I have a couple of questions about de Sitter cosmological horizons:
In this video by Leonard Susskind (https://youtu.be/n7eW-xPEvoQ?t=2324) he explains the concept of the Poincaré recurrence using particles and the cosmological horizon.
1. I always thought that matter "falling" into the horizon was forever lost (like the galaxies we see receding and fading) and that it couldn't "return", so I'm not sure if I understood Susskind. Also, would this also happen in a universe without matter? I mean, I understand that cosmological horizons in a universe with a cosmological constant would radiate similarly to how a black hole would radiate Hawking radiations from its horizon. So shouldn't something similar to what Susskind explains happen but with radiated photons from the horizon?
2. Susskind says that one escape to the recurrence problem is the decay of the cosmological constant in form of a false vacuum decay. However, since an expanding true vacuum bubble would expand at light speed and in an accelerating expanding universe the distances between galaxies will eventually expand to the point where light cannot overtake this expansion, wouldn't spacetime expansion outpace the nucleation and expansion of these bubbles? Then, could there be regions that would not be affected by these bubbles and their expansion?