Temperature is a representation of matter and energy in the universe, which is reflected in the intensity of particle motion and is an indicator of how hot or cold an object is. We all know that there is a physical concept of "absolute zero", the temperature of minus 273.15 degrees Celsius, today scientists have been able to create more than 10 trillion degrees Celsius high temperature, but "absolute zero" is considered never reached, because to Absolute zero, the internal thermodynamic movement of matter will completely stop, which is extremely difficult to do, so the exploration of the lowest temperature is also a scientific challenge.
So how low is the lowest temperature scientists have been able to create so far? A joint team of U.S. and Japanese scientists recently cooled ytterbium atoms in a laboratory to a billionth of a degree Celsius above absolute zero, the hypothetical temperature at which all atoms stop moving, exceeding the lowest temperature in the entire universe of space, according to a Sept. 13 report in Science & Technology Daily.
How did the scientists do it? It turns out that they simulated the quantum physics model first proposed by theoretical physicist John Hubbard in 1963 - Hubbard model, using a laser to limit the movement of 300,000 atoms in the optical lattice, by reducing the momentum of the particles created by the ytterbium atoms cooled matter to very low temperatures, only one billionth of a degree higher than absolute zero This is colder than the coldest known region in space, the Whirling Dart Nebula.
Just after this extremely low temperature was created, researchers also found that ytterbium atoms emerge with new properties at such extremely low temperatures, said Rice University scientist Karen Hazard, a participant in the experiment, "The result of cooling to this extremely low temperature is a real change in physics, more toward quantum mechanics."
But the extremeness low temperature created by the daily scientists mentioned above, which is one billionth of a degree Celsius above absolute zero, is not yet the lowest temperature created by humans, because in September last year, the authoritative physics weekly magazine Physical Review Letters published an article stating that researchers from three German universities have jointly created a low temperature in the laboratory that is only 38 trillionths of a degree Celsius above absolute zero, which is the lowest temperature created by humans The coldest temperature created to date.
So how did the researchers create this extreme low temperature? It is similar to the method above, also by slowing down the speed of particle motion to reduce the temperature of the system. The article claims that the excitation of Bose-Einstein condensation (BE) was combined with a magnetic lens to create a time-domain matter-wave lens system that could reduce the total internal kinetic energy of BE to 38 kelvins by placing the focus at infinity, but the researchers also say that they have not yet reached the extreme of pursuing ultra-low temperatures in this way and that this method could theoretically reduce the temperature of matter to at most 17 kelvins.
Many of you may wonder how such a low temperature can be measured? Scientists have no way to measure such a low temperature because no instrument can respond to such a low-temperature material can be judged, so there no way to measure, so how is such an accurate low-temperature value? It is calculated by reasoning from some laws of physics on particle thermodynamics, whose reference system is mainly the amount of particle motion of matter.
There should be friends will be curious, from absolute zero has been only 38 trillionths, just a little bit, scientists and then work hard, maybe the next step to reach absolute zero this thought is still too optimistic, there have been a considerable number of scientists believe that absolute zero can only approach, and never reach, because the particles can not be in motion, modern physics that matter and Energy is one, two appearances of matter, and absolute zero means let energy to 0, that is to say, let matter become 0, and how will matter become 0? How can matter become 0? This is incomprehensible! So it is generally believed that absolute zero is not possible in any space.