|Oct9-10, 12:20 PM||#1|
Einstein against Quantum theory
Im currently reading Entanglement by Amir D. Aczel. It explains the arguments for and against quantum theory at the Solvay Conference in 1930. At the conference Einstein told Bohr that he could refute the uncertainty principle for energy and time. Einstein said he designed a box with an opening in one of its walls, where a door is placed, controlled by a clock inside the box. The box is filled with radiation and weighed. The door is opened for a split second, allowing one photon to escape. The box is weighed again, from the weight difference, one can deduce the energy of the photon and thus can determine the photons energy and the time of its passage(refuting the uncertainty principle). The way Bohr found a flaw was to say that Einstein failed to account for the fact that weighing the box amounts to observing its displacement within the gravitational field. The imprecision in the displacement of the box generates an uncertainty in the determination of the mass-and hence the energy-of the photon. When the box is displaced, so is the clock inside it. It now ticks in a gravitational field that is slightly different from before. Can someone please help me understand Bohrs answer because Im having a hard time understanding why Einsteins contraption couldnt work? Why is the box displaced when you weigh it the second time?
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|Oct9-10, 01:53 PM||#2|
On a historic aside, I believe the principal source of this anecdote is Bohr's book "Discussions with Einstein ...", where Bohr's description of the discussion is less adversarial, noting "Einstein himself contributed effectively" to resolving the challenge. If your book doesn't have an illustration, it might help to look at the one from Bohr's book, reproduced here.
So you have this box on a scale, and to measure its mass, you're measuring its displacement on this scale. The idea is that due to the clock, you can know exactly when the photon left the box. The crux is that this will accelerate the box in the gravitational field, which due to GR, will dilate the time of the clock. When you put this time-dilation together with the momentum-position uncertainty and E=mc^2, you get back the time-energy uncertainty relation.
|Oct9-10, 02:08 PM||#3|
Is it time that is accelerating the box in the gravitational field or is it the fact that you are trying to measure this time itself. I hope this makes sense.
|einstein, entanglement, quantum theory|
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