Speculative new research outlines a method for detecting extraterrestrial civilizations: by catching the gravitational waves produced by the collapse, or failure, of their warp drives. Sounds wild, but the concept is grounded in the principles of Einstein’s general relativity.
Warp drives, inspired by Albert Einstein’s grasp of cosmological physics, were first mathematically modeled by physicist Miguel Alcubierre in 1994. According to Alcubierre, a spacecraft could achieve faster-than-light travel (relative to an outside observer) through a mechanism known as a “warp bubble,” which contracts space in front of it and expands space behind. The warp drive doesn’t accelerate the spacecraft locally to faster-than-light speeds; instead, it manipulates spacetime around the vessel. Such a spaceship could travel vast distances in a short period by “warping” spacetime, bypassing the light-speed limit in a way that is consistent with general relativity.
The trouble is, this model requires negative energy, a speculative form of energy where there’s less energy than empty space, which is not currently understood or achievable with today’s technology. This gap in our understanding keeps the actual construction of a warp drive, as portrayed in Star Wars and Star Trek, firmly within the realms of science fiction.
In astudy uploaded to the arXiv preprint server, astrophysicist and mathematician Katy Clough from Queen Mary University of London, along with colleagues Tim Dietrich from the Max Planck Institute for Gravitational Physics and Sebastian Khan from Cardiff University, explore the possibility that the hypothetical collapse of warp drives could emit detectable gravitational waves.
When warp drives go kablooie
The scientists don’t pretend to know how to build a warp drive, but instead use mathematical simulations to explore their potential theoretic behavior. In particular, the team focused on what might happen if a warp drive were to experience, in their words, a “containment failure.” Such a failure could result in a collapse that emits detectable gravitational waves.
“Whilst there are numerous practical barriers to their implementation in real life, including a requirement for negative energy, computationally, one can simulate their evolution in time given an equation of state describing the matter,” the scientists write in their paper, which is currently under peer review by the Open Journal of Astrophysics.
Thanks to LIGO (the Laser Interferometer Gravitational-Wave Observatory), which observes ripples in spacetime caused by cosmic events, we know that it’s possible to detect gravitational waves; LIGO has already proven capable of observing such phenomena from sources like merging black holes and neutron stars.
At first, the team sought to study the gravitational wave signals from a hypothetical accelerating ship, but they realized that the collapse of the warp bubble was a simpler first step, and that such an event would likely produce a stronger signal, as Clough explained in an email to Gizmodo. There’s no known physical mechanism to maintain a stable warp bubble, she added, which is essential for using a warp drive to travel through space, leading to the prospect of a containment failure.
“One would need to somehow control the way that the pressure responds to changes in density of the warp fluid, or impose some additional containment mechanism,” Clough wrote. “This could be analogous to how lasers are needed to confine plasma in nuclear fusion experiments. So our starting point assumes that whatever was keeping the fluid contained has somehow broken and this leads to it dispersing.” By fluid, Clough is referring to the theoretical medium or substance within the warp bubble that needs to be controlled and contained.
Ripples through spacetime
A warp drive collapse would trigger powerful gravitational waves because it involves the sudden and dramatic alteration of spacetime. The rapid redistribution of energy and matter used to distort spacetime in a warp drive would create significant disturbances, similar to how sudden movements create waves in water. This intense event would release enough energy to generate gravitational waves, akin to those produced by black hole mergers or neutron star collisions.
The resulting signal would be “very strong,” Clough said. This is due to the enormous warping of spacetime required to propel a ship forward at a significant fraction of the speed of light (10% to 30% of the speed of light, as noted in the paper). The collapse releases a substantial fraction of the energy contained in the spacetime curvature, making the signal potentially detectable.
The study relies on numerical relativity, a tool that allows physicists to simulate spacetimes under extreme conditions. This approach makes it possible to study and understand phenomena in which exceptionally strong gravitational forces play a role, such as black holes and, theoretically, collapsing warp bubbles. By simulating the gravitational wave signals that might be emitted during a warp drive collapse, Clough and her team propose a method for potentially identifying such events—should they exist.
By analyzing how the energy and gravitational waves would radiate from such an event, the researchers speculated on the signatures that advanced detectors might one day capture. The strength and frequency of the signal depend on the size of the warp bubble. In the paper, they give an example of a 0.6-mile-wide (1 kilometer) warp bubble traveling at 10% of the speed of light. Per their calculations, this should generate a 300 kHz signal that could be detected up to 3.26 million light-years away, if the signal is strong enough. A detector similar to LIGO but designed for higher frequencies could detect this signal, according to the scientists. “Proposals for such detectors exist and are feasible, but at the current time none are funded,” Clough said.
Fun to speculate
The idea of using gravitational waves to spot alien technologies is wild, no doubt. We’re still a long way from being able to use detectors such as LIGO to detect this type of alien technosignature. Moreover, we don’t actually know if aliens abide by our sci-fi-inspired concepts, so this adds another layer of conjecture. While this area of research sounds promising, it’s still deeply rooted in theory.
That said, the implications of this research extend beyond the search for extraterrestrial life. Understanding the signatures of warp drive collapses could also enhance our grasp of spacetime dynamics in scenarios that violate known energy conditions. Such studies push the boundaries of our understanding of physics, testing the limits of general relativity and potentially leading to new theoretical insights.
“Going beyond standard astrophysics as we did in this study really challenged us to adapt and push the methods to their limits, and this knowledge and experience will certainly help us as we study more challenging regimes in astrophysical applications in the future,” Clough said.