Unrelated to work: the black hole rabbit hole. It started with an article about the hypothesis that planet nine may be a primordial black hole with 3-6 Earth m

Unrelated to work: the black hole rabbit hole. It started with an article about the hypothesis that planet nine may be a primordial black hole with 3-6 Earth masses. What’s a primordial black hole? It’s one that formed in the first seconds after the Big Bang. We don’t know for sure they exist but many theories and simulations predict them. They’re an excellent dark matter candidate. Could it be that simple? Could at least a lot of the missing mass be tied up in little baseball sized embers from the birth of the universe that rarely interact with anything so we don’t see them? They’d be small, would rarely interact, and unless they are sucking in mass (causing a hot accretion disk) would be dark. Then I got onto Hawking radiation and whether micro black holes could exist. Along the way I read about loop quantum gravity (LQG) which looks to me like a decent stab at unifying QM and GR that’s much less baroque and more testable than string theory. That then led to the LQG “bounce” hypothesis for black holes. See LQG does away with true infinite mass singularities. Instead a black hole would be matter packed to its theoretical maximum density (which is still insane). From there it would quickly “bounce” and become a white hole. So wait… how do black holes persist then? Time dilation! From a the hole’s frame of reference it collapses and then instantly bounces and goes kaboom. From our frame of reference though all that gravity slows it to such a crawl that the black hole phase at or near max density looks like it’s stable. The bounce takes billions to even trillions of years! Last but not least I learned about the black hole starship idea. It’s a set of ideas about how far future intelligences could use black holes as mass energy converters to reach relativistic velocities. Might be somewhat easier (for crazy sci-fi values of “easy”) than handling antimatter. This also gives SETI yet another wild extreme technosignature to look for. … and back to the beginning I found a post about how if planet nine were a PBH we could use it to yeet probes to the stars at meaningful fractions of c… at least if we could make them able to survive insane g forces. Unlike the black hole starship this would be feasible today. It’d just be a gravity assist off a ludicrous gravity well. Here I thought black holes were dull. Turns out they’re the most extreme objects in the universe and a whole lot of the most amazing physics intersects around them. If there is any way we could tap into the phenomenon we could potentially access sci-fi levels of energy too.