[WMCoolmon]

That speeds are relative is something I've thought so obvious that I've never mentioned it. You have missions where planets are in the background and yet they don't zoom off at orbital speeds. It's fairly obvious the ship must therefore being keeping pace with the planet.

However (and it is a big however) we've got no proof that the ships engines could get a Freespace ship to that speed. Ships come out of subspace matching the speed of everything else around them. The only explanation I can think of is that they can some how match speeds with everything around them when they come out of subspace.

Really off-the-wall theory here:

Maybe that explains why ships cannot use subspace outside of a gravitational well. The intense deceleration seen is actually the ship adjusting the absolute speed at the location that it entered subspace with to the absolute speed of the gravitational field that it exited subspace in.

This could also help to explain 'stable' and 'unstable' jump points; a jump point located near two bodies moving at drastically different speeds would cause a ship to be torn apart as it attempted to gradually change velocity to match both bodies. More advanced subspace technology would allow the ship to focus on one gravitational point, hence why the Shivans can use unstable jump nodes.

Travel outside of a system would naturally be possible, but as there would be no significant gravitational force for the ship to lock on to, it would effectively become rooted at a speed of absolute 0 - and the entire galaxy would zoom past it. Alternatively, it would emerge outside of the system with the velocity of the galaxy, and the orbital velocity of the solar system that it had started from would cause the ship to be completely out of range in a matter of seconds.

You could even use this to explain Capella. By detonating Capella, this would spread the mass of the sun all over the area that the solar system had used to be. Now I don't know what the calculations exactly would be, but wouldn't that mean you could get further away from the former position of Capella and have a greater proportion of the gravity affect you? Or possibly the Shivans simply need the mass.

But regardless, destroying Capella or another sun could expand the radius of the spherical area that you can jump to in a system. By spreading it out and increasing the radius, it might be possible to jump from the outer edge of that sphere to the outer edge of the sphere of a system that wasn't originally connected to the node network in any way.

[eliex]

 That's actually not a bad theory. 

[Killer Whale]

 That's actually not a bad theory. 

[karajorma]

Really off-the-wall theory here:

Maybe that explains why ships cannot use subspace outside of a gravitational well. The intense deceleration seen is actually the ship adjusting the absolute speed at the location that it entered subspace with to the absolute speed of the gravitational field that it exited subspace in.

I'd say the deceleration is simply caused by the ship coming out of subspace. If you think about it logically roughly half the time the ship will be arriving from somewhere faster and half the time somewhere slower. But we never see a ship accelerate as it leaves subspace.

This could also help to explain 'stable' and 'unstable' jump points; a jump point located near two bodies moving at drastically different speeds would cause a ship to be torn apart as it attempted to gradually change velocity to match both bodies. More advanced subspace technology would allow the ship to focus on one gravitational point, hence why the Shivans can use unstable jump nodes.

Travel outside of a system would naturally be possible, but as there would be no significant gravitational force for the ship to lock on to, it would effectively become rooted at a speed of absolute 0 - and the entire galaxy would zoom past it. Alternatively, it would emerge outside of the system with the velocity of the galaxy, and the orbital velocity of the solar system that it had started from would cause the ship to be completely out of range in a matter of seconds.

Seems a reasonable possibility to me. I'd simply been thinking that matching speeds was part of the navigation calculations you had to do for a jump but it could just as easily simply be a side effect of actually making a jump like you say.

You could even use this to explain Capella. By detonating Capella, this would spread the mass of the sun all over the area that the solar system had used to be. Now I don't know what the calculations exactly would be, but wouldn't that mean you could get further away from the former position of Capella and have a greater proportion of the gravity affect you? Or possibly the Shivans simply need the mass.

Now we get to the bit where my knowledge of physics runs out too and I'd need a proper physicist to tell me if that works. Treating Capella as a point mass nothing would change. But I don't know where during the expansion of the new nebula that no longer becomes the sensible thing to do.

[WMCoolmon]

Actually, I think I know the answer to that, although I didn't think of it at the time. I'm pretty sure that at any point outside the mass particles resulting from the supernova, you would experience no net gravitational change. That's assuming that the sun is the only object in the solar system.

