Dyson Sphere and 100D Jump Limit

[Gray Lensman]

Or would the High tech xenophobic civ that built the DS have a way to counteract your sensors? Hmmmm....

A dyson sphere must have a very high mass, IMTU it is mass that limits jump drive function and would precip you outa JS. the 100D rule is a general navigation rule.

Of course I am in the middle of re-doing the whole IMTU anyway.......

 

[HG_B]

Near a Dyson sphere. I think the thrust of the rules is that if you're near a significant gravity well, then it does funny things to your jump drive. Being near a significant portion of a thing like a Dyson sphere would probably also have some consequences.

A Dyson sphere doesn't have a significant gravity well. That's the point.

 

[HG_B]

Actually there are rules that say if you plot such a jump you will come out when you hit the 100d mark of the body in the way, even if that is well short of your plotted destination. You still spend the full week in jump though. Effectively it is a misjump. And the implication is that ships themselves can block other ships from completing jumps if they interpose themselves between the jumping ship and the plotted destination.

This wouldn't work if the jump didn't correlate directly to normal space but the earliest clarification on this point is that it does. Jump doesn't work so much by folding space as it does by compressing it. And if that compression meets resistance in the form of significant mass (a solid) in the direct line between the two points in real space, it fails.

I've never read that rule. What version?

Yes, there is. Jump masking was introduced in GT, although Marc Miller has stated that he intended that to be the case right from the start. If your route intersects any jump limit, you're precipitated out there (at the end of the week in jump).


Hans

Never played GT but it is an interesting concept. You might end up outside the ort cloud every once in a while... Funny that Marc never talked about it in any of the versions he worked on...

 

[HG_B]

Question:
Can't passive sensors from nearby systems detect the gravity pull of the enclosed star? Even if it is fully enclosed in a Dyson sphere, it's gravity should still affect other nearby systems and objects, though of course this may take some time to detect.

If this is the case, then any nearby society studying the orbits/gravitational effects of nearby stars should eventually discover 'discrepancies' in their observed data of other nearby stars.

Then of course there are those improved Imperial higher tech sensors. What would they reveal?

Would this be the case, or am I missing something here?

Our current tech would detect it. No need for grav sensors. In MT grav tech can spot a planet 2 parsecs away using ship based sensors. Larger arrays probably much further.

 

[far-trader]

I've never read that rule. What version?

Funny that Marc never talked about it in any of the versions he worked on.

I think the first mention or inklings of it anyway were in fact by Marc, in a JTAS article on Jumpspace, iirc. I think it was in the MT rules, though possibly not as clearly annotated as to effects as GURPS took it.

You might end up outside the ort cloud every once in a while.

Possible, but extremely unlikely. The density is enough to make it long odds that anything solid would be on your plot. One of the hazards of jump, and reason for a few odd ships having gone missing over the years I'm sure, but even then it might be survivable. 1G for 1 week, hop in the lowberths set to wake you when you're 1G week out from the system. Or hunt the cloud for some icy bodies to refuel and jump in. Sounds like an adventure waiting to happen "As you desperately search for some icy bodies the sensors detect a ship!?"

 

[HG_B]

I think the first mention or inklings of it anyway were in fact by Marc, in a JTAS article on Jumpspace, iirc. I think it was in the MT rules, though possibly not as clearly annotated as to effects as GURPS took it.

Must be JTAS as MT doesn't cover this point. I think I remember the article you are referring to. (scary as I haven't read it in ~20 years)

Possible, but extremely unlikely. The density is enough to make it long odds that anything solid would be on your plot. One of the hazards of jump, and reason for a few odd ships having gone missing over the years I'm sure, but even then it might be survivable. 1G for 1 week, hop in the lowberths set to wake you when you're 1G week out from the system. Or hunt the cloud for some icy bodies to refuel and jump in. Sounds like an adventure waiting to happen "As you desperately search for some icy bodies the sensors detect a ship!?"

I'm sure no higher chance than 1:10,000 (even that is probably way too high). But, a good excuse to have the PCs dump out system once in a campaign. :alpha:

 

[Blue Ghost]

A Dyson sphere doesn't have a significant gravity well. That's the point.

