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Will future humans use warp drives to explore space? We are unable to eliminate the possibility. But if our distant descendants ever do, it won’t involve dilithium crystals and Scottish accents will have evaporated into history by then.

Warp drives have their roots in one of the most popular sci-fi franchises, but they have a scientific basis. A new paper explores the science behind them and asks whether a warp drive shield failure would emit detectable gravitational waves.

The paper is titled “What No One Has Seen Before: Gravitational Waveforms from Warp Drive Collapse,” and is published in arXiv prepress server. The authors are Katie Clough, Tim Dietrich and Sebastian Hahn, physicists from institutions in the UK and Germany.

General relativity has a place for warp drives, and Mexican physicist Miguel Alcubierre described how they could theoretically work in 1994. He is well known in space and physics circles for his Alcubierre drive.

Everyone knows that no object can travel faster than the speed of light. But warp drives can offer a workaround. By warping space-time itself, a warp drive spacecraft would not violate the faster-than-light (FTL) rule.

“Although originating in science fiction, warp drives have a concrete description in general relativity, with Alcubierre first proposing a space-time metric that supports faster-than-light travel,” the authors write.

There are clear scientific barriers to actually creating warp drive. But it is possible to simulate how it would work and how they could be detected by gravitational waves in case of failure.

Warp drives warp spacetime itself, just like binary mergers of compact objects like black holes and neutron stars. It is theoretically possible that they emit a gravitational wave signal in the same vein as mergers.

“To search for such signals and correctly identify them in measured data, it is important to understand their phenomenology and properties,” the authors explain.

It starts with understanding how warp drives can work, and for that we have to go deep into physics.

“The basic idea behind warp propulsion is that instead of exceeding the speed of light directly in a local reference frame, which would violate Lorentz invariance, the ‘warp bubble’ can travel distances faster than the speed of light (as measured by some distant observer ) by contracting the space-time in front of it and expanding the space-time behind it,” the paper states.

The first barrier is that warp drives require a zero energy state (NEC). Physics states that a region of space cannot have a negative energy density. There are theoretical solutions to this, but so far none of them are practical.

“Other issues with warp drive metrics include the potential for closed time curves and, more practically, the difficulty for humans on board in controlling and deactivating the balloon,” the authors explain.

This is because there will be no way for the crew to send signals to the front of the ship. It is difficult for events inside the bubble to affect events outside the warp bubble, as explained in an earlier article.

“From the perspective of dynamically simulating warp propulsion, the key challenge is stability,” the authors explain. The equations show that the Alcubierre Drive can initiate a warp bubble using Einstein’s equation, but no known equations can support it.

“There is (to our knowledge) no known equation of state that maintains the warp drive metric in a stable configuration over time. Therefore, while an initially deformed bubble may be required to be permanent, it will rapidly evolve away from this state, and in most cases the base fluid and space-time deformations will dissipate or collapse to a central point.”

While instability is a major obstacle to warp drives, it can also make them detectable. If the Alcubierre drive reaches constant speed, it cannot be detected. It does not generate gravitational waves and has no ADM mass. ADM stands for Arnowitt–Deser–Misner, named after three physicists.

But warp drive is only undetectable if it is constant and stable. Once it crashes, speeds up or slows down, it can be detected. In their work, the authors allow the warp drive bubble to collapse.

“Physically, this could be related to a failure in the shielding field that the post-warp civilization (probably) uses to keep the warp bubble from collapsing,” they wrote.

In their formulations the nature of the ship itself is not important. Only the warp bubble and the warp fluid inside matter.

The researchers simulated the collapse of the warp bubble. They found that the collapse generates gravitational waves with characteristics different from those generated by mergers. “The signal comes as a burst, initially without gravitational wave content, followed by an oscillatory period with a characteristic frequency of the order of 1/[R],” they write.

“Overall, the signal is very different from the typical compact binary coalescences observed by gravitational wave detectors and more akin to events such as the collapse of an unstable neutron star or the head-on collision of two black holes.”

The authors point out that although warp drive creates a GW signal, it is outside the frequency range of our current ground-based detectors. “Proposals have been made for higher frequency detectors so that a limit can be placed on the existence of such signals in the future,” they wrote.

The ship itself could also send some kind of multi-message signal, but it’s hard to know how the ship’s matter will interact with ordinary matter. “Since we do not know the type of matter used to construct the warp ship, we do not know whether it would interact (other than gravitationally) with normal matter as it spreads through the universe,” the researchers explain.

It’s a fun thought experiment. It’s possible that some kind of workaround to FTL travel will exist one day in the distant future. If it does, it may be related to a better understanding of dark matter and dark energy. If any ETIs exist, they may be able to tap into fundamental knowledge of the universe that we do not yet possess.

If they figured out how to construct and use warp drive, even with all its apparent impossibilities, their activities might create gravitational waves that our future observatories could detect, even in other galaxies. But for now, it’s all in theory.

“We caution that the resulting waveforms are likely to be highly specific to the model used, which has several known theoretical problems, as discussed in the introduction,” the authors wrote in their conclusion. “Further work will be needed to understand how common the signatures are and to properly characterize their detectability.”

No doubt some curious physicists will continue to work on it.