Sunday, September 27, 2015

Why I constructed a timeline of physicists

In a TED interview, notable inventor and entrepreneur Elon Musk was asked about his secret behind being able to address diverse technological problems, from sustainable energy to space exploration. His answer can be paraphrased in two words, "Study physics." That's how important physics is. Even sciences like chemistry and biology, and most of engineering, are higher abstractions of underlying physics. It is the foundation on which all of science and technology, and hence all of society rests.   

Isaac Newton once said, "If I have seen further it is by standing on the shoulders of giants." He wasn't just being humble, he was being frank. In physics, as it is with all fields of human thought, the birth of every great idea happened in an environment of ideas that preceded it. At times, one scientist proposed a revolutionary idea that was completely at odds with the prevailing thought. At other times, a particular set of ideas facilitated a natural progression towards another set of ideas irrespective of the individuals involved so long as people were working on it.

To get a panoramic picture of the evolution of ideas in physics, I constructed a visual timeline titled '500 Years of Physics' (see tweet above). I hope teachers, students and enthusiasts of physics find it useful. Updated PNG and PDF versions of the file are now available and I intend to keep updating and enhancing the list.

The timeline consists of people who made key contributions in fundamental and applied physics. Each one on the chronological list is associated with certain key ideas, theories, and/or experiments. Not everyone on the list was a physicist, but all of them made significant contributions to the collective enterprise called physics. Each horizontal bar starts at the birth year of the corresponding personality, and ends at his/her year of demise. The list gives an idea of contemporaries and forerunners -- who came before or after whom, who worked with whom.

Reading physics from a textbook creates an illusion of a level field; everything -- all the laws, the equations, the theories -- comes on a platter. All the struggle behind, the times elapsed and the environment within which the ideas sprang up are hidden from the students. Superimposing other historical timelines on top of this timeline puts those struggles in perspective and will hopefully help reveal some of the stories behind the science. If you love physics, take a printout of the timeline and pin it near your work desk!

Thursday, May 21, 2015

13 Online Shops for Buying Electronic Components in India

 Image courtesy:

Are you a newbie or student who wants to explore the world of electronics? Are you a hobbyist or maker who loves to tinker with electronics? Are you a practicing electronics engineer or a hands-on researcher? If your answer to any of the above questions is yes, you need to buy different types of electronics components and printed circuit boards for your projects. They may range from the most basic resistors and capacitors to highly specialized integrated circuits, sensors and development boards. 

Unless you stay in one of the metro cities of India, you will find it hard to get many of these components. Even if you stay in a metro, some components are hard to find. But thanks to the internet, we have many online shops to buy electronic parts from. I've listed 13 options here. Although I've bought from some of them, I haven't bought from all of them. I've included websites that I know people get stuff from. 

1. Free samples
Who does not like freebies? Some companies are generous enough to provide samples of their components either through their websites or if you politely request them stating your purpose and requirement. E.g. TI, Cypress, Allegro. There might be many more. If you're a student, many companies have designated personnel for university relations who can be approached.  

The rest of the list is about online destinations where you BUY the components and boards. 

[Pay in Indian Rupees]

2. Element14
Formerly Farnell electronics, Element14 is one of the biggest online stores for electronic components. They charge pretty high particularly for small numbers. However, they are sometimes the only option for hard-to-find components and are highly reliable. You might need to have TIN number to buy from them. I was able to get around that problem when I bought from them a few years back.

3. Kits 'n' Spares
Kits 'n' Spares is a subsidiary of Element14 catering to non-industrial costumers. They sell a wide variety of Do-It-Yourself electronics projects and hobby kits.

4. Nex Robotics
Nex Robotix is a spin-off from IIT Bombay that intends to cater to the robotics and embedded systems community. However, many of their products are useful for any electronics enthusiast. I've bought some nice stepper motors and breakout boards from them.

5. Explore Labs 
This Jodhpur based startup calls itself "an opensource playground" and stocks a diverse range of DIY electronics kits. They are an authorized distributor for Sparkfun Electronics in India. 

6. ProtoCentral
This Bangalore based company sells DIY electronics kits and is another authorized distributor for Sparkfun Electronics in India. They ship worldwide.

