Nikita M. Shirokov and Ilya Nachevsky used simulating colliding wormholes gravitational waves to test what happens when two Ellis–Bronnikov wormholes meet. Their three-dimensional simulations found short, powerful signals that would not match the wave pattern from black hole collisions.
Shirokov and Nachevsky
The work came from Shirokov of the Moscow Institute of Physics and Technology and Nachevsky of the Higher School of Economics. They varied the initial distance between the wormholes, their trajectories, and the properties of the phantom scalar fields that keep the passage open, then watched the pairs either attract or repel each other.
In some runs, the wormholes passed one another and then moved apart, with their throats widening significantly. In others, they moved toward each other but did not merge into one larger wormhole.
Stephen Hawking
The simulations also produced a common apparent horizon around both necks in some cases, in the region where a black hole was forming. As the phantom scalar field reached the collapse region, the horizon area shrank by about 28 percent.
That result cuts against the black hole surface theorem Stephen Hawking formulated in 1971, which says the surface area of an event horizon cannot decrease and can only increase or stay the same. The new study therefore points to a horizon behavior that does not follow the usual black hole expectation.
Ellis–Bronnikov wormhole
The result matters because the signals could give future gravitational-wave data a new target beyond the hundreds of signals already tied to black hole collisions. The research has not yet been peer-reviewed, so the next test is whether later observations can distinguish this kind of wormhole collision from a black hole event.
For now, the simulations show that an Ellis–Bronnikov wormhole collision can do more than collapse or pass cleanly through. It can also leave behind a shrinking horizon and a wave signal that looks unlike the standard black hole case.
