How does one detect a warp bubble LYs away without years of delay?

Question

This question relates to a space-strategy game I'm conceptualizing. The game is supposed to be somewhat realism-oriented, except for the existence of Alcubierre / Star Trek warp drives and the like.

There are presently 2 realistic ways to spot a warp bubble.

• Light. The effects of bending space are plainly visible in the form of light distortion. Obviously this is limited by the speed of light and is really only practical for finding craft in-system.
• Gravitational Waves. Since a warp bubble is driven partially by a front-facing gravity well, activation and deactivation of the warp drive would represent a profound change in the surrounding space. This change is felt everywhere in the form of gravitational waves, and can be detected using LIGO systems that exist today. However, it has been surmised that gravitational waves travel at the speed of light.

If the only sensible answer is some sort of ripple, why would a ripple in space travel faster than light?

Answer 1

Because you have waved your hand.

Delve deep into physics, specially quantum mechanics, and you will see that lots of things can and do travel faster than light. E.g.: many virtual particles, which are not actual objects so they don't have to obey certain laws. Information however is always limited to traveling no faster than light, so you only get that with handwaving.

On top of that: if the warp bubble in question is from an Alcubierre drive, then no one is actually traveling at FTL speeds. Rather, space is contracted around the bubble, so distances to be travelled are shorter. It is only FTL semantically.

If you do wish to sound sci-fyish though, say the ripples take shortcuts through the extra dimensions of string theory. Or if you wish to be tacky, use tachyons, which are particles constrained to traveling faster than light and which move backwards in time. Nevermind all the mess this causes as causality is thrown outta the window.

Answer 2

Warp speed probe.

You are impatient. You want information faster than light or light speed things can bring them to you. You want to know about warp bubbles on the way.

It follows that in this world you have warp bubbles. They move faster than light.

Make probes or drones that themselves have warp bubbles. They can move faster than light. Send them out to reconnoiter. If they get close to a warp bubble they will see it for what it is through one of the mechanisms that you describe in the OP. The probe will take readings of the bubble and its position, then warp back to you and report what it has found.

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If for a game I would show this distant probe-mapped region of the map as static and in grayscale, with things that were moving during the probes visit depicted as that object blurred over the area it traversed while the probe was watching.

Answer 3

The only interesting property of the Alcubierre-type warp tube geometries, versus other forms of FTL magic, is that they don't violate the speed-of-light limit locally, i.e., there are no tachyons involved. So no news of them can reach you faster than a radio signal would.

But a little known property of these solutions, closely related to the above, is that they don't and can't work like the "drives" in Star Wars or Star Trek, where you decide on a whim where you want to go and then drive there faster than the radio signal announcing your decision. It can't work that way because the exotic phlebotinum on the outside of the warp tube can't get into position fast enough without violating the local speed-of-light constraint.

The tube has to be constructed in advance, like a rail line, and the maximum speed of rail-laying can't be higher than the local speed of light. If the maximum practical speed is well below that, then you can in principle see evidence of the construction well before anyone uses the line. That doesn't tell you when the line will be used, but it tells you that no one is traveling FTL where there is no completed line.

Answer 4

The Double-Slit Scanner

The double-slit experiment shows that particles travel in ways that don't always agree with the predictions of classical physics. I have heard some its findings described as essentially proving that some particles simultaneously travel (or evaluate) multiple paths through the room (which would require the particle to travel many times the speed of light, since it would need to complete all the exploratory routes as well as the route that observers actually see). As crazy as that sounds, it seemed to be the only way to explain the facts.

So let's extend my poor layman's version of this to the cosmic scale.

I'm going to assume that any kind of warp bubble will violently displace all the particles in the immediate area of the vessel, and that displacement follows the vessel as it travels. Space is not completely empty, after all. Within any star system, there will be the heliosphere: a colossal soup of charged particles that engulfs the entire solar system, flowing outward from the star. To me, that giant, electrically charged structure seems a lot like a spiderweb (which is, after all, Mother Nature's radar).

This displacement can be detected remotely, faster than light waves would propagate, by observing the movement of subatomic particles at a monitoring site, because those particles are affected by the warp bubble's displacement in much the same way that, in the double-slit experiment, changing one slit mysteriously has an effect on the particles that "only" go through the other slit.

Now, that might not be enough to detect a vessel on the other side of the solar system that activates its warp bubble for only a very short time. But if it travels at speed for tens of minutes, the bubble will carve a giant tube through the heliopause, and I imagine that would be adequate to both detect that FTL is happening and locate roughly where it is.

You'll have to decide whether it's practical for this detection apparatus to be mounted on a vessel rather than being on the ground or a space station. However, I would suppose that the detector would be useless while it is inside a warp bubble, i.e. while the vessel its on is at warp.

The heliosphere only covers star systems. There is, of course, dust and gas in the void between the stars, but it might be too dispersed to act as a spider web. If so, that would mean that vessels traveling at FTL can only be detected once they enter a system, and that a vessel operating in ultra-deep-space could not be detected beyond lightspeed range.

I would also expect that this device would not be able to tell you anything at all about the stuff inside the warp bubble. All you would know is that a warp bubble is moving along a particular trajectory: the inside could have any kind of ship, or an alien, or a freak asteroid that creates a warp-ish bubble around itself.

The DSS also makes margaritas.

Answer 5

Let's go with Quantum effects.

We have just begun to explore the effects of Quantum physics.

Consider that physicists have now discovered that quantum effects could be what is behind seemingly impossible chemical reactions in deep space.

To see if quantum phenomena were in play, the researchers looked at reaction rates – a measure of how fast a reaction proceeds – at different collision energies. At high collision energies, classical effects dominated and the reaction rates slowed down gradually as the temperature dropped. But below about 3 K, the reaction rate in the merged beams suddenly took on peaks and valleys. This is a sign that a quantum phenomenon known as “scattering resonances due to tunneling” was occurring in the reactions. At low energies, particles started behaving as waves: Those waves that were able to tunnel through the potential barrier interfered constructively with the reflected waves upon collision. This created a standing wave that corresponded to particles trapped in orbits around one another. Such interference occurs at particular energies and is marked by a dramatic increase in reaction rates.

Take entanglement, for instance. We currently can only recognize entanglement between particles when we do the entangling. Suppose entanglement was a completely common natural phenomena? Especially in the deep 'cold' (low atomic oscillations) in space. Speculate that the universe is filled with entangled particles, and not just in pairs. Really, we only think entanglement occurs in pairs because our physics textbook simply is not thick enough. The movement of these bubbles would disrupt those entanglements. If the physics textbook was thick enough that physicists could detect disruptions in these entanglements, the presence of a bubble could be perceived much faster than light.

Answer 6

Non FTL technology has no hope of bridging that gap in time.

perhaps you use a captive, possibly partial, warp bubble (or bubbles) nearby in the detector, the details of how these detectors actually work may nor need to be explained,

This technology probably also implirs the ability to communicate faster than light. much like the relationship between radar and radio, or sonar and speech.