Archive for the ‘Physics’ Category

There are quite a few interesting articles on Einstein’s work in the Current Science Special on Einstein.
I noticed this thanks to Woit. Contributors include David Gross(Nobel ’04),Atiyah(Fields ’66 ,Abel ’03),Ashoke Sen,Ashtekar,Narlikar amongst others.
T Jayaraman of IMSc has an article on Einstein’s Political Thoughts! .
I havent read any of these articles in detail..So, no comments as of now.


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Noether’s theorem

I had earlier made a post about  Clifford’s post on the “Greatest Physics Paper”.
It is always fun to talk about history of physics and this thread certainly served that purpose. I also thought that Clifford had intended to have a debate and then run away…
But, surprisingly, he has come back to the post and it is time to Vote!!
AND Emmy Noether’s Symmetries Paper (my suggestion) is amongst the final five!
As expected, The Principia is currently leading the way…

Update : Noether’s paper is not doing very badly…it is ahead of both the Einstein Papers :))

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The Physics year is now a thing of the past. And quantum diaries , a project where numerous physicists from around the world blog about their daily lives and physics, has also reached its target lifetime of one year. A review of the past one year’s experience (by the Editor,QD) can be found in the latest Symmetry Magazine. ‘Symmetry’ is a wonderful magazine brought out by Fermilab. I have never seen this in the print form , but it looks pretty similiar to the Cern Courier.

Getting back to Quantum Diaries.. there were a few blogs which were updated regularly and has some nice posts. But, quite a few bloggers were pretty irregular! For ex, John Ellis had a blog at QD and his last post was in July’05! Prof.Ellis is a very well-known physicist and I am sure that his blog would have raked up a large amount of traffic. Anyway, some of the bloggers there hope to continue their blogging.

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Prof. AK Raychoudhri, one of the doyens of the Indian Physics Community, passed away in June 2005. He is probably one of the most under-recognised scientists of his time. Frankly, I had not heard about him till I learnt some Gen.Relativity. The famous “Raychoudhry Equation” is a crucial tool to understanding GR and played an important part in the famous work of Hawking and Penrose on Singularity Theorems. It is these theorems and the interest on compact objects that re-ignited GR research in the 70s. For those who are familiar with some GR, I would suggest that you read Prof.Dadich’s paper on the Raychoudhry equation: gr-qc/0511123

The Telegraph carried an excellant tribute to this great man. The sad part is that there was very little media attention devoted to his passing away. Here are a few abstracts from that piece :

[..]For the first time, singularities seemed inevitable in GTR, and could no longer be argued away as being artifacts of special properties of specific solutions of the Einstein equation. Again, not a result the master would have rejoiced over[..]

Here, the master is Einstein.

The central theme of the singularity theorems is how a singularity is an inevitable feature of solutions to Einstein’s GR. Raychoudhri’s equation gave hints to this property of Einstein’s equations. But the complete theorems had to wait till Hawking and Penrose.

[..]Why did Raychaudhuri himself not arrive at the singularity theorems when he possessed the key tool more than a decade in advance? The answer: he was pursuing a different programme — that of finding a spacetime free of singularities. That programme did not succeed, but careful perusal of his efforts once again bears testimony to his original approach and commitment to the subject[..]

[..]He submitted a thesis based on his work on the Raychaudhuri equation for a DSc in physics, and in 1959 was awarded the degree on the glowing recommendation of none other than John Archibald Wheeler*. Despite this, an application for a promotion to a higher position at the IACS was turned down by the authorities on some flimsy pretext[..]

After this, he joined the Presidency College, Kolkatta. He taught there for a long time. The most remarkable thing about AKR is that he taught undergrad students at Presidency. I do not know of many top-class Indian Physicists teaching at the Indian Universities. I have personally heard many of his students (now physics profs) talking about how inspiring his classes were. Prof.Dadich also lists some of AKR’s former students: Ashoke Sen, S.Bhattacharya (current TIFR Director),CV Vishveshwara,JV Narlikar and Probir Roy .

The last few lines from the Telegraph probably sums up his life in the best fashion :

[..] he was a total academic, a rarity these days. To paraphrase Einstein’s well-known remark about Mahatma Gandhi, future generations of Calcuttans will scarcely believe that such a physicist lived among us, sharing his best with so many.

This post would have served its purpose if it made ARK and his work known to a much larger audience.

*For those who didnt know, Wheeler is a highly acclaimed Theo.Physicist. He is also a well known Gen. Relativist. Feynman and some great relativists like Misner,Thorne,Wald were his PhD students.

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GMRT.. recent stuff.

This isn’t a post explaining GMRT to everyone (like my SDSC post). I would love to do it.. but even a reasonable explanation will take a long time to compile. Here , I have just collected a few media reports reg GMRT:

I came across this article on TIFR and its outposts in the latest issue of Frontline.

