,
it can shut off 
that initial formation,
and you don't have
to increase dark energy by much,
a factor of 10, possibly
we could get away with it.
We could still have enough
time to form some galaxies,
but you push high up to
a factor of 100 times, etcetera,
then you've shut off
galaxy formation.
- You shut off the [cross talk].
- You say 100 times.
That means from the discrepancy
from 10 to the 120th,
that would be to 118?
Correct. So, so we're still
talking about a sliver
of dark energy compared
to the natural value.
So, again, we might have 
this sea of universes out there
in the multiverse,
and others have gotten crazy
amounts of dark energy.
Like if you've got
the full amount
of the theoretical expected,
then boom,
then, you know,
there's a universe
between every hydrogen
atom, and that's it.
No structure formation.
And, if it went the other
direction, if it got smaller
and smaller or went negative,
that would just cause
an immediate attraction,
so you'd have a sudden universe
of black holes or something?
Absolutely. Zero would
have been the best value.
So if it had come out
to be none at all,
- everyone would've been happy.
- Right.
When you see something with
120 decimal places of zeroes
and then a 1, you think
you made a mistake
and it really is zero.
- That's right.
- But that's not the case?
That's not the case.
So, you would hope that
whatever the mechanism does,
it would be natural to multiply
by zero so there's none left.
But multiply by a factor
to leave you this sliver,
that's really worrisome.
KUHN: Worrisome to me
 is a happy word.
 It means something is amiss.
 Are there things 
 we do not understand?
 Are there deeper realities
 we have yet to discover?
 The cosmological constant,
 the so-called dark energy
 of the universe seems
 incredibly fine-tuned.
 But is this really so?
 How to explore it further?
 What about other examples
 of fine-tuning in cosmology?
 I hear the co-author 
 of A Fortunate Universe:
Life in a Finely Tuned Cosmos,
 has a distinct perspective.
 Cosmologist, Luke Barnes.
So the key stated model
of cosmology we have has about
six numbers in it that describe
how the universe starts off
and how it expands --
the basics of this is how
structure forms in the universe.
The most famous one of these
is known as 
the cosmological constant,
and when we look at what would
happen if it were different
to what it is,
you get disastrously rapid
acceleration or deceleration.
There's a small range
that we're in,
where you can have
structure form.
Okay, what are some others?
Well, one of the other important
ones is the level of lumpiness
in the early universe,
this parameter called Q.
It's when we look back 
to the cosmic background,
the lumps and bumps in that,
you know, this bit's
more dense than that bit
by one part of 100,000,
so it's all very smooth.
That sets the seeds for cosmic
growth or galaxies to form,
but we can again play the game,
what if that were different
if it were too small,
you don't have the seeds there
and the universe just stays
smooth for most of its history
and nothing forms 
that's the end of that story.
If it's too large, it seems
like you might make galaxies
that are a bit too dense, so you
wouldn't have solar systems
that sort of stay like ours is,
just is left alone for
four-and-a-half billion years
to make planets
and all those things.
Other stars would start
wandering through
which is bad news
for the planets.
If you make Q larger still, 
instead of making galaxies
via the slow sort of clumping
in process where you make stars
and all that, you instead 
make black holes.
What is Q?
It simply describes how large
the variations are away
from average density
in the early universe.
Okay. Those two. 
What are a couple others?
Another one is how much dark
matter and baryonic matter
there is in the universe,
and again,
you have to sort of be
in an interesting range there.
Dark matter actually does help
structure in our universe.
Ordinary matter has pressure,
so the pressure 
you see in a balloon.
So as gravity tries 
to make it collapse,
it will flap back
against gravity,
but because dark matter
doesn't have that,
it can collapse earlier, so 
it helps structure our universe.
Okay. So if you had
a purely baryonic universe,
it seems like you wouldn't
have as many galaxies,
but a purely 
dark matter universe
would make interesting structure
because the dark matter doesn't
seem to be able to do that,
and so we're in a sort of
interesting range there
- in the middle.
- Any others of interest?
In the earlier stages of the
universe, there's a relationship
between the rate
at which the universe expands
and how dense it is,
and so we're on this fine line
that's called, 
you know, flatness.
If that were slightly different,
the universe would either
re-collapse too quickly
under its own gravity,
or it would expand so fast
that no structure forms.
