Why does the universe exist?
Why is there — Okay. Okay. (Laughter)
This is a cosmic mystery. Be solemn.
Why is there a world, why are we in it,
and why is there something rather than nothing at all?
I mean, this is the super ultimate "why" question?
So I'm going to talk about the mystery of existence,
the puzzle of existence,
where we are now in addressing it,
and why you should care,
and I hope you do care.
The philosopher Arthur Schopenhauer said that
those who don't wonder about the contingency of their existence,
of the contingency of the world's existence,
are mentally deficient.
That's a little harsh, but still. (Laughter)
So this has been called the most sublime
and awesome mystery,
the deepest and most far-reaching question
man can pose.
It's obsessed great thinkers.
Ludwig Wittgenstein, perhaps the greatest
philosopher of the 20th century,
was astonished that there should be a world at all.
He wrote in his "Tractatus," Proposition 4.66,
"It is not how things are in the world
that is the mystical,
it's that the world exists."
And if you don't like taking your epigrams
from a philosopher, try a scientist.
John Archibald Wheeler, one of the great physicists
of the 20th century,
the teacher of Richard Feynman,
the coiner of the term "black hole,"
he said, "I want to know
how come the quantum,
how come the universe, how come existence?"
And my friend Martin Amis —
sorry that I'll be doing a lot of name-dropping in this talk,
so get used to it —
my dear friend Martin Amis once said
that we're about five Einsteins away from answering
the mystery of where the universe came from.
And I've no doubt there are five Einsteins
in the audience tonight.
Any Einsteins? Show of hands? No? No? No?
No Einsteins? Okay.
So this question, why is there something rather than nothing,
this sublime question, was posed rather late
in intellectual history.
It was towards the end of the 17th century,
the philosopher Leibniz who asked it,
a very smart guy, Leibniz,
who invented the calculus
independently of Isaac Newton, at about the same time,
but for Leibniz, who asked why is there something rather than nothing,
this was not a great mystery.
He either was or pretended to be
an Orthodox Christian in his metaphysical outlook,
and he said it's obvious why the world exists:
because God created it.
And God created, indeed, out of nothing at all.
That's how powerful God is.
He doesn't need any preexisting materials to fashion a world out of.
He can make it out of sheer nothingness,
creation ex nihilo.
And by the way, this is what
most Americans today believe.
There is no mystery of existence for them.
God made it.
So let's put this in an equation.
I don't have any slides so I'm going to mime my visuals,
so use your imaginations.
So it's God + nothing = the world.
Okay? Now that's the equation.
And so maybe you don't believe in God.
Maybe you're a scientific atheist
or an unscientific atheist, and you don't believe in God,
and you're not happy with it.
By the way, even if we have this equation,
God + nothing = the world,
there's already a problem:
Why does God exist?
God doesn't exist by logic alone
unless you believe the ontological argument,
and I hope you don't, because it's not a good argument.
So it's conceivable, if God were to exist,
he might wonder, I'm eternal, I'm all-powerful,
but where did I come from?
(Laughter)
Whence then am I?
God speaks in a more formal English.
(Laughter)
And so one theory is that God was so bored with
pondering the puzzle of His own existence
that He created the world just to distract himself.
But anyway, let's forget about God.
Take God out of the equation: We have
________ + nothing = the world.
Now, if you're a Buddhist,
you might want to stop right there,
because essentially what you've got is
nothing = the world,
and by symmetry of identity, that means
the world = nothing. Okay?
And to a Buddhist, the world is just a whole lot of nothing.
It's just a big cosmic vacuity.
And we think there's a lot of something out there
but that's because we're enslaved by our desires.
If we let our desires melt away,
we'll see the world for what it truly is,
a vacuity, nothingness,
and we'll slip into this happy state of nirvana
which has been defined as having
just enough life to enjoy being dead. (Laughter)
So that's the Buddhist thinking.
But I'm a Westerner, and I'm still concerned
with the puzzle of existence, so I've got
________ + —
this is going to get serious in a minute, so —
________ + nothing = the world.
What are we going to put in that blank?
Well, how about science?
Science is our best guide to the nature of reality,
and the most fundamental science is physics.
That tells us what naked reality really is,
that reveals what I call TAUFOTU,
the True And Ultimate Furniture Of The Universe.
So maybe physics can fill this blank,
and indeed, since about the late 1960s or around 1970,
physicists have purported to give
a purely scientific explanation of how
a universe like ours could have popped into existence
out of sheer nothingness,
a quantum fluctuation out of the void.
