Newtonian gravity is not coherent with special relativity. Einstein was well aware about it and he had to invent General Relativity (GR). Armed with the equivalence principle, a mystery since ancient times of Galileo, the equivalence between inertial and gravitational … Continue reading

# Category Archives: General Relativity

I am going to review the powerful Cartan calculus of differential forms applied to differential geometry. In particular, I will derive the structure equations and the Bianchi identities. Yes! Firstly, in a 2-dim manifold, we and introduce the Cartan 1-forms … Continue reading

The spectrum of gravitational waves!!!!! Purely gravitational wave music! The blog post today will cover two topics from elementary viewpoints: falling into a non-rotating black hole and gravitational wave “music”, i.e., gravitational wave formulae! It is a hard equilibrium … Continue reading

What is dark energy? Where does it come from? Is it constant? Is it a quantum field? Is it vacuum energy? Nobody knows what is the 70% of the Universe! In the beginning of Physics as Science, Aristotle himself introduced … Continue reading

Hi, there! Today some Kepler third law stuff plus cosmic speed calculations and formulae. Cosmic speed sounds cool…But first… From High School, you surely calculated how fast is A PLANET moving around the sun (or any star, indeed). To simplify … Continue reading

Time of Cosmic Voyages https://www.youtube.com/watch?v=xEdpSgz8KU4 This is a long post, despite not being a special post (remember I make one of those every 50 posts). What are we going to see here? A five part post! Part(I). A descriptive prelude. … Continue reading

Surprise! Twice in a day! Yes, I have much to tell yet, alive…Beyond the holographic principle, and things like gravity is Yang-Mills squared or that open strings squared are closed strings, we have had other important development in the theory … Continue reading

Hello, again! Yes, three consecutive days posting. A change! I missed blogging these months of nightmares. I hope these posts terminate your wait. The wait is over. And I can not wait too. Tempus fugit. Today, we will be discussing … Continue reading

Newton’s gravity reads: In extra dimensions, , , it reads For extra dimensions, if their size are much smaller than considered distances, , then by matching So, gravitational is weak in our … Continue reading

Happy New Year 2018, dear followers! Today is a special blog post! My 200th post! After a really terrible 2017 from the viewpoint of family, health and productivity, I wish this one will be a great year for me and … Continue reading