100d limit and gas giants

[MonkeyX]

Does the 100d limit apply to gas giants? I get that there are huge but surely less dense??

 

[CordwainerFish]

In my Traveller the limit is a function of tidal stress, not how large something looks in the viewport. (If you have a slide rule handy it's no more difficult to calculate.)

 

[NOLATrav]

Canonically I believe it does. Despite their low density they often exhibit high gravity, which is simplified by using the 100d limit.

That‘s how we play it at least.

 

[MonkeyX]

Thank you. I couldn’t find anything to the contrary. It’s a good few hours (days!) to get into and out if that limit if your jumping in and refuelling.

 

[Bill Sheil]

IMTU we agreed to set the jump limit at approximately 10+90 * sqrt(density/earth density) which seemed a good and simple compromise (I would have preferred a cube root). 10D seems to be a Mongoose hard-limit on jumping so it is a reasonable base minimum.

It meant that extremely low density stellar giants (with densities of 0.001 or less) tend towards 10D, still a considerable distance but not as bad as the 100D limit. Solar density stars and gas giants may have about 0.25 density so have jump limits at approximately 65D. Terran planet and other smaller dwarf starts have about 1 density which gives 100D.

The diameter and density of black holes are still moot though.

 

[CordwainerFish]

The diameter and density of black holes are still moot though.

The diameter of a black hole is ∞...

 

[Sigtrygg]

No, the diameter of a black hole is given by
D =(4GM)/c^2

 

[Bill Sheil]

No, the diameter of a black hole is given by
D =(4GM)/c^2

No that's the radius of the event horizon (or Schwarzschild radius).

Classically speaking a black hole (singularity) has zero radius and infinite density - but how you handwave the quantum description of the singularity and the (virtual) extent of the event horizon into game mechanics is completely open..

 

[Sigtrygg]

The size of a black hole by convention is its Schwarzschild radius, the singularity may not even exist but is a flaw with out maths that we need to find a solution to.

 

[ColinD]

My "science fiction science" reason with the 100 diameter limit is that laws of physics in Jumpspace may disregard what we call mass. That means something's size (radius) has an overriding impact in Jumpspace and that mass has almost none. This is highly debated by most sophont scientists and Jump Engineers who have had too much to drink.

 

[Geir]

I think I already rambled on about this one...for planets, including gas giants, 100D is 'close enough', or at least better than a mass-based solution. For stars, either can work across the main sequence, but it becomes problematic with giants, white dwarfs and more exotic remnants, where mass is a 'better' - at least in game terms match. So I would tend towards using mass for stars (where the equivalent of '100D' of a Sol mass star gets you to 0.93 AU) and 100D for planets, where the planetary diameter is going to give you a closer answer - multiplied by the planet's density in terms of Earth if you want a better gravity well answer. But that's just an opinion.