Jump drive discussion (yes, here we go again)

[rancke]

My take is that the jump grid creates a bubble of real space inside itself. Then (as an entirely separate process) the jump drive creates a "hole" into jumpspace. Jumpspace is fairly dense, though, so anything suddenly thrust into it would react much as if it had been slammed into a liquid at high speed (i.e. much like if it had hit a solid surface at high speed). So a large quantity of hydrogen is first injected into jumpspace, creating a bubble of "soft" jumpspace that will rapidly dissipate again[*]. Before that can happen, the jump drive slams the ship across the interface and into jumpspace.

Once inside, the jump drive's function is over and done with. you're going to emerge from jumpspace in roughly seven days, give or take, and there's nothing you can do to affect where and when. Meanwhile, the jump grid is maintained by the power plant (using as much fuel as if the maneuver drive had been going ).


[*] This bubble is often called a jump bubble, just as the bubble of realspace created by the grid is, causing much confusion and misunderstanding.


Hans

 

[mike wightman]

Actually, more than just arule of thumb, LWL also determines the maximum speed for a displacement hull before the power required to accelerate it further goes thu the roof -its a result of how water moves as a wave -the basic idea is that once you are moving as fast as a wave would if it was of your length, going faster requires either climbing the wake, or moving the sea out of the way faster than it can normally move.

That's the speed at which planing hulls hop up onto the surface of the water and move like crazy (thus hydrofoils and etc).

I've always felt it's an interesting model for jump if one assumes that a jump bubble is the same kind of thing - one that determines the maximum speed in that medium before a quantum jump is needed -thus, a jump one drive can create a jump bubble that can move up to but no further than a parsec. Grantd, this needs a 100dton bubble created by a J1 drive to differ from a 100dton bubble created by a J2 drive, but that's fairly easy to model especially since jumpspace is so weird by definition: perhaps it's a logical as a spin charge on the bubble -perhaps as odd as its color.


Lets see:

A jump drive creates a bubble of normal space that can exist in jumpspace - essentially a superparticle. It interacts with jumpspace based on its average density (thus the H2) and gradually erodes away the H2 (thus the need for refined fuel -another Grand unification topic) until it reaches a density limit, at which point it pops into normal space.

Jump difference is a linear function of density, up to the "LWL" value and there is a difference in the bubble containment field that requires a different type of interface with jumpspace. A J2 can preform a J1, but not vice versa.

Essentially, there are a few bubble configurations that allow normal matter to interact with jumpspace, and the drive creates those at the normal/jumpspace interface.....and they are quantized, not continuous. Thus, a J2 bubble is denser (more H2) and has a different "value" at the interface; it erodes differently, and thus produces more phyiscal dispacement (I dunno -time is a constant in a universe where volume and mass are oddly only semi related?) and has a maximum value of how far this displacement from the entry point is -as with a ships non-planing hull.

So: you create a Jump-n type superparticle, fill it with the needed amount of H2 up to your jump limit, and inject it into jumpspace. Minor masses (jump tanks) too near messes up the density of the bubble, and we have trouble. The density determines how far one travels from entry point, and exit is automatic, as enough normal material (H2) boils off at the interface to change the average density below that which can exist in jumpspace.

7 days +/- a bit it pops out -and hopefully you didn't mess up the interface values.

Whoops. Blather attack. I'll stop here.

Not blather at all.

I want this canonised asap.

 

[Lycanorukke]

In the case of the bubble what happens ot the hydrogen?

Does it 'leak' back into normal space (so you have a faint hydrogen trail along the jump path), does it disappear into jumpspace forever, or does it break down into energy as it is exposed to jump space physics?

What about larger objects (say a body) - would it disintergrate as it slips outside the jump field and smear itself over a few parsecs, pop into N-space intact somewhere, or disappear forever in J-Space? Or would non-molecular objects 'bounce off' the field and go along for the ride with the ship?

 

[PathfinderAP]

All these different ideas on the hows and whys..

Wasn't the principle behind J drives the same as the tech used in the philadelphia project?, an EM field?

 

[FreeTrav]

Lets see:

A jump drive creates a bubble of normal space that can exist in jumpspace - essentially a superparticle. It interacts with jumpspace based on its average density (thus the H2) and gradually erodes away the H2 (thus the need for refined fuel -another Grand unification topic) until it reaches a density limit, at which point it pops into normal space.

Jump difference is a linear function of density, up to the "LWL" value and there is a difference in the bubble containment field that requires a different type of interface with jumpspace. A J2 can preform a J1, but not vice versa.

