Warp Drive, Geekbait

[Slowvehicle]

So you're talking about a non Alcubierre scenario? (or am I missing a joke?)

Point your vessel at a distant star. Activate Alcubiere warp. After calculated interval, de-activate Alcubiere warp. Done correctly, you will emerge from your warp-bublle at some pre-specified distance frpm your target...with you original velocity WRT target unchanged. You will have to overcome that Δv at some point, with some acceleration. Unless you have a gravity polarizer, or re-normalizer, or generator, you will spend your time catching up to your target feeling as if you are lying down in a chair strapped to the floor. Why not design the craft so that "forward" points up through the ceiling?

 

[RecoveringYuppy]

Point your vessel at a distant star. Activate Alcubiere warp. After calculated interval, de-activate Alcubiere warp. Done correctly, you will emerge from your warp-bublle at some pre-specified distance frpm your target...with you original velocity WRT target unchanged. You will have to overcome that Δv at some point, with some acceleration. Unless you have a gravity polarizer, or re-normalizer, or generator, you will spend your time catching up to your target feeling as if you are lying down in a chair strapped to the floor. Why not design the craft so that "forward" points up through the ceiling?

If we're being serious...

In Alcubiere's theory there is no activation, deactivation or acceleration. And it's not terribly "useful", you can only travel to destinations that are in the bubble with you and you travel to them by the same mundane means we travel about our own bubble now.

Dr. White has been too vague at this point to judge his claims seriously, but he claims no acceleration also.

But I agree with your concern for normal craft that experience acceleration.

 

[Farsight]

The Alcubierre Drive is perfectly practical - if a source of matter with negative mass can be found.

I think I have some behind the couch. Hang on.

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

 

[tyr_13]

I'd like to know about that too.

They pretended there wasn't any in Star Trek, didn't they?

But how would it be in actuality?

This article in the Washington post says:



Is that "weeks" also from the perspective of people remaining on earth?

Yes, apart from any time dilation from the crafts conventional deltav then it would be the same time for the people on earth.

Depending on the writer, Star Trek did make allowances for time dilation with their impulse engines but not with the warp drive.

If we're being serious...

In Alcubiere's theory there is no activation, deactivation or acceleration. And it's not terribly "useful", you can only travel to destinations that are in the bubble with you and you travel to them by the same mundane means we travel about our own bubble now.

Dr. White has been too vague at this point to judge his claims seriously, but he claims no acceleration also.

But I agree with your concern for normal craft that experience acceleration.

Not from the Alcubiere's drive, there is no acceleration. However, the origin of the journey (earth and Sol's SOI) are traveling through space at a given speed in a given direction. The target (some exoplanet) is also moving through space at a given speed in a given direction, that's likely at least somewhat different than earths. You activate the drive, drop out of the drive at the destination, only to have the same direction and speed as your origin and not to the local reference. At some point you'll have to actually align your speed and direction with whatever you want to visit. That will require a conventional source of acceleration like gravity, thrust, etc.

 

[RecoveringYuppy]

Not from the Alcubiere's drive, there is no acceleration. However, the origin of the journey (earth and Sol's SOI) are traveling through space at a given speed in a given direction. The target (some exoplanet) is also moving through space at a given speed in a given direction, that's likely at least somewhat different than earths. You activate the drive, drop out of the drive at the destination, only to have the same direction and speed as your origin and not to the local reference. At some point you'll have to actually align your speed and direction with whatever you want to visit. That will require a conventional source of acceleration like gravity, thrust, etc.

But you can't activate or deactivate the drive. There is no connection between the acceleration you are talking about and the drive.

ETA: Another way of expressing this point: The assumption that when you "drop out" of this drive you'll have the same velocity you had in this space as when you left it is a completely spurious assumption because there is no way to enter or leave either space or, alternatively phrased, turn this "drive" on or off.

 

[RecoveringYuppy]

The latest round of "news" about this this drive (including the link in the OP) is the rather specific claim that if this drive is possible we should be able to get to Alpha Centauri in two weeks. Is that just total manure or is there really some justification for that specific number? (I mean even a justification that is merely 99% manure).

