Archive for the ‘Physics’ Category

I am a big fan and collector of the BBC Horizon documentaries and I was pleasantly surprised to have found an old one (probably from the year Horizon started, though I think this is from 1966) that I didn’t know exist till two weeks ago. It is on the exciting discovery of the \Omega - and features Richard Feynman and Murray Gell-Mann. It, like the old Horizon documentaries is more technical but at the same time more raw and exciting. And is worth watching only for its historical significance and age if nothing else. Definitely a collector’s item!


Strangeness Minus Three (BBC Horizon, 1964/6)

Total Runtime: 41:20

[Part 1 | Part 2 | Part3]

[Alternative Link]


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A week ago I observed that there was a wonderful new documentary on you-tube, put-up by none other than author and documentary film-maker Christopher Sykes. This post is about this documentary and some thoughts related to it. Before I talk again about the documentary, I’ll digress for a moment and come back to it in a while.

With the exception of the Feynman Lectures in Physics Volume III, Six not so easy pieces (both of which I don’t intend to read in the conceivable future) there is no book with which Feynman was involved (he never wrote himself) that I have not had the opportunity to read. The last that I read was “Don’t You Have Time to Think“, a collection of delightful letters by Feynman written over the years (Note that “Don’t you have time to think” is the same as “Perfectly Reasonable Deviations”).

Don't You Have Time To Think

A number of people including many of Feynman’s close friends were surprised to learn that Feynman wrote letters and so many of them. He didn’t seem to be the kinds who would write the kind of letters that he did.  These give a very different picture of the man than a conventional biography would. Usually, collections of letters tend to be boring and drab, but I think these are an exception.  They reveal him to be a genius with a human touch. I have written about Feynman before, like I have covered points in an earlier post which now seems to me to be overtly enthusiastic. ;-)

Sean Caroll aptly writes that Feynman worship is often overdone, I think he is right. Let me make my own opinion on the matter.

I don’t consider Feynman god or anywhere close to that (but definitely one of my idols and one man I admire greatly), I actually consider him to be very human and some one who was unashamed of admitting to his weaknesses and who had a certain love for life that’s rare. I only am attracted to Feynman for one reason : People like Feynman are a breath of fresh air in the bunch of supercilious pseudo-intellectual snobs that are abound in academia and industry. A breath of fresh air especially for the lesser mortals like me. That’s why I like that man. Why is he so famous? I have tried writing on it before. And I won’t do so anymore.

I’d like to cite two quotes that would give my point of view on the celebrity-fication of scientists, in this case Feynman. Dave Brooks writes in the Telegraph in an article titled “Physicist still leaves some all shook up” February 5, 2003:

Feynman is the person every geek would want to be: very smart, honored  by the establishment even as he won’t play by his rules, admired by people of both sexes, arrogant without being envied and humble without being pitied. In other words, he’s young Elvis, with the Earth  shaking talent transferred from larynx to brain cells and enough sense to have avoided the fat Las Vegas phase. Is such celebrity-fication of scientists good? I think so, even if people do have a tendency to go overboard. Anything that gets us thinking about science is something to be admired, whether it comes in the form of an algorithm or an anecdote.

I remember reading an essay by the legendary Freeman Dyson that said:

Science too needs its share of super heroes to bring in new talent.

These rest my case I suppose.


The only other book of Feynman that I have not read and that I have wanted to read for a LONG time is Tuva or Bust! Richard Feyman’s Last Journey. Unfortunately I have never been able to find it.

Tuva or Bust! Richard Feyman's Last Journey

There was a BBC Horizon documentary on the same. And thankfully Christopher J. Sykes has uploaded that documentary on you-tube.

This is a rare documentary and was the last in which Feynman appeared. It was infact shot just some days before his death. This documents the obsession of Richard Feynman and his friend Ralph Leighton with visiting an obscure place in central Asia called Tannu Tuva. During a discussion on geography and in a teasing mood Feynman was reminded of a long forgotten memory and quipped at Leighton, “Whatever happened to Tannu Tuva”. Leighton thought it was a joke and confidently said that there was no such country at all. After some searching they found out that Tannu Tuva was once a country and now a soviet satellite. It’s capital was “Kyzyl”, the name was so interesting to Feynman that he though he just had to go to this place. The book and the documentary covers Feynman’s and Leighton’s adventure of scheming of getting to go to Tannu Tuva and to get around Soviet bureaucracy. It is an extremely entertaining film to say the least. The end for it is a little sad though. Feynman passed away three days before he got a letter from the Soviets about permission to visit Tannu Tuva and Leighton appears to be on the verge of tears.

