OA and its reactionless drives (split)

[Stark]

Stupid, outrageous pretentious wank is not my idea of 'interesting', and OA is further lowered in my view because it's complete fan-fabrication: it was designed from the ground up as wank-fodder for elitist cockslappers.

Knob cheese, indeed.

[Gullible Jones]

Hey, OA isn't entirely shit...

It's only 95% shit.

(I'll admit this: in every OA universe short story I tried to read, I wound up stopping a couple pages in. The majority of people writing for them seem to have prose skills that make Ben Bova look like Ian McDonald.)

[Stark]

So it's absurd wank bullshit written by elitist morons who grab every buzzword they can and put zero thought into it and then write incredibly shit stories in their wankverse because they can't get their e-penis up any other way... but it's 5% good? Pfffft. Go buy some standards.

[Gullible Jones]

To elaborate on my position above... The whole thing is an absolute mess, but there's some stuff in the hodge-podge that isn't horrible, among all the other trash. Like the idea of toposophics, for instance (though the gods know that word sounds like Treknobabble, as do too many other things in OA). Scientificially, it looks pretty implausible and tripey to me, but it could be rather cool as part of a (non-fanwanked) space opera or science fantasy setting. If someone took a few of the better ideas and plot elements from it, and stripped away all the rest, they could write something decent.

You guys are right about OA being cluttered and full of crap, but I think you're throwing the baby out with the bathwater.

Then again, maybe you aren't. It's not like there's much hope of OA getting un-fucked, and to write anything decent with the material in it you'd have to create your own universe and completely rip off OA, probably resulting in lawsuits (unless they're so Stallmanist that they'd leave you alone). It's probably better off to just stay the hell away from it.

[Gullible Jones]

This is tangentially related but...

probably resulting in lawsuits (unless they're so Stallmanist that they'd leave you alone)

If you are referring to Richard Stallman, the Free Software guy here, he has personally threatened legal action to open source projects which violate the license of his GPL'd works before. As far as I know, he has never actually done it (all the examples I know of had the threatened party back down pretty quickly), but I wouldn't use his name as someone who would leave you alone.

Yeah, I guess Stallmanist was the wrong word. I'm thinking of a "you can use whatever you like from our stuff, no questions asked" attitude.

(Even then, if I wrote anything featuring toposophics, for instance, I'd feel I was ripping off some anonymous OA contributor. Not that I'd ever use a word like "toposophic", mind.)

Anyway, what I've read of OA, I'd classify it as grossly unrealistic, but semi-hard on my scale - they try to consistently explore science, but fail. Of course, I haven't actually read that much of it.

On the cheese scale, again, from what I've seen, I agree with the others here; it is rotten.

Rotten... Hmm. Can it rightly be called technobabble if it's bullshit but was not created with bullshit in mind?

I'm really not sure. I would just say that it had horribly bad physics, and categorize it as (poorly thought out, often badly written) soft SF on the cheese scale. But I guess rotten also fits. It kind of depends on the strictness of one's definition of "technobabble".

(Also keep in mind that the cheese scale only indicates the accuracy of a universe's science; not the quality of the writing and the plot ideas, insofar as that isn't affected by the science. Of course, once you get into the "rotten" category, the accuracy of the science can start to affect other stuff, so I guess in a way it can be indicative of how good a series, novel, etc. is.)

[Gullible Jones]

Hey, I'll be damned, somebody updated OA's infamous Reactionless Drives page since I last looked... Now they're based on more realistic Alcubierre stuff instead of disjointed fields.

Well, slightly more realistic. An Alcubierre drive *might* work, maybe if the laws of physics happen to be written in our favor, and negative energy is available, and it turns out that creating the bubble doesn't require violations of special relativity.

But that's not the big problem. Most of the drives work by using a bunch of little drive nodes surrounded by Alcubierre bubbles. The drive nodes are in turn magnetically coupled to the ship, and so pull it along.

Except that can't work, because anything on the inside of an Alcubierre bubble is causally disconnected from anything on the outside... Thus, no magnetic couple.

