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
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. Presumably, 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?
the deeper I look, the more elegance I glimpse:
“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.
There’s no better guarantee of failure than convincing yourself that success is impossible,
“This is often the way it is in physics—our mistake is not that we take our theories too seriously, but that we do not take them seriously enough.”
As soon as sailing caught on, people noticed that when ships departed over the horizon, their hulls disappeared before their sails. This gave them the idea that the surface of the ocean was curved and that Earth was spherical, just as the Sun and Moon appeared to be.
Amusingly, Christopher Columbus totally bungled this by relying on subsequent less-accurate calculations and confusing Arabic miles with Italian miles, concluding that he needed to sail only 3,700 km to reach the Orient when the true value was 19,600 km. He clearly wouldn’t have gotten his trip funded if he’d done his math right, and he clearly wouldn’t have survived if America hadn’t existed, so sometimes being lucky is more important than being right.
Please hold your hand up at arm’s length and check which things around you can be blocked from view by your pinkie. Your little finger covers an angle of about one degree, which is about double what you need to cover the Moon—make sure to check this for yourself the next time you do some lunar observing. For an object to cover half a degree, its distance from you needs to be about 115 times its size, so if you’re looking out your airplane window and can cover a 50-meter (Olympic-size) swimming pool with half your pinkie, you’ll know that your altitude is 115 × 50 m = 6 km. In the exact same way, Aristarchos calculated the distance to the Moon to be 115 times its size, which came out to be about 30 times the diameter of Earth.
I have fond memories of playing “Twinkle, Twinkle, Little Star” on my grandma Signe’s piano as a kid. As recently as 1806, when this song was first published, the line “How I wonder what you are” still resonated with many people, and nobody could honestly claim to really know the answers.
Einstein’s theory allows our 3-D space to be curved—even without it having any hidden fourth dimension for it to curve within.
So the question of what kind of space we inhabit can’t be settled from pure logic alone, as some Euclid fans had hoped. It can only be resolved by performing measurements—such as making a huge triangle in space (with light rays as edges, say) and checking whether the angles add up to 180 degrees.
The highest form of ignorance is when you reject something you don’t know anything about. —Wayne Dyer
Like most great breakthroughs in physics, Newton’s laws answered way more questions than those that prompted the discovery.
Einstein himself realized that a static infinite universe uniformly filled with matter didn’t obey his new gravity equations. So what did he do? Surely, he’d learned the key lesson from Newton to boldly extrapolate, figuring out what sort of universe did obey his equations, and then asking whether there were observations that could test whether we inhabit such a universe
Ignoring great insights is a venerable tradition in cosmology (and indeed in science more generally):
an MIT graduate student, the Belgian priest and astrophysicist Georges Lemaître,
If galaxies were just moving around at random, we’d expect about half of them to be redshifted and the rest blueshifted. Surprisingly, almost all the galaxies that Hubble studied were redshifted. Why were they all receding from us? Didn’t they like us? Did we say something wrong?
you can’t rear-end a speeding Porsche if you’re driving a Model T Ford.
the name Big Bang was coined by one of its detractors, Fred Hoyle, in an attempt to ridicule it.
Hubble’s initial measurement of the cosmic expansion predicted that our Universe was less than two billion years old, and geologists were underwhelmed by the idea that our Universe was younger than some of their rocks.
Cosmologists are often wrong, but never in doubt. —Lev Landau
These ideas met with considerable skepticism: if we’re willing to blame unexplained phenomena on entities that are both invisible and can pass through walls, shouldn’t we also start believing in ghosts while we’re at it?
If you ask a friend who’s a mechanical engineer to build a square kilometer radio dish with motors that can point it toward arbitrary sky directions, she’ll no longer be your friend. Figure 4.8: Radio astronomy on a big (background) and small (foreground) budget.
If you ask a friend who’s a mechanical engineer to build a square kilometer radio dish with motors that can point it toward arbitrary sky directions, she’ll no longer be your friend.
You want the telescope to be astronomical, not the budget!
This so-called snowflake fractal, invented by the Swedish mathematician Helge von Koch, has the remarkable property that it’s identical to a magnified piece of itself. Inflation predicts that our baby Universe was similarly indistinguishable from a magnified piece of itself, at least in an approximate statistical sense.
Andrei Linde is one of inflation’s pioneers, and has inspired me a lot. I’ll hear someone explain something and think it’s complicated. Then I’ll hear Andrei’s explanation of the same thing and realize that it’s simple when I think about it in the right way—his way.
While he was a student back in his native Ukraine, he refused a request from the KGB to testify against a fellow student who was critical of the authorities, despite being warned of “consequences.” Although he’d been admitted to physics grad school at The University of Kharkiv, the most prestigious physics program in the Soviet Union, the permission he required for moving there was never granted. Nor was he able to get any normal jobs. He spent a year struggling as a night watchman at a zoo before finally managing to leave the country. Whenever I get annoyed by a bureaucrat, thinking of Alex’s story transforms my frustration into grateful realization of how small my problems are.
In summary, students in Level I parallel universes would learn the same thing in physics class but different things in history class.
although these other parts of the Level II multiverse are in the same space as we are, they’re more than infinitely far away in the sense that we’d never reach them even if we traveled at the speed of light forever.
