Actually, low temperatures cannot reach -273.15 degrees Celsius (absolute zero), but can only be infinitely approximated. The high temperature of the universe also has an upper limit. According to quantum mechanical calculations, the shortest spatial length of a wavelength is the "Planck length", which can be deduced that the maximum degree of high temperature in nature is 1.41 x 10 ^ 32k, and the overall high temperature does not exist in the universe, it only occurs in the big bang of the birth of the universe. High temperatures The current world record for the lowest temperature obtained by scientists is below zero 273.144°C, very close to " absolute zero".?
On October 22, 2014, the Italian National Institute of Nuclear Physics (INP) announced that the " Low Temperature Underground Rare Events Astronomical Observatory " of the Gran Sasso National Laboratory for Particle Physics, belonging to the Italians, the U.S. National Institute of Nuclear Physics (NINP), set a new world record for the cooling of a copper cube to almost " Absolute zero". The copper cube, weighing 400 kilograms, was cooled to 6 milli-Kelvin degrees, or 273.144 degrees Celsius. The copper cube was sealed in a " cryostat ", " unique among all such devices in the world. Not only is it unrivaled by any other device in terms of size, extreme temperature and cooling capacity.
"Absolute zero" is the absolute thermodynamic temperature defined by William Thomson, Baron Kelvin of Ireland in the mid-19th century. It is an ideal theoretical value, which means that all particles in a gas have zero energy. The temperature of matter can only be approached infinitely close to, but not at or below, absolute zero. The temperature of matter depends on the kinetic energy of particles such as atoms and molecules. The laws of thermodynamics state that absolute zero can never be reached, but only infinitely approximated. This is because any space inevitably contains energy and heat, and they constantly transform into each other without disappearing. Therefore, absolute zero does not exist unless space is devoid of energy or heat from the beginning. In this space, all matter is completely free of particle vibrations and its total volume is zero.?
According to the Maxwell-Boltzmann distribution, absolute zero can be reached as long as the molecules have zero internal, kinetic and potential energy. But this is not possible because there are protons and neutrons in a moving molecule. Also, the electrons outside the nucleus of the atom cannot stand still, so the kinetic energy of the molecule cannot be zero. The kinetic, potential and internal energies of molecules have maximum limits. Molecules are made up of atoms and atomic energy has a limit. When the internal energy of an atom reaches a certain threshold, it is released in the form of a mass-energy equation. When the atom disappears, so do the molecules. Without molecular motion, temperature ceases to exist.?
In the real world, the main techniques for creating cryogenic environments close to absolute zero are laser cooling and evaporative cooling. Chinese physicist Zhu Diwen, who enjoyed the 1997 Nobel Prize in Physics with two other scientists***, invented laser cooling and magnetic-trap technology for refrigeration. Thus, absolute zero exists in theory but cannot be realized in reality. While cold has its limits, heat seems to have no end. Kelvin introduced the Kelvin temperature, which has a minimum value of absolute zero. Temperature is not without an upper limit, but this number is too large to actually measure. The problem at the center of the Sun is about 20 million degrees Celsius, and the U.S. Giant Particle Collider can generate up to 4 trillion degrees Celsius of energy, but that is far from the ultimate temperature.