2. פרושים של תורת הקוונטים בוהר: אסור לשאול איפה החלקיק בין המדידות Duality, Complementarity לנדאו: חייבים עולם הקלסי כדי להגדיר עולם קוונטי ספרי לימוד: משתנה – אופרטור, משמאות גל רק לאנסמבל פון נוימן: הכל גל שמשתנה לפי שרדינגר אבל גם קורס במדידה בוהם: גל (בלי קריסה) הוא pilot wave, המציאות חלקיקים עולמות מרובים: הכל גל, אין קריסה GRW-Pearle הכל גל, יש קריסה ( Flashes, Density) Modal Interpretation Consistent Histories Quantum Logic Information …

3. Elements of Reality Counterfactuals

4. If it were that A then it would be that B If John were to jump out of the window of 10 th floor, he would die. If Nixon were to push the nuclear attack button, there would be a nuclear holocaust. True or False? B True or False in the CF world with A, closest to the actual world. Miracles F F Time Asymmetry “closest” is not well defined, Counterfactuals are vague

5. Counterfactuals in Physics If it were that A then it would be that B True or False? B True or False in the CF world with A, closest to the actual world. No need for a miracle to have A “closest” is well defined, Counterfactuals are not vague If it were that A was measured at time t then it would be that A=a SYSTEM In “closest” CF world the system has the same description at time t as in actual world

6. Counterfactuals in Classical Physics If it were that A then it would be that B True or False? B True or False in the CF world with A, closest to the actual world. No need for a miracle to have A “closest” is well defined, Counterfactuals are not vague If it were that A was measured at time t then it would be that A=a SYSTEM Counterfactuals = conditionals In “closest” CF world the system has the same description at time t as in actual world

7. Counterfactuals in Quantum Physics If it were that A then it would be that B True or False? B True or False in the CF world with A, closest to the actual world. No need for a miracle to have A “closest” is well defined, Counterfactuals are not vague If it were that A was measured at time t then it would be that A=a SYSTEM Counterfactuals = conditionals In “closest” CF world the system has the same description at time t as in actual world

8. Counterfactuals in Quantum Physics If it were that only A was measured at time t then it would be that A=a Counterfactuals = counterfactual conditionals If it were that only B was measured at time t then it would be that B=b

10. פורמליזם הדו וקטורי

11. The two-state vector

12. ?

20. The standard (one-state vector) description of a quantum system at time t

23. We assume:

24. The standard (one-state vector) description of a quantum system

25. The time reversal of

26. The backwards evolving quantum state The time reversal of The two-state vector

27. ?

28. ? At time t:

29. ?