Essentially, there are a few bubble configurations that allow normal matter to interact with jumpspace, and the drive creates those at the normal/jumpspace interface.....and they are quantized, not continuous. Thus, a J2 bubble is denser (more H2) and has a different "value" at the interface; it erodes differently, and thus produces more phyiscal dispacement (I dunno -time is a constant in a universe where volume and mass are oddly only semi related?) and has a maximum value of how far this displacement from the entry point is -as with a ships non-planing hull.

So: you create a Jump-n type superparticle, fill it with the needed amount of H2 up to your jump limit, and inject it into jumpspace. Minor masses (jump tanks) too near messes up the density of the bubble, and we have trouble. The density determines how far one travels from entry point, and exit is automatic, as enough normal material (H2) boils off at the interface to change the average density below that which can exist in jumpspace.

7 days +/- a bit it pops out -and hopefully you didn't mess up the interface values.

Whoops. Blather attack. I'll stop here.

Wanna write this up in a bit more detail, and in somewhat more formal language? If so, I have a little corner marked "Lecture Hall and Library" to print it in...

Send it to editor@freelancetraveller.com, please...

 

[captainjack]

In the case of the bubble what happens ot the hydrogen?

Does it 'leak' back into normal space (so you have a faint hydrogen trail along the jump path), does it disappear into jumpspace forever, or does it break down into energy as it is exposed to jump space physics?

My idea is that it's related to the need for refined fuel in a bubble. As the hydrogen starts interacting with jumpspace, the strong nuclear force becomes......different. Any atom with a complex nucleus (ie more than one proton) would fall apart almost instantly -and manifest part of this as a spray of hard radiation into the bubble & its contents.(bad) With monatomic hydrogen, -Protium- one avoids this, especially if the deuterium (and tritium) fraction in natural H had been processed out - and, I assume, passed into the fusion plant where one wants a concentration of 2H2 and 3H2. With no neutrons hanging on to the nucleus, the only effect is to unbind the actual proton/electron into its constituent quarks which can be assumed to take much longer as interparticle experession of the strong force is much stronger than the remnant which simply glues the protons/neutrons together.

The other need to process fuel is to control the density quite finely -although we would have to assume a very tight tolerence if the fraction of hydrogen isotopes would add significantly to the density of the final bubble. I'm not sure about this part, yet.

The residual radiation from non-purified hydrogen could explain the misjump isses with unrefined fuel, also, so it may not be needed.

What about larger objects (say a body) - would it disintergrate as it slips outside the jump field and smear itself over a few parsecs, pop into N-space intact somewhere, or disappear forever in J-Space? Or would non-molecular objects 'bounce off' the field and go along for the ride with the ship?

...let me get back to you on that when I'm back in town (Mum wants the computer back -how SciFi is that ? )

 

[Whipsnade]

In the case of the bubble what happens ot the hydrogen?

Lycanorukke,

Well, IMTU, the hydrogen isn't used to inflate the "bubble". Instead, it's used to create the membrane that defines the bubble.

Look at a soap bubble. The soapy water forms the "membrane" or "envelope" that surrounds the air trapped inside. Look at a child's balloon. A thin layer of mylar or plastic or rubber contains the helium inside. It's similar IMTU. A membrane of hydrogen contains and defines a "bubble" of normal space within the jump space dimension being traversed.


Regards,
Bill

 

[PathfinderAP]

Why all the "hydrogen" and "bubble" theories?

If J drives are based on the philadelphia projects EM field then there was no
hydrogen, or need for such, hydrogen is just the fuel for the power plant,
the power plant powers the J drive, thats how it works,

There are ships that can use anti matter as a power source, yet they also use J drives, etc

 

[Andrew Boulton]

Why all the "hydrogen" and "bubble" theories?

If J drives are based on the philadelphia projects EM field then there was no
hydrogen, or need for such, hydrogen is just the fuel for the power plant,
the power plant powers the J drive, thats how it works,

There are ships that can use anti matter as a power source, yet they also use J drives, etc

Even at 99.99% efficiency, the waste heat from fusing all that hydrogen would vaporise the ship, so it's assumed much of it is used as coolant and/or something else.

 

[atpollard]

Even at 99.99% efficiency, the waste heat from fusing all that hydrogen would vaporise the ship, so it's assumed much of it is used as coolant and/or something else.

Unless it employs some form of Heat to Electric conversion process.
(something like an Alkali-metal thermal to electric converter, but different.)

Since modern fusion has yet to achieve a positive efficiency, perhaps efficiency is closer to +0.01%.

 

[aramis]

Unless it employs some form of Heat to Electric conversion process.
(something like an Alkali-metal thermal to electric converter, but different.)

Since modern fusion has yet to achieve a positive efficiency, perhaps efficiency is closer to +0.01%.

