Scientists have proposed another use for the world’s largest gravitational wave observatory: scanning for ripples in space-time in the wake of giant alien spacecraft.
Gravitational waves ripple when objects with mass move through space. Larger objects – such as planets, neutron stars or black holes – generate more prominent gravitational waves. These space-time ripples were first observed directly in 2015, but since then, scientists have been getting better at observing the ripples as they lap across our cosmic shores.
Now, the new calculations are published on 5 December in the preprint database arXiv (opens in new tab) suggest that the US-based Laser Interferometer Gravitational-Wave Observatory (LIGO) may be looking beyond conventional sources for these space-time ripples. A giant alien spacecraft traveling at high speed, or pushed by warp drive, would also produce telltale vibrations, the authors said.
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The LIGO detector detects gravitational waves from tiny distortions in space-time as they pass through it. Composed of two intersecting L-shaped detectors—each with two 2.48-mile-long (4-kilometer) arms and two identical laser beams—the experiment is designed so that if a gravitational wave passes through Earth, In one arm the laser light will be compressed on one side of the detector, while the other will be expanded, causing a small change in the relative path length of the beams arriving at the detector. The warping of space-time that makes up the largest gravitational waves, however, are minuscule – often a few thousandths the size of a proton or neutron – meaning LIGO is incredibly sensitive and requires strict maintenance and calibration is required.
To see how far this sensitivity could be extended, the scientists calculated the smallest object that would generate clearly detectable gravitational waves on Earth. It turns out, it would still be huge: to be detectable by LIGO, an alien mothership would need to weigh about the same as Jupiter, travel at one-tenth the speed of light, and be within 326,000 light-years of Earth. will be needed.
Are spacecraft of this scale and speed even possible? The researchers don’t know for sure, but they expect to squeeze the ship’s size into more reasonable proportions in the form of increasingly sensitive gravitational wave (GW) detectors such as the European Space Agency’s 2037 Laser Interferometer space antenna. The physicists also noted that advanced alien warp drives would create gravitational wave patterns that would be different from natural sources and, if detected, these alien waves could also provide humans with clues about how to reverse the technology.
“This is because the shape of the GW signal is completely dependent on the object’s trajectory,” they wrote in the paper. “Thus, as a burst signal is detected, one can attempt to reason out the properties of the transport mechanism present based on the shape of the GW signal.”
Originally published on LiveScience.