Recent content by Marcaias

  1. M

    Is axiom of choice applicationless?

    Ahh, thank you.
  2. M

    Is axiom of choice applicationless?

    Whoa, a theorem in what? Gödel showed it is not a theorem in ZF, and neither is its negation (assuming ZF is consistent, of course.)
  3. M

    Is axiom of choice applicationless?

    From Wikipedia:
  4. M

    Can Any Inner Product Be Defined in Infinite Dimensional Vector Spaces?

    First of all, a Hilbert space by definition must have an inner product defined on it. (A Hilbert space is a vector space over the real or complex numbers with a complete inner product.) Secondly, in a finite-dimensional space, if you fix any positive-definite matrix M, then the expression...
  5. M

    Find P.Q & Q.P from Permutations of X (1,2,3,4,5)

    "Q=2 3 4 1 5" means that this mapping happens: \begin{tabular}{ | c | c | c | c | c | } \hline 1 & 2 & 3 & 4 & 5 \\ \Downarrow & \Downarrow & \Downarrow & \Downarrow & \Downarrow \\ 2 & 3 & 4 & 1 & 5 \\ \hline \end{tabular} In other words: 1 gets mapped to 2, 2...
  6. M

    How does ZF fixes Russell's paradox?

    It's not that there's an axiom in ZF explicitly preventing Russell's Paradox, but rather ZF *doesn't* include the axiom of comprehension, which is the cause of all the trouble. Instead, it only allows for sets to be "built from" other sets, by union, by image under a function, by power set, and...
  7. M

    Does a tree exist if no one is there to observe it?

    If you intend your interpretation to be predictive in the slightest, you still need to apply the usual probabilistic Rules of Quantum Mechanics at some point or you end up simply engaging in philosophical onanism. And the fact will remain that what you call Nature probabilistically choosing a...
  8. M

    Does a tree exist if no one is there to observe it?

    If any of the people who told you "the tree doesn't even exist if we aren't around to observe it" are physicists, please smack them for me. :) To expand on what I meant... In quantum computing, it's called the "principle of deferred measurement." I believe it to be the fundamental paradox in...
  9. M

    Does a tree exist if no one is there to observe it?

    Of course not! However, the behaviour of the system is exactly the same as if all the "observations" made by the tree, the grass, the wildlife, and so on were instead made by you when you stumbled into the forest a year later.
  10. M

    Pulsed electromagnetic field therapy (PEMF therapy)

    You're not my dad. Nonetheless, done.
  11. M

    Pulsed electromagnetic field therapy (PEMF therapy)

    So, I dug up some literature. Some good: Rats love it: So do strippers: And computer programmers: And it does seem to relieve some types of chronic pain: Surprise, though, it's not a cure-all: Dogs also seemed unimpressed: So, the websites selling this stuff...
  12. M

    Pulsed electromagnetic field therapy (PEMF therapy)

    You have a Master's of Art degree in Physics.
  13. M

    Could space-time be a property of matter in string theory?

    Wouldn't this correspond (roughly) to the Heisenberg picture of QM: fixed states with evolving positions and momenta?
  14. M

    Do Non-Associative Groups Exist and What Are Their Applications?

    A group's operation is associative by definition. If you take out the associativity axiom, you get what's (apparently) called a loop. If you also remove the need for an identity, you get a quasigroup. This page on Wikipedia has a nice little table of what you call groups minus this or that...
  15. M

    Relation between rank and number of non-zero eigen values.

    By the way, you don't even need the hermitian property. The same argument works for any diagonalizable matrix A.
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