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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 ...
Alien from future's user avatar
3 votes
2 answers
84 views

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 ...
Euler-Masceroni's user avatar
5 votes
1 answer
90 views

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 ...
elfeiin's user avatar
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3 votes
2 answers
252 views

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 ...
Attila Janos Kovacs's user avatar
-2 votes
1 answer
89 views

Will this hypothetical circular singularity FTL travel warp drive work? [closed]

Not a physicist, but just wanted to know if this would work in theory: Since nothing can practically travel faster than the speed of light (for now until proven otherwise), the only way for ...
notorious-raccoon's user avatar
1 vote
2 answers
136 views

Do certain quasi-particles really have negative mass?

Do phonons for example really have negative mass or does it just seem like they have negative mass? Could one use the negative mass of certain quasi particles to meet the negative energy requirements ...
Peter's user avatar
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6 votes
1 answer
356 views

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 ...
RudyJD's user avatar
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2 votes
0 answers
60 views

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 ...
user345249's user avatar
1 vote
1 answer
149 views

Why does the Alcubierre drive need a negative energy ring specifically?

Now, maybe this is a result of my poor understanding of spacetime, but a theoretical warp bubble contracts space in front, and expands it in the back. Positive energy always contracts, so I get the ...
Mat NX's user avatar
  • 333
4 votes
2 answers
141 views

Is the kind of physics proposed for "warp drive" related to the way that space really is expanding?

As I understand, some parts of Universe really are moving faster than light -- is this expansion something we think we can create artificially? And if we can do this artificially, could it be done a ...
releseabe's user avatar
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3 votes
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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-...
user345249's user avatar
5 votes
0 answers
82 views

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 ...
Rexcirus's user avatar
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0 answers
44 views

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}...
user345249's user avatar
3 votes
2 answers
116 views

Would there be predictable observable signatures to Alcubierre-like “warp” drive usage?

Recognizing that any Alcubierre drive system requires exotic negative energy density matter that, as far as we can tell, does not exist, if somebody managed to find such stuff in the quantities ...
Todd Marshall's user avatar
4 votes
1 answer
126 views

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: $$-dt^2 + [dx-v(t) f(r) \ dt]^2=0$$ ...
benfisch's user avatar
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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 ...
user345249's user avatar
0 votes
1 answer
216 views

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 ...
Ben Warner's user avatar
-2 votes
1 answer
403 views

Why would FTL travel break causality, as oppose to the relative time reconciling as in the Twin Paradox? [duplicate]

I have heard that if faster than light travel were ever made possible, such as by an Alcubierre drive, the user would be taken backwards in time, violating causality. This is odd to me, as it already ...
Ben Warner's user avatar
13 votes
2 answers
3k views

Why does an Alcubierre drive, travelling FTL, violate causality, if the universe expanding FTL doesn't?

An Alcubierre drive seems to be plausible as a means to travel faster than light, because it doesn't move the object itself, but the space around it. it's said that matter and information can't move ...
Prido1024's user avatar
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0 votes
1 answer
146 views

Einstein propulsion system

Will an extended body(cylinder) with asymmetric energy distribution across its H axis experience free-fall(geodesic)acceleration in free space(outside of any influences) in vacuum because of the time ...
Alien's user avatar
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1 vote
1 answer
50 views

Is it possible to make something similar to Alcubierre's drive but in gas/liquid instead of spacetime?

Is it possible to use something similar to the Alcubierre's drive for traveling in the water or air? How could it be done? Is it possible to make water flow around bubble keeping it non-disturbed ...
Robotex's user avatar
  • 768
1 vote
1 answer
115 views

Could Gott's Cosmic String Time Machine hypothetically be used as a poor man's Alcubierre drive?

I have read much speculation about Gott's theoretical use of cosmic strings for time travel, but if the colliding cosmic strings accelerated the spacecraft faster than light, as Gott theorizes, could ...
Ben Warner's user avatar
2 votes
1 answer
347 views

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 ...
Ruslan Oblov's user avatar
2 votes
1 answer
154 views

"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/...
William Duff's user avatar
3 votes
0 answers
229 views

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 ...
Kemsikov's user avatar
  • 141
8 votes
3 answers
664 views

How to make a warp bubble moving?

In answer to this question it is stated that: In summary, warp drives move because they already move, or else they need to propel, and their movement is not related to spacetime expansion or ...
Martin Vesely's user avatar
4 votes
3 answers
318 views

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? ...
Thorondor's user avatar
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4 votes
3 answers
223 views

Shift Vector in Warp Equation

In the Alcubierre metric, why is there a beta with subscript multiplied by a beta with superscript? I know beta with subscript is the shift vector, but what is the difference between the two? $$\text ...
user345249's user avatar
1 vote
1 answer
283 views

How would a warp bubble interact with an atmosphere? [closed]

What would happen if a warp drive entered the Earth atmosphere? IIRC some scientists have created mathematical models that have shown that warp bubbles that don't exceed the speed of light may be ...
nick012000's user avatar
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2 votes
0 answers
35 views

Escaping from inside the event horizon [duplicate]

This is a hypothetical question. An Alcubierre Warp Drive can theoretically go any speed because space is moving and the ship is not. Could a ship equipped with this drive escape from inside an ...
Rick's user avatar
  • 2,706
1 vote
2 answers
284 views

What exactly is the motion in Warp drive?