Stephen Hawking is one of these physicists,
more recently Alex Vilenkin,
and the whole thing has been popularized
by another very fine physicist and friend of mine,
Lawrence Krauss, who wrote a book called
"A Universe from Nothing,"
and Lawrence thinks that he's given —
he's a militant atheist, by the way,
so he's gotten God out of the picture.
The laws of quantum field theory,
the state-of-the-art physics, can show how
out of sheer nothingness,
no space, no time, no matter, nothing,
a little nugget of false vacuum
can fluctuate into existence,
and then, by the miracle of inflation,
blow up into this huge and variegated cosmos
we see around us.
Okay, this is a really ingenious scenario.
It's very speculative. It's fascinating.
But I've got a big problem with it,
and the problem is this:
It's a pseudo-religious point of view.
Now, Lawrence thinks he's an atheist,
but he's still in thrall to a religious worldview.
He sees physical laws as being like divine commands.
The laws of quantum field theory for him
are like fiat lux, "Let there be light."
The laws have some sort of ontological power or clout
that they can form the abyss,
that it's pregnant with being.
They can call a world into existence out of nothing.
But that's a very primitive view of what
a physical law is, right?
We know that physical laws are actually
generalized descriptions of patterns and regularities
in the world.
They don't exist outside the world.
They don't have any ontic cloud of their own.
They can't call a world into existence
out of nothingness.
That's a very primitive view
of what a scientific law is.
And if you don't believe me on this,
listen to Stephen Hawking,
who himself put forward a model of the cosmos
that was self-contained,
didn't require any outside cause, any creator,
and after proposing this,
Hawking admitted that he was still puzzled.
He said, this model is just equations.
What breathes fire into the equations
and creates a world for them to describe?
He was puzzled by this,
so equations themselves can't do the magic,
can't resolve the puzzle of existence.
And besides, even if the laws could do that,
why this set of laws?
Why quantum field theory that describes
a universe with a certain number of forces
and particles and so forth?
Why not a completely different set of laws?
There are many, many mathematically consistent sets of laws.
Why not no laws at all? Why not sheer nothingness?
So this is a problem, believe it or not,
that reflective physicists really think a lot about,
and at this point they tend to go metaphysical,
say, well, maybe the set of laws
that describes our universe,
it's just one set of laws
and it describes one part of reality,
but maybe every consistent set of laws
describes another part of reality,
and in fact all possible physical worlds
really exist, they're all out there.
We just see a little tiny part of reality
that's described by the laws of quantum field theory,
but there are many, many other worlds,
parts of reality that are described
by vastly different theories
that are different from ours in ways we can't imagine,
that are inconceivably exotic.
Steven Weinberg, the father
of the standard model of particle physics,
has actually flirted with this idea himself,
that all possible realities actually exist.
Also, a younger physicist, Max Tegmark,
who believes that all mathematical structures exist,
and mathematical existence is the same thing
as physical existence,
so we have this vastly rich multiverse
that encompasses every logical possibility.
Now, in taking this metaphysical way out,
these physicists and also philosophers are actually
reaching back to a very old idea
that goes back to Plato.
It's the principle of plenitude or fecundity,
or the great chain of being,
that reality is actually as full as possible.
It's as far removed from nothingness
as it could possibly be.
So we have these two extremes now.
We have sheer nothingness on one side,
and we have this vision of a reality
that encompasses every conceivable world
at the other extreme: the fullest possible reality,
nothingness, the simplest possible reality.
Now what's in between these two extremes?
There are all kinds of intermediate realities
that include some things and leave out others.
So one of these intermediate realities
is, say, the most mathematically elegant reality,
that leaves out the inelegant bits,
the ugly asymmetries and so forth.
Now, there are some physicists who will tell you
that we're actually living in the most elegant reality.
I think that Brian Greene is in the audience,
and he has written a book called "The Elegant Universe."
He claims that the universe we live in mathematically
is very elegant.
Don't believe him. (Laughter)
It's a pious hope, I wish it were true,
but I think the other day he admitted to me
it's really an ugly universe.
It's stupidly constructed,
it's got way too many arbitrary coupling constants
and mass ratios
and superfluous families of elementary particles,
and what the hell is dark energy?
It's a stick and bubble gum contraption.
It's not an elegant universe. (Laughter)
And then there's the best of all possible worlds
in an ethical sense.
You should get solemn now,
because a world in which sentient beings
don't suffer needlessly,
in which there aren't things like
childhood cancer or the Holocaust.
This is an ethical conception.
