Physicists examining Albert Einstein's gravitational equations from a new mathematical angle say the equations permit a process in which gravitational structures break apart and rejoin, passing energy from gravity into matter. The finding comes from Luca Comisso, an associate research scientist at Columbia University's Departments of Astronomy and Physics and the Columbia Astrophysics Laboratory, and Felipe A. Asenjo of Universidad Adolfo Ibáñez in Chile, according to Science Daily. Their paper, "Reconnection of Gravitational Fields," was published in Physical Review D, a journal of the American Physical Society.
The researchers call the phenomenon gravitational reconnection. Science Daily reports that it closely resembles a process behind some of the Sun's most violent eruptions, and the team believes the parallel could sharpen understanding of gravity in extreme settings, including black hole collisions.
Why it matters
Magnetic reconnection is one of the universe's main engines for releasing energy. In a plasma — a gas of electrically charged particles — magnetic field lines can be dragged, twisted and stretched until they suddenly snap into new arrangements, dumping stored magnetic energy into nearby particles. That mechanism drives solar flares. Comisso described the basic idea to Science Daily: field lines in a particular configuration break and attach differently, and energy is released in the process. The field gives up energy to the plasma's particles, he said, producing explosions and other energetic events.
The new work proposes that gravitational fields can do something analogous. If confirmed, the result would add a mechanism to the toolkit for describing how gravity behaves where space-time is severely warped — regions where even the strongest computer simulations are hard to interpret, Science Daily reports.
Sheets instead of lines
The mathematics differs from the magnetic case in an important way. Magnetism is usually pictured with curved lines, like the pattern iron filings make around a magnet. Gravity, however, lives in Einstein's four-dimensional space-time — three dimensions of space and one of time — so its structures are not lines but what Comisso called field "sheets." As he put it to Science Daily, adding a dimension to a line produces a plane, much as many lines together form a sheet.
Under the right conditions, those sheets can rearrange their connections just as magnetic lines do. Science Daily notes that the sheets are mathematical representations, not physical surfaces that literally tear. Their reconnection is a way of describing the gravitational field handing energy to matter.
The result emerged from probing features of Einstein's equations that are not evident in their standard form. The pair built on earlier work, published in Physical Review Letters by Comisso, Asenjo and Maricarmen A. Winkler, which identified mathematical constraints on how space-time's geometry can bend, stretch and change over time. Those restrictions are embedded in Einstein's theory but had not previously been recognized in that shape. Asenjo told Science Daily that the equations carry constraints on space-time's evolution that are not immediately apparent, and that exposing these hidden properties opens a path toward understanding the rules governing gravitational reconnection.
In the new paper, the researchers examined what happens when the ideal conditions that normally keep gravitational structures connected stop holding. They found the connections can change — the effect they named gravitational reconnection. Comisso said some consequences stay concealed in the equations and are hard to grasp by inspection alone; rewriting the equations in a different form makes the behavior accessible.
That rewrite relies on an alternative formulation of Einstein's equations developed by physicists in recent years. It uses different variables but is mathematically equivalent to the original, describing the same physics. Its value lies in its resemblance to the equations used to model plasmas — the charged gases that make up the Sun, fill much of the space between stars, and are central to nuclear fusion experiments. Comisso has spent his career on plasma behavior, and when he and his colleagues noticed the mathematical overlap between plasma physics and gravity, they saw that tools built for magnetic fields could expose overlooked properties of gravitational fields.
More than a century after Einstein set out his theory of gravity, the proposal remains theoretical. What to watch: whether other researchers reproduce the result and whether the framework can be applied to real astrophysical observations, particularly the violent mergers of black holes.
