Back in 2019, the gravitational wave observatories LIGO and Virgo detected major ripples in spacetime.
While astronomers generally agree that the event, dubbed GW190521, was the result of two black holes colliding, a team of researchers at the Chinese Academy of Sciences has proposed a far more eyebrow-raising explanation.
As detailed in a yet-to-be-peer-reviewed paper, first spotted by ScienceAlert, the researchers suggest that LIGO and Virgo instead picked up the signals of a black hole collision in a different universe than ours.
“In this paper, we investigate the possibility of interpreting GW190521 as an echo produced by a postmerger wormhole, created from the inspiral and merger of [binary black holes] in another universe and connecting it to our own,” they wrote.
In other words, LIGO and Virgo instruments picked up the echo of a black hole collision in another universe, so powerful that it opened up a temporary wormhole to our own.
While the team acknowledged that prevailing scientific consensus “slightly prefers the standard binary black holes merger model, it is not significant enough to rule out the possibility that the echo-for-wormhole model is a viable hypothesis for the GW190521 event.”
The researchers point out that the signal detected by the observatories was “extremely short” in duration. Conventionally, when two black holes collide, the resulting waveform grows in strength as they get closer to each other, resulting in a telltale “chirp,” as ScienceAlert explains.
But GW190521 “lacks a clearly identifiable inspiral phase,” they wrote, which usually accompanies these collisions as two astronomical bodies spiral towards each other.
The inspiral phase of the collision also should’ve shown up in LIGO-Virgo observations, considering the merging black holes were estimated to be 142 times the mass of the Sun.
To support their exotic hypothesis, the researchers developed a waveform model of what would happen if the signal of a black hole collision in another universe were to echo through a wormhole. They suggest that the surprisingly short signal may have been the result of said wormhole collapsing shortly after the collision.
They concluded that their modeled waveform better matched the LIGO-Virgo signal than conventional explanations — but only “slightly,” leaving plenty of room for further research.
There’s also the tantalizing possibility that the same phenomenon has been observed again. A more recent LIGO-Virgo detection of a suspected black hole merger in 2023, the most massive one to date, also shares a “similar burst-like short duration nature with GW190521,” the researchers wrote, which could shed more light on the matter.
More on black holes: Scientists Detect Strange Signal in Gravitational Waves