Recent content by inottoe

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    Graduate Can two metrics be superposed?

    OK, thanks very much for that.
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    Graduate Can two metrics be superposed?

    I didn't know that. I'm basically stuck as to how to superpose the two metric spaces. Maybe the answer is obvious and I'm being thick.
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    Graduate Can two metrics be superposed?

    I'm pretty sure you can - you're just adding matrices.
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    Graduate Can two metrics be superposed?

    Hi. I can't find a source that shows how to superpose two metrics. For example, superposing Schwarzschild metric ds^2=\left(1-\frac{2M}{r}\right)dt^2-\frac{dr^2}{1-\frac{2M}{r}}-r^2d\Omega^2 with de Sitter metric...
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    Graduate Completely General Lorentz Transformation

    Thanks very much for that. You've just saved a good fraction of my life:redface:
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    High School How to calculate the speed of the moving point

    I'm no physician, either. But I do like to think of myself as a physicist:smile: Some simple formulae on the equations of motion can be found here: http://en.wikipedia.org/wiki/Equations_of_motion"
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    High School What happen if everything in earth becomes steady?

    At the equator: 1000mph winds and tsunamis. At the poles: nothing.
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    Graduate Inquiry about kinetic force in STR

    Not sure what you mean by 'kinetic force'. From the energy equation E^2=p^2c^2+m^2c^4 the kinetic energy is mc^2\left(\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}-1\right) whereas the total energy, E, is \frac{mc^2}{\sqrt{1-\frac{v^2}{c^2}}}
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    Graduate Gravitational Time Dilation - Is my head older than my feet?

    You could try this: http://en.wikipedia.org/wiki/Gravitational_time_dilation" . The maths isn't too complicated.
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    Graduate Gravitational Time Dilation - Is my head older than my feet?

    Yes, that's right. They experience stronger acceleration, and so are more time-dilated.
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    High School Universal Gravitational Constant

    I'll have a go. The force between two masses m1 and m2 separated by distance r is proportional to \frac{m1\times{m2}}{r^2}. But this expression alone gives units kg^2/m^2 (kg=kilograms, m=metres). But force is in units of N (Newtons), which means that whatever the proportionality constant...
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    Graduate Where is potential energy in relativistic formula of energy?

    If it's gravity, then both potential and kinetic energy are generalised as (letting c=1): -m\frac{d\tau}{dt} where d\tau^2=g_{\mu\nu}dx^{\mu}dx^{\nu} We can see this clearly when we assume spherical symmetry and consider the Newtonian limit...
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    Undergrad Why Isn't Gravity Infinite at the Center of the Earth?

    M's inside sphere of radius d
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    Graduate Are escape-trajectory-only forces possible?

    Well, nothing's definitive just yet. There's http://arxiv.org/abs/1107.2886" from a few days ago.
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    Graduate Are escape-trajectory-only forces possible?

    Just suppose for a moment that various discrepancies in spacecraft trajectories, such as the Earth flyby anomalies, are due to new physics. It’s been pointed out in various sources, for example http://arxiv.org/abs/astro-ph/0608087" , that the spacecraft happen to be on hyperbolic...