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Circles in Minkowski space: unknown notation

  1. Oct 23, 2013 #1


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    I am reading an article about Minkowski space (as a vector space, which is why I am putting my question in this rubric) which is poorly translated from the Russian, and have come across several notational curiosities, most of which I have been able to figure out. However, there is one that I do not know. Talking about positive and negative radii, the author refers to "m-m circles". (Apparently "m" is not significant, as he also refers to "n-n circles" and other letters.)
    Specifically, he says:
    "The invariant of the [Lorentz] transformations is
    -x22 = R2 = inv
    For R2>0 the orbits are n-n Minkowski circles with real radii R, for R2<0 the orbits are m-m circles with imaginary radii Ri."
    Nowhere in the paper does the author indicate that he has coined these terms; apparently they are standard terms in Russia. But I don't know any Russian mathematicians or physicists. So:
    (1) what do these terms refer to? (guesses also welcome)
    (2) are these standard terms in English? If not,
    (3) what are the corresponding standard terms in English?
    Even a partial answer will be much appreciated. Thanks.
  2. jcsd
  3. Oct 23, 2013 #2


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    "Space-like" and "time-like" spring to mind, although it may be that the author is using a different sign convention than that adopted by Wikipedia.
  4. Oct 23, 2013 #3


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    Many thanks, pasmith. That would make perfect sense in the context.

    (I am curious why "m" and "n" . "Space" and "time" in Russian don't begin with those letters. And why repeated (n-n, m-m)? But these questions would be more "Trivial Pursuit" for etymology fanatics, not for a Physics Forum, so I won't lose any sleep over such details, as long as I can understand what physics the author is referring to.)
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