Warp Drive, Geekbait

[tyr_13]

No they don't. In fact I don't see it in the article cited by the OP (it's big article though, cold be buried somewhere). But I see this statement early in the main article:

It appears you're correct. It appears in the links in that article.

Solved the problems, huh?

Yes, much of that article is hype and fluff, as already noted.

There are more than two valid "problems" (more like impossibilities) with those rings. And he (and others) frequently leave them out or even state (as the OP article does) that he's solved them.

And? That doesn't mean that you get to tern one valid criticism into several. I in no way implied that the exotic matter problem was the only one. My point was that you don't get to call every issue down the chain a different valid criticism just because there is an earlier criticism.

I get the poo-pooing, and there are a TON of issues here, but that doesn't make all the criticisms valid. I honestly don't understand that huge amount of hostility that's going along with this. We know it's not about to be done, so what's the point in trying to 'out criticize' the thing?

 

[RecoveringYuppy]

And? That doesn't mean that you get to tern one valid criticism into several.

I didn't.

I in no way implied that the exotic matter problem was the only one.

I agree.

My point was that you don't get to call every issue down the chain a different valid criticism just because there is an earlier criticism.

I don't follow that. That sounds wrong.

But even if it's true it's not relevant to what I said. I was calling this guy (and many unknown reporters) out for constantly leaving out major issues and leaving people with the impression (or outright saying) that this is imminent.

I get the poo-pooing, and there are a TON of issues here, but that doesn't make all the criticisms valid.

Hypothetically true, but is anyone actually mentioning any invalid criticisms? If so, they are getting lost in the noise as far as I can tell.

I honestly don't understand that huge amount of hostility that's going along with this. We know it's not about to be done, so what's the point in trying to 'out criticize' the thing?

It appears to me a lot of people don't know that. I've met three people in real life who have been confused to varying degrees by this. One even thinking that "Orion" is going to include warp capability.

 

[theprestige]

Wait, what? The primary propulsion system often radically changes the craft's shape and layout. While they share some elements, a plasma drive, a plasma sail, an Orion drive, an ion drive, and a chemical craft will all have major differences in layout and appearance (well, besides the ion and chemical ones which look basically the same apart from the drives themselves).

We're not talking about the primary propulsion, though. We're talking about the hypothetical hyperdrive.

Keep in mind: I'm referring to an interplanetary explorer, not an interstellar explorer.

Consider a manned spacecraft tasked with exploring the gas giants of our solar system over many years. It will need certain components, such as a propulsion system (not a hyperdrive, we're not leaving our system yet), a consumables store, a life support system, a power solution, a waste heat solution and a science payload. All of the components will have to be anchored to an acceleration frame so that the propulsion system can carry it from place to place.

Some interesting questions to consider might include the following: How does the choice of propulsion system affects the layout of the other systems? Should we invest in artificial gravity, or accept the trade-off inherent in putting Earth-optimized humans in zero-g for extended periods? At what point does increasing the size of the consumables store lead to diminishing returns in the overall design? Do certain propulsion systems or acceleration profiles lead to radically different design options or constraints? Etc.

And a ship like that, which can change its solar orbit repeatedy, in order to visit different planets and do useful science, is just as useful, orbiting Alpha Centauri B as it is orbiting Sol. It's going to look about the same, too. Once we hit upon a good propulsion system and payload combo for visiting Jupiter, I doubt we're going to do much different for visiting Alpha Centauri Bb. The only question will be, how do we get that proven interplanetary exploration design over there?

What disappoints me about Dr. White's contribution is that rather than examining...

Hrm.

You know what? I was wrong. Apparently Dr. White's job at NASA is to do exactly what he's doing: Basic research into the possibility of applying exotic concepts in physics to future space propulsion solutions. If the Alcubierre drive ever becomes a reality, it will probably be due in part to White's work.

In reality, he's responsible for the drive system on the butt (thorax, wherever) of the spacecraft. The craft itself is up to other people to design. A graphic artist wants to slap a Love Boat prow on a generic payload attached to White's Alcubierre rings? I'm okay with that, actually. Call it "Enterprise"? Sure, fine with me.

