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Another Empress Wave theory

Originally posted by kaladorn:

I much prefer the gravity answer, even if it does complicate some things (PS, I prefer the version without tidal forces where some planets do end up inside the stars limit....).
Looking at the tables in GT: First In, if you use the flat '100 diameters' rule planets in the lifezone F0 and smaller (main sequence) stars will be inside the limit. Using tidal forces and seeting the limit as being 100 diameters for Earth only M class stars have their lif zone inside the limit. Using Mass^1/2 (straight gravitational attraction) and Earth's limit as 100 diameters every main sequence star from an A5 down will have their lifezone inside the limit.

Of course seeing as we're changing things there's no reason to use '100 diameters from Earth' as the baseline. If you want to use a tidal force based limit (I like them because they're easy to calculate, being proportional to diameter x density) that puts most worls inside their sun's limit just set the baseline as being 2AU x mass (in Sols). That's about 340 diameters for a body with Earth's density, and about 215 for something of Sol's density.
 
I posted this on JTAS in a similar discussion (about where 100D limits are relative to habitable zones), this might be useful here.

These are values comparing the 100D limits to the location of the habitable zones (assumed to be at (SQRT(Luminosity) AU from the star), using the star data from pages 50 and 54 of First In.

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Type 100D (AU) Hab Zone (AU)
A0 2.5 7.35
A5 1.7 3.74
F0 1.5 2.55
F5 1.3 1.70
G0 1.1 1.22
G5 0.82 0.89
K0 0.71 0.65
K5 0.62 0.39
M0 0.51 0.25
M5 0.32 0.10
M8 0.14 0.03</pre>[/QUOTE]Using the more realistic numbers from the Geneva Stellar Structure models that I use, I get similar values: stars less massive than about 0.9 solar masses (G7-G5 V) will have their 100D limits beyond their habitable zones during their entire main sequence, and stars more massive than that will have their 100D limits within their habitable zones during their main sequence. Obviously this all goes out of the window during the red giant phases - generally the 'habitable zones' for giants are dozens of AU within the 100D limit for those stars.

So for more massive main sequence stars, the 100D limit is well within the habitable zone, but for stars less massive than about K0 V the habitable zone will be within the 100D limit and will thus require some time travelling using maneouvre drives to the planet from the jump exit point. That said, the distance would be about 1.5 AU at the very most, depending on what side of the star that the planet is relative to the jump exit point.
 
Hello Trash,

thanks for these clarifications and background data.
It turns my actual view on the fictional physics of jumpspace a bit, but I guess one could live with that quite well


Lets make you mind up about possible consequences for navigation....


regards,

Mert
 
Yes, let me also say "Thank you", Thrash, and I'll even be one of those exceedingly rare individuals who gives you your "h". :D Don't you just hate it when some loudmouth goes and makes some whacked out claim, and you ask to see his source, and he can't produce it? I know I hate it. I hate even more BEING in that position, which I am unfortunately right now.

Ok, so I have to yell at MWM for changing canon yet again. Like he's never had THAT happen to him before. :D Next thing you know, he's going to insist the ship has to be pointing toward the target. :rolleyes: So I guess it's all right that I can't find a specific source for you, since your letter from him invalidates everything anyway.

I did think of another way to "break" the system: Say I want to get to a planet that's only 1 or two parsecs away. I want to get there REALLY fast. So I load up my TJ transport (the one with the J6 drive) and I set a course for a jump SIX parsecs away. Of course, I have carefully aimed this jump so that my course will intersect the mainworld, and I will precipitate out of jump sooner than expected. That allows me, after 1-2 days, to come out of jump space.

You of course ask the question of what the nature of a jump is, and does the ship travel along that path at a constant speed or is it on the whole path at once, or some other explanation? The answer to that will answer the fast-jump question.

Better yet, if I'm jumping, and an asteroid crosses my path, but then moves on, does anything happen? It could stop me for a moment, and then let me continue. I could wind up jumping short, I could precip out immediately, or any number of other things.

It wouldn't take that many jump-buoys to block the path from a single star. Maybe 1000. There is a very narrow band that you have to protect. It moves as the mainworld moves, and you certainly don't have to be at Oort distance. May as well be a couple orbital slots away, to keep the number required down. A 1000 km sphere with a gravity generator to increase it's mass, so the average density is sufficient, gives a ball 200,000 km in diameter. A radius of 20 of these gives a shield 8,000,000 km across with 1256 or so (pi r^2) units. Considering the defenses some of these worlds have, this is exceedingly cheap. 8,000,000 km doesn't sound like much, but it will protect a 15,000 km world out to several hundred diameters of the source world.

