The Journey Begins...

Our Mathematical Universe

Max Tegmark

Part One: Zooming Out

1 What is Reality

The Journey Begins

A physics approach?

Isn't that a great way

to turn something exciting

into something boring?

When the person sitting next to me

on a plane asks what I do,

I have to options.

If I feel like talking,

I'll say, «Astronomy,»

which infallibly triggers

an interesting conversation.

[This conversation sometimes begins:

«Oh, astrology! I'm a Virgo.»

When I've instead given

the more precise answer «Cosmology,»

I've gotten answers such as

«Oh, cosmetology!»- with follow-up

questions about eyeliner and mascara.]

If I don't, I'll say, «Physics»,

at which point they typically say

something like «Oh, that was

my worst subject in high school,»

and leave me alone for the rest of the flight.

Indeed, physics was also

my least-favorite subject in high school.

I still remember my very first physics class.

With a monotonous and sedative voice,

our teacher announced that 

we were going to learn about density.

That density was mass divided by volume.

So if the mass was blah 

and the volume was blah,

then we could calculate

that the density was blah blah.

After that point, 

all I remember is a big blur.

And that whenever 

his experiments failed,

he'd blame humidity and say,

«It worked this morning.»

And that some friends of mine

couldn't figure out why their experiment

wasn't working until they discovered

that I'd mischievously attached

a magnet underneath their oscilloscope.

When the time came to apply for college,

I decided against physics

and other technical fields, and ended up 

at the Stockholm School of Economics,

focusing on environmental issues.

I wanted to do my small part

to make our planet a better place,

and felt that the main problem

wasn't that we lacked technical solutions,

but that we didn't properly use

the technology we had.

I figured that the best way

to affect people's behavior

was through their wallets,

and was intrigued by the idea

of creating economic incentives

that aligned individual egoism

with the common good.

Alas, 

I soon grew disillusioned,

concluding that economics

was largely a form

of intellectual prostitution

where you got rewarded 

for saying what the powers,

that be, wanted to hear.

Whatever 

a politician wanted to do,

he or she could find 

an economist as advisor 

who had argued

for doing precisely that.

Franklin Delano Roosevelt

wanted to increase goverment spending,

so he listened to John Maynard Keynes,

whereas Ronald Reagan wanted

to decrease goverment spending,

so he listened to Milton Friedman.

Then my classmate, Johan Oldhoff,

gave me the book that changed everything:

Surely You're Joking, Mr. Feynman!

I never got to meet Richard Feynman,

but he's the reason I switched to physics.

Although the book wasn't really about physics,

dweling more on topics such as how to pick locks

and how to pick up women, I could read

between the lines that this guy just loved physics.

Which really intrigued me.

If you see a mediocre-looking guy

walking arm in arm with a gorgeous woman,

you probably wonder if you're missing something.

Presumable, she's seen 

some hidden quality in him.

Suddenly I felt 

the same way about physics:

what did Feynman see 

that I'd missed in high school?

I just had to solve this mystery,

so I sat down with volume 1 of

The Feynman Lectures on Physics,

whch I found in Dad's bookcase,

and started reading:

«If, in some cataclysm,

all of scientific knowledge

were to be destroyed,

and only one sentence passed

on to the next generation of creatures,

what statement would contain

the most information in the fewest words?»

Whoa-this guy was nothing like

my high-school physics teacher!

Feynman continued:

«I believe it is that […]

all things are made

of atom-little particles

that move around

in perpetual motion,

attracting each other

when they are 

a little distance apart

but repelling upon

being squeezed 

into one another.»

A lightbulb went off in my head.

I read on and on and on, spellbound.

I felt like I was having

a religious experience.

I finally got it!

I had the epiphany that explained

what I'd been missing all along,

and what Feynman had realized:

physics is the ultimate intellectual adventure,

the quest to understand 

the deepest mysteries of our Universe.

Physics doesn't take 

something fascinating

and make it boring.

Rather, it helps us 

see more clearly,

adding to the beauty and wonder

of the world around us.

When I bike to work in the fall,

I see beauty in the trees

tinged with red, orange and gold.

But seeing these trees

through the lens of physics

reveals even more beauty,

captured by Feynman's quote

that opens this chapter.

And the deeper I look,

the more elegance I glimpse:

we'll see in Chapter 3 

how the trees ultimately

come from stars,

and we'll see in Chapter 8

how studying their building blocks

suggests their existence

in parallel universes.

At this time, 

I had a girlfriend studying physics 

at the Royal Institute of Technology,

and her textbooks seemed 

so much more interesting than mine.

Our relationship didn't last,

but my love for physics did.

Since college was free in Sweden,

I enrolled in her university 

without telling the Stockholm 

School of Economics administrators

about my secret double life.

My detective investigation

had officially begun,

and this book is my report

a quarter of a century later.

