LOG#155. Maximal tension, Λ and quantum gravity.

Hi, folks! Before the upcoming series of thematic blog posts (they are on their way, eager readers), I found a very interesting paper to discuss. The paper is this http://arxiv.org/abs/1408.1820 and the pdf file can be found here http://arxiv.org/pdf/1408.1820v1.pdf . The author of the … Continue reading

LOG#134. Chaplygin gas.

Warm Dark Matter candidates: neutrinos, axions, extra relativistic species currently unknown. Cold Dark Matter candidates: many. Pick one (or many!): Z primes, the lightest supersymmetric particle (LSP), gravitino, gaugino, neutralino, ELKO fields, Majorana spinors, the infinite component Majorana field, unparticles, … Continue reading

LOG#133. Spacetime foam(III).

Some conclusions of this fascinating subject and thread about the mythical spacetime foam: (1) CDM(Cold Dark Matter) and MOND seems to be complementary descriptions of the same dynamics and phenomenology. (2) MOND force law works at galactic scales. This can … Continue reading

LOG#132. Spacetime foam(II).

The second post in this thread is completely speculative. 1) Suppose that Dark Energy is some kind of “fluid” made of some long wavelength “particles” or “exotic stuff”. 2) How different are those “Dark Energy particles” from the particles we … Continue reading

LOG#131. Spacetime foam(I).

Some weeks ago, I was studying some papers and talks by Jack Ng. I am going to share with you what I have learned from them, about the wonderful subject of the “quantum spacetime foam”. Some topics and ideas I … Continue reading

LOG#128. A chaosmic TSOR returns.

Dear followers and dear readers! Time has come! I am back with the brand new TSOR and its new site. The wait is over. :). Firstly, I have some interesting things to tell you: 1) I have not finished the … Continue reading

LOG#107. Basic Cosmology (II).

Evolution of the Universe: the scale factor The Universe expands, and its expansion rate is given by the Hubble parameter (not constant in general!) Remark  (I): The Hubble “parameter” is “constant” at the present value (or a given time/cosmological age), … Continue reading

LOG#106. Basic Cosmology (I).

The next thread is devoted to Cosmology. I will intend to be clear and simple about equations and principles of current Cosmology with a General Relativity background. First of all…I will review the basic concepts of natural units I am … Continue reading

LOG#105. Einstein’s equations.

In 1905,  one of Einstein’s achievements was to establish the theory of Special Relativity from 2 single postulates and correctly deduce their physical consequences (some of them time later).  The essence of Special Relativity, as we have seen, is that  … Continue reading

LOG#057. Naturalness problems.

In this short blog post, I am going to list some of the greatest “naturalness” problems in Physics. It has nothing to do with some delicious natural dishes I like, but there is a natural beauty and sweetness related to … Continue reading