Questions tagged [warp-drives]
warp drives are generic conceptual space travel mechanisms that try to work around physical limits in the speed of propagation of light imposed by special relativity. Usually they resort to speculative science (exotic matter), or phenomena that are not yet well understood or is hard to make validation experiments (non-eternal rotating black holes)
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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 ...
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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 ...
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Minimum amount of negative energy required in warp drive spacetimes
In the pioneering work of Alcubierre, to power a warp drive-like geometry it is necessary to employ an amount of negative energy larger (in absolute value) than the whole observable universe mass.
A ...
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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 ...
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How does a world line of an Alcubierre drive look like?
In my recent question ”Speed of light and warp drives in general relativity” I asked exactly how an Alcubierre drive worked and exactly what "FTL travel" meant.
One of the comments I got stated that:
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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 ...
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Could Dark matter manipulation meet the negative energy requirements for an Alcubierre drive?
The biggest issue with the Alcubierre drive is that in order for it to expand the space behind the spacecraft, it would require negative mass with repulsive gravity. No such negative mass is known to ...
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Since gravitational waves travel at the speed of light how are Alcubierre warp drives possible?
There are clearly some very large technical challenges to overcome before actually making one but most writers seem to think Alcubierre warp drives are possible in principle.
They work by propagating ...
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Harold White's work on the Alcubierre warp drive
I've read a bit on Harold White's recent work. (A paper on Nasa's site) I haven't been able to find any comments by people claiming to know anything about the physics involved. Is this really serious? ...
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Faster-than-light communication using Alcubierre warp drive metric around a single qubit?
The Alcubierre warp drive metric has been criticized on the points of requiring a large amount of exotic matter with negative energy, and conditions deadly for human travellers inside the bubble. What ...
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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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Alcubierre Drive - Clarification on relativistic effects
On the Wikipedia article on the Alcubierre drive, it says:
Since the ship is not moving within this bubble, but carried along as the region itself moves, conventional relativistic effects such as ...
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Warp drive with gravitational waves in the nonlinear regime
gravitational waves are strictly transversal (in the linear regime at least), also their amplitudes are tiny even for cosmic scale events like supernovas or binary black holes (at least far away, ...
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Question about the travel time of a ship "using" a warp drive metric
I - The Warp Drive metric:
The Warp Drive is a geometry in a spacetime $(\mathcal{M},g)$ given (in geometrized coordinates $c=G=1$) by the following metric tensor:
$$ ds^{2} = -dt^{2}+ (dx-v_{s}f(...
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Late time behaviour of the Alcubierrie warp drive metric
The Alcubeierrie Warp Drive metric looks like $$ds^2 = -dt^2+(dx-Xdt)^2+dy^2+dz^2$$ where $X = v_s(t)f(r_s)$ and $r_s = [(x-x_s(t))^2+y^2+z^2]^{1/2}$. Now, $f(r_s) \approx 1 \quad 0 < r < R$ ...