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Phanatic
Mar 13, 2007

Please don't forget that I am an extremely racist idiot who also has terrible opinions about the Culture series.

reignofevil posted:

Feel free to try and wrap your head around just how mindbogglingly big space is. Like just to get to pluto you have to travel three billion two hundred fifty two million one hundred thousand miles. And that's if you just wanna keep the scales involved small!



OP image is very inaccurate, we can see things that are way further away than 7.5 billion light years. The edge of the observable universe is about 45 billion light years away. The universe is about 14 billion years old, so a naive calculation is that the furthest light could have traveled since the Big Bang is 14 billion light years, but that ignores the expansion of the universe itself.

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Phanatic
Mar 13, 2007

Please don't forget that I am an extremely racist idiot who also has terrible opinions about the Culture series.

Obliterati posted:

Disappointed they didn't specify Earth's size as 1x the size of Earth

Also bothered by the fact that they're saying that if A's diameter is 9 times B's, that A is 9 times larger than B. Jupiter's way more than 11 times larger than Earth. It's over 1300 times larger than Earth.

Phanatic
Mar 13, 2007

Please don't forget that I am an extremely racist idiot who also has terrible opinions about the Culture series.

actionjackson posted:

space is fuckin huge

one thing (out of a billion) I don't understand, where does gravity come from? I've heard "graviton" but is that still theoretical at this point?

There is no working theory of quantum gravity. If you treat gravity as a field and try to quantize it, you wind up with gravitons, just like if you quantize the electromagnetic field you wind up with photons. But if you do this, and try calculate any interactions of these gravitons, your calculations blow up and you wind up with infinities you can't get rid of. This is an indication that you probably don't get to a working theory of quantum gravity by simply trying to quantize gravity.

In relativity, gravity results from the shape of spacetime. The presence of mass curves spacetime, and things traveling through space travel along the shortest possible paths in that curved spacetime.

Phanatic
Mar 13, 2007

Please don't forget that I am an extremely racist idiot who also has terrible opinions about the Culture series.

PostNouveau posted:

Warping in what way?

Topologically. Space-time where mass (or energy, or a field) is nearby is no longer flat, it becomes curved, and objects in free-fall follow geodesics in that curved volume of space. From our point of view, those straight-line paths in spacetime appear to be things like orbits in space. The relationship between mass and this curvature it inflicts upon the structure of spacetime is described by the Einstein field equations.

Phanatic
Mar 13, 2007

Please don't forget that I am an extremely racist idiot who also has terrible opinions about the Culture series.

PostNouveau posted:

OK but how does this curvature of space time affect the orbits of say 3 or more bodies?

I’m sure what you mean. In a sense, this is like asking “how does the slope of this hill affect the path of the ball rolling down it?” The bodies are in free fall, they’re following shortest-distance paths through the curved background of spacetime, and those shortest-distance paths *are* the orbits. And since the bodies are massive and their masses then distort spacetime as they move, the shortest-distance paths continually change.

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