The Void Drive, which encases the whole ship in an Alcubierre bubble, is even worse. Since the ship is causally disconnected from the bubble and from the rest of the universe, there's no steering, no braking, and no peering out at the scenery. Have a nice trip.

Yes, I see soft Swiss cheese with big causally disconnected holes in it...

[MJ12 Commando]

Yes. Half-melted Swiss cheese with larger-than-usual holes sounds about right.

I mean, I like OA and all, and have contributed to it a bit, but I'm not going to say that it works under any but a fairly literary definition of "hard science fiction". It definitely isn't particularly hard, even though it tries for hardness.

IIRC the femtotech thing came out of them realizing you'd need massive subatomic conversion capability to make wormholes, then realizing that they'd need wormholes or some sort of FTL to not restart the entire project, and then someone screwed up with a brainbug and got the image of giant swarms of subatomic robots, too. Ditto for all the sub-nanotech.

I won't make any more excuses for it, though, lest I look like a loon, but generally every idiotic decision there was borne out of half arrogance and half a misunderstanding of the science they wanted to uphold.

[Gullible Jones]

Yeah, that's the impression I'm getting.

I've signed up on the mailing list (why oh why do they have to use a Yahoo mailing list instead of a BBS?); I figure I'll try to point out some of the stuff they're screwing up, starting with the way they're using Alcubierre drives. I think I got something wrong about the causal disconnection though, because someone in an Alcubierre bubble should IIRC be able to see outside it... Maybe it only works for light exiting the bubble? Still, having the drive dragging the ship along is a pretty grotesque violation of conservation of motion.

(And as it happens they haven't gotten rid of the pitch drive, so I'll have to mention that too. Also, rathe amusingly, there's another drive - a kind of multipurpose lightsail - which is classed as reactionless when it is clearly a reaction drive.)

[Winston Blake]

At least the website doesn't call itself "hard SF", though the fanboys may think otherwise.

Actually, the front page still says 'where hard science meets space opera'. Sure, where space opera chats up hard science over the internet, pretending to be a 16-year old girl, then 'meets' it in a dark alleyway and says 'Don't scream or I'll cut ya'.

[AMX]

I think I got something wrong about the causal disconnection though, because someone in an Alcubierre bubble should IIRC be able to see outside it... Maybe it only works for light exiting the bubble?

I seem to remember that the causal disconnect only happens when moving FTL; I would not recommend taking my word for it, though.

Still, having the drive dragging the ship along is a pretty grotesque violation of conservation of motion.

Thinking about it... not really, since magnetism works both ways, so the drive should get accelerated backwards while the ship is accelerating forward - if I didn't mix something up, this is not merely grotesque, it's also not reactionless, essentially using the drive itself as reaction mass (and using the alcubierre field to keep it ahead of the ship ... watching the thing stop could be amusing).

[Gullible Jones]

I think I got something wrong about the causal disconnection though, because someone in an Alcubierre bubble should IIRC be able to see outside it... Maybe it only works for light exiting the bubble?

I seem to remember that the causal disconnect only happens when moving FTL; I would not recommend taking my word for it, though.

Yeah that sounds a little iffy. Since there's no time dilation from Alcubierre drives (and you're always going slower than light within the bubble), I'm not sure there's much of a distinction.

At any rate, the energy requirements for Alcubierre/Natario drives (even for moving something the size of a proton) are bugfuck crazy. We're talking about stellar masses worth of energy to move a ship using something like the Halo Drive. Archailects are powerful, but setting off a supernova whenever they need to ship something first-class strikes me as a bit beyond them.

Still, having the drive dragging the ship along is a pretty grotesque violation of conservation of motion.

Thinking about it... not really, since magnetism works both ways, so the drive should get accelerated backwards while the ship is accelerating forward - if I didn't mix something up, this is not merely grotesque, it's also not reactionless, essentially using the drive itself as reaction mass (and using the alcubierre field to keep it ahead of the ship ... watching the thing stop could be amusing).

I'm pretty sure that doesn't work - the ship is still going up to relativistic speeds, and the drive is moving in the same direction as the ship... And the ship has much, much more momentum in one direction than the drive does in the other. No way is that okay by Newton.

