![]() ![]() This also means that the second law of Thermodynamics during the development of the universe has not been violated.About 160 years ago, the concept of entropy was introduced in thermodynamics by Rudolf Clausius. Therefore the entropy has increased with respect to the beginning of the universe, and in particular due to the formation of many black holes which make the spacetime structure of the universe more complex. ![]() Black holes contain a huge amount of entropy according to the Hawking-Bekenstein formula which relates the surface $A$ of a black hole to its entropy (where $k_B$ is the Boltzmann constant and $\cal_P$ the Planck length):Īctually, black holes are the objects of the universe which bear most of the entropy. When matter starts to agglomerate due to the effect of gravitation actually the entropy increases, in particular if it comes to the formation of black holes. Roger Penrose stresses in his books "A road to reality" and "Cycles of Time" that our universe started from very special initial conditions where spacetime was always rather homogeneous and isotropic as one can deduce from the homogenity of the CMB radiation.Īccording to Penrose the universe could have started from very different initial conditions, for instance with a more complex spacetime structure, even including black holes, a spacetime structure that would have had much more entropy.īut as the universe started from rather homogeneous and isotropic conditions its entropy was actually quite low even if the matter inside it was at thermodynamical equilibrium. Thanks in advance for providing me with a solution to the issue.įor a complete accounting of the entropy one has to consider the effects of gravitation. Me a solution to the issue, I mean, a "simple" clear-cut solution that even the layman could understand. I would be grateful to anyone who would provide For the time being, I believe that there is no paradox at all, butĪ lack of skill from my part. I am pretty sure that someone knows how to explain Therefore, the universe, in the past, had a low level ofĮntropy density (otherwise, there would not be any arrow of time). Therefore, it will be larger in the future, and it Now, the second law of thermodynamics tells us that entropy In a state of thermodynamic equilibrium, as we can easily check even in ourĮveryday life. (ii) The second point of view is as follows : both light and matter were in a high entropy density state. (matter in short) due to the strong level of interactions between all components Thermodynamic equilibrium should be shared by radiation and massive matter ![]() Before the decoupling, the universe was opaque and the When time goes on, thermal equilibrium remains a thermal equilibrium, with Photons were in thermal equilibrium, corresponding to a huge entropy density. In which, at the moment of the decoupling (say 380 000 years after the BB), It is admitted that this CMB is the relic of a radiation Have been confirmed and refined), we know that the CMB satisfies the blackīody radiation law. Since COBE (whose observations since then (i) The first point of view is as follows : It relies on two points of view, concerning theĮvolution of the universe, which are as far as I can understand contradictory. Of knowledge and I would be very grateful if someone could, in return, explain I believe that it is a "paradox" due to my lack I am going to explain what I use to call "the entropy paradox" which ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |