There are two Groombridge stars in "relative proximity" to Teegarden's star: Groombridge 1830 (30 light years from Earth) and Groombridge 1618 (16 light years from Earth). Both are flare stars, or at least presumed to be. That's why I said "one of the Groombridge stars".Melbourne Guy said:Is that Groombridge 1830, @Strato Incendus? Is it even on the flight path, it's more than twice as far away than Teegarden's Star.
Interesting that we haven't thought of that yet, isn't it?Melbourne Guy said:But how about a wandering black hole causing trouble? They are really hard to spot from a distance!
I guess it's because my default image of a black hole by now is one with a shining disc around it, i.e. one that you could spot, if only from the matter falling into it.
However, if the black hole is in interstellar space, currently not sucking up any noteworthy amounts of matter, it could indeed be completely dark, couldn't it?
It's gravitational effects should still be noticed by the ship's sensors somehow, though. So the question here is how early they would notice that?
I don't think I would have it pass by near the Sol system - we already talked about the believability (or lack thereof) of "dual armageddons". Hence, the catastrophe at home should either be caused by a solar flare from our own sun (given the relatively high frequency with which those occur over the centuries), or by WR 104 indeed going off with its gamma-ray burst during the year of the first book's plot.Melbourne Guy said:Having one intersect Sol would play havoc with events back home, and you could couple that with sympathisers on the ship who mutiny to turn it around (and fail, obviously, but their antics extend the trip) or just have a local system failure extend the trip.
So for the time being, let's focus on what a black hole could do if it somehow interfered with the ship's trajectory.
That seems like a good opportunity - but how would this work in practice? Kugelblitz drives use artificial black holes, created from light (=lasers). How would they be supposed to catch a real black hole and use it for a drive somehow? They can of course use it for swingby. But using the Hawking radiation it gives off as a means of propulsion?DaveC426913 said:I wonder if that could be tied into the plot about their new drive.
The point of artificial black holes, as far as I understand it, is that they are so tiny that they give off much more Hawking radiation than a large one. So a natural black hole, with appropriate size, would be useless as a means to power a drive, wouldn't it?
Indeed - the common thought experiment for this is replacing the sun with a black hole of equal mass. That wouldn't do any damage to Earth - at least not from the black hole itself. The sudden absence of heat would of course be a massive problem for all inhabited planets around, but that is not a unique property of having a black hole in the centre - the same would be true around e.g. a white dwarf star.DaveC426913 said:Gravitationally, a black hole is no more destructive than any star of the same mass. It would require some fancy footwork to arrange the story for it to become a cause for a significant detour.
The main question here is, analogously to having a rogue star pass by:
Could a rogue black hole pull one of the Groombridge stars (1830 or 1618) close enough to the path leading from Earth to Teegarden b for a solar flar from that Groombridge star to hit the ship as it's passing by? More importantly, could this rogue black hole do so in time (between now and 2475)?
I can imagine a rogue black hole pulling the ship off-course with its gravity - without anyone noticing the black hole, because it's completely dark (=not absorbing matter in the interstellar medium, therefore no shining disk around it).DaveC426913 said:What of the BH directly caused the course change? If they got too close before realizing anything, their course may be altered whether they want it to or not (though not by a lot without tearing the delicate ship apart).
But as I've asked above, how soon would the crew notice that? If the destination star is no longer straight ahead of them, they should pick up on that pretty quickly. Or can I use gravitational lenses somehow to get around this problem?
If anything, in this case it might be seen as diabolus ex machina - or Murphy's Law: If something can go wrong, it will.DaveC426913 said:Any plot involving a rogue black hole seems like a real deus ex machina.
But conversely, it could also be seen as the complete absence of a deus ex machina: The inherent indifference of the lifeless universe I was talking about earlier. This is something the crew is already contemplating due to the gamma-ray burst threat from WR 104: The universe isn't "trying to kill humanity"; it simply doesn't care.
Great news, then (for my story, at least - not necessarily for those stars)!AllanR said:"Astronomers estimate that there should be 100 million black holes roaming among the 100 billion stars in our galaxy."
So I could have one pass through the galactic disk "vertically", to pull a Groombridge star closer to the plane on which the ship would be travelling from Earth to Teegarden? Because the "vertical" difference (in light years) seems to be the main problem here. When viewed from above, the two Groombridge stars are actually pretty close to Teegarden's star.