If you were inside the nebula (we'll call it a nebula) created by the supernova, the gravitational forces would actually be less than if Capella were still a star. This is because the mass on the outside of the sphere would cancel out the mass further inside the sphere, closer to where Capella had used to be.

Now since the planets were also destroyed by the supernova, and the mass seemed to be propelled at an extremely fast (and probably unrealistic, but I digress ) speed away from the sun, there would be some change in the force of gravity at overall points in the system. It would probably be slightly stronger closer to the planetary debris.

So destroying Capella shouldn't have any kind of gravitational effects outside of the nebula aside from redistributing the planets' mass, so long as the supernova were a perfect sphere. Hardly something to get excited about, unless the Shivans actually destroyed Capella when the planets were roughly aligned in the direction they wanted to go. And I don't think :V: would have gone to that level of detail.

But that's not counting mass that was converted into energy during the supernova.

[karajorma]

It wouldn't have any gravitational effects on surrounding stars at first (said as much earlier in fact). But if the nebula grew until it was 10LY across and was now 1LY away from a star system is it still sensible to treat it as a point mass 6LY away? I don't think so.

Admittedly it takes thousands of years for that sort of thing to happen but we know that the Shivans did survive for thousands of years so it's not impossible that they'd have blown up Capella for something that would take thousands of years to happen.

[WMCoolmon]

It wouldn't have any gravitational effects on surrounding stars at first (said as much earlier in fact). But if the nebula grew until it was 10LY across and was now 1LY away from a star system is it still sensible to treat it as a point mass 6LY away? I don't think so.

Here's the page that explains the idea.

Unfortunately, I can't really give a mathematical basis for this. Doing the math it doesn't seem like it would work out that way. A quick particle experiment, by assuming that there are two particles on opposite sides of the sphere that lie on a line that intersects the point we're trying to look at...

If you assume a 5 m radius sphere and our point is 1 m away
G = gravitational constant
dM = infinitely small slice of mass (ie our imaginary particle)

Before:
P1 = G*dM/1^2
P2 = G*dM/11^2
P1+P2 = GdM(1+1/121) = 1.0083*G*dM

After:
P1 = G*dM/2^2
P2 = G*dM/10^2
P1 + P2 = GdM(1/4 + 1/100) = .2600*G*dM

Which is a rather huge difference. So either my poor man's calculus is wrong, or that site is wrong.

[karajorma]

Simply thinking about without the maths says no too.

If you have two stars 6LY away then all the mass of both stars will be in a single plane and add together. If you have a nebula a lot of the mass will now be above and below the plane and will cancel out the vertical component of each others attraction. So you'd end up with a much weaker attraction overall.


What I'm not certain about is if and when this becomes important. The majority of the mass of Capella probably became a neutron star or black hole after all.

[Getter Robo G]

Quick question.

Since I use GTVA in my fic, aside from gameplay there's nothing to stop them from using subspace to quickly traverse teh system from one jump node A to jump node B instead of the tiem it takes to launch fighters from a base and "escort them" through system to the jump node (for pirates/shivans, whatever)...

IE pop in Centari point A, intra system jump near point B, continue on merry way to another system...Right?
Has there ever been a mention of a "distance factor" that separates subspace ability from intra and inter system jumps?

[Koth]

Sshh, you just invalidated every escort mission in existence.

[FreeSpaceFreak]

Quick question.

Since I use GTVA in my fic, aside from gameplay there's nothing to stop them from using subspace to quickly traverse teh system from one jump node A to jump node B instead of the tiem it takes to launch fighters from a base and "escort them" through system to the jump node (for pirates/shivans, whatever)...

IE pop in Centari point A, intra system jump near point B, continue on merry way to another system...Right?
Has there ever been a mention of a "distance factor" that separates subspace ability from intra and inter system jumps?

There definitely is, although it's never stated explicitly. There is some kind of subspace 'turbulence' around every node, and at least larger ships can't jump within it (otherwise, all the escort missions wouldn't make sense, would they?). If they do try to, they get thrown off course, like the Psamtik just before she died.

[TrashMan]

It's also possible that you can't jump from one end of the system to another in one jump.
Could be that the normal jump drives have some range limit, or that the gravity of the planets or the sun has some limiting effect.

