Alcubierra Metric

[Pugdaddy]

Since the Alcubierra drive has been around for a while. I imagine the math has been checked and rechecked and is valid. What are the main problems with the theory? I see that Sonny White has addressed some of the energy problems. I also see that his research team is trying to make a tiny "warp bubble" by perpetuating space with lasers.

I was wondering if that maybe this could be adapted to say move a package from one part of the world to another instantaneously? I bet Fed ex would love this.

[ajb]

What are the main problems with the theory?

 

From what I recall there are problems with quantum inequalities, which control the negative energy densities in semi-classical gravity. You will have to look up the details yourself.

[Pugdaddy]

Can anyone tell me what "York Time " is?

[imatfaal]

Can anyone tell me what "York Time " is?

 

A bit of context might help - otherwise the best answer you will get is that York Time is British Summer (huh!) Time at present and will go to Greenwich Mean Time in a few weeks

 

I think it is a method of thinking about the time in lorentzian geometries in which there is assumed to be a constant mean curvature CMC which is proportional to the time

 

The original paper is this York, J. W. (1973). "The role of conformal 3-geometry in the dynamics of gravitation". Phys. Rev. Lett. 28 (16): 1082–1085

The unconstrained dynamical degrees of freedom of the gravitational field are identified with the conformally invariant three-geometries of spacelike hypersurfaces. New results concerning the action principle, choice of canonical variables, and initial-value equations strengthen this identification. One of the new canonical variables is shown to play the role of "time" in the formalism.

 

 

Hopefully AJB will swing by - it seems like his sort of thing

[Pugdaddy]

Sorry about being vague. I am new to the forum and not an expert. Just trying to understand things. I was reading the "Warp Field Mechanic 101" paper by Dr. Harold “Sonny” White.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015936_2011016932.pdf

It said

"The driving phenomenon that facilitates speedy travel to stellar neighbors is proposed to be the expansion and contraction of space (York Time)"

This may be beyond my level of understanding. I was hoping someone might be able to dumb it down for me. Thanks, I really appreciate the help.

[imatfaal]

Sorry about being vague. I am new to the forum and not an expert. Just trying to understand things. I was reading the "Warp Field Mechanic 101" paper by Dr. Harold "Sonny" White.

http://ntrs.nasa.gov..._2011016932.pdf

It said

"The driving phenomenon that facilitates speedy travel to stellar neighbors is proposed to be the expansion and contraction of space (York Time)"

This may be beyond my level of understanding. I was hoping someone might be able to dumb it down for me. Thanks, I really appreciate the help.

 

Beyond my understanding by a country mile!

[ajb]

Hopefully AJB will swing by - it seems like his sort of thing

 

I have not come across York time (or curvature) before. I know York is interested in the 3+1 formalism and numerical solutions to GR, as well as the use of conformal geometry in GR. I will try and hunt down the reference you have given.

[Pugdaddy]

I also cannot find much on the Net that describes the "Chung-Freese Metric". Except in Dr Whites paper. Even Wikipedia has no entries.

ajb you are on the right track as I did find this.

"A parallel with the Chung-Freese spacetime metric is drawn to demonstrate that the spacetime expansion boost can be considered a 3 + 1 on-brane simplification for higher dimensional geometric effects"

[MartinoFermi]

A bit of context might help - otherwise the best answer you will get is that York Time is British Summer (huh!) Time at present and will go to Greenwich Mean Time in a few weeks

 

I think it is a method of thinking about the time in lorentzian geometries in which there is assumed to be a constant mean curvature CMC which is proportional to the time

 

The original paper is this York, J. W. (1973). "The role of conformal 3-geometry in the dynamics of gravitation". Phys. Rev. Lett. 28 (16): 1082–1085

 

 

 

Hopefully AJB will swing by - it seems like his sort of thing

I believe York Time would likely represent the slope of the curvature in the spacetime density at the point in the warp bubble.

[Moontanman]

I am, as many of you who know me might guess, fascinated by the Alcubierre drive or Alcubierre metric but what some of you might not know is that it works at slower than light speeds and this might be the most important part of the theory. While there is some doubt about whether or not FTL is possible even with the Alcubierre metric it could, even at more rational speeds, open up the solar system to us in a way that is impossible now.

 

Even .10 c would be a vast improvement and contrary to what we see in science fiction a spacecraft that is basically very similar to the Enterprise in Star Trek (not one mission and disposable) would be very valuable for exploring and or exploiting our own solar system.

 

​In fiction you might get the idea that our solar system is small and not worth exploring but the reality is that the solar system is brobdingnagian in human terms and we can't go fast enough to explore much of it in manned spacecraft. While we probably won't interact with aliens there are hundreds if not thousands of bodies in the solar system worth visiting.

 

​Colonization and exploitation of the solar system would be greatly helped by a spacecraft utilizing Alcubierre drive and even slower than light travel would be a big advance if it was a significant percentage of light speed.

[Externet]

I bet Fed ex would love this.

Or go bankrupt, losing the bet.