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Showing posts from December, 2014

All hail Marvel Studios!

I was, and still am in a remote corner of my heart, a DC fan. But after being bomboozled by the Marvel movie franchise, I promptly switched my faith and made Stan Lee my messiah! Granted, I still haven't watched bits and pieces of the first Thor movie and I haven't watched the second installment Captain America but I can argue that I made up for this by watching Marvel's TV show,  Agents of Shield. Marvel is pushing the envelope in regards to comic book adaptation to the big and small screens alike and DC, it's biggest rival, is lagging behind, far behind. Don't get me wrong, I will still watch the Superman vs Batman movie from DC, if and when it comes out, and I have watched Nolan's Batman trilogy over and over again. And it's not like Marvel's productions are without problems of their own. But still, looking at Marvel's movie line up for the next few years, I cannot but jump up and down like a fan girl, especially Marvel's Avengers : Age of U…

Fall cleaning - Chrome extensions that I found interesting

I wanted to make note of the chrome extensions that I've come across somewhere, preferably not on my system and somewhere online because I'm afraid that I might *accidentally* format my hard drive while attempting to reinstall an OS (yes, that still happens). And maybe, just maybe, some of you will find them interesting as well. There'll only be one extension left from now on, Save to Pocket. The extensions make chrome heavy for my already burdened laptop and I don't want to trouble it any further.

(un)clrd is a chrome extension that turns the internet black and white. Daltonize is one of the more interesting extensions that I've come across on Chrome, one that exposes details so it's easier for color-blind people to notice details, which they would've otherwise missed.

Dictionary of Numbers gives an interesting quantitative perspective. Google Dictionary was another extension that I regularly used. Tex the World is an easy way to write equations using latex…

False Color Images and Multi-Wavelength Astronomy

'Why isn't the galaxy more colorful? The pictures of it that we've seen online are very very colorful' is one of the common complaints that I've gotten when we introduce students to the night skies. The concept of False color images, how they are recorded and how they are clubbed together to make the multi-colored pictures are what follow as my answer to that question.

Color, in the astronomical sense of the word, is defined as the brightness of a source in a particular filter. When astronomers talk about blue stars or red stars, they are speaking in qualitative terms that the star is stronger in the B filter than it is in the R filter, if one is using the UBVRI filters. Such filters encompass a broad range of wavelength, a few 100 nms usually. Quantitatively, emission can be characterized as continuum emission, such as blackbody radiation, and discrete emission i.e spectral lines. In the example mentioned above, if one mentions that a star is bluer, they are refe…

I'm back, with lots and lots of questions

Before I get back to business, I thank Shruti and Ritwika for taking my place when I was away. I'm trying my best to write everyday and I wanted the blog to chug along even when I'm not around. I thought about writing posts and scheduling them to be posted automatically everyday but well I didn't want to do it and I couldn't write enough posts in advance. So I ended up asking a couple of friends of mine if they could write when I was away. Luckily enough, three of the two people I asked said yes and Yayy! It has worked out wonderfully, in my opinion!

Pretty much all I did during my vacation was ask questions, a few of which are still stuck in my head. One of them is regarding satellites that specifically monitor industrial exhaust for their harmful gases.

Moving on to my next question, religion is a big deal in India. To elaborate, every (big) temple has a trust associated with it that manages all of the donations made to the god at the temple, the sale of tickets and…

An on-time - and altogether unusual-for-this-blog - movie post. No one kill me, please *wink*

Nope, not Rahul, not yet. Still Ritwika here. I am back – for one last score :P
Now, in all seriousness, the last post was pretty much all of the science I had up my sleeve. So, today, I am just going to talk about, um, whatever comes to my mind. And I have decided that a lecture on en dashes and em dashes would be boring and long-winded, and would not serve much of a purpose.
(Poruri probably will not like this, but I am going to go ahead and write about Haider, the final instalment of Vishal Bharadwaj’s Shakespearean trilogy. So, here we go.)
Before jumping into the flood of words and thoughts and emotions that this is going to be, some things need to be said. My usual fare in movies is either the light-hearted rom-com or the superbly done thriller, with a healthy dose of action thrown in, or even the superhero movie – not for me, the subtle drama or the tempestuous tragedy. To put it simply, I am no movie critic, and I definitely am not the intellectual movie-goer – I reserve my inte…

An almost-tomorrow post on biological (or, as Ani likes to say, bee-ological) physics ^_^

So, on this fine Christmas night (yes, I slept all day :D), let me start by introducing myself. I am Ritwika, friend of Rahul’s (who has graciously allowed me the use of this blog), owner of two non-functional blogs (I am that lazy), final year Physics student at IISER T, consummate PhD hunter and also, aspiring writer. Additionally, I tend to write in long, rambl-y sentences with lots of brackets and dashes. Rahul, you will have to overlook that. There, that covers all the bases.
Now, when Rahul – or Poruri, as I call him – asked me whether I could blog in his absence, I thought I could get away with writing anything that came to my head, but after having read the stuff that is here, I realise that this is a predominantly science-y blog (ooh, on that note, a huuuuge shout-out to both Poruri and Shruti for their wonderful posts). So, at least for today, I will stick to tradition.
Going back to me – I am interested in theoretical biophysics, and specifically, in looking at population dyn…

To Infinity and Beyond (the Standard Model)

​Hello there readers (yes, all four of you), I'm back with the final installment of the Particle Physics Trilogy for Astronut. In my first and second posts, I gave a brief overview of the structure of the Standard Model of particle physics and went on to make a case for the existence of physics beyond the Standard Model. In this post I'm going to talk about one of these extensions of the SM, called Supersymmetry (you can call her SUSY)- which is also what will hopefully give me my PhD at the end of <till the funding runs out> years.