[MJ12 Commando]

I think *all* the drive ideas come from http://www.nasa.gov/centers/glenn/resea ... achev.html in some form or other.

There's going to be a lot of handwaving involved in making these drives viable (otherwise we'd have them already) but I'm fairly sure that it's not too much more than what you'd need for wormholes.

The papers would have to be found, but if NASA thinks they're possible in some form or other, assuming the tools needed are handwaved into existence (which they have in OA) they should be... viable unless proven otherwise I suppose.

This is also what they mean by Plancktech-stuff that dicks around with spatial constants and etcetera, not teensy robots running around. They shouldn't have chosen those names-people are much more willing to accept the idea of space-fuckery than they are teensy subatomic robots, which femtotech and etc. give the impression of.

[MJ12 Commando]

A paper that gives at least some of the equations for the reactionless drives in OA:

http://www.zamandayolculuk.com/cetinbal/SPACEDRIVE.HTM

[Gullible Jones]

I think *all* the drive ideas come from http://www.nasa.gov/centers/glenn/resea ... achev.html in some form or other.

There's going to be a lot of handwaving involved in making these drives viable (otherwise we'd have them already) but I'm fairly sure that it's not too much more than what you'd need for wormholes.

Umm, not really. Wormholes, though not practical, are at least possible. Reactionless drives are theoretically impossible. We'd be better off dumping money into verifying Heim theory.

The papers would have to be found, but if NASA thinks they're possible in some form or other, assuming the tools needed are handwaved into existence (which they have in OA) they should be... viable unless proven otherwise I suppose.

Half of BPP seems to have been about NASA trying to find holes in the laws of physics. SF that calls itself "hard" should assume said laws are intact, unless proven otherwise.

(Note that a) you can't scientifically prove a negative, b) the burden of proof falls on the people making unproven claims, and c) there's no reason the BPP couldn't have been a complete dead end - NASA is as fallable as the rest of the government.)

This is also what they mean by Plancktech-stuff that dicks around with spatial constants and etcetera, not teensy robots running around. They shouldn't have chosen those names-people are much more willing to accept the idea of space-fuckery than they are teensy subatomic robots, which femtotech and etc. give the impression of.

They should also be less damn vague with their definitions. The way it is, those pages read less like part of a shared SF universe and more like stuff ripped from some flakey New Age site.

A paper that gives at least some of the equations for the reactionless drives in OA:

http://www.zamandayolculuk.com/cetinbal/SPACEDRIVE.HTM

From what I'm reading so far this is about seeing if there's a valid physics model that would let this stuff work.

Not all of it is ridiculous, but anything reactionless at least violates conservation of momentum, and I'm not sure but it looks like some might violate conservation of energy. Judging from your previous posts, you're probably well enough versed in physics to know that such properties are bad in anything that's supposed to work.

[MJ12 Commando]

Umm, not really. Wormholes, though not practical, are at least possible. Reactionless drives are theoretically impossible. We'd be better off dumping money into verifying Heim theory.

No, they're impossible under Newtonian physics. There's a distinction there that's fairly important.

Half of BPP seems to have been about NASA trying to find holes in the laws of physics. SF that calls itself "hard" should assume said laws are intact, unless proven otherwise.

Actually, these aren't holes, these are applications of currently-supported theories. It's not so much poking holes in the laws of physics as it is using the equations that currently work and bending them to give an idea of what might theoretically be possible.

(Note that a) you can't scientifically prove a negative, b) the burden of proof falls on the people making unproven claims, and c) there's no reason the BPP couldn't have been a complete dead end - NASA is as fallable as the rest of the government.)

Actually, proving something incorrect is the way theories are refuted. You take an example that has different results from what the theories predict.

They should also be less damn vague with their definitions. The way it is, those pages read less like part of a shared SF universe and more like stuff ripped from some flakey New Age site.

I never disagreed with that.

From what I'm reading so far this is about seeing if there's a valid physics model that would let this stuff work.

Not all of it is ridiculous, but anything reactionless at least violates conservation of momentum, and I'm not sure but it looks like some might violate conservation of energy. Judging from your previous posts, you're probably well enough versed in physics to know that such properties are bad in anything that's supposed to work.

