Something Deeply Hidden Sözleri ve Alıntıları
Something Deeply Hidden sözleri ve alıntılarını, Something Deeply Hidden kitap alıntılarını, Something Deeply Hidden en etkileyici cümleleri ve paragragları 1000Kitap'ta bulabilirsiniz.Hidden variables
But Bell’s theorem implies that any such theory requires “action at a distance”—a measurement at one location can instantly affect the state of the universe arbitrarily far away. This seems to be in violation of the spirit if not the letter of the theory of relativity, which says that objects and influences cannot propagate faster than the speed of light. The hidden-variable approach is still being actively pursued, but all known attempts along these lines are ungainly and hard to reconcile with modern theories such as the Standard Model of particle physics, not to mention speculative ideas about quantum gravity, as we’ll discuss later. Perhaps this is why Einstein, the pioneer of relativity, never found a satisfactory theory of his own.
When you perform a measurement, such as the position or spin of a particle, quantum mechanics says there are only certain possible results you will ever get. You can’t predict which of the results it will be, but you can calculate the probability for each allowed outcome.
Superposition
So what we really have is a superposition of all possible combinations of where the electron might have been located, and where the camera actually observed it to be.
Quantum mechanics isn’t magic. It is the deepest, most comprehensive view of reality we have. As far as we currently know, quantum mechanics isn’t just an approximation of the truth; it is the truth.
Quantum systems are described by wave functions rather than by positions and velocities. Just as Newton’s laws of motion govern the evolution of the state of a system in classical mechanics, there is an equation that governs how wave functions evolve, called Schrödinger’s equation. We can express Schrödinger’s equation in words as: “The rate of change of a wave function is proportional to the energy of the quantum system.”
On the other hand, in the memorable words of Richard Feynman, “I think I can safely say that nobody understands quantum mechanics.” We use quantum mechanics to design new technologies and predict the outcomes of experiments. But honest physicists admit that we don’t truly understand quantum mechanics.
One of the themes in this book is that quantum mechanics doesn’t deserve the connotation of spookiness, in the sense of some ineffable mystery that it is beyond the human mind to comprehend. Quantum mechanics is amazing; it is novel, profound, mind-stretching, and a very different view of reality from what we’re used to. Science is like that sometimes. But if the subject seems difficult or puzzling, the scientific response is to solve the puzzle, not to pretend it’s not there. There’s every reason to think we can do that for quantum mechanics just like any other physical theory.
To put things most pointedly: Why do quantum systems evolve smoothly and deterministically according to the Schrödinger equation as long as we aren’t looking at them, but then dramatically collapse when we do look? How do they know, and why do they care?
There is no such thing as “the position of the electron.” There is only the electron’s wave function. Quantum mechanics implies a profound distinction between “what we can observe” and “what there really is.” Our observations aren’t revealing pre-existing facts of which we were previously ignorant; at best, they reveal a tiny slice of a much bigger, fundamentally elusive reality.
Copenhagen interpretation
In a modern university curriculum, when physics students are first exposed to quantum mechanics, they are taught some version of these five rules. The ideology associated with this presentation—treat measurements as fundamental, wave functions collapse when they are observed, don’t ask questions about what’s going on behind the scenes—is sometimes called the Copenhagen interpretation of quantum mechanics. But people, including the physicists from Copenhagen who purportedly invented this interpretation, disagree on precisely what that label should be taken to describe. We can just refer to it as “standard textbook quantum mechanics.”
The world is a wave function, nothing more nor less. We can use the phrase “quantum state” as a synonym for “wave function,” in direct parallel with calling a set of positions and velocities a “classical state.”
Even if we think an electron wave function is a diffuse cloud centered on the nucleus, when we actually look at it we don’t see such a cloud, we see a point-like particle at some particular location. And if we look immediately again, we see the electron in basically the same location. There’s a good reason why the pioneers of quantum mechanics invented the idea of wave functions collapsing—because that’s what they appear to do.
On the one hand, quantum mechanics is the heart and soul of modern physics. Astrophysicists, particle physicists, atomic physicists, laser physicists—everyone uses quantum mechanics all the time, and they’re very good at it. It’s not just a matter of esoteric research. Quantum mechanics is ubiquitous in modern technology. Semiconductors, transistors, microchips, lasers, and computer memory all rely on quantum mechanics to function. For that matter, quantum mechanics is necessary to make sense of the most basic features of the world around us. Essentially all of chemistry is a matter of applied quantum mechanics. To understand how the sun shines, or why tables are solid, you need quantum mechanics.