So, basically what I hear
is that there are a number
of different characteristics
that all lead
to the same kind 
of fine-tuning result.
So here's the question.
Pick a constant.
What does fine-tuning mean?
What's relative?
Maybe fine tuning to you
is not fine tuning to me?
Yeah. So, one of the things that
you need to sort of set out
the problem is an understanding
of what's the set of
possibilities that
this theory opens up?
So, the numbers in this theory
are sort of part of that,
that world that 
your theory creates.
And so there's 
a set of possibilities
that the theory determines.
We have quite specific bounds
on what that number could be
within the theory itself.
So we can draw
a line in the sand,
here is where 
this number could be.
But Q, or the ratio of ordinary 
matter to dark matter
is roughly what? Four over 29,
or 30, or something like that?
Yeah. Something like that, yeah.
So how tight is that ratio --
does that need to be?
We're dealing 
with 10 percent of that, or 100?
Yeah. So, the ratio of dark
matter to baryonic matter
actually seems, 
on the face of it, fairly wide,
as long as they're kind of 
close to each other
we'll probably be alright.
The problem is we don't know
what sets those two numbers.
The physics of dark matter,
the physics of baryonic matter
are totally independent.
The fact that they would
hit about the same number
seems to be rather odd.
When you say about
the same number,
you mean the same
order of magnitude?
Order of magnitude.
If you think of it as a ratio,
it looks like in order 
of magnitude, either way,
it will be alright
for life as long
as you've got some dark matter
to help you create structure
and you still have order 
and matter
to fall in and make galaxies.
And that's still fine-tuned,
because in physics you can
have orders of magnitude of
not just one order of magnitude,
kind of like forty or something.
Yeah. And especially, if the
physics that sets these numbers
are totally different, if I say
pick a number between
one and a trillion
and pick another number
between one and a trillion,
if you end up with numbers
of the same order of magnitude,
that's kind of interesting.
It's not a totally
clear-cut case,
but there's still 
an interesting thing,
perhaps, there to be explained.
Why are these numbers
close to each other?
[♪♪♪]
KUHN: Are all astrophysicists
 entranced
 by the apparent fine-tuning
 of the universe?
 The key question
 is the tolerance ranges
 of fundamental constants.
 Like blood tests that
 show in or out of range,
 can structure and life show
 which values work
 and which do not?
 If so, rather than
 asking whether
 our universe is fine-tuned,
 can I ask
 the question in reverse?
 How much fine tuning
 would it take to make
 other kinds of universes
 friendly to life?
 I speak with an astrophysicist
 who is something of
 a fine-tuning skeptic.
 Working on star
 formation in cosmology,
 planetary habitability,
 and the long-term future 
 of the universe, Fred Adams.
Fred, fine-tuning is, to me,
a probe of what the universe is
and potentially what
it's all about.
One test of fine-tuning
is making alternatives.
What would it take to make other
kinds of universes habitable?
Yeah. We can talk about some
of the basic parameters.
The universe contains matter
and a weird kind of energy
called dark energy,
and the matter consists
of regular matter,
the baryons, the protons
and neutrons
that make up you and me,
as well as dark matter,
which we're still
trying to figure out.
So, you can imagine other
universes with different mixes
of those ingredients, and the
key question in fine tuning is:
what range of ingredients will
allow for a habitable universe,
and if our universe is
fine-tuned, the answer would be
you can't go very far
from the particular set
of ingredients we have.
One of the structures
that you're talking about
is that somehow,
in the early universe,
the universe makes fluctuations
in the matter fields,
which means there's little
bits that are denser
and little bits that
are less dense.
The amplitude 
of those fluctuations
is a key cosmological parameter.
Right.
And another key cosmological
parameter is the amount
of baryonic matter or
protons and neutrons
relative to the
number of photons.
The question is:
How low does it have
to be before it fails,
and how big does it have
to be before it fails?
And failing means that you don't
have a habitable universe
because you don't have
the right structures?
The ratio between
protons and photons --
why is that critical?
In the early universe,
our universe processes about
25 percent of the protons
into helium during the first
three minutes of our history.
If you process all 
of the protons into helium,
thereby leaving no protons left,
you need protons
for the H in H2O,
also known as water,
and without water,
- we're not the same.
- Right.
