令人不寒而慄的科學：超低溫技術如何揭開宇宙的秘密

The Large Hadron Collider, known as the LHC, is one of the most advanced scientific machines in the world. Located underground on the border between France and Switzerland, it is used by physicists to study the smallest building blocks of the universe: subatomic particles. The LHC works by smashing these particles together at high speeds and observing the results. By the 2030s, the LHC will receive a major upgrade, allowing scientists to make even more precise measurements. If any of these measurements differ from what is predicted by the Standard Model of physics, it could mean there is new physics to discover. Martin Aleksa, a technical coordinator at CERN, says this is the main goal of the LHC.

Surprisingly, the LHC relies on technology similar to what is found in supermarket refrigerators. Low temperatures are very important in scientific experiments because they can slow down particles or stabilize materials, making them easier to study. Swep, a company that makes heat exchangers, is working with CERN to develop new cooling systems for the LHC. Heat exchangers are devices that transfer heat from one fluid to another and are used in many everyday machines, like fridges and cars. The new heat exchangers will help cool parts of the LHC’s Atlas experiment to -45 degrees Celsius, reducing electronic noise caused by radiation. The system uses carbon dioxide as a refrigerant, which is less harmful to the environment than previous chemicals. This technology could also be used in other industries, such as commercial cooling in supermarkets.

Other parts of the LHC need to be even colder. More than 1,000 electromagnets in the collider are cooled to 1. 9 Kelvin, which is -271 degrees Celsius, making them some of the coldest places on Earth. At these temperatures, the magnets become superconductors, allowing electricity to flow without resistance and preventing them from overheating. Achieving such low temperatures requires gradually cooling liquid helium over several stages, a process that takes weeks. Another important cooling method is dilution refrigeration, which uses two types of helium: helium-4 and helium-3. Helium-3 is very rare and expensive, but it is essential for reaching temperatures as low as 5-10 millikelvin. These ultra-low temperatures allow scientists to study phenomena that only occur in extreme cold, such as slowing down the speed of light or simulating conditions just after the Big Bang. Dilution refrigerators are also crucial for quantum computers, which need to operate at very low temperatures to keep their qubits stable. Even imaging tiny computer chips is easier when they are cooled, as it prevents movement and allows for clearer pictures. In many ways, cooling technology is helping scientists push the boundaries of what we know about the universe and develop new innovations.