The introduction to the documentary reads as:

The story of physicist Richard Feynman’s fascination with the remote Asian country of Tannu Tuva, and his efforts to go there with his great friend and drumming partner Ralph Leighton (co-author of the classic ‘Surely You’re Joking, Mr Feynman’). Feynman was dying of cancer when this was filmed, and died a few weeks after the filming. Originally shown in the BBC TV science series ‘Horizon’ in 1987, and also shown in the USA on PBS ‘Nova’ under the title ‘Last Journey of a Genius’

Find the five parts to the documentary below:

“I’m an explorer okay? I get curious about everything and I want to investigate all kinds of stuff”

Part 1

tatu1Click on the above image to watch


Part 2

tatu2Click on the above image to watch


Part 3

tatu3-2Click on the above image to watch


Part 4

tatu4Click on the above image to watch


Part 5

tatu5-2Click on the above image to watch


After I got done with the documentary did I realize that the PBS version of the above documentary was available on google video for quite some time.

Find the video here.


Michelle Feynman

Michelle Feynman

As an aside :  though Feynman could not manage to go to Tuva in his lifetime. His daughter Michelle did visit Tuva last month!


One of the things that has me in awe after the documentary over the last week is Tuvan throat singing. It is one of the most remarkable things that I have seen in the past month or two. I am strongly attracted to Tibetan chants too, but these are very different and fascinating. The remarkable thing about them being that the singer can produce two pitches as if being sung by two separate singers. Have a look!


Project Tuva : Character of Physical Law Lectures

On the same day I came across 7 lectures which were given by Feynman at Cornell in 1964 and were put into a book later by the name “The Character of Physical Law”.  These have been made freely available by Microsoft Research. Though some of these lectures have already been on youtube for a while, the ones that were not needless to say were a joy to watch. I had linked to the lectures on Gravitation and Arrow of Time previously.

Project TuvaClick on the above image to be directed to the lectures

I came to know of these lectures on Prof Terence Tao’s page, who I find very inspiring too!


Quick Links:

1. Christopher J. Sykes’ Youtube channel.

2. Tuva or Bust

3. Project Tuva at Microsoft Research


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Here are a number of interesting courses, two of which I am looking at for the past two weeks and that i would hopefully finish by the end of August-September.

Introduction to Neural Networks (MIT):

These days, amongst the other things that I have at hand including a project on content based image retrieval. I have been making it a point to look at a MIT course on Neural Networks. And needless to say, I am getting to learn loads.


I would like to emphasize that though I have implemented a signature verification system using Neural Nets, I am by no means good with them. I can be classified a beginner. The tool that I am more comfortable with are Support Vector Machines.

I have been wanting to know more about them for some years now, but I never really got the time or you can say the opportunity. Now that I can invest some time, I am glad I came across this course. So far I have been able to look at 7 lectures and I should say that I am MORE than very happy with the course. I think it is very detailed and extremely well suited for the beginner as well as the expert.

The instructor is H. Sebastian Seung who is the professor of computational neuroscience at the MIT.

The course has 25 lectures each one packed with a great amount of information. Meaning, the lectures might work slow for those who are not very familiar with this stuff.

The video lectures can be accessed over here. I must admit that i am a little disappointed that these lectures are not available on you-tube. That’s because the downloads are rather large in size. But I found them worth it any way.

The lectures cover the following:

Lecture 1: Classical neurodynamics
Lecture 2: Linear threshold neuron
Lecture 3: Multilayer perceptrons
Lecture 4: Convolutional networks and vision
Lecture 5: Amplification and attenuation
Lecture 6: Lateral inhibition in the retina
Lecture 7: Linear recurrent networks
Lecture 8: Nonlinear global inhibition
Lecture 9: Permitted and forbidden sets
Lecture 10: Lateral excitation and inhibition
Lecture 11: Objectives and optimization
Lecture 12: Excitatory-inhibitory networks
Lecture 13: Associative memory I
Lecture 14: Associative memory II
Lecture 15: Vector quantization and competitive learning
Lecture 16: Principal component analysis
Lecture 17: Models of neural development
Lecture 18: Independent component analysis
Lecture 19: Nonnegative matrix factorization. Delta rule.
Lecture 20: Backpropagation I
Lecture 21: Backpropagation II
Lecture 22: Contrastive Hebbian learning
Lecture 23: Reinforcement Learning I
Lecture 24: Reinforcement Learning II
Lecture 25: Review session

The good thing is that I have formally studied most of the stuff after lecture 13 , but going by the quality of lectures so far (first 7), I would not mind seeing them again.

Quick Links:

Course Home Page.