Another universe-creation mechanism, proposed by Lee Smolin, involves mutating and sprouting new universes through black holes rather than through inflation. This would produce a Level II multiverse as well, with natural selection favoring universes with maximal black-hole production. My friend Andrew Hamilton from Chapter 4 may have uncovered such a universe-creation mechanism: he’s investigated an instability that occurs inside black holes shortly after they form, and it may be violent enough to trigger inflation that would create a Level I multiverse—which would be entirely contained inside the original black hole, but its inhabitants would probably neither know nor care about this fact.
The main critique has shifted from “This makes no sense and I hate it” to “I hate it.”
Everything we call real is made of things that cannot be regarded as real. —Niels Bohr
De Broglie’s thesis made waves,
These discoveries by Schrödinger have been universally celebrated as among the most important achievements of the twentieth century, and they created a revolution in both physics and chemistry. But they also left people tearing their hair out in confusion: if things could be in several places at once, why did we never observe that (while sober)?
The relativity pioneer Roger Penrose quipped: “There are probably more different attitudes to quantum mechanics than there are quantum physicists.
Perhaps we Swedes have a genetic predisposition toward badmouthing our southwestern neighbors, but when I think about the Copenhagen interpretation, I just can’t get this Hamlet quote out of my mind: “Something is rotten in the state of Denmark.” THE BOTTOM LINE • Everything, even light and people, seems to be made of particles. • These particles are purely mathematical objects in the sense that their only intrinsic properties are mathematical properties—numbers with names like charge, spin and lepton number. • These particles don’t obey the classical laws of physics. • Mathematically, the state of these particles (which should perhaps be called “wavicles”) can’t be described by six numbers (representing their position and velocity), but by a wavefunction, describing the extent to which they are in different places. • This gives them properties both of traditional particles (they’re either here or there) and of waves (they can be in several places at once in a so-called superposition). • Particles aren’t allowed to be in only one place (the Heisenberg uncertainty principle), which prevents atoms from collapsing. • The future behavior of particles is described not by
Perhaps we Swedes have a genetic predisposition toward badmouthing our southwestern neighbors, but when I think about the Copenhagen interpretation, I just can’t get this Hamlet quote out of my mind: “Something is rotten in the state of Denmark.”
I found it convenient to hail from an obscure country that most people couldn’t find on the map: my nationality allowed me to be as crazy as I wanted, quickly earning the nickname “Mad Max,” and get away with it—people would give me the benefit of the doubt and assume that this was normal behavior in Sweden
Reading Everett’s book taught me a lesson not only in physics but also in sociology: I learned the importance of going back and checking the source material for yourself rather than relying on secondhand information.
I think that often, in science, the hardest part isn’t finding the right answer, but finding the right question.
If you hit on a really interesting and well-formulated physics question, then it can take on a life of its own, automatically telling you what calculation you need to do to answer it, and the rest is almost automatic: even if the math takes hours or days, it feels a lot like mechanically pulling in a fishing line to see what you’ve caught. I’d just stumbled upon one of those lucky questions.
In 2004, I visited Wojciech Zurek in Los Alamos and discovered one of the most amazing perks of being a scientist: you get invited to visit exotic places where you spend all your time talking with fascinating people—and you get to call it work!
some scientists have elevated it to almost sacred status, and the great astrophysicist Sir Arthur Eddington had this so say: “The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell’s equations—then so much the worse for Maxwell’s equations. If it is found to be contradicted by observation—well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation
If you’re now convinced that Everett is right and bring a friend to witness your experiment, then there’s a twist, however. Whereas you stay alive in only one parallel universe, she remains present in all of them, and typically sees you die after a few seconds. So the only thing you might succeed in convincing her of is that you were a mad scientist.
can you think of all potentially lethal events in nature as quantum-suicide experiments, so that you should expect subjective immortality? You can answer this question with a simple experiment: wait and see! If one day, after a long sequence of seemingly unlikely coincidences, you find yourself to be the oldest
can you think of all potentially lethal events in nature as quantum-suicide experiments, so that you should expect subjective immortality? You can answer this question with a simple experiment: wait and see! If one day, after a long sequence of seemingly unlikely coincidences, you find yourself to be the oldest living person on Earth, then that pretty much settles it!
As the ancient Greeks replaced myth-based explanations with mechanistic models of the Solar System, their emphasis shifted from asking why to asking how.
in the spirit of Pascal’s Wager, my advice is that you should live life to its fullest and do novel and interesting things. That way, in case you’re a simulation, whoever created you will be less likely to get bored and switch you off.…
The dark energy makes our Universe expand much more slowly than during inflation, so the temperature it provides is merely a millionth of a trillionth of a trillionth (10−30) of a degree above absolute zero. This is hardly balmy, even by Swedish standards,
I’ve drawn a question mark at the center of the triangle to suggest that the three vertices (mathematical structures, formal systems and computations) are simply different aspects of one underlying transcendent structure whose nature we still don’t fully understand. This structure (perhaps restricted to the defined/decidable/halting part as per the CUH) exists “out there” in a baggage-free way, and is both the totality of what has mathematical existence and the totality of what has physical existence.
we physicists traditionally call the regularities that we understand “laws” and dismiss much of what we don’t understand as “initial conditions.”