I'm afraid that this post is going to be a bit of a let-down, because I'm putting it together in a hurry but more so because we are now near the boundaries of my knowledge of particle physics- there is still a semester to go before I take the graduate level Beyond the Standard Model course! So please bear with the occasional vagueness. 


Before I begin, I must point out that SUSY is a bit of a controversial topic in the particle physics …

The Theory Of (Life, Universe and) Everything

Look who's back (back again). 
The last post saw me attempting to give a somewhat coherent and extremely condensed introduction to the Standard Model of particle physics. As a quick recap (this is me practicing for when-or if- I ever become a professor), we saw that the SM consists of two classes of particles- fermions and bosons. The fermions are matter particles and the bosons carry forces that mediate the interactions between these fermions. All stable matter is made up of first generation fermions; and three of the four fundamental forces of nature have corresponding bosons. The gravitational force hasn't made it through the selection committee to the team yet. 
Clearly, the SM is not the ultimate theory to rule them all, and we cannot put a ring on it. The long-standing feud between Standard Model and General Relativity is just one of the many problems that makes it inherently an incomplete theory. Let's take a look at some of the rest one at a time:
The Curious Case …

Elementary (particle physics), my dear Watson

Ground Control to Major Tom: Shruti Patel checking in. Since my dear friend and fellow-physicist Rahul Poruri is homeward bound, and shall remain there for a week, I'm stepping in to continue his tradition of daily posts to Astronut. Even as I write, I'm not quite sure what this post is going to be about, so please forgive me for occasional rants and digressions. 
By the way Rahul, I totally resent you for the name of this blog- I'm never going to start my own blog because there's no way I'll come up with a name as cool as Astronut! For now, I shall try and be happy with being a guest writer!
Before I begin, a little bit on who I am and what I do; so that you can trust that my general views on science- particle physics in particular- are not entirely baseless. I graduated with a masters in Physics from IIT Madras in July this year, and I'm currently working towards (an eventual) PhD with the Theory Group at the Deutsches Electronen-Synchrotron (DESY) in Hamburg…

Shruti Patel is here!

I am going home for the next couple of days, till next friday to be exact and in my absence, my dear friend Shruti Patel will be writing the daily posts. She was my classmate at IIT Madras and she is currently pursuing a PhD at DESY. I'll let her get into the specifics of her work.

Practical Astronomy - the difference between Radio telescopes and Optical telescopes

Radio and optical telescopes observe the radio and optical portions of the electromagnetic spectrum correspondingly. But radio telescopes are fundamentally different from their optical counterparts. Radio telescopes don't have CCDs. They don't need finely polished mirrors and they are much, much bigger in size. So. Why the fundamental difference?
Let's take a detour and remind ourselves of the wave-particle duality of light. The popular young's double slit experiment is explained using the wave theory of light where as photo-ionization is explained using the particle theory of light i.e using photons.
A wave can be described using y = A cos( omega*t + phi ) where omega is two pi times the frequency, phi is the phase and A is the amplitude of the wave. A photon on the other hand can be described using h*nu where nu is the frequency of light. This fundamental difference is what, as you will see in a moment, lead to the differences between optical and radio telescopes.
Op…

Shell scripts

I've been using linux for over 5 years now and I've had to reinstall one or the other version of it every year, and sometimes more. And every time I reinstalled it, I had to install the programs that I use on a daily basis, beginning from audio/video players to browsers to linux utilities. And I've always wanted to write a shell script that would automate this task for me. It would add the relevant repositories itself, download and install them instead of me having to do everything one after another.

I finally did that today. It didn't take more than a couple of hours but I figured out how to write a small, 20-40 line, shell script that would check the system for desired programs and if not present, would download and install them. I had to search a bit to figure out how to take user input in a shell script, to give the user more freedom with which package or program to install but it was pretty straightforward. It's still missing the 'add repository' part…

Adaptive step size Runge-Kutta method

I am still trying to implement an adaptive step size RK routine. So far, I've been able to implement the step-halving method but not the RK-Fehlberg. I am not able to figure out how to increase the step size after reducing it initially.

To give some background on the topic, Runge-Kutta methods are used to solve ordinary differential equations, of any order. For example, in a first order differential equation, it uses the derivative of the function to predict what the function value at the next step should be. Euler's method is a rudimentary implementation of RK. Adaptive step size RK is changing the step size depending on how fastly or slowly the function is changing. If a function is rapidly rising or falling, it is in a region that we should sample carefully and therefore, we reduce the step size and if the rate of change of the function is small, we can increase the step size. I've been able to implement a way to reduce the step size depending on the rate of change of …

Classes in Python and adaptive step size RK method

I've never understood what the term 'Object Oriented Programming' meant. After I started programming in Python, I got introduced to functions and eventually, when I was checking out professional python code, for example from the astropy repository, I noticed classes in python. I didn't try understand what classes are by myself and the few people who attempted to explain it to me weren't successful. I finally tried last weekend what classes in python were used for, how they were different to functions. Not only did I understand what classes are but I also understood that classes are used to create objects in python.

This post and this one helped a lot in understanding how classes are written and used in Python. Now I need to look for a problem, which I am working on, which can be implemented using classes.

Moving on, a problem that I am already working on is to implement adaptive step size runge-kutta method. I am referring to Numerical Methods for Engineers by Ste…