Course Video Lectures.

Prof H. Sebastian Seung’s Homepage.



This is a Harvard course. I don’t know when I’ll get the time to have a look at this course, but it sure looks extremely interesting. And I am sure a number of people would be interested in having a look at it. It looks like a course that be covered up pretty quickly actually.tornado

[Image Source]

The course description says the following:

The amount and complexity of information produced in science, engineering, business, and everyday human activity is increasing at staggering rates. The goal of this course is to expose you to visual representation methods and techniques that increase the understanding of complex data. Good visualizations not only present a visual interpretation of data, but do so by improving comprehension, communication, and decision making.

In this course you will learn how the human visual system processes and perceives images, good design practices for visualization, tools for visualization of data from a variety of fields, collecting data from web sites with Python, and programming of interactive visualization applications using Processing.

The topics covered are:

  • Data and Image Models
  • Visual Perception & Cognitive Principles
  • Color Encoding
  • Design Principles of Effective Visualizations
  • Interaction
  • Graphs & Charts
  • Trees and Networks
  • Maps & Google Earth
  • Higher-dimensional Data
  • Unstructured Text and Document Collections
  • Images and Video
  • Scientific Visualization
  • Medical Visualization
  • Social Visualization
  • Visualization & The Arts

Quick Links:

Course Home Page.

Course Syllabus.

Lectures, Slides and other materials.

Video Lectures


Advanced AI Techniques:

This is one course that I would  be looking at some parts of after I have covered the course on Neural Nets.  I am yet to glance at the first lecture or the materials, so i can not say how they would be like. But I sure am expecting a lot from them going by the topics they are covering.

The topics covered in a broad sense are:

  • Bayesian Networks
  • Statistical NLP
  • Reinforcement Learning
  • Bayes Filtering
  • Distributed AI and Multi-Agent systems
  • An Introduction to Game Theory

Quick Link:

Course Home.


Astrophysical Chemistry:

I don’t know if I would be able to squeeze in time for these. But because of my amateurish interest in chemistry (If I were not an electrical engineer, I would have been into Chemistry), and because I have very high regard for Dr Harry Kroto (who is delivering them) I would try and make it a point to have a look at them. I think I’ll skip gym for some days to have a look at them. ;-)


[Nobel Laureate Harry Kroto with a Bucky-Ball model – Image Source : richarddawkins.net]

Quick Links:

Dr Harold Kroto’s Homepage.

Astrophysical Chemistry Lectures


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In the opening post for 2009 I had expressed my inability to post frequently because of a number of personal, professional and logistical reasons for some months this year, the posting frequency has been substantially less as compared to last year. Even though I had mentioned that I would not be around much, let me take this opportunity to apologize. However, the posting would be subdued for another month or so and then things should be back to normal.


A post having only an apology is lame, so I thought I would add to the post some of the coolest stuff I came across on the internet in the last two days.

Richard Feynman on the Arrow of Time.


Playlist (5 parts of 9:30 minutes each)

These lectures were delivered at Cornell even tough by this time he had moved to Caltech.  Don’t miss these lectures, I just love the way he teaches.

Richard Feyman on Gravitation.

Playlist (7 parts of 8 minutes each)

I get absolutely delighted watching Feynman talk.


BBC Radio 4 – Carl Sagan: A Personal Voyage

In one previous post I talked about Carl Sagan. Sagan was a wonderful man, one of the men I consider to be my personal heroes. As a kid I saw COSMOS three times, and I still watch some parts of it whenever I get the time or whenever I feel like it. The start to the series is one of the most beautiful to any TV series. COSMOS though launched in 1980 is still widely viewed and has inspired a generation of young and talented kids to science.

I just came across a programme on the BBC Radio 4 on Carl Sagan put up a few days back.  In this show Brian Cox talks about his hero – Carl Sagan. The show is very well done! The show starts with Brian Cox talking how COSMOS inspired him to take up Physics. the show is interspersed with Quotes, excerpts from the COSMOS series, interviews. And interestingly, I can tell which excerpts are from which part of COSMOS! :)


Click on the above image to Listen

However please note that the show is up only for a few days. So do hurry up to watch it. It is totally worth your one hour. I promise!

And apologies again for the much reduced posting frequency. I’ll be back soon enough.


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I came across a report on the new year eve of an old problem concerning the fantastic pattern formation and columnar jointing in nature  resolved. This particular problem  has been close to my heart as I elaborate in the paragraph below hence it was fun to read about it.