From what my (admittedly limited) physics knowledge in these fields is telling me, they seem to violate CoM and CoE by playing with the space around the vessel itself for propulsion rather than actually propelling it conventionally. This is what the Alcubierre warp drive is about-causing space to move and drag you along with it.

Although I'm not sure if you're more versed in quantum physics than me or what, because from my limited knowledge I can't see anything completely wrong with them, and the paper itself tells you why they won't violate the conservation laws.

Sure it sounds silly at first, but I'd take it at face value unless you can find a disproof of the theorems and equations somewhere, like most mathematically-backed theories.

I'll note that in the summary he states this:

To further explore the propulsive implications of any of these imbalanced force concepts, it is necessary to fully address the law of conservation of momentum. In the case of the tether example discussed above, the Earth acts as the reaction mass to conserve momentum. In the case of negative mass propulsion, conservation of momentum is satisfied by taking advantage of the negative inertia of negative mass. 14 With the remaining field drives, however, research will be required to determine how the surrounding space can be used to satisfy conservation of momentum.

One approach to conserve momentum is to consider space itself as the reaction mass. This approach evokes the old idea of an "ether." To be strictly consistent with empirical evidence, such as the Michelson-Morely experiment, any further research to revisit the idea of an ether would have to impose the condition that an ether is electromagnetically Lorentz invariant. Note that this condition is a characteristic of the ZPF.

That touches on the reaction mass and momentum issue. I hope it helps.

[Gullible Jones]

Umm, not really. Wormholes, though not practical, are at least possible. Reactionless drives are theoretically impossible. We'd be better off dumping money into verifying Heim theory.

No, they're impossible under Newtonian physics. There's a distinction there that's fairly important.

Relativity doesn't void all of Newtonian mechanics; conservation of momentum is still valid under it. As I said before, reactionless drives are impossible by current theory. There's the possibility that we'll discover loopholes that allow them, but I'd rate that possibility as pretty fucking slim; for now reactionless drives are soft SF material.

Half of BPP seems to have been about NASA trying to find holes in the laws of physics. SF that calls itself "hard" should assume said laws are intact, unless proven otherwise.

Actually, these aren't holes, these are applications of currently-supported theories. It's not so much poking holes in the laws of physics as it is using the equations that currently work and bending them to give an idea of what might theoretically be possible.

No currently supported theory allows for reactionless drives. (Messing around with inertia is another matter, but it's what we're discussing here.)

I'm sketchy on the equations, being a mere undergrad; but I'm going to hazard a guess that, just because one set of equations produces so and so result, doesn't mean that result will make any sense when fed into other equations.

(Note that a) you can't scientifically prove a negative, b) the burden of proof falls on the people making unproven claims, and c) there's no reason the BPP couldn't have been a complete dead end - NASA is as fallable as the rest of the government.)

Actually, proving something incorrect is the way theories are refuted. You take an example that has different results from what the theories predict.

What I meant is that, by observing e.g. conservation of momentum apply to everything you see, you conclude with 100% certainty that it applies to everything; however, this does not mean that there are violations of conservation of momentum. See here.

(I probably butchered part of that, but what the hell.)

They should also be less damn vague with their definitions. The way it is, those pages read less like part of a shared SF universe and more like stuff ripped from some flakey New Age site.

I never disagreed with that.

Okay.

From what I'm reading so far this is about seeing if there's a valid physics model that would let this stuff work.

Not all of it is ridiculous, but anything reactionless at least violates conservation of momentum, and I'm not sure but it looks like some might violate conservation of energy. Judging from your previous posts, you're probably well enough versed in physics to know that such properties are bad in anything that's supposed to work.

From what my (admittedly limited) physics knowledge in these fields is telling me, they seem to violate CoM and CoE by playing with the space around the vessel itself for propulsion rather than actually propelling it conventionally. This is what the Alcubierre warp drive is about-causing space to move and drag you along with it.

Things like the disjunction and pitch drives don't work that way. The disjunction drive, for instance generates a field which is displaced from its source, and therefore exerts a force on said source (note that the displaced field is already a theoretical impossibility). Such a drive imparts real momentum to a ship which uses it, and doesn't impart equal and opposite momentum to anything.