7. Tenet Technetronics
Tenet Technetronics is yet another Bangalore based online store for electronics hobbysists and engineers.

8. NSK Electronics
NSK is the third Bangalore based entry on the list. Their SP road shop is hugely popular with localites and also has an online store.

9. OnlineTPS
OnlineTPS is a Bhopal based online provider of electronics components and boards.

10. Ventor Technologies
Ventor Technologies is a Kolkata based online shop for electronics components and boards.

11. rhydoLABZ
This Kochi based online store is known as the Sparkfun of India and ships worldwide.

DangerousPrototypes visited and blogged about ProtoCentral, Tenet Technetronics, NSK Electronics, and rhydoLABZ during their India Global Geek Tour 2012.

[Pay in US Dollars]

If you can afford to pay in dollars for something that isn't available anywhere else, try the following two international biggies.

12. DigiKey

13. Mouser

I hope this was useful. Let me know of your personal experiences with them and also if you know of other reliable online stores. I expect the list to grow with time. Happy soldering!


Reader suggestions

14. Aliexpress [Suggested by Syam Krishnan]
While Element14 requires TIN number, Aliexpress is better suited for personal orders. Go to the "Electronic components and supplies" category on their website. 

15. Digibay [Suggested by John F Xavier]
John found some affordable modules at their site.

16. Robokits [Suggested by John F Xavier]
John bought servo and stepper motors from them.

17. DNA Technology [Suggested by Anonymous]

18. Hacktronics India [Suggested by Abhijit Kshirsagar]

19. eNTesla India [Suggested by Sudish Menon]


Discovered later

20. Project Point

Friday, February 6, 2015

The PhD Experience

Yesterday I gave a talk titled "The PhD Experience: Lessons learnt in five and half years." I narrated my personal experiences, thoughts and the lessons I learnt while pursuing a PhD at the Department of Electronic Systems Engineering, Indian Institute of Science. 

The key question that I try to address is, "What are the processes and tasks that get the best out of a researcher?" Considering the researcher as a system, I discuss the inputs (information and experiences), outputs (hardware, software, knowledge) and processes of this system. The presentation is targeted primarily at present and prospective graduate students. However, anybody with an interest in learning and productivity might resonate with aspects of the talk.

Here's the video of the talk [video credits: Abhijit Kshirsagar]

The pdf file of my presentation is available here.

P.S. During the talk, I mentioned the importance of developing verb vocabulary.
The Thesis Whisperer has compiled a useful verb cheat sheet that is available here.

Thursday, January 29, 2015

Learning How to Learn

This blog post is a course assignment for the Coursera MOOC titled "Learning How to Learn" taught by Prof Barbara Oakley and Prof Terrance Sejnowski, University of California, San Diego. Here I discuss my ideas and experiences with three of the learning techniques mentioned in the course: (1) Switching between focused and diffuse mode of thinking, (2) Memory: spaced repetition and associations, and (3) Interleaving.

1. Focused and diffuse mode of thinking

The pinball analogy described by Prof Barbara Oakley is a very elegant way of conveying how the focused and diffuse mode of thinking work.

Depiction of focused and diffuse mode of thinking in Prof Barbara Oakley's lecture.

The importance of playing ping-pong between these two modes in cementing the learning cannot be over-emphasized. Several accomplished people have vouched for it. Prof Arindam Ghosh at the Indian Institute of Science is a renowned scientist in the field of low-temperature nano-electronics. I happened to be team mates with him in the institute cricket team and once did an interview of him where he stressed the importance of playing sports. "Sport rejuvenates the mind. In research or, for that matter, any profession that involves a fair deal of thought, it is very easy to get stuck in a thinking loop. Sports helps break that loop so that you can start your thought process afresh, from a new perspective", he avers. You can read the full interview here.

I've come up with my own analogy to illustrate the importance of switching between the focused and diffuse modes. Picture a fly trying to escape out of a car banging against the glass window. The window is half open but the fly is pushing away at the closed part of the window duped by its transparency. Its trying really hard in its focused approach to get out of the car. But no amount of pushing and buzzing against the glass will solve the fly's problem. What it needs to do is to back away from the glass (akin to going into a relaxed diffuse mode) and come back at it a few inches from where it had approached earlier and voila! It's an open window. The problem is solved, the fly is free.

