Tag Archive for 'Physics'

Three talks and many insights…

The last week or so has been quite eventful at TIFR. We have had some famous/important visitors who have given public lectures and talks.

CO2 Laser photo (From wikipedia)

The first visitor was Prof. Kumar Patel of UCLA, the Indian origin inventor of the $CO_2$ laser. He gave two talks. The first talk was for graduate students where he shared his insights and gave us some tips. The next talk was about about using lasers to detect explosives and chemical warfare agents. Both talks were interesting but I want to share some of the tips he gave us during his freewheeling, informal conversation with graduate students:

  • Be extremely ambitious and try to solve tough problems. Its no point trying to do old, solved problems a new way. Instead, go for fresh problems. Often, the greatest advances have come from scientists who solved problems that others would have considered impossible but out of inexperience the scientist never knew that! Experience can also prove to be a hindrance because it teaches you that you “can’t” do a problem in certain ways. Young people bring a certain irreverence to research that helps them make progress on so-called “impossible” problems.
  • What level of research should you pick? Should you pick a system that is simplified to its core or should you study a system in all its beautiful complexity? There is no correct answer. By stripping a system to its fundamental components and modeling its essential features you can learn a lot. But you can loose understanding of the collective behavior of the components. A beautiful example is the human brain…you must understand its basic component, the neuron and their collective behavior. A complete understanding of the human brain is not possible without understanding both. You cannot understand collective behavior of the neurons (e.g. thinking, dreaming, planning etc.) without understanding the basic components and vice-versa. Therefore what should happen is an integrative approach to science: Some people work from top down and others work from bottom up. Both will have something valuable to teach each other. (My idea: We see this in physics today. Astronomy tries to understand huge aggregates of particles in the form of galaxies, stars, planets etc. Particle physics tries to understand the fundamental particles themselves. Both disciplines feed off and fertilize each other. What aspect of science you choose to study i.e. the building blocks like cells, DNA, protons, quarks etc. or complex systems like the human brain, the weather, galaxies, the immune system etc. is a matter of personal taste. All of them are important, worthy pursuits)
  • I asked Prof. Patel whether science is for young people only (He invented the laser at a young age of 26). (I’m sort of an “older” student who has commenced his Ph. D. so I was personally interested in knowing whether I could still make an impact. It helped me that my question also was very applicable to him because he was in his sixties!) The answer he gave was fascinating: He said that the work he had done in the last six years was work he could never have done in the past. Its always a trade off he seemed to imply. At a young age you know a lot about a narrow area and you don’t know what is impossible. At an older age you know something about everything but are burdened by “this can’t be done” and so on. Also you just can’t keep up with the level of detail in research. (My idea: At a young age you should pursue a specific line of research to every level of detail possible. At an older age your ability to keep up with this level of detail may be lost but you can think about science which combines different areas. Here your experience helps you).

Lorenz Attractor

The next talk was by a French Prof. Étienne Ghys on the Butterfly Effect. The Butterfly effect is popular description of chaos: How a small event can have extremely large impacts on a system. “Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?” is a one of those questions that have entered the public imagination. I have my own version of the Butterfly effect (intended to be a joke of course)

[Sid Butterfly Conjecture 1] No matter how insignificant or poorly cited your research paper is, like the flap of a butterfly wing that causes a tornado in Texas, your paper will eventually have a earth shattering impact on the world of science :-)

This has another humorous implication:

[Sid Butterfly Conjecture 2] All research papers whether by Einstein or obscure researchers have the same impact eventually.

Incidentally I shared Sid Butterfly Conjecture 1&2 with the French Prof when I bumped into him. He seemed to love it!

Abel Prize Logo

The third talk that I want to mention was by S.R. Varadhan a famous Indian origin mathematician from ISI Calcutta who is now at Courant Institute, NYU. S.R. Varadhan was the winner of the Abel Prize (considered the Nobel Prize for Mathematics) in 2007. I have blogged about him here.

Hoping to learn from him, I asked him about the secret to his success. The answer was “you should have passion in what you do”. True, it was boring answer but its worth mentioning here because sometimes the secrets to success are quite simple. We shouldn’t expect rocket science answers to everything. Too often, the expectation of rocket science answers or tricks means that we don’t want to concentrate on the basics (which are obvious but tough to implement) like hard work, perseverance, passion, excellence, time management and so on.

