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by kazinator 618 days ago
But causalities that don't propagate at the speed of light, and are not based on light, such as ordinary objects moving around and jostling each other, do not appear the same in every reference frame.
1 comments

if the sun were to disappear, how long would it take for you to notice?
Trick question. Am I someone on Earth? (If so, 8 minutes). Or am I in a ship that is hurtling toward the Solar System at 0.999c, roughly in line with the Sun-Earth axis? If so, although I see speed of light as c, the Sun-Earth distance is foreshortened relativistically, so it will be less than 8 minutes between me perceiving the event that the Sun disappeared and perceiving the event that the Earth lost illumination.
This doesn't argue their point.

If a neutron disappeared, you'd NEVER noticed that causality.