LOG#171. From Bohrlogy to dualities.

Old (old fashioned!) Quantum Mechanics is understood as the quantum theory before its final formulation around 1927-1931…It includes the Bohr model, the Wilson-Bohr-Sommerfeld quantization and some other tricks like the one to take into account the finite nuclear size. For … Continue reading

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#153. Guardians of the Galaxy and Special Relativity.

Dedicated to my followers, to my (cyber)friends around all over the globe, to those patient people who have been waiting for this reboot and also to Marvel for bringing us Guardians of the Galaxy in a superb and wonderful live-action … Continue reading

LOG#113. Bohr’s legacy (I).

Dedicated to Niels Bohr and his atomic model (1913-2013) 1st part: A centenary model This is a blog entry devoted to the memory of a great scientist, N. Bohr, one of the greatest master minds during the 20th century, one … Continue reading

LOG#080. A Bug-Rivet “paradox”.

Imagine that an idealised bug of negligible dimensions is hiding at the end of a hole of length L. A rivet has a shaft length of . Clearly the bug is “safe” when the rivet head is flush to the … Continue reading

LOG#075. Batmobile “paradox”.

The Batmobile “fake paradox” helps us to understand Special Relativity a little bit. This problem consists in the next experiment: There are two observers. Alfred, the external observer, and Batman moving with his Batmobile. Now, we will suppose that the … Continue reading

LOG#052. Chewbacca’s exam.

I found this fun (Spanish) exam about Special Relativity at a Spanish website: Solutions: 1) 2) 3) t=13.6 months = 13 months and 18 days. Calculations: 1) We use the relativistic addition of velocities rule. That is, where u=Millenium Falcon … Continue reading

LOG#049. Ludicrous speed.

We are going to learn about the different notions of velocity that the special theory of relativity provides. The special theory of relativity is a simple wonderful theory, but it comes with many misconceptions due to bad teaching/science divulgation. It … Continue reading

LOG#048. Thomas precession.

LORENTZ TRANSFORMATIONS IN NON-STANDARD FORM Let me begin this post with an uncommon representation of Lorentz transformations in terms of “uncommon matrices”. A Lorentz transformation can be written symbolically, as we have seen before, as the set of linear transformations … Continue reading