The joke is that the whole world could go to sleep/wake up/work at the exact same time, day or night.

To be fair, “95% of the mass/energy in the universe is undetectable to us except for how they impact the movement of entities at a galactic scale” is kinda wild too.

Everywhere we look at distant galaxies, they look like they’re moving away from us. We think this because the wavelength of the light they’ve emitted looks stretched (ie redshifted), similar to how the pitch of sound changes when an ambulance is approaching and passing you.

The fact that this is happening in all directions leads us to believe that space itself is stretching in all directions, because we don’t believe that we’re in a special part of the universe, like in the center of some event that sent all galaxies flying away from us.

If I understand this article correctly, it proposes that the redshifting could have another explanation. Looking at a distant galaxy is like “looking back in time” because the light takes time to cross the vast emptiness of space to reach us. So what if the redshifting is because the particles back when the light was emitted had different properties than they have now? The model described in the paper explains exactly how those properties could be changing in order to produce the effects that we observe.