[…]the GMRT itself is a unique research facility located in Narayangaon near Pune. It consists of 30 fully steerable gigantic parabolic dishes, each with a diameter of 45 meters. The dishes are placed over an area of 25 square kilometers, forming an incongruous landscape of vineyards interspersed with gigantic dish antennas […]

Apart from the work noted in the Frontline article, another prominent discovery was that of an energetic pulsar, a few months back. See the DH report here. In its India Special, New Scientist carried a wonderful article on GMRT.

[..]Through clever innovation, such as using a mesh of fine wires to form the reflecting surface of each dish, Ananthakrishnan and his colleagues, led by NCRA’s Govind Swarup, have created a revolutionary, low-cost design. The entire telescope cost $12 million[..]

Here is a nice pic of a dish [from NCRA]

GMRT is a fabulous facility, amongst the very best in the world when it comes to Radio Astronomy. India is now a leading center for Radio Astronomy. It is also part of the team of countries looking into the Square Kilometer Array , the next generation Radio telescope. It is quite an ambitious project. The Indian page for the project is here. A recent IE article on this specific project is here. Beware about the number quoted against ‘area required’. It says 1 million sq Km.(1/3rd India) 🙂 .. this must be wrong. The actual conference website talks about 1 million sq.m . [An aside.. This indicates the poor quality of science reporting in India. Doesn’t 1 million sq km sound odd?? I wonder why the reporter didn’t get it checked]

Hope that u enjoyed the various links… I will make a detailed post on GMRT at a later point.

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Copyright, Bill Watterson

This is just a collection of thoughts…not necessarily well-connected.

Communicating cutting edge Physics research to the public is something that is very tough. Very few physicists even try..and even fewer end up making an impact. Every time a physicist meets people who are not trained in the Physics jargon, she/he could have a very tough time in communicating with them. A prime difficulty is the kind of words that Physicists have used to name new theories and discoveries. Most names are taken from every-day experience but represent very deep physical insights and mathematical constructs.

“Relativity” is a wonderful example. People who have learnt about relativity from places other than good phy texts tend to have all sorts of notions. I had a lesson on Einstein (kinda biography) in my high school English curriculum. At one point of time, my English teacher ended up saying

“Everything is relative..isn’t that obvious?? It took this Einstein so much effort to discover ‘this’! After all, what I think about others is different from what others think about me.”

For heavens sake, this isn’t relativity!. That my teacher got it wrong is not surprising… But I wonder why people feel so confident when they talk about stuff they know very little about. Feynman has a fabulous write-up on “tea-party philosophers” in the chapter on Special Relativity in his Lectures on Physics. More recently, Rajesh Gopakumar (in a frontline article) said,

“Everything is Relative” is often the profoundly misleading conclusion …… Everything is not relative.”

I have left out a lot of stuff in between..but that does not matter. And some time, scientists themselves end up adding to the confusion. This quote of Einstein:

“Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. THAT’S relativity.”

is the most misused one. This proliferates all these English text books and leads to “philosophical” debates amongst people who haven’t understood the stuff in the first place. I guess Einstein must have been pissed off with the American media and gave them something juicy(and incorrect) to feed on. But all these complaints about laymen mis-understanding physics does not help.. as long as we don’t have people who can communicate effectively to the public in a way that leads to minimum confusion. Worse, this perceived ambiguity in Physics nomenclature is often used by people to propose their own stupid theories and sell it to the public.(ex. Quantum Healing)

Now, if Einstein was this made-for-media guy.. giving away catchy phrases, Dirac must have been the total opposite. There are fascinating stories of how supremely silent Dirac used to be. He is known to be miserly when it comes to words. Look at this interview.. it is a stunning one. I still roar with laughter when I imagine how the journo must have felt. Not a single question got an answer which had more than one word! These wonderful personalities surely go a long way in make Physics very interesting….

Back to physicists and words.. it may not be uncommon see Physicists use the word “God” in various circumstances. Many of them do it deliberately to connect with the larger population. Some(like Hawking/Sagan) are careful..while some may be more adventurous. I came across the video of an interview with Steven Wienberg, a highly respected Particle Physicist. (He won the Nobel in 79) Here, Weinberg expresses displeasure at the way “God” is used in Physics circles.
It is this interview that prompted this post!.. hope u found it interesting 🙂

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A Warning to Physicists…

from Prof. Pavel Etingof from the Math dept of MIT.
I came across this interesting “warning” while browsing thro MIT ‘s wonderful Open Course Ware site. He advises physicists not to take his course titled ” Geometry and Quantum Field Theory” , as he thinks that it would be of little use to them. He even comments that

“It is important to note that the instructor knows less QFT than a graduate student specializing in QFT or string theory.”


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