In a groundbreaking event recorded in 2019, the LIGO and Virgo observatories captured an incredibly intriguing gravitational wave signal that lasted less than a tenth of a second. This event, designated GW190521, starkly contrasts with the prolonged chirps associated with black hole binaries spiraling towards one another, instead resembling a sudden crack. The initial analysis suggested that this signal originated from a chance encounter between two black holes.
However, a recent paper introduces a more exotic theoretical interpretation: what if this was instead the echo of a black hole collision from another universe, resonating through a collapsing wormhole created by that merger?
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It is essential to note that while the collision interpretation within our universe remains the predominant explanation, the research led by physicist Qi Lai from the University of Chinese Academy of Sciences, available in preprint form on arXiv, argues that the wormhole model cannot be entirely dismissed.
If the gravitational waves were indeed indicative of a wormhole, GW190521 and similar events could not only validate the existence of these speculative structures but also furnish new methods for investigating their physical characteristics. However, that remains a considerable if.
The gravitational waves currently detectable by our instruments are minute fluctuations in spacetime induced by the collisions of massive, dense celestial objects, such as black holes and neutron stars. Importantly, it’s not merely the collision itself that generates these waves. As a pair of black holes circle one another in a binary formation, their gravitational fields produce ripples, initially weaker and gradually intensifying as they draw closer.
The resultant sound profile, or “chirp,” has an ascending waveform, as demonstrated in the video below.
GW190521 deviated from the expected inspiral signature of the gravitational waves, and with a merger mass estimated at 142 solar masses, it should have been detectable. This leads to the conclusion that the black holes were not caught in their own orbital decay but rather grazed past each other before merging due to their combined gravitational attraction.
However, Lai and colleagues propose an alternative theory: what if the system that emerged from a previous black hole merger was a wormhole that subsequently collapsed, producing just a singular brief flash of gravitational wave data? To test this hypothesis, researchers modeled a theoretical waveform of what such a gravitational wave signal would look like and then compared it to the data from LIGO and Virgo.
In their comparison, the binary black hole merger waveform slightly better matched the observed signal than the wormhole waveform. Yet, the fit is close enough to leave open the tantalizing possibility of the wormhole scenario. This suggests that GW190521 might provide humanity’s first glimpse into an alternate universe.
Nonetheless, this does not give us carte blanche to assert the existence of wormholes, as this theory relies on ambitious and speculative physics. Instead, it indicates that further exploration of wormhole theories could yield intriguing insights.
The most recent significant black hole merger, GW231123, resulted in an object 225 times the mass of the Sun and produced a similarly brief gravitational wave signal akin to GW190521. The researchers propose that comparing this event with others yet to be detected could offer a method to validate their findings and illuminate which scenario holds greater likelihood.
For a deep dive into the research findings, visit the preprint server arXiv.
