Leonard Susskind · 480 pages
Rating: (7.9K votes)
“There is a philosophy that says that if something is unobservable -- unobservable in principle -- it is not part of science. If there is no way to falsify or confirm a hypothesis, it belongs to the realm of metaphysical speculation, together with astrology and spiritualism. By that standard, most of the universe has no scientific reality -- it's just a figment of our imaginations.”
“There is so much to groak; So little to groak from.”
“the three-dimensional world of ordinary experience—the universe filled with galaxies, stars, planets, houses, boulders, and people—is a hologram, an image of reality coded on a distant two-dimensional surface. This new law of physics, known as the Holographic Principle, asserts that everything inside a region of space can be described by bits of information restricted to the boundary.”
“Before World War II, when physics was primarily a European enterprise, physicists used the Greek language to name particles. Photon, electron, meson, baryon, lepton, and even hadron originated from the Greek. But later brash, irreverent, and sometimes silly Americans took over, and the names lightened up. Quark is a nonsense word from James Joyce’s Finnegan’s Wake, but from that literary high point, things went downhill. The distinctions between the different quark types are referred to by the singularly inappropriate term flavor. We might have spoken of chocolate, strawberry, vanilla, pistachio, cherry, and mint chocolate chip quarks but we don’t. The six flavors of quarks are up, down, strange, charmed, bottom, and top. At one point, bottom and top were considered too risqué, so for a brief time they became truth and beauty.”
“Tides and the 2,000-Mile Man What causes the seas to rise and fall as if they were breathing two big breaths every day? It’s the Moon, of course, but how does it do it, and why twice a day? I will explain, but first let me tell you about the fall of the 2,000-Mile Man. Imagine the 2,000-Mile Man—a giant who measures 2,000 miles from the tip of his head to the bottoms of his feet—as he falls, feet-first, from outer space toward the Earth. Far out in outer space, gravity is weak—so weak that he feels nothing. But as he gets closer to the Earth, strange sensations arise in his long body—sensations not of falling but of being stretched. The problem is not the giant’s overall acceleration toward the Earth. The cause of his discomfort is that gravity is not uniform throughout space. Far from the Earth, it is almost entirely absent. But as he draws closer, the pull of gravity increases. For the 2,000-Mile Man, this presents difficulties even while he is in free fall. The poor man is so tall that the pull on his feet is much stronger than the pull on his head. The net effect is an uncomfortable feeling that his head and feet are being pulled in opposite directions. Perhaps he can avoid being stretched by falling in a horizontal position, legs and head at the”
“Perhaps he can avoid being stretched by falling in a horizontal position, legs and head at the same altitude. Yet when the giant tries it, he finds a new discomfort; the stretching sensation is replaced by an equal feeling of compression. He feels as if his head is being pressed toward his feet. To understand why this is so, let’s temporarily imagine that the Earth is flat. Here is what it would look like. The vertical lines, together with the arrows, indicate the direction of the gravitational force—not surprisingly, straight down. But more than that, the strength of the gravitational pull is entirely uniform. The 2,000-Mile Man would have no trouble in this environment, whether he fell vertically or horizontally—not until he hit the ground anyway. But the Earth is not flat. Both the strength and the direction of gravity vary. Instead of pulling in a single direction, gravity pulls directly toward the center of the planet, like this: This creates a new problem for the giant if he falls horizontally. The force on his head and feet will not be the same because gravity, as it pulls toward the center of the Earth, will push his head toward his feet, leading to the strange sensation of being compressed. Let’s return”
“Let’s return to the question of the ocean tides. The cause of the twice-daily rising and falling of the seas is exactly the same as the cause of the 2,000-Mile Man’s discomfort: the non-uniformity of gravity. But in this case, it’s the Moon’s gravity, not the Earth’s. The Moon’s pull on the oceans is strongest on the side of the Earth facing the Moon and weakest on the far side. You might expect the Moon to create a single oceanic bulge on the closer side, but that’s wrong. For the same reason that the tall man’s head is pulled away from his feet, the water on both sides of the Earth—near and far—bulges away from it. One way to think about this is that on the near side, the Moon pulls the water away from the Earth, but on the far side, it pulls the Earth away from the water. The result is two bulges on opposite sides of the Earth, one facing toward the Moon and the other facing away. As the Earth turns one revolution under the bulges, each point experiences two high tides. The distorting forces caused by variations in the strength and direction of gravity are called tidal forces, whether they are due to the Moon, Earth, Sun, or any other astronomical mass. Can humans of normal size feel tidal forces—for example, when jumping from a diving board? No, we cannot, but only because we are so small that the Earth’s gravitational field hardly varies across the length of our bodies. Descent”
“By itself, the Holographic Principle was not enough to win the Black Hole War. It was too imprecise, and it lacked a firm mathematical foundation. The reaction to it was skepticism: The universe a hologram? Sounds like science fiction. The fictitious future physicist Steve passing to the “other side” while the emperor and the count watch him being immolated? Sounds like spiritualism.”
“one of the key features of a black hole: different observers have paradoxically different perceptions of the same events. To”
“From time to time, we hear physicists claim that Einstein didn’t understand Quantum Mechanics and therefore wasted his time with naive classical theories. I very much doubt that this is true. His arguments against Quantum Mechanics were extremely subtle, culminating in one of the most profound and most cited papers in all of physics.12 My guess is that Einstein was disturbed by the same thing that bothered the slow student. How could the ultimate theory of reality be about nothing more concrete than our own degree of surprise at the outcome of an experiment?”
“Studies have shown that we are often so worried about failure that we create vague goals, so that nobody can point the finger when we don’t achieve them. We come up with face-saving excuses, even before we have attempted anything.
We cover up mistakes, not only to protect ourselves from others, but to protect us from ourselves. Experiments have demonstrated that we all have a sophisticated ability to delete failures from memory, like editors cutting gaffes from a film reel—as we’ll see. Far from learning from mistakes, we edit them out of the official autobiographies we all keep in our own heads.”
“If we're afraid, sometimes there are things that can feed on that fear. Fear makes it worse for us. The trick is to concentrate on what you can see and stop thinking about yourself. It works every time...”
“I wore you on me at all times
Like I now carry my pen.
Unlike your own opinion my
Belongings must have a function.
You bled through the ink of my lines and
To be my subject nursed your thirst.
Was it my fault, or your own, that you forgot
—I do not deal in tender verse.”
“I can’t wait to see what I can do, now that I’m no longer standing in my own way.”
“There’s no right and wrong with feelings. There is only what there is.” She”
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