Gravity generation through the Alcubierre Drive?

[G'th]

So lately I've been reading up on the AD and it occurred to me that, if gravity is supposed to be a result of a curvature in spacetime (Ie, you press on the blanket and everything on the blanket will slowly come towards where your finger) then wouldn't the same thing that would make an AD work also be able to be used to generate artificial gravity?

Obviously the math would be different and it would take a completely different kind of apparatus to make it work, but if I'm understanding everything I'm reading, then it does make sense that this could be a potential offshoot of the drive, and if true this could also be part of the solution to the "shielding" problem you'd have at warp, as anything that can be affected easily by gravity could be deflected using this same mechanism. 

 

*And just to note this is just a hypothetical question based on assumption that the AD is actually able to be built. So lets keep it at that. I think everyone here already knows the difficulties and chances of that actually happening.

[G'th]

Also realized I put this in teh wrong forum. Derp

[Errol]

You can report your own post so that a mod sees it and can move it for you. That is generally the best way to get their attention ASAP.

[monstah]

Done and done  

[Urses]

If i understand you right.

I think It would be somerhing more off a anti-acceleration. A field that prevents the enclosed Volume to endure changes in movement vector. For space Travels it indied  would be a great step forward.

Because you could go for much greater TWR as Today. You have much higher G-Force-Endurance this way and can use much faster changes in your Vektor and velocitie. The AD conserves your Vektor and velocitie and enabele a Change in position on the "blanket". 

[Steel]

Let's be honest here, if you're at a point where you can build and harness a drive that requires large (large is somewhat of an understatement) amounts of exotic matter with negative mass, I'm pretty sure creating artificial gravity will be pretty trivial.

[sevenperforce]

Negative mass can be used to produce a repulsive gravitational field, but nothing will produce negative acceleration in a positive gravitational field.

 

[Akira_R]

3 hours ago, G'th said:

So lately I've been reading up on the AD and it occurred to me that, if gravity is supposed to be a result of a curvature in spacetime (Ie, you press on the blanket and everything on the blanket will slowly come towards where your finger) then wouldn't the same thing that would make an AD work also be able to be used to generate artificial gravity?

Obviously the math would be different and it would take a completely different kind of apparatus to make it work, but if I'm understanding everything I'm reading, then it does make sense that this could be a potential offshoot of the drive, and if true this could also be part of the solution to the "shielding" problem you'd have at warp, as anything that can be affected easily by gravity could be deflected using this same mechanism. 

 

*And just to note this is just a hypothetical question based on assumption that the AD is actually able to be built. So lets keep it at that. I think everyone here already knows the difficulties and chances of that actually happening.

Could you link the papers you are reading?

From my very basic understanding of general relativity and the concept behind the Alcubierre Drive the answer is... sort of?

The whole deal with general relativity and gravity is that energy warps spacetime, mass is nothing but confined energy (m = E/C^2) which is why mass warps space time. The perceived "force" of gravity is nothing but objects following straight line paths in warped 4-D spacetime.

The Alcubierre Drive is a reverse solution of Einstien's field equations, where normally a configuration of matter/energy is taken and it's spacetime field is calculated, instead a field was taken and the equations were solved to find what kind of configuration of matter/energy is needed to make that field. The same thing could be done to "create" artificial gravity in a room in a spaceship, you define the warped spacetime field that would provide the associated gravity effect and solve for the configurations of mass/energy needed to do that.

While I am not equipped to solve the field equations for such a configuration I can speculate as to what it would be. Essentially you would have to have an energy concentration in the "floor" of your ship that would create enough of a warpage in spacetime as to mimic something of a planetary mass which in relativity is analogous to saying you would need a near planetary mass spaceship. Even if the field was generated by a large energy density and not by a large conventional mass (which would help you reach the densities you need for a reasonably sized space ship) this energy would still add to the momentum of the ship giving your ship the effective momentum of a planetary body, making it very hard to accelerate with any kind of conventional drive, of course if you are capable of creating and maintaining such a large amount of energy I'm sure you also have all sorts of exotic drive choices at your disposal. The real big issue, assuming you could generate such a field and moving a ship of that mass around wasn't a problem, would be the massive tidal forces at the edges of the field. Because you are trying to create a very localized warping of space time, the edges between the "flat" spacetime outside and your field would be massively distorted which would cause all sorts of spaghettification issues for objects near or on this boundary. The Alcubierre Drive also suffers from these same limitations, but they generally aren't issues given the use of the drive, for one the warp bubble is meant to fully encapsulate the ship, so tidal forces are only an issue for anything that tries to cross the edge of the bubble which isn't an intended thing, also the momentum/mass issues are less of a problem because during the actual superluminal functioning of the drive no actual accelerating force is needed as the spacetime within the bubble is "moved forward" by the contraction and expansion of the spacetime for and aft of the bubble.

Basically yes the same mechanism that would allow an Alcubierre Drive to function could also be applied to generating an artificial gravity field, however even assuming such a thing were possible it would still suffer some extreme practicality issues, specifically the death and destruction of any being/object that happens to transverse the boundary of the field.

[Steel]

16 minutes ago, Akira_R said:

...Essentially you would have to have an energy concentration in the "floor" of your ship that would create enough of a warpage in spacetime as to mimic something of a planetary mass which in relativity is analogous to saying you would need a near planetary mass spaceship...

Not only does the energy density need to be very large (how large depends on how many of the modified metrics and geometries you want to accept) but it also needs to be negative.