Well, thanks again for showing up and contributing to the discussion. Always useful to have some one of your caliber (the guy that wrote it) in on it. :cool:
 
Originally posted by TheDS:
I did think of another way to "break" the system: Say I want to get to a planet that's only 1 or two parsecs away. I want to get there REALLY fast. So I load up my TJ transport (the one with the J6 drive) and I set a course for a jump SIX parsecs away. Of course, I have carefully aimed this jump so that my course will intersect the mainworld, and I will precipitate out of jump sooner than expected. That allows me, after 1-2 days, to come out of jump space.
You'll love this - I'm pretty sure (though I can't remember who said this) that the jump still takes a week, even if you come out of jumpspace 'early'.

No, I have no idea how that works :D :cool:
 
I thought that would be the answer. I would have argued against anything else, actually.

Ok, here's some (online) j-drive info:

Select snippets from the Traveller Library :

The jumpspace tunnel is mathematically similar to an artificially created wormhole . Due to the unique topology of jumpspace, the "fall" through the tunnel takes about 1 standard week (150 to 185 hours), regardless of the distance travelled in N-space.

Ships in jump are untouchable and out of communication.

Entering jumpspace is possible anywhere, but gravity perturbations make it safest to begin a jump at least 100 diameters from a star or a world. Jumps made between 10 and 100 diameters are considered hazardous and should be avoided. Jumps from within 10 diameters are often disastrous. Oddly enough, ships cannot materialise in a gravity well. Any craft whose jump vector calls for it to break into N-space within 100 diameters is precipitated violently out of jumpspace. In some cases, this can cause severe damage to the ship or its crew.

Emphases are mine.

These snippets, which as I recall are basically the same from the holy LBBs, MT Encyclopedia, TNE mainbook, and T4 book, show that the 100 diameter thing is only relevant when you plot your jump to exit within 100 diameters of an object. What it implies to me is that ships never worry about intersecting N-space objects, because they simply CAN'T intersect them. There is no way to touch something in jump space.

At the instant that something is trying to come out, THAT is the time when something can happen, because now J and N-space are intersecting with each other. J-space doesn't like gravity, so the hole you plotted is instantly moved away. This sudden shift causes the violence felt by such an event.

The converse would seem to be true as well, such that when a ship enters jump space from within 100 diameters, the ship is "rooted" into place (it has mass, and mass means something in N-space) and so the hole cannot drag the ship out to 100 diameters. Once the ship has entered jump, the hole is allowed to move, but it doesn't matter, since the ship is already gone. Still, we could suppose that some misjumps are caused when the hole snaps to a safe location; the deeper you were in the gravity well, the more violent the snap, and the more likely it is to catch the ship and do something to it before it gets away.

I look at Jump drive as being somewhat like being on an airplane. I see J1 space as being an altitude of 30,000 feet. No mountains reach that high, so the plane doesn't hit any of them. Only while climbing or descending are we in any danger of hitting something. Of course, this is far from a perfect analogy....

But because you can't affect something in jump space, you can't EVER run into another ship there, ships NEVER precipitate onto each other, and planets NEVER have any effect, other than at the entry and exit points.

Hey, you don't happen to have a link to that other forum you were talking about, do you Thrash? Would like to see the discussion that prompted your excellent input. Thanks! Does anyone have a link to the article quoted, the one MWM wrote? thanks again.
 
Originally posted by TheDS:
mainbook, and T4 book, show that the 100 diameter thing is only relevant when you plot your jump to exit within 100 diameters of an object. What it implies to me is that ships never worry about intersecting N-space objects, because they simply CAN'T intersect them. There is no way to touch something in jump space.
I think you're reading too much into that quote. i think they mean there is no way for other ships, etc. in the normal world to interact with the ship in jumpspace.

However, a ship can obviously be precipitated previous to the planned time from jumpspace. The passage you quoted makes this very point clear.

So, it is not illogical to assume, though it may never have been stated and been ignored due to unlikelihood, that a ship *can* be forced out of jump at a place between start and finish of jump that has a 100D boundary intersection.

This is not 'touching' anything in jump space. It is forcing the precipitation into normal space.

That might seem semantic, but I don't believe the quotes you mention clash with what Mark said to Thrash (and I'm sure Mert meant no insult by dropping the 'h').


Hey, you don't happen to have a link to that other forum you were talking about, do you Thrash? Would like to see the discussion that prompted your excellent input. Thanks! Does anyone have a link to the article quoted, the one MWM wrote? thanks again.
It's on CotI I think, just someplace else (or at least, Thrash has waded in on other discussions similarly before).
 
Hi Thhrash,

sorry for the missing "h" in the last. I´ve put in two of them this time hoping to be in sync again....

Regarding our current topic I really would suggest that such essential stuff is presented in some official and centralised way.
I normally do not like to perform bibliographic researches in order to get some basic informationen about my RPG setting


Regards,

Mert
 
I did think of another way to "break" the system
Well, we know jumps always last a week*, so that won't work, but the possibility of "hitting" moving objects does really complicate things. You plot your jump perfectly, enter jumpspace, and then, say, a Tigress pops out of jump somewhere along the route, refuels, and jumps out again. Even though this happens on day 1, and the gravitational distortion only lasts a few hours, it still somehow manages to kick you out on day 7.

