As we currently know, time moves in only one direction. But in 2018, researchers found signs of activity in some gamma-ray burst pulses that appeared to be repeating, as if going backwards in time.
This is an illustration depicted by an artist about the life of a massive star as nuclear fusion transforms lighter elements into heavier ones. When nuclear fusion no longer produces enough pressure to counteract gravity, the star rapidly collapses to form a black hole. Theoretically, energy may be released along an axis of rotation during collapse, forming a gamma-ray burst.
Now, recent research has come up with a potential answer to the reasons that could lead to this time reversibility effect. If the waves in the relativistic jets that produce gamma-ray bursts are faster than the speed of light — at "faster than the speed of light" — one of the effects could be time reversibility.
Illustration of temporal reversibility. Left: Forward. Right: Back.
This accelerated wave is actually possible. We know that when light passes through a medium such as a gas or plasma, its phase velocity is slightly slower than C, the speed of light in a vacuum, and as far as we know, this is the ultimate speed limit of the universe.
Thus, a wave can travel faster than the speed of light through a gamma-ray burst jet without breaking the theory of relativity. But to understand this, we need to go back and look at the source of these jets.
Gamma-ray bursts are the most energetic explosions in the universe. They can last from milliseconds to hours, they're unusually bright, and we don't yet have a comprehensive understanding and enumeration of what causes them.
Photos of the gamma burst GRB990123 optical band showing gamma's host galaxy.
We know from observations of colliding neutron stars in 2017 that these can produce gamma-ray bursts in these collisions and shattering. Astronomers also believe that such an explosion occurs when a massive, fast-spinning star collapses into a black hole that violently ejects material into the surrounding space in a massive supernova.
The black hole is then surrounded by a cloud of proliferating material around its equator. If it spins fast enough, a pullback of the material that initially exploded would cause the relativistic jet to shoot out of the polar region, bursting through the outer layer of the native star before producing a gamma-ray burst.
Now, back to the waves that have a faster speed than the speed of light.
We know that when passing through a medium, particles can move faster than light. This phenomenon is the explanation for the famous Cherenkov radiation, which is often seen as a distinctive blue glow. This light is produced when charged particles such as electrons move faster in water than the phase velocity of light—the "roar of light."
Astrophysicist Jon Hakkila of Charleston College Hakira) and Robert Nemiroff of the University of Technology of Michigan (Robert A. Hakira) Nemirov believes that this effect can be observed in gamma-ray bursts and has been mathematically modeled to prove its principle.
Pictured: Cherenkov radiation glows in the core of an advanced experimental reactor.
They write in the paper: "In this model, shock waves in an expanding gamma-ray burst jet accelerate from subluminal to faster than light, or from faster than light to subluminal."
"Shock waves interact with the surrounding medium and produce Cherenkov and, or other collision radiation, when the speed in that medium exceeds the speed of light. Other mechanisms (such as heated Compton or synchrotron radiation) occur when the speed is slower than the speed of light. ”
The illustration shows the radiation emission process of the source in the Desitt universe that moves around the Schwarzschild black hole.
"These transitions create a set of time forward and time backward [gamma-ray burst] light curve features through the process of doubling the relativistic images."
This doubling of the relativistic images is thought to have occurred in the Cherenkov detector. When a charged particle flying near the speed of light enters the water, it moves faster than the Cherenkov radiation it produces, so suppose it can appear in two places at the same time: one image appears in time to move forward, and the other to appear in time to move backwards.
This is an illustration from an artist depicting a supermassive black hole at the center of a hot galaxy firing a stream of energetic particles toward Earth. (Image source: DESY, Science Communication Laboratory)
Note that this "doubling" activity has not been observed experimentally. But if it does happen, it could also be responsible for producing the temporal reversibility seen in the gamma-ray exposure curve, which occurs when the shock wave passing through the jet medium accelerates to faster than the speed of light, and when it slows down to the speed of subluminal light.
An artist's impression of a gamma-ray burst of jets. Image credit: S. Wiessinger/NASA's Goddard Space Flight Center.
Of course, we still need more work. The researchers hypothesized that the shock waves responsible for creating gamma-ray bursts would be large-scale waves produced by changes in density or magnetic fields — which would require further analysis. And, if the plasma involved is opaque to faster-than-light radiation, then all "bet conjectures" will be canceled.
However, the researchers say their model explains the characteristics of gamma-ray exposure curves better than models that do not include temporal reversibility.
Hakkila said: "The standard gamma-ray burst model ignores the light curve characteristics of time reversibility. But faster-than-light jet motion illustrates these characteristics while retaining a large number of Standard Model features. "
The study has now been published in the Astrophysical Journal.
The picture shows Hakira himself.
Nameless | March 9, 2020
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