What's the Ultimate Question‏

Our Mathematical Universe
Max Tegmark

Part One: Zooming Out

1 What is Reality

• What's the Ultimate Question

For as long as our humans ancestors
have walked the Earth,
they've undoubtedly wondered
what reality is all about,
pondering deep existential questions.

Where did everything came from?
How will it all end?
How big is it all?

These questions are so captivating
that virtually all human cultures
across the globe have grappled with them
and passed on answers 
from generation to generation,
in the form of elaborate creation myths,
legends and religious doctrines.


• Is our Universe infinitely old?

Yes: Hinduism, Buddhism,

No: Ahmadiyya, Apache, Aztec, Babylonian,
Bahai, Christianity, Egyptian, Greek, Hopi,
Islam, Judaism, Maya, Norse, Rastafarian,
Sumerian, Zoroastrian.

• Will our Universe last forever?

Yes: Buddhism, Greek, Hinduism, Norse, Zoroastrian.

No: Ahmadiyya, Apache, Aztec, Babylonian,
Bahai, Christianity, Egyptian, Hopi,
Islam, Judaism, Maya, Rastafarian,

• Are there other universes?

Yes: Hinduism

No: Ahmadiyya, Apache, Aztec, Babylonian,
Bahai, Buddist, Christianity, Egyptian, Greek, Hopi, Islam, Judaism, Maya, Norse, Rastafarian, Sumerian, Zoroastrian.

• If something created our Universe,
then what was it?

God/gods: Apache, Aztec, Babylonian,
Christianity, Hopi, Islam, Judaism,
Maya, Sumerian, Zoroastrian.

Egg: Egyptian, Finnish, Greek,
Hinduism, Taoism.

Elements:  Mesopotamiam, 
Egyptian (water), Norse (fire/ice).

Many cosmological questions
that we'll tackle in this book
have fascinated thinkers
throughout the ages,
but no global consensus has emerged.

The classification above
is based on a 2011 presentation
by MIT student David Hernández
for my cosmological class.

Because such simplistic taxonomies
are strictly impossible,
they should be taken  with a grain of salt:
many religions have multiple branches
and interpretations, and some fall
into multiple categories.

For example, Hinduism contains aspects 
of all three creation options shown:
according to one legend, 
both the creation god Brahma
and our Universe emerged
from an egg, which in turn
may have originated from water.


Other big questions 
tackled by ancient cultures
are at least as radical.

What is real?
Is there more to reality than meets the eye?

Yes! Was Plato's answer over two millenia ago.

In his famous cave analogy,
he likened us to people 
who'd lived their entire lives
shackled in a cave,
facing a blank wall,
watching the shadows
cast by things
passing behind them,
and eventually coming
to mistakenly believe
that these shadows
were the full reality.

Plato argued that
what we humans call
our everyday reality
is similarly just 
a limited and distorted 
of the true reality,
and that we must 
free oursrelves
from our mental shackles
to begin comprehending it.

If my life as a physicist
has taught me anything at all,
it's that Plato was right:
modern physics 
has made abundantly clear
that the ultimate nature of reality
isn't what it seems.

But if reality isn't 
what we thought it was,
then what is it?

What's the relation between 
the internal reality of our mind 
and the external reality?

What's everything ultimately made of?

How does it all work?  Why?

Is there a meaning to it all,
and if so, what?

As Douglas Adams put it
in his science fiction spoof
The Hitchhiker's Guide to the Galaxy:

«What's the answer to the ultimate question
of life, the universe, and everything?»

Thinkers throughout the ages
have offered a fascinating spectrum
of responses to the question
«What is reality?»
-either attempting to answer it
or attempting to dismiss it.

Here are some examples
(this list makes no claims to be complete,
and not alternatives are mutually exclusive).

This book (and indeed my scientific career)
is my personal attempt to tackle this question.

Part of the reason 
that thinkers have offered 
such a broad spectrum of answers
is clearly that they've chosen 
to interpret the question in different ways, 
so I owe you an explanation of how 
I interpret it and how I approach it.

The word reality can have 
many different connotations.

I use it to mean 
the ultimate nature of 
the outside physical world
that we're part of,
and I'm fascinated
by the quest 
to understand it better.

So what's my approach?

One evening back in high school,
I started reading Agatha Christie's
detective novel Death on the Nile.

Although I was painfully aware
that my alarm clock would go off
at seven a.m., I couldn't for the life of me
put it down until the mystery 
had been solved, around four a.m.

I've been inexorably drawn
to detective stories ever since I was a kid,
and when I was around twelve,
I started a detective club
with my classmates Andreas Bette,
Matthias Bothner and Ola Hansson.

We never captured criminals,
but the idea of solving mysteries
captured my imagination.

To me, the question «What is reality?»
represents the ultimate detective story,
and I consider myself incredibly fortunate
to be able to spend so much of my time pursuing it.

In the chapters ahead, 
I'll tell you about other occasions
when my curiosity has kept me up
in the wee hours of the morning,
totally unable to stop reading
until the mystery was resolved.

Except that I wasn't reading a book,
but what my hand was writing,
and what I was writing
was a trail of mathematical equations
that I knew would ultimately
lead me to an answer.


Some Responses to «What is Reality?»

• The question has a meaningful answer.

- Elementary particles in motion
- Earth, wind, fire, air and quintessence
- Atoms in motion
- Elementary particles in motion
- Strings in motion
- Quantum fields in curved spacetime
- M-theory (substitute your favorite capital letter…)
- A divine creation
- A social construct
- A neurophysiological construct
- A dream
- Information
- A simulation (à la The Matrix)
- A mathematical structure
- The Level IV Multiverse

• The question lacks a meaningful answer.

- There is a reality, but we humans 
   can't fully know it: we have no access 
   to what Immanuel Kant called «das Ding an sich.» 
   The thing in itself. (La cosa en sí. )
- Reality is fundamentally unknowable.
- Not only don't we know it,
   but we couldn't express it if we did.
- Science is nothing but a story (postmodern 
  answer by Jacques Derrida and others).
- Reality is all in our head (constructivist answer).
- Reality doesn't exist (solipsism).

I'm a physicist, 
and I'm taking a physics approach
to the mysteries of reality.

To me, this means starting
with great questions such as
«How big is our Universe?»
and «What's everything made of?»
and treating them exactly
like detective mysteries:
combining clever observations
and reasoning and persistently
following each clue wherever it leads.

No hay comentarios:

Publicar un comentario