GypsyComet
Emperor Mongoose
You really need to lose that attitude and accept that other people are playing the game right even if they aren't playing it the way you do.
Problems with nebulas in Traveller
- Thread starter Tom Kalbfus
- Start date
F33D said:
Gravity has little or nothing to do with jump shadowing and masking. The gravitational field at 100 diameters from different bodies such as stars, gas giants and rocky planets vary by many orders of magnitude. Work out the numbers for a neutron star for a real eye opener. Try using your 4th grade knowledge of gravitational dynamics to work out the numbers if you doubt me.
You're generally a smart and perceptive poster on these forums and I value your comments, but others have said that attitude is unacceptable.
We all fly off the handle a bit sometimes online. It's easy to do, but please take a deep breath before posting something like that and just try and find a way to re-phrase it more positively. I think you'll feel better for it. If you were to get banned it would be a loss to the Forum.
Simon Hibbs
Condottiere
Emperor Mongoose
My take on this, is that since jump technology seems deeply intertwined with grav technology, it really has to with actual mass creating a gravity focus.
Actually calculating the influence individual bodies have on it and keeping track of them would seem over burdensome in a pen and paper environment, probably less so when the game becomes a programme.
Actually calculating the influence individual bodies have on it and keeping track of them would seem over burdensome in a pen and paper environment, probably less so when the game becomes a programme.
Condottiere said:
Sure, I think the 100 diameter limit is a simplification for game purposes because nobody wants to have to do advanced mathematics to calculate distances for any given gravity strength for different bodies. It's an abstraction. But that leaves a lot of latitude for interpretation in our games. If someone wants to set up a situation where a protoplanetray disc is creating a jump shadow effect that is imprtant to a scenario or game situation, that's fine by me. I don't think it's worth worrying about the details.
Simon Hibbs
Exactly. It must be a simple 'rule-of-thumb' value - because a solid object whose 100D limit a ship might have to worry about could be anything from a lump of ice (a comet) to a lump of iron (an earthlike world) to a lump of hyperdense alloys that make titanium look like packing foam (a TL15 battleship).
Equally, once you bear in mind the 100D limits of dust or hydrogen in local space, you can always assume you're going to be within 100D of something. Equally, a fairly common trope I've seen is mainworlds whos orbit either is within or occasionally dips within the 100D limit of the star it orbits.
I always assume that's part of what the jump calculation setup times are - compensating for the local space environment, even if you're nominally 'in the clear'.
Equally, once you bear in mind the 100D limits of dust or hydrogen in local space, you can always assume you're going to be within 100D of something. Equally, a fairly common trope I've seen is mainworlds whos orbit either is within or occasionally dips within the 100D limit of the star it orbits.
I always assume that's part of what the jump calculation setup times are - compensating for the local space environment, even if you're nominally 'in the clear'.
So a nebula might have an 'equivalent size' based on the total mass and located at the center of mass that casts a 100 diameter jump mask over an otherwise empty volume of space ... just waiting for some careless navigator to plot a course through it and suddenly precipitate out at an unexpected 'Bermuda Triangle' of lost ships. 
[On the other topic, Is Gene Roddenberry smarter than a 4th grader?
]
[On the other topic, Is Gene Roddenberry smarter than a 4th grader?
]
Reynard
Emperor Mongoose
If you have the mass of the Earth dispersed in the size of individual bowling balls over an area from here to Mars you won't have Earth's gravitational pull at the center but the individual pull of each of those trillions of bowling balls spread over that area. Big difference.
atpollard said:So a nebula might have an 'equivalent size' based on the total mass and located at the center of mass that casts a 100 diameter jump mask over an otherwise empty volume of space ... just waiting for some careless navigator to plot a course through it and suddenly precipitate out at an unexpected 'Bermuda Triangle' of lost ships.
Which would mean you'd have to be 100D from the entire galaxy...
Actually, I was simply positing that large dispersed masses, like a nebula or the galaxy create a zone of virtual mass at their center that disrupts jump bubbles in exactly the same way that a real mass (like a planet or gas giant or sun) disrupt jump bubbles that pass within 100 diameters.F33D said:Which would mean you'd have to be 100D from the entire galaxy...atpollard said:So a nebula might have an 'equivalent size' based on the total mass and located at the center of mass that casts a 100 diameter jump mask over an otherwise empty volume of space ... just waiting for some careless navigator to plot a course through it and suddenly precipitate out at an unexpected 'Bermuda Triangle' of lost ships.
Since the mass of our galaxy is about 10^11 solar masses, if all of that mass were combined into a single sun/gas giant at the center of the galaxy, then it would be 43 AU in diameter. 100 diameters from this 43 AU virtual mass would yield a hypothetical 4300 AU radius zone at the center of the galaxy where jump drives will not safely operate. Since we are about 8000 parsecs from the center of the galaxy, this will not really affect us.
In the case of a nebula, I don't know the total mass of a nebula, but I would suspect that using the same concept as the galaxy above, the 'virtual 100 diameter' dead zone would probably only be in the range of a 1-10 AU radius sphere.