So I'm withdrawing all my complaints. I'd still like to see a serious study of competing interplanetary explorer designs, with some analysis of their costs and trade-offs. But I don't begrudge Dr. White his casual elision of those things. He's focused on other things.

Now all he has to do is find some exotic matter and figure out how to turn it on and off.

 

[arthwollipot]

There is no such thing as matter with negative mass. Just as there are no rulers with a negative length.

Not exactly.



http://en.wikipedia.org/wiki/Alcubierre_drive#Wall_thickness

You don't know that negative-mass matter doesn't have an energy density that is far greater than regular matter.

I mean, since we're talking science fiction anyway...

 

[Brian-M]

All of the components will have to be anchored to an acceleration frame so that the propulsion system can carry it from place to place.

Given that re-usable inter-planetary spacecraft wouldn't be capable of landing (they'd carry detachable shuttles with them so they don't have to get the entire thing down to the ground and then back into space), and given that low acceleration over long periods of time is just as effective for interplanetary travel as high acceleration over short periods of time, we can conclude that these craft will not need to be designed to withstand much acceleration at all.

Combine this with the fact that they don't have to be aerodynamic, you can design them to be pretty much any shape you want.

ETA: I think an interesting design would be to have central engineering-module with two or three habitat modules tethered to it (air, power and communication lines would be attached to the tether).

With long-enough tethers even a slow rotation would provide the occupants of the habitat modules enough "gravity" that they won't have to suffer medical complications from zero-gravity due to spending months or years on these long voyages.

 

[Aepervius]

I always saw the alcubierre drive to be a thought experiment similar to any impracticable others , by taking parameter of an equation and straining them in unrealistic values. It is to be placed in the category of "nice story bro".

 

[theprestige]

Given that re-usable inter-planetary spacecraft wouldn't be capable of landing (they'd carry detachable shuttles with them so they don't have to get the entire thing down to the ground and then back into space), and given that low acceleration over long periods of time is just as effective for interplanetary travel as high acceleration over short periods of time, we can conclude that these craft will not need to be designed to withstand much acceleration at all.

I never said they'd have to withstand any acceleration, just that they and the propulsion system would have to be anchored to a common acceleration frame if they wanted the propulsion system to move them anywhere.

The amount of acceleration they'll need to withstand will of course depend on the mission requirements and parameters. Long slow acceleration may be great for traveling long distances, but you might need something a bit more sudden and forceful if you want to enter and leave planetary orbits.

Combine this with the fact that they don't have to be aerodynamic, you can design them to be pretty much any shape you want.

Which leads us directly to the question, "what shape do you want?" Or, "what shape is optimal given our resources and goals, and other constraints?"

ETA: I think an interesting design would be to have central engineering-module with two or three habitat modules tethered to it (air, power and communication lines would be attached to the tether).

With long-enough tethers even a slow rotation would provide the occupants of the habitat modules enough "gravity" that they won't have to suffer medical complications from zero-gravity due to spending months or years on these long voyages.

Works for me. I'd love to see a version of NASA's "eagleworks" that focuses on these kinds of designs, with serious engineering analyses, comparisons, and recommendations for various mission profiles.

I mean, the Alcubierre drive is a nice fantasy and all, but a multi-year manned mission to the Jovian moons would be actually interesting

 

[Brian-M]

Long slow acceleration may be great for traveling long distances, but you might need something a bit more sudden and forceful if you want to enter and leave planetary orbits.

Why would you need something more sudden and forceful for that?

Gradually spiraling into or out of orbit should be enough, as long as the course is carefully selected to avoid colliding with other orbiting bodies.

 

[theprestige]

Why would you need something more sudden and forceful for that?

Gradually spiraling into or out of orbit should be enough, as long as the course is carefully selected to avoid colliding with other orbiting bodies.

It's a trade-off, right? More time spent in transfer orbits means packing more consumables to keep your crew alive while they wait to arrive on station. It also means more of the mission time is spent in transit, rather than on station doing science.

