Gamma ray bursts, powerful flashes of light, are the brightest events in our universe that last no longer than a few seconds or minutes. Some are so bright that they can be seen with the naked eye, like the burst of GRB 080319B, discovered by the NASA Swift GRB Explorer mission on March 19, 2008.
But despite their intensity, scientists do not know the cause of gamma-ray bursts. Some people in general believe that these are messages of alien civilizations. And scientists managed to recreate a mini-version of the gamma-ray burst in the laboratory, opening a completely new way of investigating their properties. The results were published in Physical Review Letters.
One of the reasons for the emergence of gamma-ray bursts is that they are somehow born in the process of ejecting jets of particles created by massive astrophysical objects, such as black holes. This makes gamma-ray bursts extremely interesting for astrophysicists. Their detailed investigation can reveal the key properties of black holes in which these flares are born.
The rays emitted by black holes mainly consist of electrons and their "antimaterial" companions-positrons. All particles have antimatter, which are identical to them in everything except the charge. Such rays should have strong magnetic fields. Rotation of these particles in the field generates powerful bursts of gamma radiation. At least so our theories predict. But no one knows how these fields should be born.
Unfortunately, there are several problems in studying these outbursts. They not only live very little, but – and this is most problematic – and are born in distant galaxies, sometimes a billion light years from Earth.
Therefore, you rely on something that is incredibly far away, appears randomly and lives for a few seconds. It's like trying to figure out what the candle is made of, having only glimpses of candles that are lighted from time to time thousands of kilometers away from you.
The most powerful laser in the world
Recently it has been suggested that the best way to figure out how gamma is born -splashes, – simulate them on a small scale in the laboratory, creating a small source of electron-positron beams, and see how they develop, left to their own devices. Scientists from the United States, France, Britain and Sweden have managed to create a small version of this phenomenon using the most powerful lasers on Earth like the Gemini laser belonging to the Rutherford-Appleton Laboratory in England.
How powerful is the strongest laser on Earth? Take all the solar energy that covers the whole Earth, and squeeze it to a few microns (the thickness of a human hair) – and get the power of a Gemini laser shot. By engaging the laser with a complex target, scientists were able to release superfast and dense copies of astrophysical jets and create superfast animations of their behavior. The result is amazing: scientists have taken a real jet that extends thousands of light years and compressed it to several millimeters.
Scientists for the first time were able to observe key phenomena that play an important role in creating gamma-ray bursts, like self-generation of magnetic fields that live a long time. This made it possible to confirm some large theoretical predictions about the strength and distribution of these fields. Our current model, which is used to understand gamma-ray bursts, is on the right track.
This experiment will be useful not only for understanding gamma-ray bursts. Matter, consisting of electrons and positrons, is an extremely interesting state of matter. The common substance on the Earth consists mostly of atoms: heavy positive-charged nuclei, surrounded by light clouds of negatively charged electrons.
Due to the incredible weight difference between these two components (the lightest nucleus weighs 1836 times the electron), almost all the phenomena that we experience in our daily lives stem from the dynamics of electrons that respond much faster to any input from outside (light, other particles, magnetic fields, etc.) than the nuclei. But in an electron-positron beam, both particles have the same mass, so the discrepancy in reaction time is completely eliminated. This leads to a multitude of fascinating consequences. For example, in the electron-positron world there would be no sound.
Why should we even worry about such far-off events? In fact, there is why. First, understanding how gamma-ray bursts are born will allow us to understand much more about black holes and open a large window to understanding how our universe has emerged and how it will evolve. Secondly, there is a more subtle reason. SETI – the search for extraterrestrial intelligence – is looking for messages from extraterrestrial civilizations, trying to catch electromagnetic signals from space that can not be explained in a natural way (mainly for radio waves, but gamma-ray bursts are also associated with this radiation).
Of course, if you point the detector at space, you will receive many different signals. But in order to isolate the transmissions of sentient beings, at first it is necessary to make sure that all natural sources are known which can and should be eliminated. A new study will help to understand the radiation of black holes and pulsars, so when we come across them again, we will know that they are not extraterrestrials.