[Retsof]

For the asteroid field escorts there's a simple explanation, they don't want to come out of subspace inside an asteroid. 

[WMCoolmon]

Simply thinking about without the maths says no too.

If you have two stars 6LY away then all the mass of both stars will be in a single plane and add together. If you have a nebula a lot of the mass will now be above and below the plane and will cancel out the vertical component of each others attraction. So you'd end up with a much weaker attraction overall.

The vertical components would be canceled out in any case. If you have two stars, there will be a hemisphere above the plane and below the plane for both of them. Treating things as point masses is only an approximation; there's not a magical distance or gradient where the properties of gravity suddenly change.

What I'm referring to is that at a given point in the system, you'd have a great deal of mass that was now closer to you in a nebula. But you'd also have a great deal of mass further away. So if you were outside our spherical nebula, you'd get pulled in the same direction; the question is whether or not it would be with the same magnitude. If the vertical forces didn't cancel out in a given plane, you'd be pulled in a vertical direction; which would make no sense unless you had more mass above the plane than below it or vice versa. But then the plane would have to run between the suns (which would have to have different masses) or you'd need a lopsided star.

But canonically speaking, Capella only has one star. There is no other stars in the missions based in Capella, and the CB states:

We are on the threshold of a new apocalypse. Though the juggernauts have not engaged our warships, they have set course for the Capella star. We can only speculate about their intentions, but this development cannot bode well for the Alliance.

I don't think the existence of a second star could be classified on a need-to-know basis. "Pay no attention to the nuclear fireball outside your starboard viewport!"

What I'm not certain about is if and when this becomes important. The majority of the mass of Capella probably became a neutron star or black hole after all.

Maybe, but we don't know for sure since the supernova itself was artificially induced. That also adds a lot of complexity to the situation - would the highly dense mass of a black hole change something about subspace that less dense objects wouldn't do? etc etc.

We have got to ask Stephen Hawking about this the next time he visits HLP...

[Getter Robo G]

K thanks for the replies.

I'll be taking some creative license then with intra-system jumps.

[karajorma]

There definitely is, although it's never stated explicitly. There is some kind of subspace 'turbulence' around every node, and at least larger ships can't jump within it (otherwise, all the escort missions wouldn't make sense, would they?). If they do try to, they get thrown off course, like the Psamtik just before she died.

Given that the Carthage, and Dashor weren't pushed off course I don't believe that. The Psamtik may have been pushed off course due to the fact that the portal was uncharted and they didn't have time to improve the jump calculations or some other reasons but given that other ships have jumped in close to nodes on numerous occasions (The Iceni being the best example) I don't buy that you can't jump in close.

The reason for escort missions may be more simple. Jump engines need to recharge. Perhaps it's considered safer to be a moving target than a sitting duck waiting closer to the node for recharge.

The vertical components would be canceled out in any case. If you have two stars, there will be a hemisphere above the plane and below the plane for both of them. Treating things as point masses is only an approximation; there's not a magical distance or gradient where the properties of gravity suddenly change.

I'm not saying there is. Think of this in terms of vectors. For two stars 6LY apart the horizontal component is very large and the vertical one is basically negligible in comparison. When a nebula is 10LY across the vertical component is almost as big as horizontal one. That means a lot of the gravity is being cancelled out and the overall gravitational attraction felt by the remaining star is consequently much smaller.

My point is that its hard to say whether that's important or not. Depends on whether subspace nodes are simply dependant on the gravitational field of the local star or whether its dependant on all the stars in the vicinity too.

What I'm referring to is that at a given point in the system, you'd have a great deal of mass that was now closer to you in a nebula. But you'd also have a great deal of mass further away. So if you were outside our spherical nebula, you'd get pulled in the same direction; the question is whether or not it would be with the same magnitude.

It wouldn't be exactly the same, that's what I'm getting at above. How big a difference it would make depends on how much mass Capella has ejected during the supernova and how big the nebula has become. My point is that I can't give numbers for that since I don't remember the maths any more.

Remember I'm not talking about effects within the Capella system only. I'm talking about the Capella explosion possibly having gravitational effects on other star systems.

We have got to ask Stephen Hawking about this the next time he visits HLP...