[Akira_R]

10 minutes ago, Steel said:

Not only does the energy density need to be very large (how large depends on how many of the modified metrics and geometries you want to accept) but it also needs to be negative.

Interesting, how difficult would it be to explain why the energy needs to be negative? I would assume the energy in the floor would need to be positive, as it needs to create a gravitational field with the "down" direction perpendicular to the floor, which could mean compressing/contracting spacetime as I understand it. My understanding of why the Alcubierre drive requires negative energy has to do with it's need to expand space time behind the vessel, and normal energy causes space time contraction. 

I haven't taken differential equations yet which I believe is needed to actually work the field equations, however I have a fairly solid grasp of Calc 1 (in the US higher educational system), so don't be afraid to get a little mathy if it's needed lol.

[Steel]

1 hour ago, Akira_R said:

Interesting, how difficult would it be to explain why the energy needs to be negative? I would assume the energy in the floor would need to be positive, as it needs to create a gravitational field with the "down" direction perpendicular to the floor, which could mean compressing/contracting spacetime as I understand it. My understanding of why the Alcubierre drive requires negative energy has to do with it's need to expand space time behind the vessel, and normal energy causes space time contraction. 

I haven't taken differential equations yet which I believe is needed to actually work the field equations, however I have a fairly solid grasp of Calc 1 (in the US higher educational system), so don't be afraid to get a little mathy if it's needed lol.

Oh I though you were talking Alcubierre still. The artificial gravity thing I'm not so sure on.

You will indeed need differential equations, as well as tensor calculus, which if you're lucky you might get in a Calculus 4 course at university, but most likely not even then. I'm not saying GR is impossible, but even at university the people who do it tend to be final year undergraduate or graduate level physics or mathematics students.

Edited March 30, 2017 by Steel

[Akira_R]

21 minutes ago, Steel said:

Oh I though you were talking Alcubierre still. The artificial gravity thing I'm not so sure on.

You will indeed need differential equations, as well as tensor calculus, which if you're lucky you might get in a Calculus 4 course at university, but most likely not even then. I'm not saying GR is impossible, but even at university the people who do it tend to be final year undergraduate or graduate level physics or mathematics students.

That's what i thought, man I can't wait to get there, just a couple more years!

I love GR, a lot of the theory and basics of it can be grasped with just a basic understanding of algebra, you can even do some playing around with transformations and spacetime diagrams with out needing to really get deep into calculus. It's when you really start getting into stuff like this that you need to pull out the heavy math guns.

A really good source for some easy to grasp but still information packed videos on GR and other physics stuff is the PBSspacetime channel on youtube.

https://www.youtube.com/channel/UC7_gcs09iThXybpVgjHZ_7g

Their playlists The Origin of Matter and Time, and Curved Spacetime in General Relativity are two of my favorites.

Edited March 30, 2017 by Akira_R

[PB666]

On 3/30/2017 at 10:32 AM, G'th said:

So lately I've been reading up on the AD and it occurred to me that, if gravity is supposed to be a result of a curvature in spacetime (Ie, you press on the blanket and everything on the blanket will slowly come towards where your finger) then wouldn't the same thing that would make an AD work also be able to be used to generate artificial gravity?

Obviously the math would be different and it would take a completely different kind of apparatus to make it work, but if I'm understanding everything I'm reading, then it does make sense that this could be a potential offshoot of the drive, and if true this could also be part of the solution to the "shielding" problem you'd have at warp, as anything that can be affected easily by gravity could be deflected using this same mechanism. 

 

*And just to note this is just a hypothetical question based on assumption that the AD is actually able to be built. So lets keep it at that. I think everyone here already knows the difficulties and chances of that actually happening.

Gravity is a faux force. Space-time creates the illusion of gravity. Quantum gravity is supposed to be the most fundemental force in the universe, and it is very difficult to parse out of its dominion.  Thus creating negative gravity would have to have some aspect of space-time as a negative value. The curvature of space-time is caused by energy and its mass equivalents, therefore you would have to have negative mass or negative energy at one end of the drive. Energy is driven from entropy and entropy and time are woven together.

The interesting thing about our observed universe is that while time can go backwards, on the space-time scale it does not. Some have speculated that from the origin we went this way in time and maybe half the universe went the other way in time. Thus if such a negative energy/negative mass circumstance is possible, but not on our temporal side of the universe.

In statistics we run into the circumstance all the time where one observed limit of something is always zero, if the expected value is 1 you have a skewed distribution, if the mean probability is a million you have a near normal distribution. The skewing in the observations gives a pretty good indication that you have found the limit. When you get to the very low end of measurement and you start seeing the skewed distribution of sampled values, then you pretty much know your never going to go below that limit. In Quantum physics such a finite limit is laughable, but we have never observed what happens at the transition between quantum and relativistic observations .. .vis a vis we have different interpretations, (Copenhagen, multiple worlds, . . . . ). You can postulate all you want on the possibility of negative time, energy or mass but until we can observe then transiting into space-time, speculation is what they are.

 

[YNM]

I suppose to get a "gravity" you need some changing potentials so... well, the easiest way would be to gather a lot of mass-energy 

[HebaruSan]

In what sense would this be "artificial" gravity? Sounds like regular gravity.

[Akira_R]

On 4/12/2017 at 1:47 AM, HebaruSan said:

In what sense would this be "artificial" gravity? Sounds like regular gravity.

Indeed, you could say it's artificially induced gravity, as yhe field is not arising from "natural" processes.