Recent content by Blake Barr

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    B Infinite vs Expanding Universe: A Physics Conundrum Explained

    I am not sure I understand your question. Are you asking if I am sure that his example would require that space-time has a boundary? Or did you interpret this as me saying that space-time has a boundary?
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    Why is spacetime shown on a 2 dimensional plane?

    The key is that if you showed a representation of space-time distortion around a body by drawing the three-dimensional spatial representation you get a drawing that is very confusing and hard to understand. Lines and grids all over the place. A bowling ball on a sheet just works better.
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    B LIGO: Detecting Gravity Wave Sources

    This may help: "But gravitational-wave emission is not isotropic: for a compact binary, more power is emitted perpendicular to the binary’s orbital plane than in the plane. Detectors are not uniformly sensitive either. They are best at detecting overhead sources, and are completely insensitive...
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    B LIGO: Detecting Gravity Wave Sources

    Technically not a plane but for simplification purposes I used a plane since on the scale we are talking about the distance between the detectors is so small compared to the distance to the event. Without knowing distance it would not be a cone though, since we are not really bringing the line...
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    B Infinite vs Expanding Universe: A Physics Conundrum Explained

    But the balloon itself is stuff. Your example assumes the universe, the actual space-time, has a boundary. Is space expanding to hold the stuff or is the stuff simply spreading out to fill the space?
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    B LIGO: Detecting Gravity Wave Sources

    The waves "pass through" matter so it can detect sources in any direction. Basically you can calculate a single direction and then rotate that vector around the base of the detectors to create a disc-like shape that extends essentially in a plane that passes through the Earth. So the source can...
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    B Infinite vs Expanding Universe: A Physics Conundrum Explained

    I tend to think of it as the universe is infinite, spatially, but the stuff in it is expanding. Love stuff.
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    B LIGO: Detecting Gravity Wave Sources

    There are two different LIGO detectors. The difference in time between the wave measurements of the two detectors can be used to determine the direction it is coming from, sort of, since it would be a point along that angle rotated 3 dimensionally around the base - a ring of possibilities...
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