4 ms·

We can predict the behavior of a continuous signal, since it's an ongoing stream of similar events. And we can predict the averages that we can expect to see, b

We can predict the behavior of a continuous signal, since it's an ongoing stream of similar events. And we can predict the averages that we can expect to see, but for a single, individual emission of one photon, when we provoke or stimulate the emission of that photon we can't be sure EXACTLY how the photon was emitted, until it bombards the detector, and changes the detectors state. THEN we can infer from the detector, the original state. The reason it's difficult to know the precise situation of a photon, in-flight, is because it's been emitted from a moving target, whose precise state is difficult to control perfectly: a live atom. Without having perfect control of the atom that sends off the spinning, oscillating particle, we have a hard time discerning the exact circumtances of the spin/oscillation imparted upon it. We can hazard guesses, but when we're right, it's only because we get lucky. Not because we controlled it. EDIT: The reason is there are two factors driving the emission: 1. The external behavior of the electon shells 2. The internal nuclear behavior of the protons and neutrons (which do not behave simply as a clump of spherical marbles, the nucleus is it's own volatile, nebulous construct) And, oh yeah... 3. Any other random cosmological events that might sail in from outer space (literally), as fortuitous signals

FrankenPC 13y ago
Well, that makes the most sense to me. But, I've always thought this is how the universe worked. Infinitesimal forces acting on a given outcome make precision prediction impossible. I still don't get how quantum mechanics is "spooky". Maybe without a math degree I never will.
- lutusp 13y ago
  > I still don't get how quantum mechanics is "spooky". Really? Measuring a particle's state at a street corner in Columbus, Ohio instantly causes its partner particle in the Andromeda Galaxy to assume the opposite identity, isn't spooky? http://en.wikipedia.org/wiki/Quantum_entanglement http://en.wikipedia.org/wiki/Quantum_entanglement Opening a box containing a cat, a vial of poison, and a radioactive sample instantly causes the cat to become either alive or dead, where before the cat was in a superposition of states, i.e. neither alive nor dead. Not spooky? http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat > Maybe without a math degree I never will. No need for a math degree. The weirdness of quantum theories is obvious without a knowledge of advanced mathematics. "If you think you can talk about quantum theory without feeling dizzy, you haven't understood the first thing about it." -- Niels Bohr.
- qwerty_asdf 13y ago
  Mostly, there are a number of unresolved questions which seem to defy measurement and experimentation, and so instead of getting elbow deep in real world experiments, in an effort to reliably re-create outcomes (experiments that predict what will happen next, when carrying out certain steps), many practitioners of physics have had to spend entire careers "at the drawing board", concocting mathematical theories, on paper, that "add up" to the unexpected, unreliable, confusing things that happen in the real world, even when vacuums, clean rooms, and massive radiation shielding (in the form of miles-deep mine shafts beneath entire mountain ranges sometimes) fail to exert control over. Things like: https://en.wikipedia.org/wiki/Quantum_nonlocality https://en.wikipedia.org/wiki/Quantum_nonlocality (aka: spooky interactions at a distance) Quantum Non-locality seems (seems) to produce scenarios where two particles are stimulated using ostensibly unrelated mechanisms, but then also seem to exhibit cause-and-effect behavior where influencing one particle inexplicably influences the other particle, even though they may be (presumptively) incapable of influencing each other at the point in time and space when the correlating behavior is observed. How did particle A affect particle B? Did you touch it? What happened? No one touched it?! Also unexplained is the: https://en.wikipedia.org/wiki/Double-slit_experiment https://en.wikipedia.org/wiki/Double-slit_experiment This kind of interference pattern holds up, even at atomic scales, when diffracting x-rays through barriers of crystalline samples. Recently, there has