Confused at a Higher Level

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About some problems in quantum mechanics& quantum electrodynamics; arguably one of the funniest talks ever given about QED.

Published in: Technology, Spiritual
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Confused at a Higher Level

  1. 1. Confused at a Higher Level •  "Before I came here I was confused about this subject. Having listened to your lecture I am still confused. But on a higher level." - Enrico Fermi
  2. 2. Two clouds on horizonBlack body radiation Properties of light
  3. 3. Black body radiation
  4. 4. Atoms
  5. 5. Paradox #1: Double-slit paradox •  How can you be in two places at once when you aren’t anywhere at all? - Firesign Theater
  6. 6. Double slit
  7. 7. Bullets and waves
  8. 8. Delayed choice
  9. 9. Quantum eraser
  10. 10. Delayed choice & quantum eraser
  11. 11. Six Blind Men & the Elephant
  12. 12. Shut up andcalculate
  13. 13. Collapse
  14. 14. Many worlds
  15. 15. Paradox #2: Infinite means zeroQuantum electrodynamics continuously tosses up quantities which are:1) Infinite2) Really small (but o*en measurable)
  16. 16. Lamb shi*
  17. 17. Renormalization
  18. 18. But tiny
  19. 19. Casimir effect, classical
  20. 20. Casimir effect, quantum
  21. 21. Infinite and tiny•  ``It appears therefore that the theory as it stands now must be strangely near to the final solution, yet it cannot possibly be correct, as the mathematical procedure used to extract these results is plainly unacceptable. - Heitler
  22. 22. Paradox #3: how can time go both ways at one time?
  23. 23. Entropic timetime •  Time measured by increasing entropy: emit •  The direction bombs explode in, eggs “Opposite cracks in, people age thermodynamics in, and the like. arrows of time” •  Unfortunately, L. S. Schulman Schulman has shown that this can go both ways!
  24. 24. Acme Wormhole Construction Company Visser’s recipe for a time machine: 1.  Acquire a traversable wormhole 2.  Induce a “time-shi*” between the two mouths of the wormhole 3.  Bring the wormhole mouths together
  25. 25. Davies’s How to Build a Time Machine How do you go about constructing a traversable wormhole and turning it into a time machine?
  26. 26. Black Holes & Timewarps - Kip S. Thorne
  27. 27. “Time’s Up for the Time Bandits” •  Cover Story in New Scientist, 20th of September 2003 •  Forget about coming back to murder your great-grandfather. It never happened, and there are forces out there making sure it never will.
  28. 28. ConundrumFor better or for worse, most canonical quantum field theories are found by starting with a classical field theory and then quantizing it. To be sure, there is something intellectually unsatisfactory about this: given that quantum theory is the more fundamental theory, we would prefer to work in the other direction, that is, to recover classical field theories from quantum starting points – Wallace
  29. 29. “This is often the way it is in physics – our mistake is not that we take our theories too seriously, but that we do not take them seriously enough. It is always hard to realize that these numbers and equations we play with at our desks have something to do with the real world. Even worse, there often seems to be a general agreement that certain phenomena are just not fit subjects for respectable theoretical and experimental effort.” – Steven Weinberg
  30. 30. Through the looking glass I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. Now my own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose. – J. B. S. Haldane

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