This is not a RAW concept, just a fun 'what if'.
Are you sure that it would have no measurable grav from a jump viewpoint? The Earth is about 4-5 times the density of a gas giant, yet both have exactly the same "100 diameter" safe jump limit. It does not seem to be something that behaves EXACTLY like normal gravity, does it?F33D said:
Let me ask another question.
The Crab Nebula exerts a gravitational force on our sun. It is tiny, but it is a force.
Would the gravitational force exerted on the sun be greater, less or identical if the mass of the Crab Nebula was gathered into a sun with the same density as Jupiter or our sun?
My background is heavily into simple Newtonian physics expressed using algebra equations, but I have a strong hunch that the gravitational force on an external object would be identical for any given mass no matter what its density might be.
I am willing to be proven wrong, but it will require at least some proof.
One can only get so far debating imaginary physics using real physics.
Jump space and 100 diameter limits fall well within the category of imaginary physics.
If you want nebulae to have no effect on jump space ... OK, that's your right.
If you want nebulae to cast a staggering 100 diameter limit across light years ... OK, that is also your right.
If I want to treat objects like a point mass and calculate 100 diameters off an assumed density and a virtual diameter ... so what's wrong with that.
GypsyComet
Emperor Mongoose
Planetary nebula (those that result from end-of-life stars) are going to be pretty diffuse and very unlikely to grab a ship out of jump or possess any sort of jump horizon. There may be a few clumps that used to be the star's planets, but they will only have the jump horizon of a planet.
Pre-solar nebula (what I was calling "Nursery Nebula" earlier) are a different critter. They are coalescing, not dispersing, and are often doing to in multiple places at once. At some point in that coalescence their jump effects transit from "none" to "small body", which means they would be like jumping into the (rather silly) asteroid field from Empire Strikes Back: lots of individual masses trying to pluck you out of jump space. Some will be big enough to do so, some won't, and that will be steadily changing. Eventually that will start to change to "large body" effects. Hitting the jump horizon of these bodies will be like emerging into a fog, but it won't be the fog that grabbed you. The mass at the center did that, so you hope for your sake that mass is one of the future planets and not a future star...
The fog will eventually clear or be blown away as the star or stars finish coalescing and light up, leaving an arriving survey party with a collection of still smoldering worlds.
Some of the largest stellar nurseries are going through all of these stages at the same time in some location, but the smaller ones probably stay in one mode for all of Human history. System formation takes millions of years, and catching a system that is ending its foggy stage just as you arrive is a once-per-empire event, if that.
It is also worth noting that all of the stellar nurseries we know about are well outside Charted Space.
Pre-solar nebula (what I was calling "Nursery Nebula" earlier) are a different critter. They are coalescing, not dispersing, and are often doing to in multiple places at once. At some point in that coalescence their jump effects transit from "none" to "small body", which means they would be like jumping into the (rather silly) asteroid field from Empire Strikes Back: lots of individual masses trying to pluck you out of jump space. Some will be big enough to do so, some won't, and that will be steadily changing. Eventually that will start to change to "large body" effects. Hitting the jump horizon of these bodies will be like emerging into a fog, but it won't be the fog that grabbed you. The mass at the center did that, so you hope for your sake that mass is one of the future planets and not a future star...
The fog will eventually clear or be blown away as the star or stars finish coalescing and light up, leaving an arriving survey party with a collection of still smoldering worlds.
Some of the largest stellar nurseries are going through all of these stages at the same time in some location, but the smaller ones probably stay in one mode for all of Human history. System formation takes millions of years, and catching a system that is ending its foggy stage just as you arrive is a once-per-empire event, if that.
It is also worth noting that all of the stellar nurseries we know about are well outside Charted Space.
But the combined gravitational effect of the crab nebulae on an object outside of the crab nebulae is greater than the combined gravitational effect of our entire solar system on an object outside of our solar system.F33D said:
What is the diameter of the Earth for determining the 100 diameter jump distance? The diameter of the solid part or the diameter of the atmosphere?
What is the diameter of a gas giant for determining the 100 diameter jump distance? The diameter of the solid core, the liquid 'ocean' or the hydrogen atmosphere?
What is the 100 diameter jump distance for a large world (10,000 km diameter) with a trace atmosphere 1 AU in diameter?
I do not see your automatic justification for completely ignoring an object with 5+ solar masses.
Where are the references in the RAW that make it clear at what density I am free to ignore a star and at what density it becomes a jump hazard?
What "everything written in Trav references" are you basing your conclusion on? ("everything written in Trav references" is a little vague).
atpollard said:
I didn't. There is no single object with that mass in that multi light year area of space. Now, in the VERY much smaller area of our solar system there IS an object with a mass of 1 solar. The TOTAL effect on a ship within our solar system, grav wise, is MUCH greater than the effect of the scattered gas (over many cubic light years of a nebula.) That is COMPLETELY axiomatic based on how much the curvature of space would be locally. The planets ALONE in our solar system would create more curvature for a ship within the system too. Otherwise you couldn't jump into a system with multiple stars.