 

[tyr_13]

But you can't activate or deactivate the drive. There is no connection between the acceleration you are talking about and the drive.

ETA: Another way of expressing this point: The assumption that when you "drop out" of this drive you'll have the same velocity you had in this space as when you left it is a completely spurious assumption because there is no way to enter or leave either space or, alternatively phrased, turn this "drive" on or off.

That's contrary to my understanding of the dynamics. While I am using rough language for simplicities sake, you do in fact activate and deactivate the drive, 'stopping' the bubble. I'm not sure I understand your objection unless it's related to the drive not being able to work in the first place or that if it did, one would not be able to end the warp effect because you can't interact with the bubble itself.

The latest round of "news" about this this drive (including the link in the OP) is the rather specific claim that if this drive is possible we should be able to get to Alpha Centauri in two weeks. Is that just total manure or is there really some justification for that specific number? (I mean even a justification that is merely 99% manure).

It depends on if the work of Dr. White turns out to be 99% manure or not.

 

[Hlafordlaes]

I'd like to know about that [time dilation] too.

They pretended there wasn't any in Star Trek, didn't they?

But how would it be in actuality?


Is that "weeks" also from the perspective of people remaining on earth?

A ship using such a drive would never travel at any significant percentage of c, so no time dilation aboard. It is based on manipulating spacetime so that it warps (compressed ahead, expanded behind). It's a way of making distances shorter, not travel speeds higher.

People back on Earth would have little to measure. They would need to wait for signals sent by the ship at c to arrive back on Earth. The eventual news would be that the signal received, traced to its time of origin, would yield an FTL result for the ship's voyage time before the emission at destination.

Star Trek used "subspace" communications to circumvent this problem of
phoning home. Apparently the writers were devotees of string theory (use small dimensions to cross to a new point and emerge again in normal space).

 

[Belz...]

A ship using such a drive would never travel at any significant percentage of c, so no time dilation aboard. It is based on manipulating spacetime so that it warps (compressed ahead, expanded behind). It's a way of making distances shorter, not travel speeds higher.

Indeed. The ship doesn't actually move relative to the space around it. The space around it moves relative to the space around it.

People back on Earth would have little to measure. They would need to wait for signals sent by the ship at c to arrive back on Earth.

Not necessarily. You could use warp probes to communicate back and forth.

 

[RecoveringYuppy]

It depends on if the work of Dr. White turns out to be 99% manure or not.

What we can see in the "news" is total nonsense and extreme hype. There's a ton of bad news out about this and Harold White is the only thing it all seems to have in common. It's becoming hard to believe it's all just bad reporting.

I'm not sure I understand your objection unless it's related to the drive not being able to work in the first place or that if it did, one would not be able to end the warp effect because you can't interact with the bubble itself.

Those are both extremely valid objections, but that wasn't what I was taking issue with. You seem to be saying that when the "ship" is flying "normally" it should have "up" be in the direction of accelaration. That's not an issue. But when these things are "warping" they are claimed to not involve accelaration, so "up" and "direction of accelaration" are both meaningless in that context.

That's contrary to my understanding of the dynamics. While I am using rough language for simplicities sake, you do in fact activate and deactivate the drive, 'stopping' the bubble.

I'm not aware of any version of this that include "activate" and "deactivate" options that is worth taking seriously. There's basically three levels of "currently viewed as impossible" that have to be surmounted. What is the proposal for stopping or starting something based this theoretical phenomena?

 

[Delvo]

Regarding a theoretical warp drive, would passengers actually experience time dilation? I understand that it works by warping time-space versus traveling through it. So would that actually negate the time dilation that would be expected from moving a similar distance through space-time in the same time frame?

Instead of time dilation, you'd get time travel.

 

[Loss Leader]

Oh my god, we have to build this now. Like, today. We have to drop all other priorities - social security, national defense, everything - and build this ship.

 

[RecoveringYuppy]

Oh my god, we have to build this now. Like, today. We have to drop all other priorities - social security, national defense, everything - and build this ship.

I've seen what appear to be serious requests about how to contribute money to this project in many blogs about this. I suppose it's better than buying homoepathic drugs, but it still rings of scam.