No, I think it's the whole reason this topic is here. Jumping from a planet's surface screws with the jump drive because of the proximity. The further out you are, the safer your jump. A Dyson sphere is a unique situation, or so I think. Largely because probably only a portion of its mass is going to affect jump "mechanics", whatever they are.

 

[rancke]

Really? Ew. Don' like it. NIMTU.

And not really in the OTU either. At least, the economic consequenses of the extra time that it would take to jump to somewhere on the other side of the star is not really explored anywhere.

Personally, I think it could be used to good effect. Not just because these extended trips in normal space will give pirates a slightly better chance to make a living, but also because it would create travel seasons. People would tend to visit a particular neighboring world more when their own world was on one side of its star than when it was on the other, because it would be cheaper. There are storytelling possibilities there, IMO.


Hans

 

[rancke]

Never played GT but it is an interesting concept. You might end up outside the ort cloud every once in a while...

Extremely unlikely. The chance of intersecting any object in the oort cloud is literally astronomically small. The real consequence would be variable trip times and consequent variable travel costs.



Hans

 

[mike wightman]

MWM's article in JTAS 24 does not mention but does hint at jump masking.

The 100d rule only applies for entering and leaving jump space in this bit:

When ships are directed to exit jump space within a gravity field they are precipitated out of jump space at the edge of the field instead.

a few paragraphs later we get:

On the other hand, there seems to be a built-in safety feature for ships trying to leave jump space within 100 diameters of a world. Ships naturally precipitate out of jump as they near the 100 diameter limit.

The first quote and the first part of the second quote imply that the 100d rule only applies if the ship is actually trying to exit jump space.
It's the second part of the second quote that the GT authors developed into jump masking.

 

[rancke]

MWM's article in JTAS 24 does not mention but does hint at jump masking.

True.

The first quote and the first part of the second quote imply that the 100d rule only applies if the ship is actually trying to exit jump space.
It's the second part of the second quote that the GT authors developed into jump masking.

One of the GT authors asked Marc Miller about it. MM stated that intervening jump limits along the route did indeed interrupt jumps and that that's the way he'd intended it all along. After that, the GT authors didn't have much choice in the matter.

I don't know if he told MGT the same and why (if he did) it didn't show up in MGT (Or did it? I'm not very well versed in the MGT rules), or why, if he didn't, he didn't. Maybe he changed his mind.

As I said above, I can see some obvious plot possibilities in jump masking, and if I was to participate in a poll, I'd probably vote to retain it, but I wouldn't mind it much if it was explicitly removed from the OTU. What I would mind, very much indeed, is some official products using jump masking and other official products ignoring it. That's just messy.



Hans

 

[BlackBat242]

I read that as I always have... they precipitate out only if they have "dropped close enough to the jumpspace/real-space interface"... i.e. when they are in the process of preparing to drop out of jumpspace.

If they are safely at the higher levels* of jumpspace, then they are fine, and don't precipitate out.

That is why a jump course can take a ship "within 100d of a mass" and have no effect on its course as long as its planned drop-out point is greater than 100d from that body.

A ship can "pass through" a star without any effect as long as it is fully within at least J-1 space.



* differing levels correspond to J-1, J-2, etc, with higher J-numbers being a higher energy state, similar to the hyperspace "bands" in David Weber's writings.

 

[rancke]

I read that as I always have... they precipitate out only if they have "dropped close enough to the jumpspace/real-space interface"... i.e. when they are in the process of preparing to drop out of jumpspace.

If they are safely at the higher levels* of jumpspace, then they are fine, and don't precipitate out.

That is why a jump course can take a ship "within 100d of a mass" and have no effect on its course as long as its planned drop-out point is greater than 100d from that body.

A ship can "pass through" a star without any effect as long as it is fully within at least J-1 space.

