sábado, 7 de janeiro de 2017

O William Lane Craig é um embaraço...

Se eu fosse filósofo, teria vergonha de tê-lo como colega. Mas os cientistas não devem julgar todos os filósofos por causa apenas deste que é um embaraço para a profissão - Por que o argumento cosmológico dele é a coisa mais idiota que eu já ouvi (uma das razões):

«Craig, for his Kalam Cosmological Argument to stand, needs this universe to have an absolute beginning since1) Everything which begins to exist has a cause for its existence2) The universe began to existC) Therefore, the universe has a cause for its existenceSo Craig needs premise 2 to be correct. As a result, he does his best to laud the science/cosmology which defends premise 2, cosmology which concludes that there was an absolute beginning. He also does his level best to debunk science which concludes that the universe was past eternal or has had successive bounces, such with some scenarios of Loop Quantum Cosmology (this may include time starting again and again – I believe there are inflationary and cyclical models of LQC – as Wilson-Eqing states, “LQC naturally gives a bouncing universe: the big bang singularity is resolved.” For those particularly adept at understanding such matters, the cyclical nature of the universe driven by LQC is reviewed here by Yongge MA in the Journal of Cosmology.). For an overview on the idea of the Big Bounce in cosmology, see the wiki entry here. See also skydivephil’s own video concerning LQC.One such cosmological model which defies premise 2 is Sir Roger Penrose’s Conformal Cyclic Cosmology or CCC. Penrose was himself one of the original purveyors of the Standard Model, with Hawking, which led to the conclusion that there was a singularity which defined an absolute beginning at the Big Bang. Here is the wiki entry on CCC:The conformal cyclic cosmology (CCC) is a cosmological model in the framework of general relativity, advanced by the theoretical physicists Roger Penrose and Vahe Gurzadyan.[1][2][3] In CCC, the universe iterates through infinite cycles, with the future timelike infinity of each previous iteration being identified with the Big Bang singularity of the next.[4] Penrose popularized this theory in his 2010 book Cycles of Time: An Extraordinary New View of the Universe.Penrose’s basic construction[5] is to connect a countablesequence of open FLRW spacetimes, each representing a big bang followed by an infinite future expansion. Penrose noticed that the past conformal boundary of one copy of FLRW spacetime can be “attached” to the future conformal boundary of another, after an appropriate conformal rescaling. In particular, each individual FLRW metric  is multiplied by the square of a conformal factor  that approaches zero at timelike infinity, effectively “squashing down” the future conformal boundary to a conformally regularhypersurface(which is spacelike if there is a positive cosmological constant, as we currently believe). The result is a new solution to Einstein’s equations, which Penrose takes to represent the entire Universe, and which is composed of a sequence of sectors that Penrose calls “aeons”.The significant feature of this construction for particle physics is that, since bosons obey the laws of conformally invariant quantum theory, they will behave in the same way in the rescaled aeons as in the original FLRW counterparts. (Classically, this corresponds to the fact that light cone structure is preserved under conformal rescalings.) For such particles, the boundary between aeons is not a boundary at all, but just a spacelike surface that can be passed across like any other. Fermions, on the other hand, remain confined to a given aeon. This provides a convenient solution to the black hole information paradox; according to Penrose, fermions must be irreversibly converted into radiation during black hole evaporation, to preserve the smoothness of the boundary between aeons.The curvature properties of Penrose’s cosmology are also highly desirable. First, the boundary between aeons satisfies the Weyl curvature hypothesis, thus providing a certain kind of low-entropy past as required by statistical mechanics and by observation. Second, Penrose has calculated that a certain amount of gravitational radiation should be preserved across the boundary between aeons. Penrose suggests this extra gravitational radiation may be enough to explain the observed cosmic acceleration without appeal to a dark energymatter field.As you will see in skydivephil’s video, there does seem to be empirical evidence supporting this model. Originally, such claims were met with controversy, but more recent work by researchers such as Meisner are far more robust.»