So what is reality, then?

My goal with 

this audaciously titled chapter

isn't to arrogantly try to sell you

on an ultimate answer

(although we explore 

intriguing possibilities

in the last part of the book),

but rather to invite you along

on my personal journey of exploration,

and to share with you 

my excitemente and reflections

about these mind-expanding mysteries.

Like me, 

I think you'll conclude

that whatever reality is,

it's wildly different 

from what we once thought,

and a fascinating enigma

at the very heart 

of our everyday lives.

I hope you will, like me,

find this places everyday problems

such as parking tickets and heartaches

in a refreshing perpective,

making it easier to take them in stride 

and focus on enjoying life

and its mysteries to the fullest.

When I first discussed my ideas

for this book with John Brockman,

now my book agent, he gave me

clear marching orders:

«I don't want a textbook

-I want your book.»

So this book 

is a scientific autobiography of sorts:

although it's more about physics

than it's about me, it's certainly

not your standard popular science book

that attempts to survey physics

in an objective way,

reflecting the community consensus

and giving equal space

to all opposing viewpoints.

Rather, it's my personal quest

for the ultimate nature of reality,

which I hope you'll enjoy

seeing through my eyes.

Together, we'll explore the clues

that I personally find the most fascinating,

and try to figure out what it all means.

We'll begin our journey

by surveying how

the whole context 

of the question

«What is Reality?»

has been transformed

by recent scientific breakthroughs,

with physics shedding new light

on our external reality

from the largest (Chapters 2-6)

to the smallest (Chapters 7-8) scales.

In Part I of the book,

we'll pursue the question

«How big is our Universe?»

and seek its ultimate conclusion

by traveling out 

to ever-larger cosmic scales,

exploring both our cosmic origins

and two types of parallel universes,

finding hints that space is

in a sense mathematical.

In Part II of the book,

we'll relentlessly pursue the question

«What's everything made of?»

by journeying into the subatomic microcosm,

examining a third kind of parallel universe

and finding hints that 

the ultimate building blocks of matter

are also in a sense mathematical.

In Part III of the book,

we'll take a step back

and consider what all this might mean

for the ultimate nature of reality.

We'll begin by arguing that

our failure to understand consciousness

doesn't stand in the way

of a complete understanding

of the external physical reality.

We'll then delve into my most 

radical and controversial idea:

that the ultimate reality

is purely mathematical,

demoting familiar notions

such as randomness, complexity,

and even change to the status of illusions,

and implying that there's a fourth

and ultimate level of parallel universes.

We'll wrap up our journey 

in Chapter 13 by returning home, 

exploring what this all means 

for the future prospects

of life in our Universe,

for us humans

and for you personally.

You'll find our travel planner

in the following with my reading tips.

_______

How to read this book.

If you've read lots 

of modern popular-science books

and feel that you already understand

curve space, our Big Bang,

the cosmic microwave background,

dark energy, quantum mechanics, etc.,

then you may consider skipping

Chapters 2, 3, 4 and 7

after reviewing the «Bottom Line»  boxes

that follow them.

If you are a professional physicist,

you might consider skipping

Chapter 5 as well.

But many concepts that

may sound familiar

are startling subtle,

and if you can't answer 

all of questions 1-16 in Chapter 2,

I hope you'll learn 

from the early material as well

and see how the later chapters

logically build on it.

Zooming Out - Chapters 1-6

(What is reality on the largest scales?)

Chapter Title

1. What is Reality?

2. Our Place in Space

3. Our Place in Time

4. Our Universe by Numbers

5. Our Cosmic Origins

6. Welcome to the Multiverse

Focus of the Chapter

1. Introduction

2. How big is space?

3. History of our Universe

4. Precision cosmology

5. Cosmological inflation

6. Level I and II parallel universes

Zooming In - Chapters 7-8

(What is reality on the smallest scales?)

Chapter Title

7. Cosmic Legos

8. The Level III Multiverse

Focus of the Chapter

7. Quantum mechanics

8. Quantum parallel universes

Stepping Back - Chapters 9-12

(Is reality math?)

Chapter Title

  9. Internal and External Reality

10. Physical and Mathematical Reality

11. Is Time an Illusion?

12. The Level IV Multiverse

Focus of the Chapter

  9. The role of consciousness

10. The «reality is math» idea

11. Making sense of it

12. The ultimate multiverse

Title of the Chapter

13.  Life, Our Universe and Everything

Focus of the Chapter

13. Future of Universe and humanity

Status of Each Chapter

  1.  Mainstream

  2.  Mainstream

  3.  Mainstream

  4.  Mainstream

  5.  Mainstream

  6.  Controversial

  7.  Mainstream

  8.  Controversial

  9.  Controversial

11.  Extremely Controversial

12.  Extremely Controversial

13.  Controversial

______

A fascinating journey awaits us.

Let's begin!