In Search of Schrödinger's Cat: Quantum Physics and Reality
by John Gribbin
22 popular highlights from this book
Key Insights & Memorable Quotes
Below are the most popular and impactful highlights and quotes from In Search of Schrödinger's Cat: Quantum Physics and Reality:
“In the world of the very small, where particle and wave aspects of reality are equally significant, things do not behave in any way that we can understand from our experience of the everyday world...all pictures are false, and there is no physical analogy we can make to understand what goes on inside atoms. Atoms behave like atoms, nothing else.”
“...the best things in science are both beautiful and simple, a fact that all too many teacher conceal from their students, by accident or design.”
“Nothing is real unless it is observed”
“...true story of quantum mechanics, a truth far stranger than any fiction.”
“Sir Arthur Eddington summed up the situation brilliantly in his book The Nature of the Physical World, published in 1929. "No familiar conceptions can be woven around the electron," he said, and our best description of the atom boils down to "something unknown is doing we don't know what".”
“It isn't just that Bohr's atom with its electron "orbits" is a false picture; all pictures are false, and there is no physical analogy we can make to understand what goes on inside atoms. Atoms behave like atoms, nothing else.”
“...there is no underlying reality to the world. "Reality," in the everyday sense, is not a good way to think about the behavior of the fundamental particles that make up the universe; yet at the same time those particles seem to be inseparably connected into some invisible whole, each aware of what happens to the others.”
“It is better to debate a question without settling it than to settle a question without debating it.”
“There is no absolute truth at the quantum level”
“In 1906, J. J. Thomson had received the Nobel Prize for proving that electrons are particles; in 1937 he saw his son awarded the Nobel Prize for proving that electrons are waves. Both father and son were correct, and both awards were fully merited.”
“Every problem in quantum physics had to be first “solved” using classical physics, and then be reworked by the judicious insertion of quantum numbers more by inspired guesswork than cool reasoning.”
“Heisenberg's uncertainty relation measures the amount by which the complementary descriptions of the electron, or other fundamental entities, overlap. Position is very much a particle property - particles can be located precisely. Waves, on the other hand, have no precise location, but they do have momentum. The more you know about the wave aspect of reality, the less you know about the particle, and vice versa. Experiments designed to detect particles always detect particles; experiments designed to detect waves always detect waves. No experiment shows the electron behaving like a wave and a particle at the same time.”
“If the business of physics is ever finished, the world will be a much less interesting place in which to live . . .”
“The one sure thing we know about the quantum world is not to trust our common sense and only to believe things we can see directly or detect unambiguously with our instruments. We don't know what goes on inside a box unless we look.”
“whole universe can be thought of as a delayed-choice experiment in which the existence of observers who notice what is going on is what imparts tangible reality to the origin of everything. Following”
“Motion in space can proceed in any direction and back again. Motion in time only proceeds in one direction in the everyday world, whatever seems to be going on at the particle level. It’s hard to visualize the four dimensions of spacetime, each at right angles to the other, but we can leave out one dimension and imagine what this strict rule would mean if it applied to one of the three dimensions we are used to. It’s as if we were allowed to move either up or down, either forward or back, but that sideways motion was restricted to shuffling to the left, say. Movement to the right is forbidden. If we made this the central rule in a children’s game, and then told a child to find a way of reaching a prize off to the right-hand side (“backward in time”) it wouldn’t take too long for the child to find a way out of the trap. Simply turn around to face the other way, swapping left for right, and then reach the prize by moving to the left. Alternatively, lie down on the floor so that the prize is in the “up” direction with reference to your head. Now you can move both “up” to grasp the prize and “down” to your original position, before standing up again and returning your personal space orientation to that of the bystanders.* The technique for time travel allowed by relativity theory is very similar. It involves distorting the fabric of space-time so that in a local region of space-time the time axis points in a direction equivalent to one of the three space directions in the undistorted region of space-time. One of the other space directions takes on the role of time, and by swapping space for time such a device would make true time travel, there and back again, possible. American mathematician Frank Tipler has made the calculations that prove such a trick is theoretically possible. Space-time can be distorted by strong gravitational fields,and Tipler’s imaginary time machine is a very massive cylinder, containing as much matter as our sun packed into a volume 100 km long and 10 km in radius, as dense as the nucleus of an atom, rotating twice every millisecond and dragging the fabric of space-time around with it. The surface of the cylinder would be moving at half the speed of light. This isn’t the sort of thing even the maddest of mad inventors is likely to build in his backyard, but the point is that it is allowed by all the laws of physics that we know. There is even an object in the universe that has the mass of our sun, the density of an atomic nucleus, and spins once every 1.5 milliseconds, only three times slower than Tipler’s time machine. This is the so-called “millisecond pulsar,” discovered in 1982. It is highly unlikely that this object is cylindrical—such extreme rotation has surely flattened it into a pancake shape. Even so, there must be some very peculiar distortions of space-time in its vicinity. “Real” time travel may not be impossible, just extremely difficult and very, very unlikely. That thin end of what might be a very large wedge may, however, make the normality of time travel at the quantum level seem a little more acceptable. Both quantum theory and relativity theory permit time travel, of one kind or another. And anything that is acceptable to both those theories, no matter how paradoxical that something may seem, has to be taken seriously. Time travel, indeed, is an integral part of some of the stranger features of the particle world, where you can even get something for nothing, if you are quick about it.”
“in 1906, ill and depressed, unhappy about the continuing opposition of many leading scientists to this kinetic theory of gases, he killed himself,”
“Une with diffraction, just as if we let a thousand”
“Nothing is real unless we look at it, and it ceases to be real as soon as we stop looking.”
“The electrons not only know whether or not both holes are open, they know whether or not we are watching them, and they adjust their behaviour accordingly.”
“single electron, or a single photon, on its way through one hole in the wall, obeys the statistical laws which are only appropriate if it ‘knows’ whether or not the other hole is open. This is the central mystery of the quantum world.”
“...it is not the way of science to sit idly back and hope that someone will come up with a "better" answer to our problems. In the absence of a better answer, we have to face up to the implications of the best answer we've got.”
