Warp drives can generate gravitational waves

Will future humans use rockets to explore space? We are not in a position to rule out that possibility. But if our distant descendants ever do, it won’t involve dilithium crystals, and Scottish accents will have faded into history by then.

Warp drives have their roots in one of the most famous fictional stories of all time, but they have a scientific basis. A new paper explores the science behind them and asks whether warp control failures could produce detectable gravitational waves.

The paper is titled “What no one has seen before: gravitational waves from a collapsing warp drive,” and has been submitted to arXiv preprint server. The authors are Katy Clough, Tim Dietrich, and Sebastian Khan, physicists from British and German institutions.

There is room for warp drives in General Relativity, and Mexican physicist Miguel Alcubierre explained how they might work theoretically in 1994. He is well known in space and physics circles for his Alcubierre Theory.

Everyone knows that nothing can travel faster than the speed of light. But warp drives can provide a workaround. By changing time itself, a spacecraft with a rotating drive would not be breaking the faster-than-light (FTL) law.

“Despite the nature of science fiction, warp drives have a real explanation in general relativity, with Alcubierre first proposing a dimension of spacetime that supported faster-than-light travel,” the authors write.

There are obvious scientific obstacles to developing a warp drive. But it is possible to model how one would work and how they might be detected through gravitational waves in the event of failure.

Warp drives distort spacetime itself, as do binary mergers of compact objects like black holes and neutron stars. It is theoretically possible that it produces a gravitational wave signal in the same vein as the connections.

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

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

“The main idea behind warp drive is that instead of directly exceeding the speed of light in the local reference frame, which would violate Lorentz invariance, the ‘warp bubble’ can travel a distance faster than the speed of light (as measured by some distant. observer) by putting time in front of it and extending time behind it,” the paper says.

The first limitation is that warp drives require a Null Energy State (NEC). Physics says that a region of space cannot have a negative energy density. There are theoretical works for it, but currently, none of them are practical.

“Other issues with the measurement of warp drive include the possibility of closed time loops and, from a more practical point of view, the difficulty of those on board in controlling and disabling the bubble,” the authors explain.

This is because there would be no way for the crew to send a signal to the front of the ship. It is difficult for events inside the bubble to affect events outside the bubble, as the previous paper explains.

“From the point of view of dynamically simulating warp drive, the main challenge is stability,” the authors explain. Equations show that Alcubierre Storage can initiate a collapsing bubble using Einstein’s Equation, but no known equations can sustain it.

“There is (to our knowledge) no known equation of state that can maintain the warp drive metric in a stable configuration over time. Therefore, while one may require that initially, the Warp Bubble is stable, it will quickly change from that state. , and, in most cases, warp fluid and spacetime distortions dissipate or collapse into the core.”

While the lack of stability is a major drawback for folding drives, it is also what can make them stand out. If the Alcubierre Drive reaches a constant velocity, it cannot be detected. It does not emit gravitational waves and has no ADM mass. ADM stands for Arnowitt–Deser–Misner, named for three physicists.

But the warp drive is not only available if it is constant and stable. As soon as it breaks down, accelerates or slows down, it can be detected. In their work, the authors allow the bubble of the warp drive to collapse.

“Physically, this can be attributed to the breakdown of the containment field that post-war civilizations (probably) use to support the warp bubble against collapse,” they write.

In their creation, 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 produced gravitational waves with characteristics different from those generated by mergers. “The signal comes as a burst, initially without gravity wave content, followed by an oscillatory period with a frequency characteristic of 1/[R],” they write.

“In general, the waves are very different from the typical merged binary mergers observed by gravitational wave detectors and are more similar 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 the warp drive creates GW waves, it is beyond the range of our current primary detectors. “Proposals for high-frequency detectors have been made, so in the future, one can set limits on the presence of such signals,” they write.

The ship itself may also be sending some sort of multi-messenger signal, but it’s hard to know how the ship’s matter would interact with normal matter. “Since we don’t know the type of matter used to make the warp ship, we don’t know if it would interact (apart from gravity) with normal matter as it spreads through the universe,” the researchers explain.

This is a fun thought experiment. It is likely that some sort of solution to FTL travel will exist one day in the distant future. If possible, it could be related to a better understanding of dark matter and dark energy. If any ETIs exist, they may be in a position to use fundamental knowledge of the universe that we don’t have yet.

If they have figured out how to create and use a warp drive, even with all the seemingly impossible odds, their activities could create gravitational waves that our future probes could detect, even in other galaxies. But for now, it’s all theoretical.

“We caution that the obtained waveform may be very specific to the model used, which has several theoretical problems, as discussed in the Introduction,” the authors write in their conclusion. “Further work would be needed to understand how specific the signatures are and to properly characterize their detectability.”

Of course, some aspiring physicists will continue to work on this.