The problem is that we know the energy of fusion quite well; if we presume 50% of the Jfuel is actually fused, and 99% of the non-heat energy from that is captured, the remaining heat residue is sufficient to heat-saturate the mass of the ship to 5000°K or so... at which point almost everything aboard is vapor, and in vacuum, it's going to disassociate.

Even at 1% being burned, and 99% non-heat absorbed, it's sufficient to heat soak a ship to unsurvivable levels, counting cooling it with the thermal mass of the rest of the fuel to plasma states.

 

[captainjack]

The problem is that we know the energy of fusion quite well; if we presume 50% of the Jfuel is actually fused, and 99% of the non-heat energy from that is captured, the remaining heat residue is sufficient to heat-saturate the mass of the ship to 5000°K or so... at which point almost everything aboard is vapor, and in vacuum, it's going to disassociate.

Even at 1% being burned, and 99% non-heat absorbed, it's sufficient to heat soak a ship to unsurvivable levels, counting cooling it with the thermal mass of the rest of the fuel to plasma states.

Can't be the case. My players just jumped outsystem and they weren't vaporized, even a little bit (and more's the pity). I think you have your suspension set to low....

 

[captainjack]

Why all the "hydrogen" and "bubble" theories?

If J drives are based on the philadelphia projects EM field then there was no
hydrogen, or need for such, hydrogen is just the fuel for the power plant,
the power plant powers the J drive, thats how it works,

There are ships that can use anti matter as a power source, yet they also use J drives, etc

Presumably, at least IMTU, they would still have to carry H for the jump bubble/membrane, whatever.

 

[captainjack]

By the way, Bill, Mike -thanks for the compliments !

 

[aramis]

Can't be the case. My players just jumped outsystem and they weren't vaporized, even a little bit (and more's the pity). I think you have your suspension set to low....

I tend to find the opposite; on the other hand, quite a few people have theirs set to "anything goes" and "Science? Bah! No Science Allowed!"

What I mean by the bit you quoth is simply this: the Jump Fuel can not be used as fusion fuel nor coolant because any means of doing so results in unsurvivably high volumes of energy. Consider this: FAR less than one kiloliter of hydrogen was fused in the first H-bomb tests; those bombs vaporized dozens of cubic meters of rock, and had yields in the dozens of kilotons. Pumping a half-ton-per-minute of fusion fuel (the slowest rate in canon ships for jump fuel) is the equivalent of a major strategic warhead every minute.

So the jump fuel can NOT be primarily fusion fuel.

Further, hydrogen carries very little heat for a given mass, and therefore makes a really poor coolant. So using it as coolant is of both negligible effect and little sense. Therefore, there truly must be some other use. I dislike the hydrogen bubble, but it's the only logical use for all that fuel.

 

[Icosahedron]

Maybe Jumpspace is a superconductor and all that fusion energy just vanishes into the abyss.

Unfortunately, the rules were created 30 years ago by a group of gamers sitting round a table, with a 'bah, no science' approach to their jump drive. Any attempt to retcon science into a situation that never included science in its design is going to be problematic.

Traveller isn't real. Sometimes you just have to accept that and move on.

 

[Lycanorukke]

Unfortunately, the rules were created 30 years ago by a group of gamers sitting round a table, with a 'bah, no science' approach to their jump drive. Any attempt to retcon science into a situation that never included science in its design is going to be problematic.

True to some extent - Traveller has no shortage of problems with real science(tm), but at least it usually makes an effort with the basics even if it is pure handwavium in the end.

The catch is though, if everything 'bad' is just waved away as "ignore it/suspend reality for a bit" without even a crude justification, pretty soon you may as well have people deflecting fusion bolts with laser swords and cute teddy bears with rocks beating up Imperial marines in B-dress. And that isn't Travelller IMHO.

 

[FreeTrav]

... the equivalent of a major strategic warhead every minute.

These are the magic words. The answer to the question "What's all the H2 for?" is "You use a little bit to power the Philadelphia Effect generator to get you into Jump Space. Then, you need to move. The way you do that is to set off a SERIOUS hydrogen bomb under your tail every minute." Jump Drive is really an implementation of Orion.

You can't really believe I'm serious, now, can you?

 

[rancke]

You can't really believe I'm serious, now, can you?

"Can if I wants to!"


Hans

 

[aramis]

These are the magic words. The answer to the question "What's all the H2 for?" is "You use a little bit to power the Philadelphia Effect generator to get you into Jump Space. Then, you need to move. The way you do that is to set off a SERIOUS hydrogen bomb under your tail every minute." Jump Drive is really an implementation of Orion.

Well, it's almost as good as the hydrogen bubble... But the bubble still has it, because the bubble doesn't make your children have 3 eyes and 7 fingers...

You can't really believe I'm serious, now, can you?[/SIZE]

One would hope not... but around here, one can never be truly certain...