Search results

  1. belliott4488

    Appropriate distribution for minimum distance

    I have what I think is probably a basic question from probability and statistics (about which I'm pretty ignorant). If I have a set of projectile trajectories that were generated by a Monte Carlo process, and I'd like to know the probability the projectile will come within distance d of some...
  2. belliott4488

    How does GR describe acceleration from non-gravitational forces?

    I have a pretty basic question - one that should have occurred to me long ago, but I never really thought about before. We all know how the effects of gravity are described by the curvature of spacetime - rubber sheets and all that - as well as the equivalence of inertial and gravitational...
  3. belliott4488

    Fortran How to move on from Compaq Visual Fortran

    My group at work uses several pieces of legacy Fortran code which we've always compiled using Compaq Visual Fortran. Since CVF has not been supported for while now and is not (easily) compatible with Windows 7, I'd like to move to a more up-to-date compiler and IDE. I'm trying Simply Fortran...
  4. belliott4488

    Web link for crackpot test?

    I'm sorry - I know this is archived somewhere around here but I couldn't find it ... Can anyone give me a link for the set of tests used to identify a crackpot (either the theory or its author). I've forgotten who had it on his website - someone at Princeton, maybe?? I've got a live one on...
  5. belliott4488

    Kernel density estimation for non-I.I.D. data

    I am wondering if Kernel Density Estimation (KDE) is appropriate for some data analysis I'm working on. I have a simulated process that produces a large number N of pieces of debris, and I want to know how these objects are distributed spatially. In other words, I'd like to estimate a density...
  6. belliott4488

    Liouville's Eq. applied to debris in space

    A colleague of mine has suggested using Liouville's Equation in order to calculate the probability of collision between spacecraft and debris fragments produced by collisions in space. The application would be to take the known initial states of all the debris fragments, to determine the phase...
  7. belliott4488

    Probability of N or more from uniform distribution

    If I have N objects uniformly placed at random in a 1-d box of length b, how do I calculate the probability of finding one or more objects in a given length? Here's what I mean: I assume a uniform probability density of 1/b, that is, P = 1/b for 0<x<b and P = 0 everywhere else. I now place N...
  8. belliott4488

    Basic probability question: 1 or more objects in N cells

    Sorry that subject is vague. Here's the question: If I have N objects randomly placed into M cells (M>N), what is the probability that I will find one or more objects in any one cell? Here's why I'm asking, or rather, here's why I'm confused: I have one object that has been placed at...
  9. belliott4488

    What's up at the LHC?

    I've been a little out of touch recently, and I don't know what's going on out there. Haven't they started running some beam tests? Everything okay so far?
  10. belliott4488

    Correlating input and output in Monte Carlo simulations

    I'm pretty ignorant when it comes to statistics, so I'm hoping that there's an easy answer to my question (this is the good part of ignorance): If I have run a set of Monte Carlo simulations of some process, where I have some set of input parameters that I've drawn from known distributions...
  11. belliott4488

    Geometry puzzle: plane X cylinder = ellipse

    Actually, this is just a plain old geometry problem, really - no special tricks or anything. It just has a very nice solution, which someone showed me years ago (I take no credit). Can you prove that the intersection of a right circular cylinder and a plane is an ellipse? (Assume the...
  12. belliott4488

    How does black hole evaporation end?

    Someone asked me what happens when micro-black holes evaporate, and I have no idea, not really knowing anything about the theory of black holes, other than what you learn in a first course in GR. What he was asking was whether the black hole just keeps emitting energy (in the form of Hawking...
  13. belliott4488

    Statistical test for spherical uniformity?

    I have a large sample of vectors in 3-space, and I would like to how uniformly they are distributed. Ultimately I'd like to know how uniform the angular distribution as a function of magnitude. What I mean by that is that if I divide the space into spherical shells, will the vectors whose...
  14. belliott4488

    More crazy, but logical, people

    Okay, here's a follow-up of sorts to my earlier post about green-eyed people who must kill themselves. It turns out that the stranger who caused all this trouble was later caught by a fishing boat and brought back to the town to be tried for his offense. He was, of course, sentenced to...
  15. belliott4488

    Does Coriolis really cause water to drain one way?

    We've all heard that water spirals down the drain in a clockwise direction in the Southern hemisphere and counter- (or anti-) clockwise in the Northern hemisphere, due to the Coriolis effect from the rotation of the Earth. I've also heard that this is a myth, and that if you calculate the...
  16. belliott4488

    How'd they figure that? (logic puzzle)

    Okay, here's my favorite brain teaser. Sorry if an equivalent version has appeared here before. On a remote island somewhere there was an ancient country whose population consisted of 200 people with green eyes and 800 people with blue eyes. The citizens of this country were all happy and...
  17. belliott4488

    U(2) and SO(3)

    What's the correct way to state the relationship between these two Lie groups? One is the "covering group" of the other, right? Okay, then - what's that mean, to a non-expert? I know the basics, i.e. SO(3) can be represented by rotation matrices in 3-space, and U(2) does the same in a...
  18. belliott4488

    Is the designation as matter vs. antimatter arbitrary?

    Is the designation as "matter" vs. "antimatter" arbitrary? I think this should be a very elementary question, but I haven't seen it addressed anywhere before. (but pardon me if it has been, and I just missed it.) I know that it is arbitrary to designate the electron as a matter particle and...
Top