[Suggestion] Black Holes and danger

Black holes aren't dangerous. I believe they should be, and they can be pretty exciting based on what we know about them. First thing, we need to be able to navigate around black holes, a usually disorienting task because they are generally small and intensely distort light around them. They also pull space around them because they are spinning, this creates an area called the ergosphere.

Edit: I've replaced the images in these posts to reflect the version I'm more satisfied with. So the text may talk about a crosshatch pattern that's missing from the image.

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Edit: The original versions here
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It is important to note, the ergosphere meets the event horizon at "the poles" of the BH. The thicker the ergosphere, the more of an ellipse.

This is all for naught, of course, if we don't get a re-buy screen if we make a mistake and bite it. Dropping out of supercruise within the ISCO should put your vessel on a suicide trajectory. Time to spool up that FSD!

Sagittarius A* is my only example since I fleshed out the concept on my flight over there. I may add some more (poorly 'shopped) examples with different black holes, since the journal already includes their spin, giving some great variety. The details of how to figure this stuff out is in a spreadsheet I made here: https://docs.google.com/spreadsheets/d/1PctiAecLA6EDMEJzf66_5hmAPhajKElJQ4YVAnMbXmI/edit?usp=sharing
The math is a little involved, but only needs to be done once per BH, certainly something stellar forge can handle.

For Sagittarius A* I used a ~3.66 million solar masses to match a "measured" size of 15.5432 solar radii (Schwarzschild radius, IRL it should be about 4 million SM anyway), The actual event horizon is slightly less. You can see the difference above, though even that small region is 2.6 Ls thick! The ISCO (outer circle) is about 100 Ls radius. The red circle is bigger than expected yes. Probably to do with the fact that Sag A* is only 500 000 SM, yet for some reason the radius is 15.5432 SR which is 36.07 Ls. We should not be dropping out of witchspace 30 Ls from Sagittarius A* !!!

It seems the VFX for black holes in general are simply missing the actual event horizon, with light wrapping around again and again, and coming out of the event horizon with ease.

I've checked some values for other BH in game, there is quite a lot of variation. BD+28 4211 C is relatively slowly spinning and only has an ergosphere 4 cm thick! Whereas HIP 63835 B gets a layer 22 km thick!

Yes I know I haven't considered the photon sphere. I'm manually making these images as examples, so I'll leave it there. I have also not considered non-spinning BHs as I don't consider them to be a physical reality, even in stellar forge.

Honestly, they could even just put in a re-buy screen if you hit the body exclusion zone and I would be more satisfied than "your FSD doesn't let you suicide into navigational hazards".
 
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Black hole XTE J1748-288
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163.9 Solar Masses, inner event horizon radius of 483.4 km, ergosurface radius at 484.1 km, giving a ergosphere thickness of 754 m. The outer ring with the arrows around it is the ISCO (innermost stable circular orbit) at 1.45 Mm (1450 km). This black hole is rotating at a period of 102.6 ms.

I removed the crosshatch from the main area, as the existing GUI is a lot more sparse. This fits a lot better. Also, if anyone is wondering, yes that is the correct event horizon. It's less than a km different than the size reported by scanning it (from the journal). In other words, no it doesn't really look like a black hole so that red circle may in fact be unnecessary if they fix their VFX.

Also, sorry I forgot to export at 720p instead of 1080.
 
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So much for lots of variation. Most of the BHs I've surveyed have a variety of spin, but they are all too slow for any significant physical change that a player could notice. All the procedural ones appear to have an ergosphere less than 100 or so metres thick. Several astronomically known BHs are spinning faster, and have a thicknesses of tens of km.

There is one black hole besides Sagittarius A* that has significant spin. GRO J1735-27 A has a reported spin of 0.17 ms! After working out the math in the spreadsheet above, apparently the fastest a BH of that mass can spin is ~0.825 ms! Yep the math is not correct in Stellar Forge for this one, or for the supermassive black hole at the center of our galaxy. So here I just put the max spin I could in and produced these GUI concept shots.
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Weighing in at 66.57 solar masses, at maximum spin the event horizon is at about 98 km radius, the ergosurface peaks at nearly 197 km radius, and the ISCO sits out at 295 km. Note that 253 km is the body exclusion zone in Elite: Dangerous. Also worth noting again is the VFX are incorrect. The event horizon should be black (duh)! This and Sagittarius A* are the only black holes I know of in-game that have an ergosphere thicker than about 20 km (this one is 98.3 km thick).

The VFX from the movie Interstellar are widely cited as something to aspire to. The scientist Kip Thorne showed the equations for how light would behave near a black hole to the VFX artists, so I agree with this. Don't worry, you shouldn't have to run a bunch of transcendental functions to make it work right. Here's a fairly simple example: https://www.shadertoy.com/view/XlBXzd Also https://www.shadertoy.com/view/Xsc3RH Space Engine 0.98 also does black hole VFX well. It (incorrectly) warps the lens flare effect though.

Since the procedural black holes are much more "boring" :rolleyes: and I don't anticipate many more of these "impossible" black holes with super fast spin (in fact I would prefer this be fixed, as the spin has no effect yet), I won't be talking about the ergosphere thing anymore. I'll just leave that spreadsheet as is, with the data on some interesting objects as they exist in-game today.

I would still eventually like to see the ISCO and your ship getting pulled into a spiralling trajectory around a black hole put in the game someday.

Edit: I updated this and the last post's images to remove the elements behind the event horizon.
 
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Consider that you are in a FTL vessel flying in its own fold of space-time - the universal speed limit doesn't apply to you, so a swath of assumptions about black holes don't apply. Danger remains if you drop out of FTL where the gravity gradient is too steep, from accretion discs, or from radiation.
 
Good suggestion, and while FTL ships have their own bubble it surely would affected by the black hole.

Right now we basically get 'stopped' before/at event horizon, but yeah, there should be some effect, on ships really. It is a black hole after all.
 
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