A Childhood Story: When I was in grade 2, my pappa got me a set of Childcraft Worldbook. It had some very interesting pictures. I was too young to understand the text completely but I used to love looking at the pictures. There was a very nice picture and a short accompanying article on the Giant’s Causeway in Volume 6 – Our World, on page 31 . However, I enjoyed reading this particular article as it had a story of the kind that kids are attracted to. It said that a lot of people before the turn of the century thought it was made by a giant, Fionn Mac Cumhail, to travel from Ireland to Scotland, and that this explained why the mostly regular hexagonal blocks that made up the Giant’s Causeway were so huge. I was fascinated by the story, but there was a short note at the end – It is believed that these columns were made by volcanic activity. I think fascination is fundamental to most science and art, when talking of science it has to be coupled with its seemingly opposite characteristic – skepticism. I think the line on volcanic activity making the structure did just that. Over the years whenever I saw a picture of the Causeway, I used to wonder how it (specifically the shapes) might have formed. And a PhD student has answered that question now!


The Giant’s Causeway: On the coast of northern Ireland, there is an area of about 40,000 interlocking basalt columns extending into the sea. Most of the columns are hexagonal and fit very neatly, the neatness of this structure inspired a number of legends of an “intelligent designer”.

giantscauseway_1[A view of the Giant’s Causeway on the northern Irish Coast : Image Source]

Click to Enlarge

giants_causeway[A view of the Basalt Columns on the Causeway: Image Source -BBC]

A structure similar somewhat to the Giant’s Causeway is the Devil’s Postpile in California.

What is known is that in the Paleogene period, there was intense volcanic activity in the region (Antrim), and that it is what formed the structures. However, what was not known was how was it that such specific forms, shapes were formed.


Research: PhD student Lucas Goehring and his adviser Dr Stephen Morris of the department of Physics  of the University of Toronto have been working on the problem above. They found out that the size of the columns that varies from one site to another varies as according to the speed of cooling of the lava from an eruption/flow. Using a combination (as required for such a task) of solid mathematical theory provided by Harvard Prof L Mahadevan, good experimentation and field work at the actual sites the researchers solved the problem of what determines the size of the columns.The field work involved making measurements in-situ i.e on the columns to determine at what rate had the lava cooled to form them.

The key to understanding and confirming their ideas was reproducing the phenomenon in the lab, that they did using simple materials. The idea was to use water and corn- starch, which cracks when dried and forms very similar columns as the ones talked about. Controlling the drying rate, a relationship between the size of the columns and the cooling rate was worked out.

starch_expt[Image Source – Reference 1]

The above is the experimental setup for the one just described above. According to Goehring : “The columns are formed as a sharp front of cooling moves into the lava flow, assisted by the boiling of groundwater, As the front advances, it leaves behind a crack network which evolves into an almost hexagonal arrangement. This network carves out the columns.”. They found out that the slower the cooling the much larger the columns.


For more detailed information on the research carried out in this regard, I’d direct you to pages from Goehring’s website.

>> Experiments

>> Field Work

>> Models

>> Extensions

He in the above pages gives a quite accessible picture of their findings and their work. Perfect, especially for somebody like me who is not trained in the field in which this research has been carried out, but are very interested in how it was done.

The findings of this work appeared in the December issue of the proceedings of the national academy of sciences.


Quick Links:

1. Order and Disorder in Columnar Joints

2. Workshop on Emergent Pattern Formation

3. U-Toronto Press Release


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I recently discovered a series of three lectures by the legendary physicist Hans Bethe given in 1999. Bethe was a professor at  Cornell University almost all his life and these lectures given at age 93 had been made public by the University quite a while ago.


[Hans Bethe at the blackboard at Cornell in 1967: Image Source and Copyright – Cornell University ]

These lectures are on the Quantum theory for expert and the non- expert alike. Due to some engagements I am yet to view them, however I am still posting them as I am sure these as given by Bethe himself would be great.

From the Cornell University Webpage for these lectures:

IN 1999, legendary theoretical physicist Hans Bethe delivered three lectures on quantum theory to his neighbors at the Kendal of Ithaca retirement community (near Cornell University). Given by Professor Bethe at age 93, the lectures are presented here as QuickTime videos synchronized with slides of his talking points and archival material.

Intended for an audience of Professor Bethe’s neighbors at Kendal, the lectures hold appeal for experts and non-experts alike. The presentation makes use of limited mathematics while focusing on the personal and historical perspectives of one of the principal architects of quantum theory whose career in physics spans 75 years.

A video introduction and appreciation are provided by Professor Silvan S. Schweber, the physicist and science historian who is Professor Bethe’s biographer, and Edwin E. Salpeter, the J. G. White Distinguished Professor of Physical Science Emeritus at Cornell, who was a post-doctoral student of Professor Bethe.