I know that there exists something like the Alcubierre warp bubble, and there are many threads here about it, but unfortunately the answers didn't help me to understand what the basic principle is... ...
Charles Tucker 3's user avatar
-1 votes
4 answers
588 views

Does this research paper prove that warp drives are impossible? [closed]

Does this preprint prove that warp drives are impossible? J. Santiago, S. Schuster and M. Visser, "Generic warp drives violate the null energy condition" It states that the NEC (Null Energy ...
Local45953's user avatar
0 votes
1 answer
43 views

Energy distorting space

We know that mass distort space and time. Can energy do the same? How much heat will it take to create an observable effect? can we make a warp drive on that principle? By heating one end of a space ...
gunslinger's user avatar
0 votes
0 answers
50 views

Warp drive small scale experiments "proof of concept" [duplicate]

Possible small scale warp drive experiments, or small scale experiments with quantum mechanics to model space-time warping? Why is it so difficult to engineer a small scale warp drive even though ...
Local45953's user avatar
9 votes
3 answers
3k views

Erik Lentz's faster-than-light soliton

It's well known that, in relativity, if you can go faster than light, you can go backwards in time and create a paradox. Also, attempts to create "warp-drive" space-times in which something ...
Mitchell Porter's user avatar
6 votes
4 answers
2k views

Analogy for Lentz soliton

Analogy for Alcubeirre Warp Drive: Every explanation of warp drive in layman terms has this sentence in it: "The Warp Drive will contract space in thier front and expand space behind." (I ...
Rounak Sarkar's user avatar
2 votes
0 answers
131 views

Testing space-time warp on a smaller scale, "Breaking the Warp Barrier: Hyper-Fast Solitons in Einstein-Maxwell-Plasma Theory" [duplicate]

So according to this paper it creates a warp drive without the need of negative energy to operate which many think does not exist in reality. So my question is what would you do to experimentally ...
Local45953's user avatar
3 votes
1 answer
63 views

The center of energy of a closed system maintains constant velocity in the vacuum of space. How can a warp drive overcome this rule?

In the following paper Introducing Physical Warp Drives by Alexey Bobrick, Gianni Martire they state 5.2. Constructing warp drives: Warp drives, being inertially moving shells of normal or exotic ...
Chahé Adourian's user avatar
1 vote
1 answer
224 views

Will an Alcubierre Drive arrive before a beam of light, if sent between two stationary observers?

First, I'm not a physicist, just an engineer, and my first language is not English, so forgive any strange wording. I have a simple thought experiment about Alcubierre Drives: Imagine two stationary ...
foolo's user avatar
  • 143
2 votes
2 answers
76 views

Compressing the Earth to a 20-meter-wide sphere would only subtract one hour of time? (General relativity)

The Internet has exploded with news that the Applied Physics Institute of New York published a paper claiming that superluminal speeds can be achieved using a type of Alcubierre Drive, but without the ...
Kurt Hikes's user avatar
  • 4,509
1 vote
0 answers
215 views

Could LIGO detect an Alcubierre drive being used within 10 light-years of the Solar system? [closed]

Maybe this question is too speculative... But is it possible that LIGO would detect the ramp-up and ramp-down of an Alcubierre drive being used within 10 light-years of the Solar system? Also, if the ...
user1402154's user avatar
4 votes
1 answer
300 views

Warp drive causality issue, and a possible error in a paper?

Take a look at this paper on "Warp Drives and Causality:" https://doi.org/10.1103/PhysRevD.53.7365 The author attempts to argue that the Alcubierre Drive spacetime could exhibit Closed ...
Joeseph123's user avatar
0 votes
1 answer
84 views

In an Alcuibierre like warp drive, what is the velocity of the object after the warp trip?

Presume a ship is traveling in an Alcubierre-like warp bubble. For concreteness, let us say that it began in a geostationary orbit (that term is used to indicate that the ship is in fact orbiting ...
Michael Stachowsky's user avatar
2 votes
1 answer
59 views

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, $f(r_s) \approx 1 \quad 0 < r < R$ ...
Dr. user44690's user avatar
3 votes
1 answer
127 views

Geodesics in an Alcubierrie Warp Drive metric

The geodesics in an Alcubierrie Warp Drive metric are given by $$\dot{t} = 1 \quad \dot{x} = X\dot{t} \quad y, z = \text{constant}$$ where $X = \dot{x}_s(t) f(r_s)$. Here $f(r_s)$ is a shape function ...
Dr. user44690's user avatar
3 votes
2 answers
392 views

Is this solution for interstellar travel viable?

I have in mind a way to enable FTL travel. Is this way viable? In the paper: "Weighing the vacuum with the Archimedes experiment" we can see the dependency of the gravitational repulsion ...
Giovanni Cambria's user avatar
4 votes
0 answers
193 views

Frame dragging Warp drive [closed]

Is it possible to use frame dragging to make a warp drive? For example: a space ship with "frame dragging generators" that constructively interfere between them to let space be dragged in ...
Geert VS's user avatar
  • 111
2 votes
1 answer
299 views

Dark energy as negative matter for Alcubierre drive

Can dark energy be used for the Alcubierre drive as a substitute for negative mass? After all, to make the Alcubierre drive work, it is necessary to expand the universe behind it, and that is what ...
J. Doe's user avatar
  • 23
5 votes
1 answer
283 views

The Explosive Force of the Braking Alcubierre Drive - What would this look like? [closed]

The Alcubierre Drive and faster than light travel more generally may be locked away in the realm of fiction forever. That might be depressing to some people but I think their impossibility is really ...
White Dwarf's user avatar
0 votes
1 answer
222 views

Alcubierre drive: what is the nature of exotic matter? [closed]

In connection with Alcubierre drive we often hear about necessity of an exotic matter in order to produce a negative energy density. I suspect that such matter has no place in standard particle model. ...
Martin Vesely's user avatar