 

[Belz...]

Those are both extremely valid objections, but that wasn't what I was taking issue with. You seem to be saying that when the "ship" is flying "normally" it should have "up" be in the direction of accelaration. That's not an issue. But when these things are "warping" they are claimed to not involve accelaration, so "up" and "direction of accelaration" are both meaningless in that context.

I assume the ship has to travel via conventional means when not going at FTL speeds. Assuming no artificial gravity, the "up" question might be relevant.

 

[RecoveringYuppy]

I assume the ship has to travel via conventional means when not going at FTL speeds. Assuming no artificial gravity, the "up" question might be relevant.

Yes (sort of), but then what's the point of bring it up in a discussion of FTL?

The bigger problem is the assumption that these ships will have a choice between "conventional speeds" and FTL. That assumption depends on about three levels of currently impossible stuff, no solution in sight, "problems" being resolved.

 

[tyr_13]

What we can see in the "news" is total nonsense and extreme hype. There's a ton of bad news out about this and Harold White is the only thing it all seems to have in common. It's becoming hard to believe it's all just bad reporting.

I don't think it's hard to believe at all. That it's all bad reporting that is. Science reporting has this sort of hyperbole in it as almost a standard feature. That Dr. White has done a few interviews, a presentation, and worked with a 3D artist probably speaks more to his being a scifi geek dream like a lot (most?) of us. Who doesn't like talking about the out there stuff and imagining what it might look like?

That doesn't mean we ignore valid objections of course, but I'm not going to just assume his actual work is bunk. I'm also not assuming it's solid. Until more papers and experiments are done, I'm not assuming either.

Those are both extremely valid objections, but that wasn't what I was taking issue with. You seem to be saying that when the "ship" is flying "normally" it should have "up" be in the direction of accelaration. That's not an issue. But when these things are "warping" they are claimed to not involve accelaration, so "up" and "direction of accelaration" are both meaningless in that context.

But I clarified in my first response to you that in discussing this ship, it wouldn't always be warping. Conventional acceleration would still be a factor even if a 'warp' drive is it's main feature. In fact, that would be a consideration on any ship we're talking about for space travel. Discounting it would be like discounting how to mount tires or other landing gear on a airplane. After all, it doesn't need those when flying!

I'm not aware of any version of this that include "activate" and "deactivate" options that is worth taking seriously. There's basically three levels of "currently viewed as impossible" that have to be surmounted. What is the proposal for stopping or starting something based this theoretical phenomena?

I think it has to do with the same models that bring the energy costs down to hypothetically manageable levels. Having a bubble with a greatly reduced wall thickness that's oscillating and not completely stable.

 

[Belz...]

Yes (sort of), but then what's the point of bring it up in a discussion of FTL?

The comment was about the ship's design, which has to take all functions into consideration.

 

[RecoveringYuppy]

The comment was about the ship's design, which has to take all functions into consideration.

OK. I'll bite. How do we know that during mundane travel that "design" won't have the floors perpendicular to acceleration? Is the "design" really that far along?

 

[theprestige]

OK. I'll bite. How do we know that during mundane travel that "design" won't have the floors perpendicular to acceleration? Is the "design" really that far along?

My train of thought goes something like this: If the visible morphology of your fictional space ship suggests a heritage leading back to ocean-going ships, it indicates both a lack of imagination and a lack of realism. Personally, I enjoy drawing the "realism" line somewhere between "assume a working Alcubierre drive" and "give it a promenade deck like the goddamn Love Boat".

So for me, the design is dumb--to the point that NASA should be deeply embarrassed to have its name associated with the thing--for reasons entirely unrelated to the Alcubierre rings astern.

Post hoc rationalizations or retroactive continuity amounting to "no, seriously, our floors are all realistically aligned inside" doesn't impress me, any more than the idea of a workable Alcubierre drive impresses you.

It's not a design, it's a caricature, and a tired cliche of a caricature at that.

 

[Jimbo07]

From school, competitions, seminars and as a space travel enthusiast, I've come to at least one conclusion:

Everybody's got a Power Point spaceship.