Anyway, so between nothingness
and the fullest possible reality,
various special realities.
Nothingness is special. It's the simplest.
Then there's the most elegant possible reality.
That's special.
The fullest possible reality, that's special.
But what are we leaving out here?
There's also just the crummy,
generic realities
that aren't special in any way,
that are sort of random.
They're infinitely removed from nothingness,
but they fall infinitely short of complete fullness.
They're a mixture of chaos and order,
of mathematical elegance and ugliness.
So I would describe these realities
as an infinite, mediocre, incomplete mess,
a generic reality, a kind of cosmic junk shot.
And these realities,
is there a deity in any of these realities?
Maybe, but the deity isn't perfect
like the Judeo-Christian deity.
The deity isn't all-good and all-powerful.
It might be instead 100 percent malevolent
but only 80 percent effective,
which pretty much describes the world we see around us, I think. (Laughter)
So I would like to propose that the resolution
to the mystery of existence
is that the reality we exist in
is one of these generic realities.
Reality has to turn out some way.
It can either turn out to be nothing
or everything or something in between.
So if it has some special feature,
like being really elegant or really full
or really simple, like nothingness,
that would require an explanation.
But if it's just one of these random, generic realities,
there's no further explanation for it.
And indeed, I would say
that's the reality we live in.
That's what science is telling us.
At the beginning of the week,
we got the exciting information that
the theory of inflation, which predicts a big,
infinite, messy, arbitrary, pointless reality,
it's like a big frothing champagne
coming out of a bottle endlessly,
a vast universe, mostly a wasteland
with little pockets of charm and order and peace,
this has been confirmed,
this inflationary scenario, by the observations
made by radio telescopes in Antarctica
that looked at the signature of the gravitational waves
from just before the Big Bang.
I'm sure you all know about this.
So anyway, I think there's some evidence
that this really is the reality that we're stuck with.
Now, why should you care?
Well — (Laughter) —
the question, "Why does the world exist?"
that's the cosmic question, it sort of rhymes
with a more intimate question:
Why do I exist? Why do you exist?
you know, our existence would seem to be amazingly improbable,
because there's an enormous number of genetically possible humans,
if you can compute it by looking at
the number of the genes and the number of alleles and so forth,
and a back-of-the-envelope calculation will tell you
there are about 10 to the 10,000th
possible humans, genetically.
That's between a googol and a googolplex.
And the number of the actual humans that have existed
is 100 billion, maybe 50 billion,
an infinitesimal fraction, so all of us,
we've won this amazing cosmic lottery.
We're here. Okay.
So what kind of reality do we want to live in?
Do we want to live in a special reality?
What if we were living in the most elegant possible reality?
Imagine the existential pressure on us
to live up to that, to be elegant,
not to pull down the tone of it.
Or, what if we were living in the fullest possible reality?
Well then our existence would be guaranteed,
because every possible thing
exists in that reality,
but our choices would be meaningless.
If I really struggle morally and agonize
and I decide to do the right thing,
what difference does it make,
because there are an infinite number
of versions of me
also doing the right thing
and an infinite number doing the wrong thing.
So my choices are meaningless.
So we don't want to live in that special reality.
And as for the special reality of nothingness,
we wouldn't be having this conversation.
So I think living in a generic reality that's mediocre,
there are nasty bits and nice bits
and we could make the nice bits bigger
and the nasty bits smaller
and that gives us a kind of purpose in life.
The universe is absurd,
but we can still construct a purpose,
and that's a pretty good one,
and the overall mediocrity of reality
kind of resonates nicely with the mediocrity
we all feel in the core of our being.
And I know you feel it.
I know you're all special,
but you're still kind of secretly mediocre,
don't you think?
(Laughter) (Applause)
So anyway, you may say, this puzzle, the mystery of existence,
it's just silly mystery-mongering.
You're not astonished at the existence of the universe
and you're in good company.
Bertrand Russell said,
"I should say the universe is just there, and that's all."
Just a brute fact.
And my professor at Columbia, Sidney Morgenbesser,
a great philosophical wag,
when I said to him, "Professor Morgenbesser,
why is there something rather than nothing?"
And he said, "Oh, even if there was nothing,
you still wouldn't be satisfied."
So — (Laughter) — okay.
So you're not astonished. I don't care.
But I will tell you something to conclude
that I guarantee you will astonish you,
because it's astonished all of the brilliant,
wonderful people I've met at this TED conference,
when I've told them, and it's this:
Never in my life have I had a cell phone.
Thank you.
(Laughter) (Applause)