It was inspirational to hear from two Indian origin scientists who have reached the heights of success in their fields. Can I apply their suggestions in my life? Only time will tell.

Quantum Nonsense: How authors abuse Quantum Theory

Jack Canfield BookI’m currently reading Jack Canfield’s “The Success Principles: How to Get from Where You Are to Where You Want to Be”

Its a well written book and all I’m charged up and motivated. Could this book be the answer to all that I want to achieve in life? :-)

Unfortunately, the author does not know much about science. All the examples he uses in the book are of successful writers, businessmen, politicians, social workers, athletes and so on…(well at least there is no example about a scientist till page 65). Why is that scientists and science doesn’t enter the realm of writers in general? Why is the general awareness of science so low, even though science and technology are responsible for the rapid change in the world today? Sample a paragraph in Jack’s book that simply does not make sense:

If you plan your day the night before — making a to-do list and spending a few minutes visualizing exactly how you want the day to go — your subconscious mind will work on these tasks all night long. It will think of creative ways to solve any problem, overcome any obstacle, and achieve your desired outcomes. And if we can believe some of the newer theories of quantum physics, it will also send out waves of energy that will attract the people and resources that you need to help accomplish your goals. (pg 65-66, emphasis mine)

Actually this is not Jack Canfield’s own point for he refers to a large number of authors who have made this bizarre link with Quantum Physics in a footnote.

As a someone who does Quantum Physics almost everyday I know that such a statement is a wild conjecture. Even if there is a 6th sense, it is unlikely that Quantum Physics is involved in the mechanism….

Two lessons:

  • Scientists please involve the public a little bit more in your work…I know you’re trying but please try harder
  • Science is a very exact discipline…you can’t draw conclusions about Quantum Physics, for instance, and apply them to your daily world because some analogy makes sense or a specific physical system reminds you something in your own world. Check with a scientist…better still learn some elementary science…

Detecting Extra-Solar Planets

Inner solar system wikipedia image

If we wish to discover if there is intelligent life outside our solar system we must first look for planets like Earth that orbit around other stars. Now thats difficult. Planets don’t emit light like stars so are extremely faint, almost invisible to our most powerful telescopes.

But there an indirect method that we can use to infer if a star has planets orbiting it. The method does not allow us to see the planets but simply infer that they are there.

If you have studied celestial mechanics you would have learnt that planets do not circle their parent star. Actually the star and the planet both orbit the center of mass of the system. Here is an excellent animation taken from wikipedia that illustrates the concept. The cross is the center of mass of the system.

Check out this blog entry for more details. Part 2 of the blog entry.

planet star

As you can see, the star wobbles as the planet goes around it. Light emitted from this star will be blue shifted as the star is approaching Earth and red shifted as it recedes from Earth. This periodic Doppler shift will allow you infer the existence of planets around other stars. Of course, there are lots of caveats and complications but this is the essential concept.

Its is tremendously simple but amazing idea and I wanted to blog about it, even though umpteen websites talk about the same thing.

Here is a good article that talks about this method in greater detail

Book Review: The Science of JET by John Wesson

Cartoon of a basic Tokamak
From the JET site. Link

Nuclear Fusion may be the answer to our energy problems. Its environmentally friendly (unlike Nuclear Fission which produces long lived radioactive waste) and does not cause global warming (No CO2 emissions). Moreover, Nuclear Fusion reactors can never explode like Nuclear Fission Reactors (e.g. Chernobyl).

The problem is that we still don’t know how to do Nuclear Fusion efficiently! Nevertheless, we are close to mastering the technology. In 20-30 years controlled Nuclear Fusion may become a reality.

JET was an experiment by the European Union that solved many problems in the field of controlled thermonuclear fusion. The JET Tokamak program was active for about two decades until 1999.

John Wesson, a member of the Jet Team has written a freely available book The Science of JET. You can download the book here and here. (Use the first link. The fonts are messed up in a few places on the second link).