But even if he explained it I doubt we could understand it. No that wasn't a voice box joke for the one person tasteless enough to think it was!

[Retsof]

We have got to ask Stephen Hawking about this the next time he visits HLP...

Anybody think we could get him to?  

But even if he explained it I doubt we could understand it. (No that wasn't a voice box joke for the one person tasteless enough to think it was!   )

There are some people (like myself) who are interested in real science almost as much as, (if not equal to) science fiction.  So some of us could at least puzzle out what was being said.

[WMCoolmon]

The vertical components would be canceled out in any case. If you have two stars, there will be a hemisphere above the plane and below the plane for both of them. Treating things as point masses is only an approximation; there's not a magical distance or gradient where the properties of gravity suddenly change.

I'm not saying there is. Think of this in terms of vectors. For two stars 6LY apart the horizontal component is very large and the vertical one is basically negligible in comparison. When a nebula is 10LY across the vertical component is almost as big as horizontal one. That means a lot of the gravity is being cancelled out and the overall gravitational attraction felt by the remaining star is consequently much smaller.

Ahh, okay. Then the site I linked to earlier may actually be right.

The horizontal component will also move closer to the second sun too. And based on my last set of calculations, we know(?) that that will affect the second sun much more so than the particles moving vertically only and the particles on the other side of the original sun. It looks like the two might actually cancel each other out.

Moving vertically:

Before:
P1x = (G*dM/6^2)*cos0
P1y = (G*dM/6^2)*sin0

P2x = (G*dM/6^2)*cos0
P2y = (G*dM/6^2)*sin0
Px = P1x + P2x = .0556G*dM

After:
P1x = (G*dM/7.8102^2)*cos(atan2(5,6))
P1y = (G*dM/7.8102^2)*sin(atan2(5,6))

P2x = (G*dM/7.8102^2)*cos(atan2(-5,6))
P2y = (G*dM/7.8102^2)*sin(atan2(-5,6))
Px = P1x + P2x = .0252*G*dM

Moving towards the other sun:

P1 = G*dM/6^2
P2 = G*dM/6^2
P1+P2 = .0556G*dM

P1 = G*dM/1^2
P2 = G*dM/11^2
P1+P2 = 1.0083*G*dM

There's also particles in the x axis which will behave much more like the vertical particles. I think you'd need to do the full integration to know for sure.

My point is that its hard to say whether that's important or not. Depends on whether subspace nodes are simply dependant on the gravitational field of the local star or whether its dependant on all the stars in the vicinity too.

That's not even what I was saying in the first place. I'm not talking about subspace nodes at all, nor am I talking about more than one sun. Quit bringing up new topics into this discussion; it's hard enough when neither of us have a very good grasp of the physics involved.

We know that intrasystem subspace drives depend on a gravitational field.
Assumption: There is a threshold to the gravitational field beyond which it is too weak for intrasystem subspace drives to work.
Question: Would destroying the Capellan sun increase the distance from the system's center that the required field strength exists?
Experiment: Does expanding the mass of the Capellan sun cause the gravitational force at a constant point outside both the nebula and the sun to increase or decrease?

It wouldn't be exactly the same, that's what I'm getting at above. How big a difference it would make depends on how much mass Capella has ejected during the supernova and how big the nebula has become. My point is that I can't give numbers for that since I don't remember the maths any more.

Remember I'm not talking about effects within the Capella system only. I'm talking about the Capella explosion possibly having gravitational effects on other star systems.

Fine, then go start your own thread instead of trying to derail my reasoning We know that intrasystem jump drives will not reach to other systems under ordinary circumstances. If the answer to the question for my experiment is "Yes", then it's possible that intrasystem jump drives could reach there. If the answer is "no", then we know that they still wouldn't.

IIRC it would take years for the effects to reach other solar systems anyway, so what it would actually do would be irrelevant as subspace travel is generally conducted on the order of hours or minutes.

[karajorma]

Oh wait. My bad. Since this thread is all about nodes I thought I was on this thread.

[WMCoolmon]

Ahh, that makes much more sense now.

EDIT: Also, - your entire example about the vertical component is completely invalidated by both that link I supplied (Which I got from you) and contradicted by the argument you made in the other thread. Why did you argue against it here?