I look at Jump drive as being somewhat like being on an airplane.
Exactly the analogy I like to use.

Does anyone have a link to the article quoted, the one MWM wrote?
http://members.aol.com/_ht_a/kagekiha/traveller/jtas/jumpspac.htm

Mr. Miller's current ruling trumps canon
Yeah, that's exactly the problem :-(

"When you broke the laws of physics, did you seriously think there wouldn't be a price?" --Smitty, Event Horizon
A rather appropriate choice of sig...

*But then for 20 years we "knew" ships in jump couldn't interact with n-space objects...
 
On another board is someone who uses "thrasher" and people constantly forget the 'h', so I figured it was the same here... :shrug:

Anyhow, thanks for putting up a link to the article. Hopefully there's nothing wrong with it being there.
 
There is a line in MWM's essay on jumpspace (see link above) that may add more justification to TheDS's argument.

"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."
The physics of jump sub-section, emphasis is mine.
 
Now I'm confused - I thought masking and shadowing were the same thing...

If 100d limits overlap, treat them as a single object. You exit jumpspace when you hit this.

If there's a space between them, and this is your desired exit point, then you exit jumpspace in that space.
 
The answer is that you NEVER re-enter n-space within 100 diameters of ANYTHING. That's the whole point. The ENTRY-POINT can't be within 100 diameters of anything. Your question, then, is meaningless. I think it's meaningless whichever version of reality you're using.

The only time jump-masking makes a difference is if you're jumping from behind an object, to try and go to its other side.

With the previous model, you simply find the closest point in N-space to where the intended exit-point was that is not within 100 diameters of anything bigger than a fart. The more the exit point has to move, the more severe the jump-shock. If the distance is within the normal accuracy tolerance, no big deal. You don't even notice. If it's significantly further, you start to notice.

Now if jump is limited by diameter, I wanna know what happens when you're near an object like Eta Carinae . This is a star that's bigger than our whole solar system! Its average density is not much greater than that of SPACE. You could probably penetrate its atmosphere and not even notice. You could probably have planets orbiting within it! (Well, maybe not...)

Things like this, and superdense objects (black holes, neutron stars), of course, are why the jump limit needs to be defined by an object's mass or tidal force or density.
 
Originally posted by TheDS:
Things like this, and superdense objects (black holes, neutron stars), of course, are why the jump limit needs to be defined by an object's mass or tidal force or density.
The case you cite isn't quite sufficient justification. The classic system still works.
In the case of the neutron stars/black holes it looks a bit dodgy (how big is 100 * 0)? But in the case of the supergiants, they may fall below the 'significant mass' threshold (or at least, the concentration of mass, density) to even generate a 100D precipitation field.

Note, I too prefer gravity derived results, but the classic system can still work with supergiants, just not so good with black holes (then again, if you're that close, it probably doesn't matter if you precip out or not, you'll be sucked in....).
 
Perhaps Citizen Thrash will, for me, define clearly the distinction between

Jump Masking

and

Jump Shadowing

Apparently they are similar but not the same, and I'd like to appreciate the distinction.
 
Originally posted by kaladorn:
But in the case of the supergiants, they may fall below the 'significant mass' threshold (or at least, the concentration of mass, density) to even generate a 100D precipitation field.
Even if that is the case, there's still a point inside the supergiant where the density or mass is high enough to measure a 100D limit from.

However, I'm not sure what the point TheDS is trying to make here is any more - we've been told the OTU answer (what MWM said) and in terms of the OTU that's what we're lumbered with. So I presume he's continuing the discussion from the point of view of his own Traveller universe, yes?
 
Heck, I dunno what I'm saying, as regards the supergiant. The jump point would be inside it in any case. Sorry for the babbling...


Just pretend I didn't say it.
toast.gif


But the other thing still stands.
 
Hi,

I go with Thomas/Kaladorn....
Please give us some of Your defintions.

I made my mind up a little bit about the new jump stuff and asked myself again, if now a jump could be interupted by ANY object 100Ds, which passes jump route at any time during jump ?

Doesn´t that also mean, that any large objects (main stars, gas giants) especially in the departure star system may block quite a angle segment of possible destination jump vectors
(if you are near to that 100D limit) ?
Also this would might result in quite remarkable propabilities, that a destination main world could not be reached efficently from one neighbour system because of its unlucky position in the "shadow" of some other large object in that system. Here it could be a consequence to have to jump from A to position B in order to be able to get to position C.
Is that, what jump shadowing should mean ?

Well, when I was younger jumping was much more easy


Though I am normally quite glad about all official things, I increasingly tend towards neglegting all these stuff and use the "transitionspace does not like certain levels of gravity" and "jumpspace is untouchable" system.

I get the slight impression, that all of the consequenses of the presented canonical stuff were not analysed in a detailed way.....

But perhaps we get more convincing answers, soon.

Best regards,

mert
 
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