2. Memory: Spaced Repetition and Associations

I tend to browse and read about a diverse range of subjects. In the process of looking up new information all the time, I might not repeat what I already learnt and hence tend to forget many of the things that I learn. On the contrary, when it comes to identifying plants along with their common and scientific names and their key features, I found that I had a very good memory. The key difference that I noticed was that of spaced repetition. Every time I take a walk in the campus to and from my laboratory, I notice these plants and recall their names while observing them. This routine of recall and spaced repetition helped cement the details of these plants in my mind. I now intend to use the same technique in other aspects of my learning.

Another common problem that I had was to frequently forget where I parked my bicycle possibly because I'm absent minded, not paying attention while I'm parking. Lately, I started leveraging my good plant memory for solving this problem. Every time I park my bicycle, I notice the nearest tree. By building this association, the next time I'm looking for the bike I just have to recall the tree and I find my bike!

3. Interleaving

Prof Barbara Oakley stresses the importance of interleaving one's learning using various techniques and from various perspectives. This helps in gaining a better understanding and in better retention of the material. An interleaving technique that I often use and that has helped me in learning various subjects is what I call "Repeated Classification" of the material. I shall illustrate this technique in the following paragraphs.

Number based classification
After having studied a chapter or several chapters of a book on a subject XYZ, I try to cull out all the numbers mentioned in the text and put them together in a list called "XYZ in numbers." E.g. recently I attended a colloquium by Prof Arnab Rai Choudhuri titled "The mysterious magnetic personality of our sun." I distilled out the numbers he presented at various points of the talk as follows.

The sun in numbers:
Surface temperature of sun = 6000K
Temperature at sunspots = 3000-4500K
Temperature of corona discharge = 1,000,000K
Strength of the sun's poloidal magnetic field = 0.3T
Strength of the magnetic field at sunspots = 10T
Time taken by the sun to complete one rotation about its own axis = 27 days
Time period of the sunspot cycles = 11 years
Time period of the polar magnetic field reversals = 22 years

Time based classification: (when)
Another form of classification is based on the historical timeline of events pertaining to a field of study. Systematically listing down the years of occurrence of significant events provides a sense of how a particular field evolved and creates a storyline that makes it easier to grasp the complete picture. Call it the "Timeline of XYZ."

Spatial classification: (where)
Making a list of places and the associated events is another handy way of classifying. Marking the places on map is even better. This can provide insights on how geographically diverse or concentrated the development of a particular field has been. Call it the "XYZ map."

People based classification: (who)
List down the names of all the people associated with the field of study, preferably along with their significant contributions and quotes. Here's a list of the people who appeared in the 'Learning How to Learn' course lectures and interview videos along with a memorable quote or key take-way from each of them:

Dr Barbara Oakley: "Do not just FOLLOW your passions. Instead, BROADEN your passions."

Dr Terrance Sejnowski: "Unfortunately, there is no instruction manual for the brain."

Dr Robert Bilder: "Disagreeability can spark creativity."

Daphne Gray-Grant: "Do not edit while writing!"

Benny Lewis: "Why children learn language easily is because they are not afraid of making mistakes."

Dr Norman Fortenberry: "Multi-mode input is critical for learning."

Scott Young: "Learn a language by immersing yourself in it."

Amy Alkon: "Fast reading tip: approach a book like a buffet; do not eat everything!"

Dr Robert Gamache: "Study every subject everyday, even if it is for only 10 min"

Dr Keith Devlin: "Switching from one task to another is when one is most likely to fall into the procrastination trap."

Dr Richard Felder: "Don't wait for that 'block of time' to get things done. Do the task in short bursts with whatever time slots are available."

Dr Rebecca Brent: "Give your subconscious an assignment."

John G Maguire: "The secret to good writing is objects, not ideas."

Kalid Azad: "The ADEPT method of learning: Analogy, Diagram, Example, Plain English, Technical Description."

While we looked at questions like how many, how much, when, where and who, several other ways of classification are possible using 'what' based questions. E.g. classifications based on techniques, methods, objectives, products, types, resources etc. There are no limitations to how many different ways you can classify the material and play with it providing various insightful perspectives. It is down to your own imagination. Happy learning!