Tricksters in the Sky.


Following my last post on black holes, I want to write a small post focusing on what other kinds of objects could be in the sky. A more specific question is: What other objects does General Relativity (GR) predict?

Also, physicists have long known that GR as it stands currently, cannot account for all the matter in the universe. In fact, 85% of the universe must be what we call “Dark Matter“. Now, whether Dark Matter could be made up of many possible things. And it could very well be made up of “dark” bosonic particles.

Turns out there are many possible “compact” objects in the sky. Schwarzschild metric is the metric which describes the space-time around a spherical symmetric static object and turns out it can be applicable to different kinds of stars such as normal stars (Luminous stars made up of hydrogen and helium), which could turn into red and white dwarfs, neutron stars and some other hypothetical stars known as Boson Stars. Mind you, here we are assuming that the Standard Model of Particle Physics is the only valid model for these stars.

My personal favourites are called Boson Stars, especially because they can mimic black holes. So what are these stars and how are they different from the usual stars as we know them?

Boson Stars (BS) are stars which are made up of elementary particles called “Bosons”. They are solutions to Einsteins Equations which can be found using numerical GR. One of the simplest kind of Boson Stars would have no self interaction force between the bosons other than being held together by gravity. However, in order to stabilise them, you would probably require some kind of repulsive potential between the bosons in order to stabilise them against gravitational collapse due to gravity pulling everything in.

Such a simple BS, would not have any electromagnetic radiation or light being emitted which would make them very hard to detect. In fact, they can have masses close to masses of black holes and without having any light emission, might not be indistinguishable from them! And this is why they caught my interest. They are like silent dark spies in the night sky, steadily spinning around without any one knowing about their existence. How exciting is that!

In a recent paper, me and my collaborators modelled a very simple Boson Star with a repulsive potential which could be made up of “dark” Bosons. Since these do not have any electromagnetic coupling, when two BS which are in a binary system, rotating around each other, finally collapse, they will radiate energy in the form of gravitational waves, just like black holes. We calculated the amount of gravitational wave radiation would be emitted from mergers of binary Boson star systems in the universe such as this one and we discussed whether detectors such as LISA and EPTA would be able to detect them or not. Turns out in certain ranges LISA might just be lucky!

Here a few favourite things about Bosons Stars that people have said on the internet and some lists it has found a place on:

All I can say is, if you exist, you go girl!! I am rooting for your existence!

Black Holes!


As a kid, I used to look up to the sky and try to count the number of stars. But I wasn’t as intrigued by what happened inside of them till I heard the story of black holes. For the first time, I was super intrigued by these seemingly super mysterious points in our universe. What are they? How are they made? What happens inside of them?

While the question of what happens inside of them might be the subject of another upcoming post, if scientists manage to crack that code, I did manage to learn about how they are theoretically predicted as well as experimentally formed. Lo and behold, stars had a lot to do with it!

In Einstein’s General Relativity, we can write down the Einstein’s equations and calculate the solutions to these equations. A particular class of solutions which are called as Vacuum Solutions, exist, among which the “Schwarzschild Solution” is a special one. This is a metric which describes the space-time around a spherically symmetrical mass in the universe and it looks like this:

If we calculate the poles of this equation, we find that the equation predicts an event horizon as well as a singularity! If a star many times the mass of the sun goes through the whole chain of nuclear fusion events and ends up quite heavy, it would at some point collapse under its own weight and would form a blackhole if it is trapped inside it’s own event horizon! At this point, the mass and gravitational force of this star becomes so high that not even light can escape the confines of the event horizon! And thus, we do not have a direct probe for the inside of this hole due to which it looks black to us!

And thus, it is a black hole!! And to top this post off, here is a picture of a blackhole swallowing a star!

Taken from here.

Diversity in Constructions: Who are our cities built for?


In this blog post, I will touch upon a not often thought of topic. How do architecture and physical details add to the lack of diversity in our workplaces?