The Science of JET is a fantastic non-technical book. It explains everything you need to know about fusion via Tokamaks in a wonderfully simple fashion. Plasma confinement has a reputation for being a very tough subject but John Wesson makes it simple. If you have studied college physics you will be able to follow the book very easily.

John Wesson stresses concepts. You come away with a good understanding of Tokamaks. There are also lots of interesting stories that make the book part tutorial and part historical account.

What you will learn/gain from the book:

  • A good feel of plasmas. How they are confined magnetically in Tokamaks
  • A good understanding of plasma heating techniques like RF heating, neutral beam heating and Ohmic heating
  • A good understanding of important components of Tokamaks like Diverters, Toroidal and Poloidal coils etc.
  • How to achieve fusion. Basic concepts like fusion triple product, energy confinement etc.
  • H-modes, Instabilities, confinement, energy losses etc.
  • The technology behind various components of a Tokamak fusion reactor
  • History of the field and other experiments in Japan and US

The book sparked my interest in controlled fusion. Here is a list of resources and videos that will be useful while reading John Wesson’s book.

Wikipedia entry on Tokamaks

Fusion Basics from the JET site

The Plasma Edge (really good article)

Some advanced articles from the JET site

Nice JET movie, Another Movie

ITER: The successor to JET

ITER is an international collaboration unlike JET, which was mainly European. A prototype nuclear fusion reactor (ITER) is expected to produce 500 MW of power. India is part of the international collaboration!

India’s latest Tokamak, SST-1 (slightly outdated website)

Institute for Plasma Research, Gujarat, India

Overview of Tokamak Results

Impossible Crystals

Impossible Crystals

This is a story of how the impossible became possible. How, for centuries, scientists were absolutely sure that solids (as well as decorative patterns like tiling and quilts) could only have certain symmetries – such as square, hexagonal and triangular – and that most symmetries, including five-fold symmetry in the plane and icosahedral symmetry in three dimensions (the symmetry of a soccer ball), were strictly forbidden. Then, about twenty years ago, a new kind of pattern, known as a “quasicrystal,” was envisaged that shatters the symmetry restrictions and allows for an infinite number of new patterns and structures that had never been seen before, suggesting a whole new class of materials. By chance, solids with five-fold symmetry were discovered in the laboratory at about the same time. Even so, for nearly twenty years, many scientists continued to believe true quasicrystals were impossible because, they argued, such a pattern could only be formed with complex and physically unrealistic inter-atomic forces.

Impossible Crystals is an abstract but ultimately satisfying video lecture by Paul Steinhardt, Albert Einstein Professor of Physics at Princeton University. The presentation is targeted at the layman but realistically, some background in solid state physics/symmetry is necessary to appreciate what Steinhardt is saying. You don’t need a high speed internet connection: you can simply download the PDF and listen to the MP3 of the presentation. There are many other public lectures available for download at Perimeter (see link that follows).

Link to the presentation (look for Impossible Crystals)

Wikipedia entry for Quasicrystal

Wikipedia entry for Aperiodic Tiling

Another teaser image

quasicrystal

String Theory Lectures at TIFR by Shiraz Minwalla

Shiraz Minwalla String Theory Lectures

If you are interested in a “from-the-scratch” string theory course here is one by our very own Shiraz Minwalla. The lectures are ~500 MB each in .avi format.

The lectures are held twice a week and are likely to continue till middle of 2008 at least, I am told.

Warning: These lectures are not for the faint of heart. A bachelors in physics is really the prerequisite here. I’m an out-and-out experimental physics guy but I think there is great merit in String Theory. Check out my blog entry on a video lecture by Nobel Laureate David Gross that touches upon why String Theory is a good idea.

Tip: See the first lecture for info about textbooks and other course related announcements.

High Energy X-Ray Imaging

High Energy Focussing Telescope

It is extremely difficult to focus high energy electromagnetic radiations by using mirrors and lenses.  The photons are so energetic that they simply pass through the material that is trying to reflect or focus them! Various tricks and techniques are used to focus soft x-rays. The Chandra space telescope is successfully able to focus soft x-rays.

There is an extremely interesting and simple video lecture by Caltech graduate student Hubert Chen on how to focus hard x-rays (upto 100keV). Hubert Chen works on the High Energy Focusing Telescope Project (HEFT).

Link to Video