So you could kill the universe
if you're able to make
all of the protons
synthesize into helium
 in the first three minutes.
So that would be too many
protons relative to photons?
Yeah. So if the universe has
a higher ratio of protons
to photons, then matter
domination starts earlier,
which means structures
can form earlier.
And that can give 
the universe more leeway
in the forming of structures.
You can get away 
with a lower amplitude.
So, what the claim is, is that
our universe is not necessarily
the best-fine-tuned universe
for the creation 
of complexity in structure?
That is true.
In fact, I would argue that
if you and I were to sit
down at the blackboard,
it might take us many years, we
could design a better universe.
[laughter]
And I've been trying
to do that, right?
Nobody ever accused
you of modesty?
No, no. No one's ever
accused me of that.
So, a better universe would
have larger fluctuations,
and the reason
is that that would make
structure formation
easier, more robust,
and the theories that we have,
which are premature,
are easier to understand
if that fluctuation level
is larger, not smaller.
So if the amplitude
is larger than in our universe,
it's easier for an
inflationary theory to work.
It's then easier for
the universe to make galaxies
and then stars 
and planets and people.
Sure. And it happens
more quickly.
It happens more quickly,
it happens more robustly.
Now, there is a danger
of going too far--
Obviously.
...in which case you get 
the galaxies to be too dense.
Too many things in the middle
will collapse to the black holes
that form in the middle
of galaxies.
And if the stellar
environment is too dense,
you can kill 
the universe in two ways.
You could have the stellar
fly-bys so frequently
you'll strip planets off stars,
and you also have
the background radiation field
so intense that it's too hot.
However, there's 
a sort of a sweet spot.
If you make the galaxy
the right density,
then you can make
the background night sky
the same brightness
as our day sky.
Then every planet is habitable.
[laughs]
And that's actually 
a better universe than ours,
because then all the planets
in that sweet spot will be
habitable, but at least 
will have the right temperature,
and that's not as constrained
as our universe.
Is there a possible danger
that in your constructing
a universe that would
be better than ours,
you're actually leaving out some
things that you don't know?
Oh, that's 
a very valid critique,
and in spite
of my seeming arrogance,
we are well aware that we
actually do not understand
all the things 
that we need to for life.
[♪♪♪]
KUHN: If Fred is right,
 other kinds of universes
 could be more efficient
 in producing life-bearing
 structures like planets,
 which would seem 
 to suggest that fine-tuning
 in our universe is not
 as fine as advertised.
 Again, the importance
 of fine-tuning turns on
 how narrow or how
 broad the tolerances
 around fundamental constants,
 while still being consistent
 with the formation 
 of stars and planets,
 and with sufficient time
 for the generation 
 and evolution of life.
[♪♪♪]
 But is there a still deeper
 critique of fine-tuning?
 I meet a pioneer
 in transforming cosmology
 into a precision science,
 one of the organizers
 of the Physics
 of Fine-Tuning Conference,
 Joseph Silk.
Joe, to see the application
of fine-tuning in cosmology,
are there other
areas of cosmology
that lend itself to 
a fine-tuning kind of analysis?
Okay. So here's maybe the most
basic example of all: the sun.
Okay?
So, why is the sun
the master it is,
and why are all
the stars in the universe
the mass of the sun
within a factor
of 10 or 20, okay,
or 30, whatever.
You know, they could
be much more massive.
They could be rocks,
they could be moons,
they could be almost anything.
So one of the early realizations
in fine-tuning studies
was to say,
well, the sun is a competition
between the force of gravity,
and the outward pressure
of the radiation,
and there's an actual
balance between those two
that you can express
in terms of
two fundamental
constants of nature.
So one is the fine
structure constant,
which controls 
sort of chemistry basically,
and the other one is
the gravitational analog of that
which is the ratio of gravity
to electromagnetic force
with a pair of electrons 
or protons.
Okay, so you take
a gas cloud, let's say,
and you ask the question
let's imagine it gets cold,
it breaks up into smaller bits,
the smallest bit might
eventually form a star.
And what you find when you do
this fragmentation calculation
to try to form a star,
is that you can express
the minimum size of a fragment
in terms of fundamental
constants,
but you get the wrong number.
You don't get
the mass of the sun,
you get the mass of a planet.
And it can't be a planet
because at the beginning
you didn't have 
the silicates and the RN [sic]
that the planets are made of
so the calculation
is simply wrong.