been an experiment developed which may finally explain this behavior: http://web.mit.edu/newsoffice/2010/quantum-mechanics-1020.html http://web.mit.edu/newsoffice/2010/quantum-mechanics-1020.ht... http://www.youtube.com/watch?v=fnUBaBdl0Aw http://www.youtube.com/watch?v=fnUBaBdl0Aw https://en.wikipedia.org/wiki/Pilot_wave https://en.wikipedia.org/wiki/Pilot_wave ...but this would suggest that there are unseen, unmeasuable forces (from parallel dimensions?) influencing our particles in this universe, at all times, and in unexpected ways. If this is true, what does it all mean? Is the sky falling?! Who knows?! These sorts of unexplained behaviors, made physicists very nervous in the early half of the 20th century, since maybe attempts to build city destroying weapons might have horrible, unpredictable triggers or uncontrollable, world-destroying, runaway chain-reaction outcomes, never to be understood (not unlike the black hole fear mongering surrounding the LHC's publicity). Keep in mind that these ideas were kicking around before an atom bomb was anything other than science fiction. The fears and impatience often strike a chord like Dr. Emmett L. Brown's fear of a universe-destroying temporal paradox in Back to the Future.
- rprospero 13y ago
  The thing that's "spooky" about quantum mechanics is that it is NOT just infinitesimal forces causing precision to be impossible. That's more chaos than quantum. Here's a bit from my own research. I start with a neutron whose spin is pointed up. I then use magnets to bend the neutron's trajectory depending on whether it's spinning to the left or the right. Since the spinning in the up state is a linear combination of spinning in the left or right states, it just so happens that I don't know whether the neutron bends to the left or the right. For most of the neutrons, that's all I do. Another set of magnets pulls the beams back together. They get to the end of the instrument and I measure whether they're spinning up. Since I haven't done anything besides split the beam, they're all still spinning up. However, for a small fraction of the neutrons, I measure which way they bent. I know know whether it is spinning left or spinning right. Let's say it's spinning left. Well, just as spinning up is a linear combination of spinning left and right, spinning left is a linear combination of spinning up and down. Since I know that the beam is spinning left, I no longer know whether it's spinning up or down. When I measure this neutron at the end of the instrument, it only has a fifty percent chance of pointing up. This isn't a couple of photons hitting a particle and changing the velocity slightly. I've gone from all of my neutrons pointing up to only half of them pointing up. You might immediately assume that the problem is that I did something to the neutron when I measured whether it was pointing left or right. The "spooky" thing about this is that I didn't do a single thing to that neutron to measure which way it was spinning. The way I perform the measurement is that, after I split the neutron beam, I put a wall in one of the beams. The other path, however, is just the same as it was before. I haven't touched any of these neutrons. Each of these neutrons goes through the exact same fields and paths as they did in the experiment where all the neutrons were pointed up, except no half of them are pointed down. Quantum mechanics doesn't just say that you have to touch something to measure it and that will effect the outcome. It says that performing a measurement will effect the outcome, even if you don't touch it. That's where some people get spooked. ---- To preemptively answer a couple of questions: 1) No, you can't use magnets to bend neutron beams based on the Lorentz force. However, the neutron does have a magnetic moment which produces a potential with a magnetic field. This leads to an index of refraction change that causes a slight angular splitting of the neutron beam. Nothing ever gets separated by more than a micron. 2) No, I don't really put in a wall to measure just the left spinning neutrons. There's a solid material whose density fluctuations over the micro length scale serve as my effective wall. Thus, I don't actually get half the neutrons flipping at the end of the experiment, but rather a fraction proportional to how much information I get about the left right spin from my single wall.