Yes, that's also how I played it for many years. So evidently we both read it wrong. During the playtest I tried to argue the authors out of introducing/elucidating jump masking. But like it or not, Marc Miller happens to own the game. I've argued on occasion that not even MM can change the laws of logic (when two different bits of canon couldn't logically apply to the same universe), but that's not involved here. Jump masking is perfect possible -- well, at least just as possible as the other way around. So it really is Marc's decision (In the OTU -- not in your TU or mine).


Hans

 

[jawillroy]

But like it or not, Marc Miller happens to own the game...So it really is Marc's decision (In the OTU -- not in your TU or mine).

That Jumpspace article in the JTAS did a lot to confirm me in my preference for ATUs, be they MTU or YTU, 'cause I thought a lot of the official interpretation of jump for the OTU just didn't fit at all.

 

[mike wightman]

I don't like jump masking because it allows for the deliberate blocking of jump routes by, for example, maneuvering asteroids into the path of ships jumping in from adjacent systems. Not easy but definitely doable.

Or how about using artificial gravity generators to precipitate ships out of jump space?

 

[mike wightman]

I read that as I always have... they precipitate out only if they have "dropped close enough to the jumpspace/real-space interface"... i.e. when they are in the process of preparing to drop out of jumpspace.

If they are safely at the higher levels* of jumpspace, then they are fine, and don't precipitate out.

That is why a jump course can take a ship "within 100d of a mass" and have no effect on its course as long as its planned drop-out point is greater than 100d from that body.

A ship can "pass through" a star without any effect as long as it is fully within at least J-1 space.



* differing levels correspond to J-1, J-2, etc, with higher J-numbers being a higher energy state, similar to the hyperspace "bands" in David Weber's writings.

That's how I do it too IMTU - once in jump space you are cut off from the 'real' universe. It's only on entry and exit where gravity can have an affect.

The way I see it is there are 3 statements - 2 support the above view and the third implies jump masking. I'll go with the majority

 

[HG_B]

I read that as I always have... they precipitate out only if they have "dropped close enough to the jumpspace/real-space interface"... i.e. when they are in the process of preparing to drop out of jumpspace.

If they are safely at the higher levels* of jumpspace, then they are fine, and don't precipitate out.

That is why a jump course can take a ship "within 100d of a mass" and have no effect on its course as long as its planned drop-out point is greater than 100d from that body.

A ship can "pass through" a star without any effect as long as it is fully within at least J-1 space.


* differing levels correspond to J-1, J-2, etc, with higher J-numbers being a higher energy state, similar to the hyperspace "bands" in David Weber's writings.

That's how I read it and always played it.

 

[jawillroy]

I think it's important for jumpspace to be separate from realspace, except at the points of entry and exit. The way I see it is that jumpspace is the way we get around Einstein; if an object in jump is subject to interference by realspace objects along its course, then it seems to me that jump should be equally subject to relativity and everything that goes with it. That'd mess up EVERYBODY's time lines, I bet.

 

[rancke]

I don't like jump masking because it allows for the deliberate blocking of jump routes by, for example, maneuvering asteroids into the path of ships jumping in from adjacent systems. Not easy but definitely doable.

No, it really isn't practical. The distances involved are far too large for anyone to block anything with the size of asteroids you can move about in any useful timeframe for any reasonable sum of money.

Or how about using artificial gravity generators to precipitate ships out of jump space?

The arrival point of a ship after a one-parsec jump can be predicted to within 3000 km. Good luck building a generator that can generate artificial gravity over that distance. And that's if you know precisely where the ship is going to aim, something that would change constantly as the origin and destination worlds moved along their orbits. Plus, there's not any one optimal point in space for jumping at any given time, but a rather large circle. The odds against anyone being able to predict ahead of time the spot a ship will choose to jump from are literally astronomical.


Hans

 

[rancke]

The way I see it is there are 3 statements - 2 support the above view and the third implies jump masking. I'll go with the majority

What you have are two equivocal statements and one unequivocal one that trumps the rest.

Don't get me wrong, as I said above, I wouldn't mind having that explicit statement revoked, but until it is, I'm going to consider it definitive as long as i'm working with the OTU. As for my own universe, I've come around to the opinion that jump masking enhances the story possibilities of the universe, so I'll probably keep it even if it is decanonized.


Hans