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Alcubierre drive 
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#19
Jan913, 10:52 AM

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Looking at PF i do see that, love the conversation



#20
Jan913, 11:22 AM

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#21
Jan913, 11:45 AM

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So, any idea what this "exotic matter" is or might be? Whatever works?



#22
Jan913, 11:49 AM

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#23
Mar513, 05:04 AM

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Supposing the energy problem had been solved and your ship had all the energy it needed at its disposal. My question is; "What would you do with the energy?"
How would it be expended? How would it be radiated?  If this was just an engineering problem, what would be the solution? Would it be channelled as electricity through metal coils to generate intense electomagnetic fields? Or would it need to be used in some other way? Sorry if its a basic question, but all the talk seems to be about generating the energy and not how you would use it! 


#24
Mar613, 11:21 PM

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Welcome to PF;
Once you have the energy  finding uses for it (guessing you mean: "when it isn't being used for the drive") usually takes care of itself. I imagine the military may want to release it all in one go at the destination for example. A lot of the answer will depend on what form the energy takes and how much there is. Without that information  there is no way to answer. 


#25
Mar713, 08:20 AM

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#26
Mar713, 09:24 AM

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No, I think you misunderstand me (probably because I didnt explain itvery well) What I mean is; What do you do with the energy in order to make it create a warpbubble? If you had tonnes of antimatter and tonnes of matter  all contained and ready to be borught into contact to generate energy the the energy generated would be in the form of photons  essentially heat & light  how would you then use this (electromagnetic) energy to create a warp bubble? 


#27
Mar713, 10:04 AM

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#28
Mar713, 10:13 AM

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If it is 'exotic matter' you need and not energy then I rephrase my question; "What would you do with the exotic matter to make a warp bubble"? 


#29
Mar713, 11:01 AM

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I am not aware of any theoretically well motivated approaches for building a warp bubble. The main effort in such theoretical investigations is simply to reduce the required amount of exotic matter. Please see the abstract [also, the contents if you want more detail] of the review paper posted by George Jones above: http://arxiv.org/abs/0710.4474 There are also analyses of the what would happen to the occupant of a warp bubble, and to the planet they got near. These show the occupants would be vaporized, and the destination would be vaporized. It is fun to speculate on these ideas, but it is wildly unlikely anything will come of it. In pop sci speculative mode, or sci fi stories, you ignore or minimize the problems. 


#30
Mar713, 04:34 PM

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http://en.wikipedia.org/wiki/Exotic_...#Negative_mass To get a warpenvelope, you have to make your exotic matter into a particular shape. That's in the articles... some sort of torus is favorite. Probably the simplest way to think of this is that you are trying to make a gravitational field that is a very unusual shape. In GR, gravity is described by curving spacetime  and spacetime curves in response to energy distributions... which is why there is all this talk about energy requirements: matter has mass which is very dense energy  so it is handy for making gravity. Unfortunately the gravitationat field needed to go FTL without breaking any of the Rules is so weird that the matter/energy needed may not even exist (up until recently, imaginary matter would mean that the situation is certainly not possible!) but the investigation may tell us something about the relationship between GR and QM. That help? 


#31
Mar813, 05:49 AM

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So to bring it back to a 'hypothetical' question of engineering; Assuming you had access to the right kinds and amounts of exotic matter, you would simply put one kind of matter at the front of the ship and the opposite kind of matter at the rear of the ship to make it go? Or, in terms of energy; Emit the right kind of particles at the front and the right kind of particles at the rear? 


#32
Mar1213, 03:21 AM

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But that's the basic concept... very very basic. You also need to revise your ideas about the relationship between particles and energy. 


#33
Mar1213, 11:30 AM

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I'm just interested in what set of physical\mechanical attributes and their distribution in relation the vessel would need to exist in order for the vessel to begin to create the spacetime distribution around itself that would propel it in a given direction. The emphasis has so far been on the impracticalities of; Producing the energy required Obtaining right kinds of 'exotic' matter Handling the amounts of 'exotic maater' The radiation problems The problems of destroying your destination etc... I'm aware of all those issues and im not really interested in those issues, as I realise this ship isnt going to get built any time soon. I was just wondering, theoretically, what you would have construct (schematicallY0 from an engineering point of view in order for the vessell to to go! Or rather spacetime go around it. So far the diagrams show the shape of the warp bubble and how spacetime would need to be warped around with a dip at one side and a peak at the other etc... but I cant see any indication of what (mechanically) the ship would need to be doing to create this shape. (theoretically of course) 


#34
Mar1213, 11:32 AM

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If you could go FTL, you could go backwards in time. That in itself may be the most damning bit of evidence against the possibility.



#35
Mar1213, 03:45 PM

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To be fair  these are part of the set of physical\mechanical attributes and their distribution in relation the vessel that would need to exist in order for the vessel to begin to create the spacetime distribution around itself that would propel it in a given direction. Your question amounts to "if we have solved all that [on your list above] what else is needed?" Bottom line  the engineering of how to get the distributions needed, never mind how to turn it on and off, depend on the exact form that the negative energy takes. Therefore  nobody knows enough to answer the question you have posed in the way you seem to want  i.e. in an "engineering/schematic type of way. That is partly why I'm not going into great detail about the exact shape  it will be a 3D structure that looks like a pair of toruses with flattened crossections. No doubt the distribution will get tweaked further as more people work on the problem. If you want the details  go to the original papers and learn the math. 


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