Gamma-Ray Bursts From Black Holes May Actually Be 'Time-Reversed'

The strange behavior of gamma-ray bursts piques the interests of scientists who noticed that time appeared to repeat itself backward during these events.

Gamma-ray bursts are extremely luminous signals emitted by black holes during a star's collapse. It's short-lived but is known to be one of the most energetic and brightest explosions found in the universe.

There's a lot that astronomers still don't know about gamma-ray bursts, but the new observations are a step forward to understanding these powerful light bursts as well as massive stars and black holes.

Time-Reversing Properties

In a new study published in The Astrophysical Journal, researchers reveal that gamma-ray bursts demonstrate "complex time-reversible wavelike residual structures." This means that the light waves are ejected and then sent back out once again in the opposite order.

Jon Hakkila, lead study author from the Graduate School at the College of Charleston in South Carolina, explains to Live Science that most of the energy of gamma-ray bursts are in the form of pulses or blips.

Hakkila isolated the brightest pulse to observe it more closely and then noticed that these pulses had "little side blips." The team found that each pulse featured three peaks where light increased and then decreased in intensity a few times.

The peaks appeared in the data like mirror images as the parts of the first pulses that were first ejected came last during the following pulses.

The team observed this strange phenomenon in six particularly bright gamma-ray bursts, according to Science Alert, noting that only the most luminous gamma-ray burst light curves displayed the time-reversed properties.

"They all have this signature of brightness that fluctuates and then it turns around and goes backwards in time," Hakkila describes to Live Science.

Potential Explanations

One likely explanation for the time-reversal is likening the phenomenon to the behavior of a blast wave, according to Hakkila. Upon a star's explosion, a blast wave would move outward and light up the material it passes through. Then the wave may have hit a reflective surface that pushes it back the way it came, lighting up the same materials in reverse order.

Science Alert suggests that the clouds of materials could also be arranged in a series of concentric rings so that when the wave or impactor passes through the denser clouds in the center, it appears like a reflected signal.

For now, scientists aren't quite sure what the eerie time-reversed properties of ultrabright gamma-ray bursts are.

Hakkila doesn't want to rule anything out — even stranger, far-fetched theories. After all, he points out, a gamma-ray burst is essentially the creation of a black hole.

"And there's all sorts of very odd things that happen with both space and time and the relationship between space and time in the vicinity of a black hole," he says. "I'm not going to exclude any kind of weird thing."