(You are right about the Alcubierre drive not violating CoM for a ship inside the modified region though. Locally, an Alcubierre drive ship isn't even moving. It's a cheat that puts Jesus of Nazerath to absolute shame.)

Although I'm not sure if you're more versed in quantum physics than me or what, because from my limited knowledge I can't see anything completely wrong with them, and the paper itself tells you why they won't violate the conservation laws.

I'm not well versed in QM, all I know about it comes from lay reading and such. At any rate I'll read up.

Sure it sounds silly at first, but I'd take it at face value unless you can find a disproof of the theorems and equations somewhere, like most mathematically-backed theories.

Again, these are extraordinary claims. This is not the sort of stuff you take at face value on first sight.

I'll note that in the summary he states this:

To further explore the propulsive implications of any of these imbalanced force concepts, it is necessary to fully address the law of conservation of momentum. In the case of the tether example discussed above, the Earth acts as the reaction mass to conserve momentum. In the case of negative mass propulsion, conservation of momentum is satisfied by taking advantage of the negative inertia of negative mass. 14 With the remaining field drives, however, research will be required to determine how the surrounding space can be used to satisfy conservation of momentum.

That is a good point about negative mass. I'm pretty sure that having positive and negative masses in a spacecraft would result in zero net force though.

As for the other stuff, I'm not buying it until they can come up with a solid reason that it doesn't violate CoM, and neither should OA.

One approach to conserve momentum is to consider space itself as the reaction mass. This approach evokes the old idea of an "ether." To be strictly consistent with empirical evidence, such as the Michelson-Morely experiment, any further research to revisit the idea of an ether would have to impose the condition that an ether is electromagnetically Lorentz invariant. Note that this condition is a characteristic of the ZPF.

That touches on the reaction mass and momentum issue. I hope it helps.

Ah, I've seen that before... A long time ago, in fact - there was a Poul Anderson story where a "reactionless" lightspeed drive used the rest of the universe as reaction mass.

I'm not sure if that would work or not; it looks to me like it would come into conflict with relativity because it requires a static background. It's a hell of a trick at any rate.

[Gullible Jones]

Ghetto edit:

No currently supported theory allows for reactionless drives. (Messing around with inertia is another matter, but it's what we're discussing here.)

Should have been "not what we're discussing here."

[AMX]

Yeah that sounds a little iffy. Since there's no time dilation from Alcubierre drives (and you're always going slower than light within the bubble), I'm not sure there's much of a distinction.

As I remember it, the problem is not, technically, time dilation - it's simply that the bubble moves so fast that light can't keep up, thereby cutting off the lightcone.

At any rate, the energy requirements for Alcubierre/Natario drives (even for moving something the size of a proton) are bugfuck crazy. We're talking about stellar masses worth of energy to move a ship using something like the Halo Drive. Archailects are powerful, but setting off a supernova whenever they need to ship something first-class strikes me as a bit beyond them.

Now my memory is getting seriously foggy, but didn't the Alcubierre metric include equal amounts of positive and negative mass?
From a purely mathematical POV, you could produce that from nothing, since it's always net zero.

I'm pretty sure that doesn't work - the ship is still going up to relativistic speeds, and the drive is moving in the same direction as the ship...

Actually, the space the drive is in is moving in the same direction as the ship - not the drive itself.

And the ship has much, much more momentum in one direction than the drive does in the other. No way is that okay by Newton.

That's simply bad math, not an issue with the concept as such.

[Gullible Jones]

Yeah that sounds a little iffy. Since there's no time dilation from Alcubierre drives (and you're always going slower than light within the bubble), I'm not sure there's much of a distinction.

As I remember it, the problem is not, technically, time dilation - it's simply that the bubble moves so fast that light can't keep up, thereby cutting off the lightcone.

I

At any rate, the energy requirements for Alcubierre/Natario drives (even for moving something the size of a proton) are bugfuck crazy. We're talking about stellar masses worth of energy to move a ship using something like the Halo Drive. Archailects are powerful, but setting off a supernova whenever they need to ship something first-class strikes me as a bit beyond them.