View Introduction (Quick Time Required)

The introduction has been given by Edwin E. Salpeter and Silvan S. Schweber.

Lecture 1


View Lecture 1 (Quick Time Required)

Lecture 2


View Lecture 2 (Quick Time Required)

Lecture 3


View Lecture 3 (Quick Time Required)



View Appreciation (Quick Time Required)

Note: All the images above and also the text giving an introduction to the lectures are a copyright of Cornell. Please comply with the terms of use associated with them.


1. Download Apple Quick Time

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It is logical to believe that there exist millions of planets in the “vicinity” of our part of the universe alone. However, limited due to tools and the extremely vast distances to be dealt with, we have only been to locate about 300 extra-solar planets, and these have been located indirectly. That is, by observing gravitational wobbles by tracking the star over a period of time it can be known if it is tugged at by an object like a planet.

Why is it difficult to Image the actual planets, one might ask? Well the reason is simple, the distances we deal with are so huge the star simply outshines the planet, making it very difficult to image the planets moving around the star. How does one avoid this problem? The idea is very practical. A occulting bar is used to block out the brightest part of the star’s image so that the blinding light is reduced. Other more specialized techniques can improve things by reducing the light further.

Also another strategy used by professional astronomers looking into deep space for planets over the last two decades has been to focus on systems expected around young stars. The reason being that if the formation of the planetary system is recent the planets would be significantly brighter from the heat of their formation. Much like our early solar system. It would be very difficult to look into space for a planet that is nestled in a star system like that of our Sun of today. This is because the planets would be very very faint (as they would be older and hence colder) and hence very very difficult to image.

However for the first time we have ACTUALLY been able to see extra-solar planets. This is a HUGE step, culminating from years of painstaking observations and focus. These planets are gaseous and probably will have no trace of life. However, the fact that we have been able to image them has a LOT of meaning. Some astronomers have said that it might not be very fantastic to think that we might in a very short time vector be able to observe some Earth like planet that is more likely to have life (carbon based, atleast of the type we know), now this is something that one could not even THINK of some years ago. It was probably fantasy to think we could be able to image planets like our own, now suddenly it looks quite possible.

The first image below, taken by the Hubble telescope shows a ring of dust surrounding the star Fomalhaut (derived from the Arabic فم الحوت fum al-ḥawt, meaning “mouth of the whale”) which is only 25 light years away in the constellation Piscis Australis. This star can be seen with the naked eye in the night sky. The lower right inset image is a composite image from the images taken in 2004 and 2006. Paul Kalas and his team of the University of California at Berkeley found out the planet.  This planet completes orbit around its star every 872 years.

fomalhaut[Image Source: HubbleSite]

The radial streaks are scattered starlight. The planet’s temperature is 260 degrees, quite cool compared to other exoplanets. This dot is about three times the weight of Jupiter and about three times as far from the star as compared to how far Pluto is from our sun. This dusty ring around Fomalhaut is suspected to be something like the Kuiper belt of our solar system.

This star system was expected to have planets in 2005.

The following is a video on the same:

A ring of dust surrounds the star Fomalhaut. Images taken with the Hubble Space Telescope in 2004 and 2006 show that a white dot just inside the dust ring moved in the intervening two years. Researchers believe the dot is a planet that weighs no more than 3 Jupiter masses and lies about three times as far from its star as Pluto does from the Sun (Courtesy of Paul Kalas/UC Berkeley)

Yet another fantastic finding was the discovery of a planetary trio orbiting the star HR 8799 in the constellation pegasus. About 130 light years away, the planets found are from 7-10 times the size of jovian Jupiter. With the farthest of the lot sitting at a distance of 68 AU from HR 8799 (1 AU is the distance between the earth and the Sun). These planets are still glowing because of the heat resulting from contraction after their formation. Their orbit was measured by far IR techniques at the Keck and Gemini North telescopes in Hawaii.


This near-infrared composite image shows the nearby star HR 8799 (multi-coloured blob) and its three planets (red dots at upper left, upper right and just below the star). The planets are 7 to 10 times as massive as Jupiter (Image: National Research Council Canada).

Wow! I am awed once again by the ability of astronomers to find out even the most obscure of dots amongst a nasty conundrum of dots. And even more by the discovery itself. And let me not talk about the images we have above.

I have always harbored a fantasy, that is to be on the crew of humans who get to travel to such a far off land on a Super Daedalus or Super Orion type space-ship. It would take some years (space-ship time). But ofcourse when I return to Earth I would not find anybody I know. For, centuries would have passed as per Earth time by the time I get back. ;)

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