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# Presentation1 part 2 newnewnew

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### Presentation1 part 2 newnewnew

1. 1. Does White determine Hardness? So we can answer this question by using our boxes
2. 2. So –let’s send in some random electrons, and lets send them into a color box, and lets take the electrons that come out the white apparature
3. 3. So –I am going to take a piece of metal, scrape off some electrons, and then send them in
4. 4. They come out about ½ and ½, and I take those that come out the white apparature
5. 5. I want to know does-white determine hardness ? and I can do that-by sending the white electrons into the hardness box-and seeing what comes out
6. 6. Then I will find that 50% come on hard and 50% come out soft
7. 7. Then I will find that 50% come on hard and 50% come out soft
8. 8. And now –lets take the situation and reverse this
9. 9. And now –lets take the situation and reverse this You will again get 50/50
10. 10. So if you take a white electron and send it in a hardness box –you are at even odds
11. 11. And If I send a soft electron into a color box- you are still at even odds
12. 12. So-now-what we are gonna do is run so pseudo experiments –which will lead us to some more complicated experiments
13. 13. So for example-take this last experiment-take electons into color box – coming out the white apparature (some one behind you)
14. 14. The send into a Hardness box-then send the soft electron into a color box And what do you expect to happen-
15. 15. Well lets think about the logic here-anything into the hards box-must be measured to be white And we just did the experiment that if we send the electron into the hardness box 50% it comes out the hard apparature and 50% in comes out the soft apparature
16. 16. Since colors are repeatable-our prediction-is that of the electrons that are incident upon the color box-100% will come out white and 0% should come out black
17. 17. • Except that class is all wrong • We said already knowing the color does not predict the hardness-but this electron –which was previously measured to be white-is subsequently measured and sometimes it comes out white – sometimes it comes out black- 50/50 percent of the time
18. 18. • What that tells you is that you can not think of an electron that is “black” and “soft” written on it-because apparently that “black” and “soft” Is not a persistent thing
19. 19. What that tells you is that you can not think of an electron that is “black” and “soft” written on it-because apparently that “black” and “soft”Is not a persistent thing
20. 20. Meaning that once it is “black” it stays “black”-so what is going on here?
21. 21. If i would had changed the experiment-the same results would have been produced (23.28)
22. 22. So the first natural move would be to say that “there is a property of the electron that we have not measured yet?”-that determines weather it comes out the second color box “black or white” (24.09)
23. 23. So people have spent a tremendous amount of time and energy looking at the initial electrons
24. 24. And looking with great care
25. 25. Some feature which determines which port –they come out of-and the shocker is no one has every found such a property
26. 26. For Ms Walsh-the boxes are • To measure electron spin • And to measure Lx and Ly
27. 27. • The Stern–Gerlach experiment demonstrated that the spatial orientation of angular momentum is quantized. It demonstrated that atomic-scale systems have intrinsically quantum properties, and that measurement in quantum mechanics affects the system being measured. In the original experiment, silver atoms were sent through a non-uniform magnetic field, which deflected them before they struck a detector screen. Other kinds of particles can be used. If the particles have a magnetic moment related to their spin angular momentum, the magnetic field gradient deflects them from a straight path. The screen reveals discrete points of accumulation rather than a continuous distribution, owing to the quantum nature of spin. Historically, this experiment was decisive in convincing physicists of the reality of angular momentum quantization in all atomic-scale systems
28. 28. • The Stern–Gerlach experiment involves sending a beam of particles through an inhomogeneous magnetic field and observing their deflection. The results show that particles possess an intrinsic angular momentum that is closely analogous to the angular momentum of a classically spinning object, but that takes only certain quantized values. Another important result is that only one component of a particle's spin can be measured at one time, meaning that the measurement of the spin along the z-axis destroys information about a particle's spin along the x and y axis
29. 29. Spin up and spin down • https://www.khanacademy.org/science/physics/quantum- physics/quantum-numbers-and-orbitals/v/quantum-numbers
30. 30. How To Understand Quantum Superposition Yes!!!!!!!!!!!!!!!! • https://www.youtube.com/watch?v=hkmoZ8e5Qn0 • The spin of the electron is 2 different axis • So spin up (black) –in x direction (soft) • And spin down (white) – in y direction (hard)
31. 31. Goto the web site-then go to the video • Since the Pauli matrices do not commute, measurements of spin along the different axes are incompatible. This means that if, for example, we know the spin along the x-axis, and we then measure the spin along the y-axis, we have invalidated our previous knowledge of the x-axis spin. This can be seen from the property of the eigenvectors (i.e. eigenstates) of the Pauli matrices that: • https://en.wikipedia.org/wiki/Spin_(physics)#Measurement_of_spin_ along_the_x-.2C_y-.2C_or_z-axes
32. 32. https://en.wikipedia.org/wiki/Spin_(physics)#Mea surement_of_spin_along_the_x-.2C_y-.2C_or_z- axes
33. 33. Heisenberg's Uncertainty Principle Explained • https://www.youtube.com/watch?v=a8FTr2qMutA
34. 34. https://www.youtube.com/watch?v=a8FTr2q MutA
35. 35. • Other things • MIT22_02S12_midterm2010sol.pdf • http://www.phys.ufl.edu/~pjh/teaching/phy4604/tests/test3solns.pd f
36. 36. Color-up spin or down spin • Hardness- x axis or y axis