Now my memory is getting seriously foggy, but didn't the Alcubierre metric include equal amounts of positive and negative mass?
From a purely mathematical POV, you could produce that from nothing, since it's always net zero.[/quote]

Eh, no.

First off, in the best case it requires a few milligrams of negative energy and a stellar mass or so worth of positive energy, unless I'm remembering things completely wrong.

Second, you'd be right about producing both positive and negative energy from a purely mathematical POV. IIRC though, according to QM you can't isolate negative energy, as any action you can take to do so will introduce at least an equal amount of positive energy.

I'm pretty sure that doesn't work - the ship is still going up to relativistic speeds, and the drive is moving in the same direction as the ship...

Actually, the space the drive is in is moving in the same direction as the ship - not the drive itself.[/quote]

Right, my bad. This might lead to a problem with the drive getting pushed out of the bubble though, unless my brain has gone totally foggy - remember the drive is disconnected from the bubble once it's done generating it.

(And if the drive can't be pulled out of the bubble for whatever reason, shouldn't the ship end up colliding with the bubble, since theres no force on the drive counteracting that of the magnetic couple?)

And the ship has much, much more momentum in one direction than the drive does in the other. No way is that okay by Newton.

That's simply bad math, not an issue with the concept as such.

Bad math? As far as I can tell the whole concept is bad math. Think about it. If the ship and the drive are the same mass (for the purpose of argument), you can have the magnetic couple pulling the ship and the drive together with the same acceleration.

Now start up the drive. It starts speeding off in its Alcubierre bubble at .9 c or whatever, gaining no momentum at all... which causes the ship to accelerate to keep up, gaining mucho momentum. Totally bogus, man.

[AMX]

Eh, no.

First off, in the best case it requires a few milligrams of negative energy and a stellar mass or so worth of positive energy, unless I'm remembering things completely wrong.

Second, you'd be right about producing both positive and negative energy from a purely mathematical POV. IIRC though, according to QM you can't isolate negative energy, as any action you can take to do so will introduce at least an equal amount of positive energy.

Maybe, I guess.

Right, my bad. This might lead to a problem with the drive getting pushed out of the bubble though, unless my brain has gone totally foggy - remember the drive is disconnected from the bubble once it's done generating it.

Indeed, I think.

(And if the drive can't be pulled out of the bubble for whatever reason, shouldn't the ship end up colliding with the bubble, since theres no force on the drive counteracting that of the magnetic couple?)

Probably.

Bad math? As far as I can tell the whole concept is bad math. Think about it. If the ship and the drive are the same mass (for the purpose of argument), you can have the magnetic couple pulling the ship and the drive together with the same acceleration.

Now start up the drive. It starts speeding off in its Alcubierre bubble at .9 c or whatever, gaining no momentum at all... which causes the ship to accelerate to keep up, gaining mucho momentum. Totally bogus, man.

You missed the part about magnetism working both ways again.
The bubble increases the distance between ship and drive, adding no momentum - that one is correct.
But the acceleration of the ship is, in a correctly calculated world, compensated entirely by the drive getting pulled in the opposite direction.

[Darth Wong]

It seems to me that whenever you run into people espousing something as "hard science fiction", it's only "hard" in the sense that deep-fried cheese has a crusty shell. It's still cheese.

[NecronLord]

You can tell when it ceases to be 'hard' science fiction. When it's anything more sophisticated than a hypothetical trip to Mars, you're obviously just making wild and unprovable assumptions and thus 'soft'...

That is of course, an exxaggerated view, but it does show the kind of thinking a lot of 'hard sci fi' ranters encourage.

[Redleader34]

On the topic, If I had a short story about a trip to an asteroid that took several weeks using Orion style drives in the 2100s, that would be hard sci fi?

[Gullible Jones]

Probably. Depends on the drives and the distance involved, as well as other tech appearing in the story.

[MJ12 Commando]

On the topic, If I had a short story about a trip to an asteroid that took several weeks using Orion style drives in the 2100s, that would be hard sci fi?

The Orion Drive is currently the only viable interstellar drive that we can manufacture TODAY if we needed it.

Yeah, that'd be pretty damn hard sci-fi. :p