Physics, Astronomy & Cosmology / Re: Is the inverse square law only approximately correct in general relativity?« on: 25/06/2022 10:08:47 »
Quote from: Eternal STudent
The reasoning about Event Horizons is almost backward.I was not thinking about a horizon at a fixed distance.
- After all, the size of our observable universe is not at a fixed distance - it expands at the speed of c.
- But space can expand faster than c, so (in principle) there are distant galaxies that people on Earth could see today, but
which will not be visible in 10 billion years, because the expansion of space has carried them outside our visible universe.
- If you posit some particle that travelled at c/10 (and didn't slow down), there would be regions of our visible universe that could never detect these particles, because the space in between is/will be expanding faster than c/10.
Usual disclaimer: Ignoring intergalactic medium, electrostatic forces, magnetic fields, etc which will change the velocity and/or direction of real beta particles.
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