Hypothetical spacetime tunnels may appear in LIGO and Virgo data
Gravity wave detectors have discovered magical black holes. But one unknown may be wormholes.
A black hole coiling into a wormhole will create a strange pattern of space-time waves that gravitational wave observatories can pick up at LIGO and Virgo, physicists reported on July 17 on arXiv.org. The waves flickered back and forth as the black hole passed through the wormhole, then back.
Wormholes are hypothetical objects in which space-time is etched on a tunnel that connects distant cosmic locations or possibly different universes (SN: 8/5/13). From the outside, wormholes can look like black holes. But while something that fell into a black hole was trapped there, something that fell into a wormhole could reach the other side.
No wormholes have been proven. “It’s certainly speculation, with a capital S,” said physicist William Gabella of Vanderbilt University in Nashville. However, if they did, researchers would be able to detect wormholes using gravitational waves.
Gabella and her colleagues examined a black hole with a mass five times in the Sun and orbit a wormhole about 1.6 billion light-years from Earth. When the black hole circled the wormhole, the researchers expected it to be initially coiled inside, as if it was gripping another black hole. First of all, the resulting gravitational waves resemble a standard signature for two black holes, a pattern of waves that increase in frequency over time and are known as chirping.
But when it gets to the center of the wormhole, called the “neck,” the black hole will pass through it. The researchers wondered what would happen if black holes appeared in a distant land like the rest of the universe. In this case, the gravitational waves of the first universe will suddenly die. In the second universe, the black hole will appear before spinning again. It will then return to the first universe through the wormhole.
When the black hole returns, it first exits the wormhole, potentially creating an “anti-chirp,” a pattern of gravitational waves that oppose a chirp, before descending. repetitive gravitational waves broke in silence. When the black hole loses enough energy to produce gravitational waves, its journey ends when it settles on the neck of the wormhole.
“You can’t copy this using two black holes, so that’s a clear sign for a wormhole,” said physicist Dejan Stojkovic of the University of Buffalo in New York, who was not involved in the research. The waves “should stick like a sore thumb,” he said.
According to the general theory of relativity, which describes gravity as a result of the curvature of space-time, wormholes are possible. But a real discovery means that there are kinds of weird things physicists don’t understand. This is because a negative mass component is needed to open the neck of a wormhole to prevent it from collapsing, and there is no known material suitable for the calculation.
The Advanced LIGO or Laser Interferometer Gravitational-Wave Observatory based in the United States and Advanced Virgo in Italy detects waves from black holes or dense stellar bodies called neutron stars. These massive objects revolve around each other before being combined.
Scientists have now discovered such mergers, which have been confirmed by more than a dozen since 2015, with the much-awaiting confirmation. But at some point, physicists need to focus on more unusual possibilities, says physicist Vítor Cardoso of the Instituto Superior Técnico in Lisbon, Portugal. “We have to look for some strange but exciting signals.”
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