Our Mathematical Universe
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.
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.
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!
«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
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
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
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.
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?)
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
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?)
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?)
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
11. Extremely Controversial
12. Extremely Controversial
A fascinating journey awaits us.