CERN's new project is to build a mechanism that will be almost four times larger than the largest device in existence. But what exactly is it for?
The Large Hadron Collider (LHC) is arguably one of the most mysterious devices in the world. It sits in a 27-kilometer-long circular tunnel on the border between France and Switzerland, and its main task is to collide the smallest particles of the universe.
This mechanism became famous all over the world in 2012, when CERN (European Organization for Nuclear Research) announced the discovery of the Higgs boson. The theory of the existence of this elementary particle appeared many decades ago, the mathematical calculations behind the standard model of elementary particles assumed that it exists, but no one could fix it before the experiment at the LHC.
And now CERN is talking about plans for the future. Experiments with the help of the LHC have been carried out since 2009 with interruptions to update the mechanism. Now, just such a break, and the LHC will be launched again in 2021, after which it will work for several more decades.
But the existing projects are so ambitious that CERN has been discussing a proposal to build a successor to the LHC for several years. And now the employees of the organization are ready to tell about their vision of the future.
Now called the Future Circular Collider (FCC), plans for its construction were announced in January 2019. The BCC is much larger and more powerful than the current accelerator. While this is just a plan, it has not yet been accepted. If the plan is implemented, experiments at the BCC will begin in the 2040s.
According to CERN, the total cost of construction will amount to just over 200 billion kroons (over 1.5 trillion rubles - approx. Transl.). The organization's member countries will finance the project for several decades. Norway is one of 22 member countries of CERN and will contribute approximately 240 million kroons (over 1.8 billion rubles) in 2019.
Promotional video:
But why do we need a new particle accelerator, what scientists hope to achieve with it?
Long-long tunnel
The LHC is laid in the same tunnel as the previous particle accelerator, just a new filling was placed there. The work of the previous device was curtailed in 2000.
But a completely new tunnel 100 kilometers long will be built for the BCC. Due to the increased length of the particle accelerator, the particles will collide with much more force.
“For a hundred years, the collision of small pieces of matter with great force has been perhaps the most important experimental method for studying the structure and composition of matter,” says Anders Kvellestad, a particle physicist at Imperial College London.
In fact, the CERN plan calls for the construction of several devices in the same tunnel, which will be located one after the other. The first mechanism will collide electrons and positrons, and it can be used for more accurate measurements and studies, for example, the Higgs boson, about which far from everything is known.
It will also be possible to detect quantum trails of completely new unknown particles without making direct observations.
New physics?
In addition to other experiments involving the collisions of electrons and nuclei of lead atoms, it is planned later to build a very powerful mechanism by which protons will collide with protons in the tunnel.
“In particle physics, the collision of a proton with a proton resembles a sledgehammer, while the collision of an electron with a positron can be compared to a small geological hammer. The former gives more power, while the latter is more accurate."
The power of the particle beam itself is measured in teraelectronvolts (TeV). The LHC, 27 kilometers long, can handle 14 TeV, while the new accelerator will withstand power up to 100 TeV.
Higher energies allow you to "lure out" more massive particles, which may not have been observed before, and it is possible that the results of such experiments will give an idea of completely new physics, explains Kvellestad.
Because the universe is still full of things that scientists do not understand. For example, there is no answer to the question of what dark energy and dark matter really are, although they are central concepts in our current understanding of the universe.
There is also a big problem in modern physics. General relativity and quantum field theory, which describes elementary particles, do not coincide. There is currently no explanation for gravity itself, which fits into both models.
Regardless of how you look at it, there is something missing in understanding the universe. Many explanations are offered, but researchers need proof.
And physicists were hoping that the current particle accelerator of the LHC would provide a hint about new physics. This has not happened yet, but the LHC will work for many more years.
“We now know all about some small but interesting discrepancies between theory and practice in the existing data. Therefore, I expect the results of the next round of the LHC's work to show us whether these discrepancies are due to the "new physics" or are they just statistical variations,”says Kvellestad.
But there are also some doubts about the plans to build new particle accelerators.
Will it really do something?
German physicist Sabine Hossenfelder is one of the critics of the MCC proposal. She wrote a book about how physics is too concerned with the "beauty" of equations.
In a column in The New York Times, she criticizes the project, in particular, for the fact that CERN offers it with the same promises made before the construction of the LHC: to find dark matter and clarify the origin of the universe.
The problem is that such a result cannot be guaranteed in any way, says Hossenfelder. Physicists were almost certain that they would find the Higgs boson with the help of the LHC, but now they have no such promising targets.
Supersymmetry is a theory that predicted the existence of several different particles that could fill in the gaps in the Standard Model, but these particles have not yet been touched upon in experiments.
Hossenfelder argues that physics should be exploring other possibilities for now, and it is better to wait with the construction of a large accelerator, focusing on the question of why the supposed particles did not appear in the LHC.
If you're interested, you can read more about the criticism of the project on her blog. She also says that if with the help of the LHC it is really possible to find something in the coming years, then the picture may change.
Basic research
“After the discovery of the Higss boson, we no longer have any theoretical 'guarantees' that we will find new particles in the next generation of experiments,” says Anders Kvellestad. research state - when no one knows what may be revealed in the next experiment."
"There are several examples of discoveries in the history of physics that no one foresaw."
Kvellestad believes that even if physicists disagree on what to expect from these experiments, this should not be an argument against conducting large new experiments.
Thanks to the new particle accelerators, scientists will be able to better investigate and measure already known particles, Kvellestad said.
Need to build a bigger mechanism, but not now?
“There is no doubt that the future path of particle physics research lies through a larger mechanism,” says Bjørn Samset, researcher at the Cicero Center for International Environmental and Climate Research. He is an elementary particle physicist by training and worked at CERN.
"The only question is whether it's time to build it or whether it's better to focus on other things for now."
He also believes that physics would probably benefit more if other projects were evaluated in more detail first, which could help better understand what exactly the new device might find.
Samset cites dark matter as an example.
"Many hoped that the LHC would have enough energy to create the particles that dark matter may be made of."
Many theories have been put forward and some have been refuted, but many still need to be verified. The question is whether it might not be better to focus on other methods, such as special sensors, with which you can directly capture dark matter.
If the BCC is built, this will not happen soon, but Samset emphasizes that it is very important to discuss such projects in advance.
“The danger of waiting is the loss of experience. Technicians at CERN are real magicians, they make the accelerator do incredible things. If we don't start planning the next project now, a lot of this experience could be lost."
At the same time, he believes that experience can be transferred within the framework of other projects. But he is confident that huge accelerators will still be built.
"Such a mechanism should be built, and it will be built, but maybe it's too early yet?"
Lasse Biørnstad
