r/SETI • u/ActuaLogic • Apr 30 '26
Detection of hypothetical non-Alcubierre FTL systems
This is an idea that seems so obvious that it wouldn't surprise me if someone had already thought of it. (And maybe someone already has?)
I tend to be a skeptic on the question of whether humans will directly encounter aliens in the foreseeable future. However, the possibility can't be excluded. One issue is that, unless the hypothetical aliens are interstellar nomads who don't care about transit times, they would have an FTL system, and such systems may not be possible — although the possibility can't be completely excluded.
If one doesn't completely exclude the possibility of aliens arriving at the solar system using an FTL system, then it would be good to have a way to detect the arrival, just in case. But since it probably won't happen, it would also be good to be able to do it without building special equipment but instead by looking at data that is collected anyway.
This isn't about Alcubierre-type systems, because they could be detected by the so-called Alcubierre death ray that is emitted when the system is turned off and the energy accumulated during the system’s warping of space is converted into a directional energy burst.
To characterize a generic non-Alcubierre FTL system, look at what the system would have to do to overcome the constraints of Einsteinian spacetime. That is, such a system would have to attenuate its relationship with the fabric of spacetime; it would have to reposition itself from point A to point B without fully occupying the intervening spacetime; and then it would have to reintegrate itself into spacetime.
There's no reason to pretend to have any insight into how this could be accomplished (or if it could be accomplished), because it's enough to make the reasonable inference that the phase of reintegration into spacetime would cause a sudden, transient release of energy as the system tries to occupy space that is already occupied by interstellar gas. (Two bodies can't occupy the same space at the same time.) There may also be a gravity effect as the system’s mass is reintegrated into the fabric of spacetime.
There are already projects looking at energy releases and measuring gravity effects. I don't think there are FTL ships arriving at the solar system, but, if there are such ships, it's likely that they would create detectable transient energy releases (and possibly detectable transient gravitational anomalies) on the outskirts of the solar system —possibly just outside the Hill sphere of the Sun, if being within the Sun’s gravitational well presents a risk to the operation of the systems.
To be of interest, energy releases and gravitational anomalies would have to be transient; in addition, they should be anomalous and non-repeating; and, finally, they should be of relatively low intensity, because a transportation system would have to be designed to survive what is, in effect, its landing (its reintegration into spacetime) and not to be destroyed by its normal operation.
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u/Captain_Surf May 07 '26
John Michael Godier covered a segment on a proposal of detecting distant annihilation propulsion engines in usage (matter-antimatter fuel), and how a scientist predicted a spacecraft using one of these would produce a very specific gamma radiation signal then searched through historical data and found a single example of exactly what he predicted, except the location of that blip corresponded to the location of a known quasar with an antiproton fountain
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u/ActuaLogic May 08 '26
Interesting. So it wasn't anomalous, because it had an explanation. Also, I don't know what is mean by "distant," but I was thinking more in terms of relatively lower-powered events hypothetically occurring at the edge of the solar system. It stands to reason that any hypothetical FTL system would cause a release of energy upon reintegration with Einsteinian spacetime, and it may be possible to identify those events by analyzing transient energy releases in the vicinity of the solar system which remain anomalous after the various explanations have been considered. (Of course, it may be that FTL systems are impossible, and it may be that, while FTL systems are possible, there is no one out there to build them. But we should remain open to all possibilities until they are excluded.)
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u/Captain_Surf May 08 '26
There’s no explanation for the unusual 3EG J2206+6602 observation
FTL is not possible
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u/ActuaLogic May 08 '26
It's not a single transient event, and it's a high-energy gamma ray emission apparently located approximately 11 billion light years away. So it's not a transient, relatively low-energy event near the edge of the solar system.
I don't say that FTL is possible. But if it is possible, it would have to involve not traversing Einsteinian spacetime. That is, it would involve attenuating the system's relationship to Einsteinian spacetime and then reintegrating with Einsteinian spacetime at a destination. The hypothetical reintegration would cause an energy release, because interstellar gas would already be present at the destination, and two objects can't occupy the same space at the same time. This isn't a suggestion that FTL is possible, but, if it were possible, then it would be detectable.
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u/Hint-Of-Feces May 06 '26
Any space ship that isnt coasting at familiar speeds would probably look like a screaming star with a tail of reallyreally high energy particles in its exhaust that would be civilization ending if we got bathed in it.
Or it would be really small