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Comment by monkeycantype | Hacker News Reader

So if Copernicus and Einstein were drinking coffee with Galileo and Hawking on a little planet orbiting this star, trying to formulate an Alpha Sagittaricentric model of the galaxy, how much would Einstein and Hawking be contributing to the conversation? How important is relativity to explaining what they would be observing of the light from other stars?

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Well for starters colours would be all weird.

Not hugely.

Relativity only matters at very high relative speeds, which hardly exist inside the galaxy.

Is 8% of the speed of light not a very high relative speed?

[Layman here] The Lorentz factor is 1/sqrt(1-v^2/c^2) = 1/sqrt(1-0.08^2) = 100.3%, so dilation effects would be obviously measurable but not particularly huge (0.3%).

One question, foes it exists outside of the galaxy?

Yes: https://en.wikipedia.org/wiki/Astrophysical_jet

So none of the numerous blackholes in our galaxy have astrophysical jets? Seems unlikely, maybe small, thin, and/or far enough not to be observed, but that doesn't mean they aren't there.

Generally they're associated with quasars and formedby supermassive black holes at the centers of active galaxies, which our galaxy doesn't really qualify for. However, while relatively quiet, Sagittarius A* does accelerate things to fairly high speeds, and it is thought that it might have some faint jets and an accretion disk.

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