I have been thinking about this for a while because for a long time, ever since I have been in cold countries, for example, Canada, UK, US and have been in a shared office, I have had to have an extra of 4-5 layers always on the back of my chair handy in case I needed them. And I inevitably needed them. Sometimes, the overall office temperature was just too low, otherwise my office mates (inevitably males) would get really hot and open the window. Now, this very innocent sounding details can be very very mischievous. Here is how. Every day, I would ask if I could close the window, once and then twice and would be too embarrassed the third time since it is hard to repeat the same things over and over again, and of course, their problem of feeling too hot was also legitimate. However, the age old adage of compromise for females usually clicked into my brain and even though I would try to push hard to stay there and work, the cold temperature would not allow me to after a bare half an hour and I would make some or the other excuse and go home for the day.

I was also very aware that this made me feel/seem like I was working less than others, so I worked weekends and week nights leading to a high level of mental stress. Not being in the office at strategic times also made me feel a little disconnected from many people who would eventually come to matter by the time I needed recommendations. This in a larger picture eventually leads to gender gaps. The gender data gap is both a cause and a consequence of the type of unthinking that conceives of humanity as almost exclusively male.

So, while I was thinking this, I never actively tried to look for data to see what that problem was and how to address this problem which was clearly structural. And a few days ago, I stumbled upon this article which presented the following data:

“The formula to determine standard office temperature was developed in the 1960s around the metabolic resting rate of the average man. But a recent Dutch study found that the metabolic rate of young adult females performing light office work is significantly lower than the standard values for men doing the same activity. In fact, the formula may overestimate female metabolic rate by as much as 35%, meaning that current offices are on average five degrees too cold for women. This leads to the odd sight of female office workers wrapped in blankets in the summer, while their male colleagues wander around in shorts.

Not only is this situation inequitable, it is bad business sense: an uncomfortable workforce is an unproductive workforce. But workplace data gaps lead to a lot worse than simple discomfort and inefficiency. Over the past 100 years, workplaces have, on the whole, got considerably safer. In the early 1900s, about 4,400 people in the UK died at work every year. By 2016, that figure had fallen to 135. But while serious injuries at work have been decreasing for men, there is evidence that they have been increasing among women. The gender data gap is again implicated, with occupational research traditionally focused on male-dominated industries.”

The link to the whole article is here for those of you curious cats who want to know more.

But here you go! Now, this is an example towards a very very important realisation. I was once told by a physicist, “if you are feeling confused about something, it’s because there is something new to learn there. It’s not invalid. ” And it applies to life! If you are uncomfortable, then it is probably because of a reason, and often it might be structural and wide spread. So talking and researching about these things might actually lead us to build more diverse, inclusive and efficient workplaces rather than blindly following data. As always, the question to ask is what are the possible causations towards a correlation?

And a more immediate question. What are the ways we can go towards unbuilding our gendered city and work spaces and work towards more contemporary inclusive architecture?

Obsessed With Gravity

Physics Poetry

We all have an artistic side. For years and years, physicists have always considered gravity a flighty mistress, a temptress, the ultimate mystery and the holy grail of physics. Needless to say as a poet and a gravitist, ultimately both my worlds collided and I decided to write a poem on my passion on a cold day in the year 2015 when I was a Perimeter’s Scholar International Student and trying not to go crazy.

So, here you go, a poem on gravity and the different approaches to it.

“Obsessed with Gravity”

Gravity sitting and thinking on a stool,

It’s slipping and sliding on a Reimann Pool,

The Riccis and scalars are here and there

The Gammas form a connection that cares.

Its fate was dreamt in Einstein’s sleep

where Hilbert trusted it to Minkowski’s keep,

The g..s wanted to be in the thick of things

and thus entered the action with a leap.

The 5th dimension knocked at a tense time

on the doors of both Kaluza and Klein,

It said I can roll up really small

If only you can make me gravity’s hall!!