Also by measuring the speed of expansion over time (the nebula) they can figure the internal gravitic force. (hint, it is MUCH less than an object experiences from the Sun while within the bounds of this system...)
Local curvature of space can't be the defining factor: 100 gas giant atmosphere diameters from a gas giant does not have the same 'curvature' as 100 solid planet diameters from a planet which does not have the same 'curvature' as 100 photosphere diameters from a sun. Whatever is happening at '100 diameters' it is not a simple matter of gravity gradient.F33D said:
Since knowing what it is "not" doesn't get us over the finish line, and there are no specific rules for nebulae in Traveller, your OPINION that Nebulae have no effect is no more or less valid than my OPINION that the 100 diameter limit is based on the original 'pre-nebulae' size of the star and persists as long as the matter that comprised that star still exists.
It is not your opinion that rubs me the wrong way, it is your insistence that your opinion is fact while other opinions are wrong that bothers me.
atpollard said:
In trav that is what it is supposed to measure. The 100D limit being a simplification so Refs aren't recalculating for every single body in space from/to which a ship might jump.
I know you don't like it but that's how it works. Do you want me to give an intentionally false answer?
Reynard
Emperor Mongoose
"Since knowing what it is "not" doesn't get us over the finish line, and there are no specific rules for nebulae in Traveller, "
There is no specific rule in Traveller or in the many, many articles in various publications describing nebulas because they are exceeding rare in our section of space, real or OTU. Their effects on the game are mostly visual. Where there are nebulas there are not many stars with habitable or even usable planetary bodies. Look at a map of our own local stars and discover how many have flare stars - planet killers - there are. They exist and have an effect yet the Traveller rules don't include them either along with neutron stars, pulsars and , god help us, black holes because none of these are very useful to the game.
"your OPINION that Nebulae have no effect is no more or less valid than my OPINION that the 100 diameter limit is based on the original 'pre-nebulae' size of the star and persists as long as the matter that comprised that star still exists."
We've been trying to describe real world physics and why, on so many levels, nebulas don't matter. That is no reason YOU can't, in your universe, have nebulas or I should say A nebula because they are HUGE and span many parsecs with the birthing star far enough away it didn't decimate many or most other systems with it's super blast and the matter and energy of the expelled sun to form the initial intense expanding cloud. Your nebula could be at an extreme edge of the cloud where energy dispersed by distance and the gasses have cooled. Still could be radiation effects our Earth never experiences to mess up sensors and thus jumping. Just because Traveller didn't create a rule for everything, real or fictional doesn't stop anyone. We don't know if jump exists but we know how nebulas works and that's what people are stating. You need to state "in my Traveller universe" and we understand the why.
"It is not your opinion that rubs me the wrong way, it is your insistence that your opinion is fact while other opinions are wrong that bothers me."
Truthfully, it is 'in fact' and stating your opinion as also real fact is actually wrong. Again, you either prove, with references, your fact is truth or accept fact and state you have an alternative for the system and game mechanics. Marc Miller said similarly when he stated for the game that cold fusion works but people understand, so far, cold fusion isn't real.
There is no specific rule in Traveller or in the many, many articles in various publications describing nebulas because they are exceeding rare in our section of space, real or OTU. Their effects on the game are mostly visual. Where there are nebulas there are not many stars with habitable or even usable planetary bodies. Look at a map of our own local stars and discover how many have flare stars - planet killers - there are. They exist and have an effect yet the Traveller rules don't include them either along with neutron stars, pulsars and , god help us, black holes because none of these are very useful to the game.
"your OPINION that Nebulae have no effect is no more or less valid than my OPINION that the 100 diameter limit is based on the original 'pre-nebulae' size of the star and persists as long as the matter that comprised that star still exists."
We've been trying to describe real world physics and why, on so many levels, nebulas don't matter. That is no reason YOU can't, in your universe, have nebulas or I should say A nebula because they are HUGE and span many parsecs with the birthing star far enough away it didn't decimate many or most other systems with it's super blast and the matter and energy of the expelled sun to form the initial intense expanding cloud. Your nebula could be at an extreme edge of the cloud where energy dispersed by distance and the gasses have cooled. Still could be radiation effects our Earth never experiences to mess up sensors and thus jumping. Just because Traveller didn't create a rule for everything, real or fictional doesn't stop anyone. We don't know if jump exists but we know how nebulas works and that's what people are stating. You need to state "in my Traveller universe" and we understand the why.
"It is not your opinion that rubs me the wrong way, it is your insistence that your opinion is fact while other opinions are wrong that bothers me."
Truthfully, it is 'in fact' and stating your opinion as also real fact is actually wrong. Again, you either prove, with references, your fact is truth or accept fact and state you have an alternative for the system and game mechanics. Marc Miller said similarly when he stated for the game that cold fusion works but people understand, so far, cold fusion isn't real.
