Galaxies seldom exist in isolation. Instead, gravity draws hundreds to thousands of them together, generating huge clusters that are the universe’s biggest objects. Scientists have determined that the hydrogen gas inside galaxy clusters is very hot—roughly 10 million degrees Kelvin, or approximately the same temperature as the sun’s core—and that hydrogen atoms can’t survive at such temperatures. The gas is really a plasma made up of electrons as well as protons.
But there’s one problem: there’s no clear reason for how or why the gas remains so intense. It should have chilled within the age of the cosmos, according to standard physics. But it hasn’t happened.
Laboratory simulations
The difficulty for anybody attempting to solve this problem is that you can’t really replicate these very hot and magnetic circumstances in your garden. Nevertheless, there is already one location on Earth in which you can do so: the world’s most powerful laser laboratory. The National Ignition Facility at Lawrence Livermore National Laboratory can produce such extreme circumstances, albeit for only a split second in an amount the size of a dime.
Researchers collaborated to use the National Ignition Facility in Livermore, California, to simulate the hot gas found in massive galaxy clusters. The researchers concentrated 196 lasers on a single small target, resulting in a white-hot plasma with powerful magnetic fields that lasts just a couple of billionths of a second.
This gave them enough time to notice that rather than a uniform temperature, the plasma had hot and cold spots.
This is consistent with one of the main hypotheses for how heat is stored within galaxy clusters. Heat would typically be readily diffused when electrons clash with one another. The entangled magnetic fields within the plasma, on the other hand, might impact these electrons, forcing them to swirl in the way of magnetic fields, preventing them from scattering and spreading their energy equally.
The simulations were carried out using a computer program known as FLASH, which was created at the University of Chicago. Researchers may use the code to model their laser investigations in great detail before they carry them out, ensuring that they get the results they want.