It also means less science gets done between the launch of the mission and the mean time to failure of key components. Which in turn means some combination of having to pack more spare parts, more periods of elevated risk for the crew, and having to end the mission with more science left undone so you can bring the crew home safely.

It also means more psychological stress on the crew. The longer the mission, the worse it gets.

If you're looking at Jupiter, and spending quality time with a few of its moons, it also means giving up good transfer opportunities when certain conjunctions present themselves. Even if the orbital configurations are entirely predictable, the mission itself is bound to deviate at least somewhat from the original plan. Having the flexibility to exploit or even create new opportunities might be nice.

Anyway, I never said we must have (relatively) forceful and sudden accelerations. I said such accelerations might be necessary. It depends on the mission constraints and the trade-offs you're interested in.

Would you at least agree that the rest of the spacecraft must be attached to the propulsion system somehow? That's really all I was trying to say. If you're convinced that low and slow is the best possible solution, who am I to tell you you're wrong? I'd still like to see NASA do some serious studies, though.

 

[Roboramma]

I think he was commenting more on the but in:

Long slow acceleration may be great for traveling long distances, but you might need something a bit more sudden and forceful if you want to enter and leave planetary orbits.

There's nothing that really separates those two cases such that the latter but not the former should require higher acceleration.

 

[Mudcat]

The bigger problem is the assumption that these ships will have a choice between "conventional speeds" and FTL.

Because that's a sensible design feature. You would need a way to maneuver about at sublight in order to align to your target, enter or leave stable orbit, et cetera. The only reason that no sublight maneuvering would be feasible would be with warp probes.

 

[Belz...]

Because that's a sensible design feature.

"Essential" is more like it, I think.

 

[RecoveringYuppy]

Because that's a sensible design feature. You would need a way to maneuver about at sublight in order to align to your target, enter or leave stable orbit, et cetera. The only reason that no sublight maneuvering would be feasible would be with warp probes.

You seem to have completely missed two points.

One: It's not the "sublight maneuvering" I'm expecting is going to present the issues.

Two: Being essential to you and/or "us" probably isn't considered as a concern when the universe decides what it's natural laws are. The fact is there is no known, even theoretical, way to turn this phenomena on or off.

 

[theprestige]

I think he was commenting more on the but in:


There's nothing that really separates those two cases such that the latter but not the former should require higher acceleration.

I wouldn't say that either case requires higher acceleration, as long as your propulsion system produces enough thrust to at least get you started on your way. I was thinking of requirements more in terms of other mission constraints, as I alluded to in my previous post.

 

[Roboramma]

The fact is there is no known, even theoretical, way to turn this phenomena on or off.

According to wikipedia, at least as far as I can understand what's being said, there seems to be:

http://en.wikipedia.org/wiki/Alcubierre_drive

The need for exotic matter raises questions about whether one can distribute the matter in an initial spacetime that lacks a warp bubble in such a way that the bubble is created at a later time, although some physicists have proposed models of dynamical warp-drive spacetimes in which a warp bubble is formed in a previously flat space.[10] Moreover, according to Serguei Krasnikov,[11] generating a bubble in a previously flat space for a one-way FTL trip requires forcing the exotic matter to move at local faster-than-light speeds, something that would require the existence of tachyons, although Krasnikov also notes that when the spacetime is not flat from the outset, a similar result could be achieved without tachyons by placing in advance some devices along the travel path and programming them to come into operation at preassigned moments and to operate in a preassigned manner. Some suggested methods avoid the problem of tachyonic motion, but would probably generate a naked singularity at the front of the bubble.[12][13] Allen Everett and Thomas Roman comment[14] that Krasnikov's finding "does not mean that Alcubierre bubbles, if it were possible to create them, could not be used as a means of superluminal travel. It only means that the actions required to change the metric and create the bubble must be taken beforehand by some observer whose forward light cone contains the entire trajectory of the bubble."

That seems to be saying that you can take flat space-time, arrange (exotic) matter in a particular state of motion along the path of the spacecraft (this must be done slower than the speed of light, of course and so takes planning), in such a way that it will create the space-time curvature that we're calling a "warp-bubble".

