Recent content by Amanheis

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    What made Einstein think the universe was steady?

    I disagree, if I remember correctly Hilbert actually came up with the Einstein equations a little before Einstein, using the Lagrangian derivation and Einsteins previous work. But since Einstein did all the heavy lifting, they are attributed only to him. The the "blunder" part: We only know...
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    Who was the first one to say universe is expanding?

    According to Simon Singh's "Big Bang", Einstein introduced the cosmological constant to have a static solution. It was considered an ugly modification by most scientists, even by Einstein himself, but a steady state universe was the only imaginable possibility at the time. Friedmann then came up...
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    How to Quantify Statistical Significance of Model Deviation from Data Points?

    Not quite. We already kind of know the value of Y(Feb 2012). For the sake of clarity let's choose a date in the ast, say the average temperature at some place in the year 1500. Also I will adopt my notation from the original post. We already kind of know how the temperature behaves over time...
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    How to Quantify Statistical Significance of Model Deviation from Data Points?

    Yes, the error bars are predicted. I am basically using the specifications of the experiment and the Fisher matrix formalism to assess the quality of the constraints that will be put on fiducial values of a set of parameters.
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    How to Quantify Statistical Significance of Model Deviation from Data Points?

    I don't understand. How am I supposed to do that? The actual observed value won't be available until several years from now. And "observed value" implies that it is observed, I don't see how I can calculate it.
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    How to Quantify Statistical Significance of Model Deviation from Data Points?

    I need to quantify the statistical significance of how much a model deviates from a given set of data points, and I cannot do a fit. Let's say the model is a one-parameter description of some time dependent quantity f_a(t). I have data points at n different times including error bars, so pi =...
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    Logarithm Notation: log(x) or ln(x)?

    If I had a say in that matter, I would define the logarithm as follows. Base e: ln or log Base 10: lg Base 2: ld Base a: log_a
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    Expansion and Conservation of Energy

    Energy in GR is simply not conserved in the sense that we are used to. You might have found an example for how to gain energy. On the other hand, you could use a battery to shoot a laser beam on a mirror that is a couple mega parsecs away, then use the returning light and the photoelectric...
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    Is Learning Detailed Math Still Necessary in the Age of Computers?

    Stephen Wolfram's brother Conrad makes some pretty valid points arguing against everyone in this thread. Short excerpt: Nowadays is all about problem solving, which usually involves the following steps: 1) Identify the problem 2) Make it so that you can calculate the solution 3) Do...
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    How did matter go so far so fast?

    The matter didn't "go there", it always has been there. Right after the big bang, the universe and its contents were pretty homogeneous. Expansion of spacetime can not be thought of as an explosion of matter at a specific point. Note that this doesn't address the deeper issues of your...
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    Math/Physics Tattoo Idea Request - Warren

    There is a square missing, it should be E^2 instead of E in the energy-momentum relation. How does this happen? I noticed it within 2 seconds of looking at that picture. You'd think people would pay more attention to what they permanently write on their skin. Then again, I've seen a lot...
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    Python What is the Python syntax for checking if a number is a palindrome?

    You are not supposed to give out full solutions to Project Euler problems. Please remove it.
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    Physics Differential Geometry in Physics

    Classical mechanics can be described in terms of symplectic manifolds. See the freely available book by Abraham and Marsden, Foundations of Mechanics: http://caltechbook.library.caltech.edu/103/
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    Why You Should Not Fly Delta Airlines

    Luckily, I never had any major issues with any airline, in fact, delta was the best I ever flew with. Then again, my expectations for any airline are really, really low... I wonder why you are surprised though: It most likely stated something like that in the terms of agreement which you agreed...
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    Does Gravity Wave Travel Faster Than Light Wave Near a Black Hole?

    I have to agree with Passionflower. I was asked this exact question in an exam with Prof. Bartelmann, and the answer is (sadly it's not the one I gave) that the event horizon is only an event horizon in the frame of an observer at infinite distance. In the case discussed here, the observer will...
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