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I thought the act of observation was what caused the uncertainty. But it appears to me that you’re saying that may not be the case. Could you please enlighten m
by wadkar 9y ago
I thought the act of observation was what caused the uncertainty. But it appears to me that you’re saying that may not be the case. Could you please enlighten me? What causes the uncertainty if not the act of measurement (observation?)
Do the two terms, observation and measurement have different meaning? Could you please explain me the difference? Thanks much!
- QAPereo 9y agoA really good way to get an intuitive grasp is to spend some time getting a handle on quantum tunneling.
- wadkar 9y agoI do happen to know quantum tunneling a bit. I had the fortune to use a electronic tunnel microscope to observe the surface of gold (Ag) surface. But I can’t seem to “intuitively grasp” it
- QAPereo 9y agoThe electron’s wavefunction isn’t localized like the classical “billiard ball” and has a nonzero chance of being on the other side of a barrier. The truth is that it has a nonzero chance of being on the other side of the galaxy, albeit a much lower chance than tunneling across a microscopic barrier. In macroscopic terms, the only way you could pin the thing down is by stopping it cold (in microscopic terms, you’d detect it by interacting with it, a la a photon detector). This isn’t just a matter of equipment you use to detect the electron, or photon, or anything with an apparent de Broglie wavelength. It really is a matter of the electron existing with some level of uncertainty regarding correlated variables like position and momentum. Mind you At high energy’s macroscopic objects will display characteristic wavelength, and be obviously subject to the same uncertainty. It’s just that in our universe, in our lives, we live at very large scales and low energies compared to an electron.
- marcosdumay 9y agoFundamental uncertainty is indeed caused by different observations "interfering with each other. And that interference is only inevitable because of the observer effect. It's kind of meaningless to claim that observation is the cause of the uncertainty, but I do think you are on the right path. Still, even being related, the observer effect and the fundamental uncertainty are different concepts. For example, observations may not interfere at all, but they would still change your system.
- wadkar 9y agoErr, I must confess this is confusing to me. On one hand the GP stated that observation and the “inference” or the uncertainty are two different phenomena. But you seem to suggest otherwise. Did I get something wrong here?
- marcosdumay 9y agoThey are different, but related. Observation effect is: when you observe a characteristic of an object, you change that object on a way that what you observed (that was one of some possibilities) is now the only possibility. Uncertainty is: there are some characteristics that when you observe one of them, you change the others invalidating any previous measurement.
- QAPereo 9y agoUncertainty doesn’t require observation, you may be thinking of perturbation?
- akvadrako 9y agoFundamental uncertainty has nothing to do with observations - it's inherit in the physical/mathematical representation of a state as explained by the comment above yours.
- marcosdumay 9y agoHum... Uncertainty is not about states, it is about observables. It is a characteristic of the Universe that you can't measure momentum and position with perfect accuracy, it does not matter what state the stuff you are measuring is in. And it happens because observing momentum messes with the objects position, and the other way around.
- hackinthebochs 9y agoThe physics is really a distraction when it comes to understanding the origin of the uncertainty principle. The uncertainty principle in physics is really due to the mathematics of whats called conjugate variables. Consider a particle moving through space. You observe the point particle at some instantaneous time. Since you've only observed one instance in time, the frequency content of the path the particle carves out could be anything. That is to say, the observed position is consistent with all possible frequencies so you can't rule anything out yet. As you expand the time window of your observation, the set of possible corresponding frequencies shrinks. The longer you observe, the more you can hone in on the frequency of the particle. It's like how astronomers have to observe an asteroid over a long period of time to be certain of its trajectory. But what if you asked where exactly the frequency f of the particle occurred? At what point was the frequency exactly f? The problem is you needed to observe the particle over a period of time to confidently determine the frequency f, and so you no longer can give a precise location of where f occurred. Frequency and position are conjugate variables: as you learn one more precisely, you necessarily lose precision in your knowledge of the other one.
- emerged 9y agoThis was by far the most concise and easily understood description of the uncertainty principle I've heard.