Short fast jumps, long slow jumps, and the 7.0 LY limit

[Ranthe]

One interesting thing I've noticed with the Advanced Navigational Array is that it frequently seems like the shortest route with fewest witchspace jumps between two systems over (say) 12.0 LY apart is also the slowest - and the longer route with more jumps is the fastest. Which is counter-intuitive, especially as due to the 7.0 LY limitation on witchspace jumps your ship is typically forced to spend a significant amount of time in normal space travelling to a convenient refuelling point (a station, fuel satellite, or the local star to sun-skim with your fuel scoops), so in theory more frequent jumping / refuelling would incur a greater time penalty than less frequent jumping. After all, here on Earth the flight-times for transoceanic airliners with refuelling stops are greater than those which can fly non-stop, and this is why commercial aircraft have been built with sufficient range to fly (say) Auckland to Los Angeles non-stop instead of having to refuel en route in Apia and Honolulu.

So if the Advanced Navigational Array calculations are correct, this anomaly exposes a significant property of travelling through witchspace... which may also explain (in-game) the 7.0 LY witchspace jump limit and why no Oolite ship carries more than 7.0 LY worth of Quirium in standard tankage.

One possible explanation is that the greater the length of the jump, the longer it takes to pass through the tail end of a witchspace wormhole compared to a shorter jump, possibly due to the amount of "kick" into witchspace that a ship gets when entering the wormhole. At the start of the wormhole entry the ship is travelling quite fast, but due to (handwave) wormhole physics the ship starts to slow down... and the longer the wormhole is, the slower - relatively speaking - the ship is travelling though the tail end before it exits. This means that short jumps would result in an overall faster transit time through the witchspace wormhole as the ship would be moving relatively faster in the last half of a short jump as opposed to a long one.

The 7.0 LY limit can also be explained in the same way. It is possible that the wormhole tail slow-down effect for a ship dramatically increases past the 4.0-5.0 LY point, so that if a jump of 7.5 LY or over was attempted the ship would have lost sufficient speed so that it never leaves the wormhole (and is either stuck in hyperspace or between dimensions). Therefore, 7.0 LY is the maximum "safe" limit for a standard witchspace jump. In-system refuelling methods such as sun-skimming, fuel stations and GalSec stations means that there is little incentive to install additional fuel capacity at the expense of cargo or weapon loads other than for the truly dedicated, and commercial imperatives of "not building capacity that will never be used" means that no shipbuilders in the Oolite universe have any incentive for constructing ships with standard fuel tanks that will carry more than 7.0 LY worth of Quirium. Galactic hyperdrives are not subject to this wormhole effect as (handwave) different principles are used in galactic wormhole generation as opposed to "standard" witchspace drives.

The only problem with the this theory for the 7.0 LY limitation is that the safety limit could be controlled by the witchspace navigation computer without the need to artificially limit the size of fuel tanks, leaving a ship to perform multiple < 7.0 LY short jumps on a single 20.0 LY capacity tank without frequent refuelling or risking getting lost in witchspace. Given that there's tankers carrying large quantities of Quirium about the Ooniverse, and we've established in the "Tankers" thread that tankers don't regularly go "BOOM!" just because they're hauling bulk Quirium, a 20.0 LY capacity fuel tank isn't inherently impossible or unsafe from a technical perspective.

It's possible of course that the 7.0 LY fuel tank limit is regulatory in nature, rather than technical. Maybe GalSec classes every ship with Quirium tanks greater than 7.0 LY capacity as "Tankers", and taxes them to the point where 7.1+ LY capacity fuel tanks are just not in demand outside of Quirium haulage companies...

[Diziet Sma]

Counter-intuitive? You mean you've never heard of the inverse-square law?

[another_commander]

The many-jumps-are-faster-than-few-jumps is a well established game mechanism which is specifically designed to add an element of thought and strategy and has been proven to be anything but counter-intuitive. Will you take the quick route and risk being attacked more or will you try to get with the least possible number of jumps to the destination, which could be somewhat safer, but may put your contract at risk? Decisions, decisions. Also, if and when someone ever writes an ambush mission, this might actually be one of the ways to be at destination before your prey and be able to set an ambush.

As Diziet Sma has pointed out, the formula is very simple and is: TravelTimeBetweenSystems(hrs) = DistanceBetweenSystems(LY) * DistanceBetweenSystems(LY).

And the Navigation Array calculations are correct, you can rely on them.

[Wildeblood]

Counter-intuitive? You mean you've never heard of the inverse-square law?

It is counter-intuitive because the further you travel at super-luminal velocity the less time should pass. (Actually, I think you're supposed to emerge from a wormhole before you enter it.) Something about real and imaginary numbers, and tachyons only being real if the sign of the time dimension is reversed, or somethin'. Some guy from CERN did try to tell me once, but "whoosh" for me if it involves maths.

As Diziet Sma has pointed out, the formula is very simple and is: TravelTimeBetweenSystems(hrs) = DistanceBetweenSystems(LY) * DistanceBetweenSystems(LY).

