All Questions
Tagged with warp-drives general-relativity
89
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What is the gravitational field of a hole in an infinite perfect crystal?
Or equivalently and more interestingly: In the early universe when there was uniform H/He gas everywhere, gravitational field was close to 0 everywhere. Every test particle was pulled from all sides ...
3
votes
2
answers
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How is Alcubierre's warp drive propeled forward?
What is the exact mechanism of the warp drive that propels it forward? I know that it creates negative pressure behind it and a positive pressure in front of it but how does this actually propels it ...
- 165
5
votes
1
answer
90
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Would the effective speed of an Alcubierre drive be limited by the propagation speed of gravity?
The idea of a warp drive is to "expand space behind the ship and contract it in front"- in this way reaching a target destination faster than one could conventionally. However, the actual ...
- 87
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How does the "York time" measure the expansion of space; why is it equal to the divergence of the comoving observer's four velocity for warp drive?
The mysterious York time, θ is important in warp drive topic. It is plotted on the famous diagrams and is considered the measure of the mechanism that "drives" the warp drive bubble at ...
6
votes
1
answer
356
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Are there any Alcubierre Style metrics for sub-luminal speed warp drives?
In most literature I have found, research into the Alcubierre Metric, and Warp Drives seems to be highly focused on the plausibility of superluminal travel.
Today I was thinking to myself that maybe ...
- 481
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0
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Killing Vectors in The Alcubierre Metric
According to this article about the Alcubierre metric, the metric can be transformed in a way that results in "spherical symmetry" about the x-axis. I have to assume they meant to say ...
- 323
3
votes
1
answer
79
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Volume Elements Inside The Warp Bubble
I'm trying to understand how to calculate proper spacelike volumes of metric tensors that have off-diagonal terms. Right now I'm considering a slower-than-light Alcubierre metric:
$ds^2=(v^2f^2-1)dt^2-...
- 323
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Violations of the Achronal averaged null energy condition
Many energy conditions have been shown to be violated in the past in semiclassical gravity, for instance when considering Klein-Gordon quantum scalar fields. Victims include the WEC (Weak Energy ...
- 4,963
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Proper spacelike distance in Alcubierre manifold
How do I find the proper spacelike $x$-coordinate on a constant $t$ hypersurface in the two dimensional Alcubierre manifold? The metric is given by
$$\mathrm{d}s^2=(v^2f^2-1)\mathrm{d}t^2-2vf\mathrm{d}...
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votes
1
answer
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Is observing (superluminal) velocity independent of choice of coordinates for asymptotically flat spacetimes?
Alcubierre's warped metric in ($1+1$)D is typically given in the form of:
$$ds^2 = -dt^2 + [dx-v(t)f(r) dt]^2 \ \ .$$
Then it is nicely discussed how manipulating:
$$-dt^2 + [dx-v(t) f(r) \ dt]^2=0$$
...
- 103
2
votes
2
answers
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Calculating proper volume in the Alcubierre spacetime
I'm trying to calculate the proper volume of a portion of the alcubierre spacetime to see how it compares to the euclidean volume element. As I understand it, the proper volume element in cartesian ...
- 323
2
votes
1
answer
349
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How was this warp bubble generated?
The Debrief just reported that DARPA just "accidentally" created the world's first warp bubble. The actual paper is available here.
My layman understanding is that warp drives were so far ...
- 161
2
votes
1
answer
154
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"Swimming" in flat spacetime
Is it possible for a machine with a velocity of zero to translate its position in a perfectly flat region of spacetime? This is possible in curved spacetime https://groups.csail.mit.edu/mac/users/...
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How warp drive could be faster than light? [closed]
If the speed of gravity is as fast as the speed of light then there is no way a warp drive could curve the fabric of spacetime faster than the speed of light. Then how does a warp drive actually make ...
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3
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When can information escape from a black hole through a warp bubble-like spacetime?
It is well known that nothing can escape a black hole, including gravitational radiation. Many questions have been asked here about this topic, such as:
Can gravitational waves escape a black hole?
...
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