Alcubierre Drive: Constant Velocity or Acceleration?

[djg1508]

I did, indeed, misunderstand you :) Let's see if I have you now: PAllen has already explained that the energy is a special kind - it's negative. This implies that the matter is "exotic" - i.e. it has a negative mass.
http://en.wikipedia.org/wiki/Exotic_matter#Negative_mass

To get a warp-envelope, 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 space-time - and space-time 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?

Thanks for sticking with me on this!

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?

 

[Simon Bridge]

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?

No - you need it to be the right shape as well.
But that's the basic concept... very very basic.

You also need to revise your ideas about the relationship between particles and energy.

 

[djg1508]

No - you need it to be the right shape as well.
But that's the basic concept... very very basic.

You also need to revise your ideas about the relationship between particles and energy.

In what way "revise"?
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 space-time 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 I am not really interested in those issues, as I realize this ship isn't 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 space-time go around it.

So far the diagrams show the shape of the warp bubble and how space-time would need to be warped around with a dip at one side and a peak at the other etc... but I can't see any indication of what (mechanically) the ship would need to be doing to create this shape. (theoretically of course)

 

[1977ub]

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.

 

[Simon Bridge]

In what way "revise"?

You know: "revise". Review, check, reassess - go back to the materials where you formed the ideas with a critical eye to your current understanding. You made a distinction between energy and mass for example. I will not go further here as I don't want to stray too far off topic. If you are still puzzled, after your review, feel free to make another thread.

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 space-time distribution around itself that would propel it in a given direction.

I get that and have answered to this point as clearly as possible.

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...

etc etc... yeah I know.
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 space-time 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?"

I was just wondering, theoretically, what you would have construct (schematically) from an engineering point of view in order for the vessell to to go! Or rather space-time go around it.

The pop articles usually include an artists impression of the kind of thing you'd get if the exotic matter took a form similar to normal matter.

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.

So far the diagrams show the shape of the warp bubble and how space-time would need to be warped around with a dip at one side and a peak at the other etc... but I can't see any indication of what (mechanically) the ship would need to be doing to create this shape. (theoretically of course)

The space-warp diagrams can be misleading. The actual bubble is four dimensional and the articles can only print in 2D.

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.