I have been working on a newsletter, called the "3+1 Hyperspace" -- and I think it is a nice place for me to explain things in a much less technical fashion than I do over here. So if you want a nice set of posts about things that are beautiful, like the thermodynamics of black holes, or maybe the comparison between string theory and loops, then that is the place for you! By subscribing, you would get all my posts right in your inbox -- and I know what you are thinking, "hmm.. but I like my inbox to be clear and clean". Yes, but surely posts about how black holes form, and about singular ..read more

One interesting thing about the field equations is the way it relates matter content on a manifold $\mathscr{M}$ with the curvature on it. But, you could ask why it is correct to even try to relate them. And that is what this post is about.  The entire thing starts by considering "matter fields" on $\mathscr{M}$. What this means is to consider some field $\phi (r, t)$ on $\mathscr{M}$. These could be any fields -- in the most elementary case, you could be talking about a real massive scalar field, $\Phi $. Now, these fields would have an interesting feature with them, the Lagrangian for i ..read more

 I am being honest -- I have no idea at all why I am writing this -- perhaps because I realized that I was getting bored while typing a new post (the great debate -- string theory vs loop quantum gravity). I am not usually into writing and spending time on these things, but I found this pretty interesting. And quite click-baity! And just to say, I guess I maybe liked the movie, it is just not the kind that I would want to see a lot, unlike say Interstellar or Inception. But this was interesting. For those of you who saw the Dark knight (2008), you must have found it great for a numbe ..read more

 OK. I admit I have no work at all, and I should hope that I won't work until I get a free head cleared of thing I "have to do", I "should have done", and things I "forgot after wearing long sleeves"$^{1}$ and too sweet things. So, expect a lot of these posts for the next week or so. So, coming to the point -- we saw before that there are a lot of things to consider -- Baryon asymmetry, QCD phase transition, and the question of things going on near $t=0$, such as the very creation of elements starting from the Big Bang Nucleosynthesis (BBN). And an interesting question pops up over here ..read more

 I started using softwares to simulate things only quite recently -- for instance, the only few numerical relativity softwares I am slightly acquainted with are EinsteinToolkit, Astropy and CAMB. But I started thinking of one particularly interesting question from some time, that I felt was worth penning a post about. If it is possible to simulate the merging of two black holes in a computer, or the rate of expansion of the universe, then is it possible to simulate an entire universe in a computer? Which would be quite an interesting thing for two reasons -- firstly, there is no poss ..read more

 I had written an answer on Quora about "why physicists (don't) seek a theory of everything", and I thought it would be worth re-writing it here, because I am particularly enthusiastic about answers that require a lot of thought, and this one is one of the answers that took me an hour to compose. So here: ---------------Why do certain physicists seek a theory of everything?------------------------ (*Ahem*) They don’t. They don’t seek a “theory of everything”, but they sure do want a unification of gravitation and the quantum mechanical aspects of physics. You could ask, “well, that sounds ..read more

 I wanted a nice website for all my works, from papers to interesting articles and technical notes. My personal website used to be Vaibhav Kalvakota, which I couldn't work on a lot. But three days ago, I came across OpenScholar, and in a day or so my new homepage is ready! I made sure that I added the right sections first -- I started with the "resources" section, where I added my articles and technical notes sections. Next, publications, although I need to work on separating presentations and papers. Then I added some more pages, like popular works (although we all know I barel ..read more

Sometimes a problem in mathematics is more or less staggering -- maybe because of its complexity, or the shear amount of work it takes to imagine it. But some problems are staggering, just because of the intuitive solution to the problem.  You are in a show. In front of you, there are three doors -- behind one of them is a brand new Tesla. behind the other two? Cats. The host of the show comes forward to you -- she tells you to pick a door. Say you pick door "A". She goes close to the door to open it, and turns back to you with a sly smile. "Or, how about I open a door?" she says, while o ..read more

 It has been two days since it has been raining heavily. Normally I wouldn't think too much about it, but today I spent some time to think about something I found particularly interesting, something "un"-physics, something chaotic. This is what is called as the "butterfly effect" in chaos theory. This has to do with the dynamics of systems where even a minor perturbation in the conditions would lead to unpredictable and chaotic results, kind of like a butterfly flapping wings in Tokyo causing a series of air pressure variations that lead to a storm many thousand miles away in New York. Th ..read more

Interstellar (2014) has always been my favorite movie, for its cinematographic, musical and scientific excellence. And one of my favorite details of it has been the black hole. I thought about it today, and I felt I could describe a little of what made Gargantua quite scientifically reasonable. There are three types of black holes that can be identified -- a Schwarzschild black hole ($M$), a Kerr black hole ($M,\; J$) and a Reissner-Nordstrom black hole ($M,\; Q$). There is also another kind of black hole, a Kerr-Newmann black hole, described by ($M,\; J,\; Q$). Gargantua, the black hole in th ..read more