Yes, it's equally simple in the code - just one line. I saw it a few days ago in passing, but when I went looking for it today after reading Ranthe's post, I couldn't find it again. Slippery little sucker.

[Ranthe]

Counter-intuitive? You mean you've never heard of the inverse-square law?

<slaps head> Of course! I'm forgetting my Heinlein...

"It seemed to me that it ought to take at least eight times as long at one gee as at eight - more like sixty-four. [...] I made a rough plot and saw the trouble. Squared time cut down the advantage - because the more boost, the shorter the trip, and the shorter the trip the less time in which to use the built-up speed." ("Have Space Suit, Will Travel")

The many-jumps-are-faster-than-few-jumps is a well established game mechanism which is specifically designed to add an element of thought and strategy and has been proven to be anything but counter-intuitive. Will you take the quick route and risk being attacked more or will you try to get with the least possible number of jumps to the destination, which could be somewhat safer, but may put your contract at risk? Decisions, decisions. Also, if and when someone ever writes an ambush mission, this might actually be one of the ways to be at destination before your prey and be able to set an ambush.

I figured as much from a gameplay perspective, no disagreement there.
I was thinking of how the above might be explained in-game, but it seems that I overcomplicated the thing. Inverse-square law eliminates the need to handwave wormhole physics

[Zieman]

It is counter-intuitive because the further you travel at super-luminal velocity the less time should pass. (Actually, I think you're supposed to emerge from a wormhole before you enter it.) Something about real and imaginary numbers, and tachyons only being real if the sign of the time dimension is reversed, or somethin'. Some guy from CERN did try to tell me once, but "whoosh" for me if it involves maths.

But in Oolite you don't travel at superluminal speeds, you just take a short-cut via Witchspace.
The topology of Witchspace is different than the topology of (Oolite) truespace, so doubling the distance between witchspace entry and exit points in truespace quadruples the time needed to spend in Witchspace. And maybe somewhere between 7.0 & 7.1 LY apparent truespace distance, the Witchspace topology changes wildly making transit time (near-) infinite or perhaps minus infinite, thus setting that mysterious 7 LY limit.

[Cody]

The many-jumps-are-faster-than-few-jumps is a well established game mechanism...

Short jumps are not only faster - if you suffer a misjump on a short jump, you'll probably still have enough fuel left in the tank to escape from IS.

[Smivs]

Short jumps are not only faster - if you suffer a misjump on a short jump, you'll probably still have enough fuel left in the tank to escape from IS.

...and of course you will have more fuel available after a successful jump as well - very useful if you hit trouble.

[Diziet Sma]

OMG.. Smivs has turned into a Christmas Pudding..

<slaps head> Of course! I'm forgetting my Heinlein...

"It seemed to me that it ought to take at least eight times as long at one gee as at eight - more like sixty-four. [...] I made a rough plot and saw the trouble. Squared time cut down the advantage - because the more boost, the shorter the trip, and the shorter the trip the less time in which to use the built-up speed." ("Have Space Suit, Will Travel")

Now there's a book I haven't read in too many years.. thanks! I'll have to dig it up.

[Pleb]

The thing is, if you make a ship be able to carry more than 7 light years of fuel, it makes it to easy to travel across the galaxy and limits your encounters with hostile ships, meaning that it will actually make the game harder as getting to that all important rank of ELITE! I did try once changing the values of how far you can travel in the code and 7 light years is the perfect distance to be able to jump by, any longer and it makes things to easy, and any shorter and it cuts you off from the rest of the galaxy...

[Rese249er]

[Kirk Voice]Theoretical Wormhole Physics regarding 7.0LY:
Tanks or.. quirium collections... larger than 7.0LY are prone to the.. random crystallization of Quirium. The reason no-one has... heard of crystallized quirium is that crystallization causes a molecular cascade effect that spreads.[/Kirk Voice]
The Quirium Cascade Mine is primed by powering up gravitic generators to cause it deliberately, but was kept to 7.0 ly to prevent misfire.

[Cody]

... and 7 light years is the perfect distance to be able to jump by...

Fiendishly clever, is that... even 7.2 is too far!

[Pleb]

Fiendishly clever, is that... even 7.2 is too far!

And 6.8 is too short, lol!

3 Light Years:



5 Light Years:



6 Light Years:



Although with 6 it doesn't disconnect any systems in Galaxy 1...

[Commander McLane]

Fiendishly clever, is that... even 7.2 is too far!

And 6.8 is too short, lol!

Actually, 6.8 is exactly right, because in Oolite 7LY is exactly the same as 6.8LY.

The simple reason is that all distance between systems are multiples of 0.4. Therefore, there is no distance of 7.0LY in the whole game. 6.8LY is the biggest distance you can cover with a jump, the next biggest distance that you even can encounter is 7.2LY.

[Pleb]

Lol ok well 6 light years kinda worked (see example pics above) but 5 light years is definetely too short!