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  1. martinbn

    I Spinorial Maxwell's equations

    Yes, the components are constant, so all the derivatives will be zero. In curved space-time you need the theorem that there is a unique connection with the given properties, one of which is that the ##\epsilon## has zero covariant derivative.
  2. martinbn

    I Lorentz metric on real type (1,0;1,0) tensors

    ##o ##o_A o^A=\epsilon_{BA}o^B o^A=0## The two form ##\epsilon## is antysymmetric. Everything is orthogonal to itself.
  3. martinbn

    I Black hole formation watched from a distance

    I meant that I understand the question to be about a generic formation of a black hole.
  4. martinbn

    A Center of a linear algebraic group

    Aren't the maximal abelian subgroups conjugate to the diagonal subgroup?
  5. martinbn

    I Black hole formation watched from a distance

    But it doesn't, because my question was "what are Schwarzschild coordinates for a black hole?", not just for the Schwarzschild black hole.
  6. martinbn

    I Black hole formation watched from a distance

    Is this for my question? The thread is about black hole formation. The Schwarzschild is eternal it cannot be relevant.
  7. martinbn

    I Black hole formation watched from a distance

    What are Schwarzshild coordinates?
  8. martinbn

    I Black hole formation watched from a distance

    Is there a reason why you expect that the answer shouldn't depend on what exacly the formation is, and on what time coordinate you use? Or do you have something more specific in mind?
  9. martinbn

    A Center of a linear algebraic group

    Of course, but it is a single point and has dimension 0.
  10. martinbn

    A Center of a linear algebraic group

    There are plenty of groups with trivial or finite centre, hence zero dimensional. So ##c(m)## can be zero for nonzero ##m##.
  11. martinbn

    A Assumptions of the Bell theorem

    Be careful you start to sound a lot like a crackpot. It is a slippery slope, once you go that way it is hard to go back. :wink:
  12. martinbn

    A Assumptions of the Bell theorem

    Not a prerequisite, but given that the other option is refuted by observation, it is the only possibility.
  13. martinbn

    A Assumptions of the Bell theorem

    The question shouldn't be about between what entities the influence is. It should be about what entity carries the influence. If you don't have a field that propagates, from one to the other, faster than light, then talking about FTL causal influences is a missleading choice of words.
  14. martinbn

    A Assumptions of the Bell theorem

    Let me guess. The two of you mean different things by FTL causal influences.
  15. martinbn

    A Prime Factorization Theorem and Number Systems

    The example given by @fresh_42 is exactly what Wiles is talking about. The rings of integers in number fields do not always have unique factorization. If they did Fermat's last thereom would have been much easier to prove.
  16. martinbn

    I Bohmian mechanics and String theory

    The way I understand this is that Bohmian mechanics is incompatible with string theory as much it is incompatible with quantum field thoery.
  17. martinbn

    I Bohmian mechanics and String theory

    Given that string theory is relativistic and Bohmian mechanics practitioners believe that relativity is "wrong", how could they be compatible?
  18. martinbn

    I Does QM offer a solution to Zeno's paradoxes?

    The paradox can be modified a little. Knowing that the resulution lies in the fact that one can add infinitely many numbers and still get a finite number, say ##\frac12+\frac14+\frac18+\cdots = 1##. Then do the following. Switch the light on for half a second, then switch it off for a quarter of...
  19. martinbn

    A Quantum linear code/ Dual Code (CSS) proof

    If ##x\in C^\perp## then it is clear. If not, then there is a ##c_0\in C## such that ##x\cdot c_0 =1##. The you have ## -1\sum_{c\in C}(-1)^{x\cdot c}=(-1)^{x\cdot c_0}\sum_{c\in C}(-1)^{x\cdot c}=\sum_{c\in C}(-1)^{x\cdot (c-c_0)}=\sum_{c\in C}(-1)^{x\cdot c} ## The last equality is because...
  20. martinbn

    I Rigorous: Where is the Quantum System Prior to Measurement?

    Why 1 or 0? What if for some place the probability is 0.1?
  21. martinbn

    B Is an experiment planned to discern determinism and randomness in QM

    Which does not change no matter what A does.
  22. martinbn

    B Is an experiment planned to discern determinism and randomness in QM

    Ok, here is a new pair of socks. Can you point to the left one, please! Oh, you cannot! Then what is predetermined about the leftness/rightness of the socks?!
  23. martinbn

    I Natural direction of pushforwards and pullbacks

    I'd say for functions is quite clear, because it is just composing with the map. For dual objects it goes the opposite way. Since vectors evaluate on functions, they are pushed forward. One forms evaluate on vectors, so they are pulled back.
  24. martinbn

    B Is an experiment planned to discern determinism and randomness in QM

    You are missing the point. Suppose I have two new socks, neither has been molded by my left or right foot. One of the socks is white, the other is black. Sometimes the outcome of my experiment will be a white left and a black right, sometimes a black left and a white write. Also your complaint...
  25. martinbn

    Challenge Math Challenge - September 2021

    Small nitpicking: I don't agree that a topological group and a Lie group are the same thing.
  26. martinbn

    B Is an experiment planned to discern determinism and randomness in QM

    I have a pair of new identical socks. I put one, let's call it A, on my left foot and it beomes a left sock. Instantaniously the other sock, let's call it B, becomes a right sock. Was B a right sock all along or did the sock A change it? Is there a cause and effect relationship? I personally...
  27. martinbn

    A Condition for a spacelike surface to be achronal

    Not always. Take Minkowski remove a square and take two points near oposite sides.
  28. martinbn

    A Condition for a spacelike surface to be achronal

    What about a two dimensional (1+1) cylinder and a space-like spiral? It is not achronal but it is complete.
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