FrankenPC 13y ago

Well, that makes the most sense to me. But, I've always thought this is how the universe worked. Infinitesimal forces acting on a given outcome make precision prediction impossible. I still don't get how quantum mechanics is "spooky". Maybe without a math degree I never will.

lutusp 13y ago
> I still don't get how quantum mechanics is "spooky". Really? Measuring a particle's state at a street corner in Columbus, Ohio instantly causes its partner particle in the Andromeda Galaxy to assume the opposite identity, isn't spooky? http://en.wikipedia.org/wiki/Quantum_entanglement http://en.wikipedia.org/wiki/Quantum_entanglement Opening a box containing a cat, a vial of poison, and a radioactive sample instantly causes the cat to become either alive or dead, where before the cat was in a superposition of states, i.e. neither alive nor dead. Not spooky? http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_cat > Maybe without a math degree I never will. No need for a math degree. The weirdness of quantum theories is obvious without a knowledge of advanced mathematics. "If you think you can talk about quantum theory without feeling dizzy, you haven't understood the first thing about it." -- Niels Bohr.
qwerty_asdf 13y ago
Mostly, there are a number of unresolved questions which seem to defy measurement and experimentation, and so instead of getting elbow deep in real world experiments, in an effort to reliably re-create outcomes (experiments that predict what will happen next, when carrying out certain steps), many practitioners of physics have had to spend entire careers "at the drawing board", concocting mathematical theories, on paper, that "add up" to the unexpected, unreliable, confusing things that happen in the real world, even when vacuums, clean rooms, and massive radiation shielding (in the form of miles-deep mine shafts beneath entire mountain ranges sometimes) fail to exert control over. Things like: https://en.wikipedia.org/wiki/Quantum_nonlocality https://en.wikipedia.org/wiki/Quantum_nonlocality (aka: spooky interactions at a distance) Quantum Non-locality seems (seems) to produce scenarios where two particles are stimulated using ostensibly unrelated mechanisms, but then also seem to exhibit cause-and-effect behavior where influencing one particle inexplicably influences the other particle, even though they may be (presumptively) incapable of influencing each other at the point in time and space when the correlating behavior is observed. How did particle A affect particle B? Did you touch it? What happened? No one touched it?! Also unexplained is the: https://en.wikipedia.org/wiki/Double-slit_experiment https://en.wikipedia.org/wiki/Double-slit_experiment This kind of interference pattern holds up, even at atomic scales, when diffracting x-rays through barriers of crystalline samples. Recently, there has been an experiment developed which may finally explain this behavior: http://web.mit.edu/newsoffice/2010/quantum-mechanics-1020.html http://web.mit.edu/newsoffice/2010/quantum-mechanics-1020.ht... http://www.youtube.com/watch?v=fnUBaBdl0Aw http://www.youtube.com/watch?v=fnUBaBdl0Aw https://en.wikipedia.org/wiki/Pilot_wave https://en.wikipedia.org/wiki/Pilot_wave ...but this would suggest that there are unseen, unmeasuable forces (from parallel dimensions?) influencing our particles in this universe, at all times, and in unexpected ways. If this is true, what does it all mean? Is the sky falling?! Who knows?! These sorts of unexplained behaviors, made physicists very nervous in the early half of the 20th century, since maybe attempts to build city destroying weapons might have horrible, unpredictable triggers or uncontrollable, world-destroying, runaway chain-reaction outcomes, never to be understood (not unlike the black hole fear mongering surrounding the LHC's publicity). Keep in mind that these ideas were kicking around before an atom bomb was anything other than science fiction. The fears and impatience often strike a chord like Dr. Emmett L. Brown's fear of a universe-destroying temporal paradox in Back to the Future.
rprospero 13y ago
The thing that's "spooky" about quantum mechanics is that it is NOT just infinitesimal forces causing precision to be impossible. That's more chaos than quantum. Here's a bit from my own research. I start with a neutron whose spin is pointed up. I then use magnets to bend the neutron's trajectory depending on whether it's spinning to the left or the right. Since the spinning in the up state is a linear combination of spinning in the left or right states, it just so happens that I don't know whether the neutron bends to the left or the right. For most of the neutrons, that's all I do. Another set of magnets pulls the beams back together. They get to the end of the instrument and I measure whether they're spinning up. Since I haven't done anything besides split the beam, they're all still spinning up. However, for a small fraction of the neutrons, I measure which way they bent. I know know whether it is spinning left or spinning right. Let's say it's spinning left. Well, just as spinning up is a linear combination of spinning left and right, spinning left is a linear combination of spinning up and down. Since I know that the beam is spinning left, I no longer know whether it's spinning up or down. When I measure this neutron at the end of the instrument, it only has a fifty percent chance of pointing up. This isn't a couple of photons hitting a particle and changing the velocity slightly. I've gone from all of my neutrons pointing up to only half of them pointing up. You might immediately assume that the problem is that I did something to the neutron when I measured whether it was pointing left or right. The "spooky" thing about this is that I didn't do a single thing to that neutron to measure which way it was spinning. The way I perform the measurement is that, after I split the neutron beam, I put a wall in one of the beams. The other path, however, is just the same as it was before. I haven't touched any of these neutrons. Each of these neutrons goes through the exact same fields and paths as they did in the experiment where all the neutrons were pointed up, except no half of them are pointed down. Quantum mechanics doesn't just say that you have to touch something to measure it and that will effect the outcome. It says that performing a measurement will effect the outcome, even if you don't touch it. That's where some people get spooked. ---- To preemptively answer a couple of questions: 1) No, you can't use magnets to bend neutron beams based on the Lorentz force. However, the neutron does have a magnetic moment which produces a potential with a magnetic field. This leads to an index of refraction change that causes a slight angular splitting of the neutron beam. Nothing ever gets separated by more than a micron. 2) No, I don't really put in a wall to measure just the left spinning neutrons. There's a solid material whose density fluctuations over the micro length scale serve as my effective wall. Thus, I don't actually get half the neutrons flipping at the end of the experiment, but rather a fraction proportional to how much information I get about the left right spin from my single wall.