Any GURPS stats for black holes, pulsars, etc?

[doctorevilbrain]

I was wondering where the 10x solar mass Blackhole came from. I don't expect Doc Smith to how about the Blackhole at the center of the galaxy back then.

[doctorevilbrain]

]I was wondering where the 10x solar mass Blackhole came from. I don't expect Doc Smith to know about the Blackhole at the center of the galaxy back then.

[AlexanderHowl]

Average mass of a stellar black hole.

[David Johansen]

So just take the square root of five times the blackhole's mass to find it's telekinetic (one direction only) Strength.

[DataPacRat]

Originally Posted by Agemegos

The radiation is repulsive, and less intense than a weapon

I'm wondering at what point that detail no longer holds true - where the radiation becomes stronger than, say, five hundred thousand d6 damage per second.

Originally Posted by Agemegos

The shields on spaceships in the Lensman universe make them immune to weapons with beams far more intense than that. The wall-shields on a speedster cope easily with particles of dust and molecules of interstellar gas impacting at 120 parsecs per hour.

That might be more due to the physics of the Bergenholm generator than purely the shields. Such a generator produces a field with a particular volume, and presumably shape; Doc Smith didn't go into the details, but it's plausible that the field is shaped to extend in front of a ship, far enough to 'catch' potentially-hazardous particles and render them at least partially inertialess before those particles impact the shields. (GURPS Lensman mentions that it takes a certain number of milliseconds for an inertialess field to fully form, but I'm not sure if that can be extrapolated to figure out how much time it would take to de-inertia-ize a random dust grain.)


I've been eyeing 4e's Spaceships 5, page 40, which contains a table describing how much dDmg a STL ship takes from ablative dust-grains. However, that damage appears to scale with the Lorentz factor of how fast the ship is going, which kind of breaks down when an FTL drive is in play. Still, it gives some potentially useful numbers. At 0.9c, the Lorentz factor is 2.294, and a ship suffers 48 dDR per year. (Or 48*3d=144d6 dDmg, if dDR runs out.) That would mean that at Lorentz 100, at 0.99995c, a ship would ablate 4,000 dDR per year (or 12,000d6 dDmg, or 120k d6 dmg per year, or about 48 dmg per hour). I just might be able to work up some further numbers for denser-medium relativistic impacts based on that.

I seem to recall some mention that damage-scales were tweaked between GURPS 3e and 4e, something about squares versus cubes. Does anyone know what the factor of change (if any) was?

[whswhs]

Originally Posted by David Johansen

So just take the square root of five times the blackhole's mass to find it's telekinetic (one direction only) Strength.

That doesn't sound right. For a homogenous body, its HP equal 8 times the cube root of its mass (in "pounds," because GURPS tends to treat mass and weight as interchangeable).

[AlexanderHowl]

So, that would give an average stellar black hole a ST of around 35 billion or so?

[whswhs]

Originally Posted by AlexanderHowl

So, that would give an average stellar black hole a ST of around 35 billion or so?

Well, an HP. It doesn't have an ST, having no musculature or comparable structures, and its telekinetic ST could be anything. Though I suppose you could estimate it from the force needed to escape from it (if you weren't inside the event horizon).

[Agemegos]

Originally Posted by whswhs

Well, an HP. It doesn't have an ST, having no musculature or comparable structures, and its telekinetic ST could be anything. Though I suppose you could estimate it from the force needed to escape from it (if you weren't inside the event horizon).

There are most probably no such things as event horizons in the Lensman universe. Places where the ether is so drastically warped that not even LIGHT ITSELF can escape, perhaps. But that would be without infinite time dilation or any other relativistic phenomena.

[Agemegos]

Originally Posted by DataPacRat

I'm wondering at what point that detail no longer holds true - where the radiation becomes stronger than, say, five hundred thousand d6 damage per second.

Let's see. 120 parsecs per hour is 4.22 × 10^14 metres per second, and the interstellar medium is around 50 000 000 molecules per cubic metre. Divide by Avogadro's number. Molar mass of hydrogen is two grams. 0.000 07 kg/m²/s. ½mv² = 6.23 × 10^24 watts per square metre. Frontal area of a speedster would be a bit over six square metres. Call that, say, four by ten to the twenty-fifth power joules per second.

Spaceships beam damage table. Treat as a neutral particle beam. Four by ten to the nineteenth MJ. Nineteen powers of ten from 3 MJ => nineteen doublings from 3 dice decadal damage. Three million d6 of damage going "dink!" every second.

That might be more due to the physics of the Bergenholm generator than purely the shields.

Maybe. I have an idea that I remember reading about matter impacting the wall-shields and being smashed, besides imposing a drag, and not about it being turned free outside the wall-shield. But I'm not about to hunt the reference down.