In the image below, you can see the mushroom cloud from the 1952 Ivy Mike explosion, the first fusion bomb ever detonated. In the process of fusion and fission of nuclei, colossal energy is released, thanks to which we today are tremblingly afraid of nuclear weapons. Recently it became known that physicists have discovered an even more energetically powerful subatomic reaction than thermonuclear fusion, which takes place on the scale of quarks. Luckily, she doesn't seem to be particularly suited for weapon crafting.
When a couple of physicists announced the discovery of a powerful subatomic process, it became known that scientists wanted to classify the discovery, because it could be too dangerous for the public.
Was there an explosion? Scientists have shown that two tiny particles known as down quarks could theoretically coalesce in a powerful burst. The result: a large subatomic particle known as a nucleon and a bunch of energy splashing out into the universe. This "quark explosion" could become an even more powerful subatomic analogue of thermonuclear reactions that occur in the nuclei of hydrogen bombs.
Quarks are tiny particles that cling to each other to form neutrons and protons inside atoms. They come in six versions, or "flavors": top, bottom, charmed, strange, topmost (true), and bottommost (adorable).
Energy events at the subatomic level are measured in megaelectronvolts (MeV), and when the two lowest quarks merge, physicists have found that they emit a whopping 138 MeV. This is about eight times stronger than the single nuclear fusion that occurs in hydrogen bombs (a full-scale bomb explosion is composed of billions of similar events). Hydrogen bombs fuse together tiny hydrogen nuclei - deuterium and tritium - to form helium nuclei and a powerful explosion. But each of the individual reactions inside such a bomb only releases 18 MeV, according to the Nuclear Weapon Archive. This is much less than in the fusion of the lowest quarks - 138 MeV.
“I have to admit, when I first realized that such a reaction was possible, I got scared,” says one of the scientists, Marek Karliner of the Tel Aviv University in Israel. "Fortunately, it wasn't all that bad."
With all the power of fusion reactions, a single reaction is not all that dangerous. Hydrogen bombs draw their terrifying power from chain reactions - the cascading fusion of many nuclei at once.
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Carliner and Jonathan Rosner of the University of Chicago determined that such a chain reaction would not be possible with cute quarks, and before publication they shared their concerns with colleagues who agreed with their conclusion.
“If I thought for a microsecond about the military use of such a process, I would not write about it,” says Carliner.
To trigger a chain reaction, nuclear bomb makers need an impressive supply of particles. An important property of pretty quarks is that they cannot be collected in stocks: they cease to exist after one picosecond after creation, and during this time light can only travel half the length of a salt granule. After that time, the pretty quark decays into a more common and less energetic type of subatomic particle - the up quark.
It is possible to create separate reactions of fusion of pretty quarks in a kilometer-long tube of a particle accelerator, the scientists say. But even inside the accelerator it is impossible to accumulate a large enough mass of quarks to cause any damage to the world. Therefore, there is nothing to worry about.
The discovery itself is incredible because it was the first theoretical evidence that subatomic particles can be synthesized with the release of energy, says Carliner. This is a completely new territory in the physics of the smallest particles, which was opened thanks to an experiment at the Large Hadron Collider at CERN.
This is how physicists arrived at this discovery.
At CERN, particles travel around a 27-kilometer ring underground at the speed of light and then collide. Scientists then use powerful computers to sift through the data from these collisions, and strange particles sometimes appear in that data. In June, for example, the data showed a "doubly charmed" baryon, or a bulky cousin of the neutron and proton, made up of two cousins of the "pretty" and "up" quarks, the "charmed" quarks.
Charmed quarks are very heavy compared to the more common up and down quarks that make up protons and neutrons. And when heavy particles bind to each other, they convert a large chunk of their mass into binding energy, and in some cases leave energy that escapes into the universe.
Carliner and Rosner found that when two charmed quarks merge, the particles bind with energies of the order of 130 MeV and eject 12 MeV of the remaining energy. This fusion of charmed quarks was the first particle reaction of this magnitude to release energy. She became the main thesis of a new study published on November 1 in the journal Nature.
The even more energetic fusion of two pretty quarks, which bind at 280 MeV and eject 138 MeV when they merge, is the second and more powerful of the two reactions found. While they remain theoretical and unproven under experimental conditions. The next step will follow shortly. Carliner hopes that the first experiments demonstrating this reaction will be carried out at CERN over the next few years.
Ilya Khel