And so you learn, when you
look at this more carefully
with more physics and more
understanding that, in fact,
you make these
minimal size lumps,
dense clumps of gas,
but then stuff equates
onto them, okay?
It's different physics.
It's not just physics
of fragmentation,
it's physics of growth.
And it doesn't stop
there, either,
because then you
suddenly realize, well,
if growth, then, determines
the final size of my gas clump,
why does it stop
at the mass of the sun
 and go into hundred-thousands.
It could become a black hole.
And then you realize that,
no what happens next is that
as this clump gets roughly
the mass of the sun,
it starts producing
what we call feedback.
It gets hot enough
and any lines of force,
though, can get tangled
enough to give you forces
 that stop the gas equating.
So it's a combination
of, first of all,
the fundamental fine-tuning,
which gives you the basic
scale, plus complex physics.
In this case, accretion
and feedback, and that --
so that means what we once
thought was fine tuning
is really nothing other
than complexity, basically.
We're here by
self-regulation, you know?
And that
self-regulation, though,
is that kind of 
a fine-tuning itself?
Well, you know,
in some other universe
where these constants
might be very different,
you'd end up 
with different massed stars.
But what we see around us
is the result much more
of complexity 
and self-regulation
than any initial choice
of the fundamental constants.
That's what one has to realize.
And obviously, you have
to have enough pressure
and temperature to cause fusion?
It's all force balance,
but coupled 
with highly nonlinear physics.
That means you don't
even recognize
what went into it
at the beginning,
and it all comes 
from self-regulation.
And I think the same is true
in biology or consciousness.
If you weren't able
to explain those,
you'll find yourself tackling
with similar arguments
that are very, very
different from fine-tuning.
Interesting.
Are there other examples
in cosmology?
Well, there, for example,
is the mass of the galaxy.
Why is the mass 
of the galaxy the way it is?
And, again, it turns out that
you can calculate, you know,
the mass of a big gas
cloud and it turns out
it's a balance again
between gravity,
causes collapse,
and the rate at which it could
lose energy by atomic cooling,
atoms bouncing into ions
and electrons and things,
exciting them 
and then radiating.
And that gives you
a natural scale.
Clouds too big cannot
lose energy, therefore
they stay hot, therefore
they cannot ever make stars.
I can calculate the average
mass of the galaxy,
we can learn why the Milky Way
is the mass it is.
But when you go 
to the surveys of galaxies
you find that most
galaxies are very small
and there aren't
that very many big ones.
And if you go
to a theory of structure
with only dark matter in,
then it predicts 
too many small galaxies,
and too many big galaxies
compared to what we see
by enormous numbers.
So, again, something
else is needed
and so this, again, is
complexity and self-regulation.
[♪♪♪]
KUHN: Can fine tuning probe
 the nature of the cosmos,
 offer clues
 to the mystery of existence?
 Fine tuning is often 
 deemed a fact
 and used to reach grandiose
 metaphysical conclusions
 by philosophers, theologians,
 and even physicists.
[♪♪♪]
 But does fine tuning truly
 cry out for explanation?
 Not if other universes
 could be tuned better.
 Not if fine tuning reflects
 deeper mechanisms.
[♪♪♪]
 Is there sufficient evidence
 to take fine-tuning seriously?
[♪♪♪]
If so, which I believe, then ask
 how might fine-tuning
 come about?
 There seem only
 three kinds of answers;
 two are natural, one is not.
 One, a new deep physics
 yet to be discovered,
 which would constrain
 the fundamental constants
 to be only that which
 they are and nothing else.
 This looks less likely.
[♪♪♪]
 Two, a multiplicity
 of universes, a multiverse,
 each with its own set of laws,
 and only in those rare cases
 where structure
 and life is possible,
 can sentient beings arise
 and marvel about fine-tuning.
[♪♪♪]
 Three, a causative mechanism
 beyond naturalism.
 Though, to some, this would
 be God or something like God.
 There are other candidates,
 however bizarre,
 such as alien simulations,
 and quantum theories
 of retro-causation.
[♪♪♪]
 Fine tuning, I bet,
helps us get...closer to truth.
ANNOUNCER:
 For complete interviews
 and for further information
please visit closertotruth.com.
[♪♪♪]
