“The sun will become dark like a hair shirt, and the moon will not give its light ... The powers of heaven will shake and all the elements will fade away ...” These words were spoken about two thousand years ago, describing in artistic images how the end of time or the thermal death of the Universe will occur. But eighteen centuries passed before researchers approached the study of this problem from a scientific point of view. In fact, as soon as humanity discovered the basic laws of thermodynamics, this question should have arisen sooner or later. Arguing logically, if any natural principle operates in a closed system, why not assume that this very tendency works in relation to the whole universe?
The hypothesis of the thermal death of the Universe was first put forward by William Thompson in 1852, but later, in 1865, it was formulated in more detail by R. Clausius. He extrapolated to space the second law of thermodynamics. According to this rule, every closed system tends to equilibrium when the radiation energy goes into heat. "Death" occurs when the maximum level of entropy is reached. At this moment, no exchange of energy occurs, since all of it passes into heat. And since there is no reason to believe that anything else exists besides space, Clausius concludes, our Universe can also be considered as a closed system, and the same law applies in it.
Naturally, neither Thompson nor Clausius even suggested that the thermal death of the Universe would happen soon, but the predictions of even a very distant doomsday made a lot of noise in the scientific community and generated various refutations of such a hypothesis. As early as 1872, the scientist L. Boltzmann put forward the theory of fluctuations. According to her, our Universe is too huge and complex to die such a simple death. It has always been and will remain in a state of isothermal equilibrium, however, deviations from this state will always occur and will always occur in its various parts. That is, such bursts, emissions of energy will not allow the mechanism to transfer all the energy of the universe to heat to start.
Modern science has neither confirmed nor refuted the hypothesis that the thermal death of the Universe will inevitably occur. The concept of the Big Bang, which supposedly happened about 14 billion years ago and gave birth to everything, does not prove yet that only cosmic microwave radiation acts in space . It is also necessary to take into account the effect of an alternating gravitational field. The theory of A. Friedman deserves special attention: the Universe filled with gravitating matter is not stationary, it either expands or contracts. And if so, ever increasing entropy does not lead the system as a whole to thermodynamic equilibrium.
The thermal death of the Universe can also be called into question from the standpoint of the general theory of relativity. We still know too little about our world to judge with absolute certainty whether our world is closed and whether something else exists beyond its borders. Perhaps other external forces and systems act on it? The laws of physics known to us do not have to be applicable on a scale of unlimited space, say the defenders of the eternity of radiation in the universe. The stars light up and go out, but the system itself is in equilibrium, which, however, does not lead to thermal death of everything.
Despite the fact that the concept of a possible demise of the Universe was neither confirmed nor refuted by modern science, this question began to worry not only “physicists”, but also “lyricists”. Science fiction writers are especially inspired by the possible death of all living things. So, Isaac Asimov literally predicted the chilling end of all life in his story “The Last Question”. The heat death of all organics formed the basis of the plots of many Japanese cartoons and anime series.