[Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

Greetings, all!

For a Hyperspace whose distances are proportional to Truespace distances (i.e. if Truespace distance between Sol-Antares and Sol-Sirius correspond as A:B, then Hyperspace travel time at a given speed between Sol-Antares and Sol-Sirius also corresponds as A:B, and this is true for any three solar systems), under the assumption that problems with causality/relativity are either handwaved or carefully fixed, there appears to be a problem that I do not know how to solve.

For a modest HS travel speed of 1ly/week (roughly 10M mps), even if we assume that ships can attain truespace speeds of 1K mps, this means that sizes of HS and TS correspond as 1:10K. For a fast hyperspace of 1pc/day (200M mps), and same TS speed, that jumps up to 1:200K.

This means that an exit sphere (a sphere that instantly 'falls' from HS to TS, along with its contents) of a 100-meter-long ship (a reasonable mid-sized ship of space op(e)rah sort), the TS volume corresponding equals a whopping 1000km, or an even bigger 20,000km if we want travel speeds of roughly 1pc/day (which is one ten-thousandth of an au).

I suspect the requirement to have such large exit spheres (and the similar problem with entry spheres) will result in the solar systems feeling overcrowded. However, not requiring anything like that might result in nasty collisions (and is likely to be weaponized in a MAD sort of way).

Anyone got ideas how such mapping is best worked out?

* == this likely means that HS curvature is proportional to Truespace curvature, right?

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

I'm not sure I get your meaning (don't really know what an "exit sphere" is), but on a solar system scale 20,000 km is a flyspeck. So no need to worry, unless you have oodles of such objects flying around.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

An exit/entry sphere is a sphere with a Truespace diameter that corresponds to the largest dimension of a ship in Hyperspace. This is important because if two ships try to simultaneously (or in quick succession) enter Hyperspace while in each other's spheres, they will suddenly occupy the same volume in Hyperspace, which will result either in a collision or in fusion (or some other nasty reaction, definitely not healthy for the ships/crew).

And as I mentioned before, 20K km is not a flyspeck - it is 1/10,000 of an AU, or roughly 1½ the diameter of Terra. On a busy orbit around a planet, it's quite a volume (things get easier in the Oort, though). And remember, this is if ships can attain 1K mps. If ship engines cannot attain that speed (but the setting demands HS travel to be as fast), then an even more drastic ratio is required.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

Also not quite sure about your meaning, but two things come to mind. Would you be okay with variable HS speed, i.e. acceleration after entering and deceleration before exiting? If that's okay, you can drastically cut down on the distance a ship would cover just before exiting.

Also the the uncertainty where exactly you exit HS is alone a good reason not jump out of HS anywhere near planetary bodies and the like without the usual need for "gravity distorting space-time" technobabble to make manoeuvre drives useful.

Edit: Ah, got it. You assume a HS where relativity holds true, but distance is changed proportionally. That's a bit tricky and I can't really give you any suggestion except for going with a lower speed limit and making HS communication efficient and ubiquitous. There is probably a lot of space traffic control going on in major systems.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

So, I did get you right. But if that's a known problem, people will learn to work around it, and navigators will be mighty careful to stay out of each other's spheres.
Yeah, right. 1.5 earth diameters is still very much in the "aw cute" range for celestial bodies. Unless dozens of ships arrive* or leave at the same time, it won't even crowd the orbit. It hurts my brain to calculate how many ships could jump between the orbits of Earth and Mars at any one moment, but it must be 6 digit numbers, even if you don't go for 3 dimensions. Ships will simply be spending quite some time in realspace going for their actual destinations, or there will have to be some kind of tugboat service. Hyperspace ship comes in, drops cargo, moves 20K clicks, hops out. Tugboat comes in, picks up cargo, takes it to planet.

*Actually, I realised that arrival is unproblematic. Since two arriving ships always have different HS coordinates (unless they crashed in HS), they will arrive at least 20K km apart.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

Put like that it's quite neat - and leads to the consequence that multiple ships won't leave hyperspace in close formation, since their respective exit spheres will be quite so far apart (unless multiple ships can share an exit point).

So, Entry Points are the real issue, since 2 ships closer than 20K km apart (using the particular scale/speed) are in serious danger of entering HS within the same 'hyper-space'!
How much pseudo-science can you cope with?
Perhaps opening a 'jump point' creates a 'bubble' of real-space which protrudes into HS, and these 'bubbles' won't intereact - they push against each other to keep the entry spaces separate.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

I just realised I didn't even account for movent in Hyperspace. Consider this: a ship 100m long vacates its entry point in HS within 10ms. That means that with a computer coordinated jump pattern, even a fleet of 100 ships could easily jump from the same entry sphere within a few seconds. A planet could handle traffic volumes of thousands of ships a day and never get into the slightest trouble, if there is a ground station handing out jump clearances to all leaving ships.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

You're definitely seeing this clearly - the only assumption is that ships 'move' while entering HS.
If a ship does or can make a static jump from a point in real space to a point in hyperspace, and can then start up an accelerate away - it could occupy the entry sphere for as long as it wants.

Still, you seem to have boiled to problem down to the same basic issues as any hyperspace system has - knowing if/when there might be another ship on the other side of your jump point.

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

That's right. I assumed that most ship captains would be smart enought not to do that, since it would be dangerous. But of course, the pseudoscience might say you appear in HS standing still. In that case there would have to be a bigger jump interval that takes into account acceleration time. Again, the smart thing to do would be not to linger.

EDITh thinks it would be a very devious tactic to "mine" popular jump points by dropping massive items in HS and watching with glee as emerging vessels get shredded....

Re: [Space] [Spaceships] : Mapping Hyperspace onto Truespace . . .
 

Some more fun with hyperspace movement in this system:
Rogue Squadron approaches a hostile system. They fly in line astern, Rogue Leader taking point with Rogue 2 100m behind and 3 through 5 each 100 meter behind the preceding vessel. Also, each vessel's center line is shifted 10 cm to the left of the preceding vessel's center line. Their hyperdrives are computer-controlled and synchronized to Rogue Leader's hyperdrive, with a precise, cumulative 20.05ms delay for each following vessel. Now, Rogue Leader jumps. 20.05ms later, Rogue 2 jumps, appearing precisely 200m to port of Rogue Leader. The other ships follow suit, and less than a 10th of a second later, they are in truespace, line abreast, front towards enemy. You could send in 50 ships a second like this without significant dispersal. Hope my math is right, but the more I think about it, the less the whole exit/entry sphere problem looks like a problem.