In a future post, I will explain about the various metaphors (which are not so metaphorical in gravity theory). So stay tuned!

About a Singular Man


Today the great physicist and mathematician that was Stephen Hawking passed away. I was lucky to have recently met him at a conference at Cambridge titled “Gravity and Black Holes”.

Roger Penrose writes an obituary here, John Preskill dedicated a poem and John Barrett writes a short memory.

While many can share the joy of having had a chance to talk to Prof Stephen, I cannot say the same about myself. Even though I do not consider myself as someone who gets tongue tied at the mention of celebrities, I did not at the right moment know what to say to him even though I was getting my picture clicked with him and helped click several pictures of him with his friends.

You have to understand, for a young PhD student like me, working on the exact same topics as him, meeting someone like him seems absurd. It could be delightful, but in the climax of all the emotions enveloping you, it just seems absurd. Why? You ask. Well, because, what do you say to someone like him? What do you not say? How do you approach him? How do you know you are not annoying him? Someone might say confidence is the sign of the truly intelligent and if that is so, then maybe I lack in it. But let’s come back to the story, there I was, standing right near him, getting my pictures taken after having humbly asked if that was okay with him (to which his secretary replied with a resounding yes!) and then, not knowing what to say. In the end, I thanked him for his seminal contributions and mentioned that it was very nice to meet him in person. But then I was flummoxed.  By this time, I had heard numerous quotes about his humorous and witty side and sat through talks regarding his earliest designs of the Gravitational Waves detector (and why it failed) as well as on his discovery of the Hawking Radiation. I had heard talks such as “The gravitational memory effect: what it is and why Stephen and I did not discover it” by Gary Gibbons, “Stephen, Gary, and the first gravitational wave detections” by Bruce Allen and “One step forward, one step back” by Gary Horowitz and had been reduced to spits of laughter at regular intervals. I had seen pictures of him bantering with students (and was jealous of all of them). I had (half) read the brief history of time, but fully read his earlier papers. I had watched a movie about him!I had already constructed millions of scenarios and broken sentences in my mind of what to say to him and rejected them as sounding too desperate and silly. And there I was sitting at a dinner in his honour and hearing personal stories about him.

It is all very well in movies and books, where the protagonist just goes up to their role model and just whips out their hand in a handshake and says in a suave manner “I want to be the next you, you know”. But how do you do that in the real world and not come across as a crack pot? Do I go up and discuss how I did not like the misrepresentation of his wife’s book in the movie, “The Theory of Everything”?  Or do I go up and ask him what he thinks of some of my crackpot ideas on space-time?

And so in the end, I settled for wishing him a very good health and thank for his inspirational work and told him that I was nervous having to come up and say something to him. And then just as I saw his finger twitch on his machine and was deciding whether to wait after having rambled on my words in one fast go (my friends would tell you how fast I speak), when his secretary thanked us saying “Stephen is very happy to hear your kind words” and with a wry look of disappointment, I slunk away and went to talk to his students and now amazing researchers in their own right, Fay Dowker and Strominger to discuss some hopefully interesting physics.

For a collection of of articles, videos and scientific papers linked to the work, see here.

This is not to say that everything about this giant must be romanticized, but that maybe someone else come forward inspired by his scientific legacy to inspire millions more in turn.  In fact, we must take the time to remember and thank his amazing wife and partners, for enabling him to reach the potential he has. We should take this opportunity to reflect upon the fact that so many other brilliant people do not have access to the same opportunities. Instead of worshipping people that succeed in spite of their disabilities, we may then enable more people with technology and support.

For me, what I will always remember is the starting of his talk where the motorized voice spat out, “Can you hear me?” which seemed like a voice coming from black holes or aliens from another planet directly reaching out to us to ask if we can hear them yet.


This post was originally published in The Quantum Messenger where I contribute occasionally.