 

[RecoveringYuppy]

I guess opinions about what constitutes "known theory" are somewhat subjective but I certainly wouldn't read that as a "known way to turn this phenomena on or off".

But even if I granted it status of "theoretical way to turn one on", it still depends on two phenomena not known to exist.

ETA: Abstract for the source of that comment: http://arxiv.org/abs/gr-qc/9702049

 

[edd]

According to wikipedia, at least as far as I can understand what's being said, there seems to be:

http://en.wikipedia.org/wiki/Alcubierre_drive


That seems to be saying that you can take flat space-time, arrange (exotic) matter in a particular state of motion along the path of the spacecraft (this must be done slower than the speed of light, of course and so takes planning), in such a way that it will create the space-time curvature that we're calling a "warp-bubble".

If you're going to mess with exotic matter within an achievable light cone, why not make a stable wormhole instead?

 

[theprestige]

I get the poo-pooing, and there are a TON of issues here, but that doesn't make all the criticisms valid. I honestly don't understand that huge amount of hostility that's going along with this. We know it's not about to be done, so what's the point in trying to 'out criticize' the thing?

There's not really a ton of issues, only two.

The first issue is that the Alcubierre drive is such a remote possibility at the moment that drawing pictures of spaceships that use it is on the same level as a tween girl trying on her playground boyfriend's surname in her composition book. "Ms. Drive. Mrs. Alcubierre Drive. Mr. and Mrs. Nigel Worthington Alcubierre Drive, Esq." Etc.

The second issue is that NASA is apparently paying people to create brochureware of a Love Boat named "Enterprise" like they're onto something special and important. Your tax money paid for that grade-school crap. Shouldn't you be asking Dr. White to show you an actual warp drive?

 

[tyr_13]

The second issue is that NASA is apparently paying people to create brochureware of a Love Boat named "Enterprise" like they're onto something special and important. Your tax money paid for that grade-school crap. Shouldn't you be asking Dr. White to show you an actual warp drive?

That's not what Dr. White is paid to do, and that's not what it sounds like he did. An artist created it by advising with Dr. White, I doubt it was on NASA's time, and I don't see a thing to indicate that the artist was even paid.

So Dr. White gets hype over his fringe work (his direct work is plasma drives and thrusters), some cool pictures to put on his presentations about it, the artist gets to make a cool looking ship, 'science' blogs get an easy hit generating story, and we get some neat pictures to look at. I don't see where money entered into it apart from ad rev from the blog hits, let alone tax money.

As for showing the actual warp drive,

"We're utilizing a modified Michelson-Morley interferometer — that allows us to measure microscopic perturbations in space time," he said. "In our case, we're attempting to make one of the legs of the interferometer appear to be a different length when we energize our test devices." White and his colleagues are trying to simulate the tweaked Alcubierre drive in miniature by using lasers to perturb space-time by one part in 10 million.

(source)

Which is where I imagine some actual tax dollars are going.

EDIT: Seriously, the blog by Mark Rademaker, the artist, should make things more clear. Part of the most recent post.

"We made a theory conforming concept to motivate people to pursue a STEM career." I'm not sure how that translates in "NASA's new warship". It seems the universal press translator is either broken or only translates what it thinks we want to hear.

FUN: I think we have established that we still want to go to the stars. The sooner the better even.
SAD: To see real scientists acting all weird and skeptical over an artistic concept.

EDIT2: Turns out that Mark and I used to post designs to the same forum, and I recognize a lot of his other works from there. I thought the name sounded familiar.

 

[RecoveringYuppy]

EDIT: Seriously, the blog by Mark Rademaker, the artist, should make things more clear. Part of the most recent post.

Up until I hadn't considered the artist to be at fault (and still don't). However, he's being very disingenuous here:

We made a theory conforming concept to motivate people to pursue a STEM career." I'm not sure how that translates in "NASA's new warship". It seems the universal press translator is either broken or only translates what it thinks we want to hear.

Scroll down the post where he first used that phrase (The "IXS Enterprise" post): http://mark-rademaker.blogspot.com/

His words: "The IXS Enterprise, a very early concept of the first real warpship". The press didn't have to translate anything.