Physicists Say Gravity Could Break and Reconnect Like the Sun's Magnetic Fields

Gravity may be able to break and reconnect in new arrangements, much like the magnetic fields that power solar flares, according to a new theoretical study reported by ScienceAlert and Live Science. The work comes from physicists Luca Comisso of Columbia University and Felipe Asenjo of Adolfo Ibáñez University in Chile.

The result is a mathematical one. Gravitational reconnection has not been observed, and the researchers say it does not require any new physics.

What is gravitational reconnection?

On the Sun, magnetic field lines are normally frozen into the hot, electrically charged gas called plasma and are carried wherever it flows. Where that rule breaks down, the lines can snap and rejoin in a process called magnetic reconnection, which releases energy in bursts such as solar flares, Live Science explained.

Comisso and Asenjo asked whether gravity could do something similar. They returned to Einstein's equations of general relativity, using a mathematical approach known as the tetrad formulation, in which some aspects of gravity can be expressed through quantities resembling electric and magnetic fields. Their calculations suggest that, under certain conditions, gravitational fields can reconnect in new configurations.

What are gravitational field sheets?

In an earlier paper published in Physical Review Letters, the pair, working with physicist Maricarmen Winkler of Adolfo Ibáñez University, showed that gravitational fields can form two-dimensional structures called field sheets, according to Live Science and ScienceAlert. One dimension of each sheet stretches through space and the other through time. A snapshot at a single instant catches a sheet as a line, similar to the field lines drawn around a magnet.

Comisso told ScienceAlert that these sheets are not physical objects but mathematical structures that help visualize the gravitational field. As spacetime evolves, they can stretch, bend and, under some conditions, break and reconnect. He stressed that this does not mean spacetime itself tears apart. Instead, the gravitational field changes how different regions of spacetime are connected.

What the new study found

The new study, published Oct. 28 in Physical Review D, found that sheets do not always stay frozen in place. Live Science reported that the researchers showed breaking the frozen-in rule does not by itself guarantee reconnection. Sometimes the sheets only slip relative to the flow carrying them and stay intact because they are frozen into a different flow. Genuine reconnection happens only when no such alternative flow exists.

The team also derived equations for how quickly reconnection could occur and how it affects the exchange of energy and momentum between gravity and matter. It also alters gravitational helicity, the gravitational counterpart of a quantity that measures how twisted and interlinked magnetic field lines are. Frozen-in sheets keep their helicity fixed, while reconnection can create or destroy it.

Comisso said the work is built on established theory: "Everything follows from Einstein's general relativity."

What it means and what comes next

Any direct effect on everyday life is unlikely. ScienceAlert noted that even gravitational ripples from colliding black holes change the length of LIGO's 4-kilometer arms by less than the width of a proton, so reconnection would not necessarily be something people could see or feel.

The potential value is in understanding. Physicists can already simulate dramatic changes in spacetime, such as black hole collisions or core-collapse supernovae, but those calculations do not necessarily reveal the mechanism behind energy transfer. Identifying magnetic reconnection as a mechanism has deepened understanding of the Sun, and gravitational reconnection could offer a similar framework, Comisso told ScienceAlert.

What might trigger it in nature remains an open question. Live Science reported that the researchers' candidates include singularities thought to lie at the hearts of black holes, the combined effect of gravitational ripples too small to track individually, and quantum effects linked to Hawking radiation. Comisso said one of the most interesting possibilities is a role in extreme events such as black hole mergers or neutron star collisions. Detectors such as LIGO have been recording gravitational waves since 2015, and the team wants to know whether reconnection could leave a recognizable signature in them. Comisso said the answers are not yet known.

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Around Prague, based on reporting by ScienceAlert, Live Science

Cover photo: U.S. Department of Energy from United States / Wikimedia Commons (public domain)