The proverbial (not Schrodinger’s) cat is out of the bag: the Nobel Prize in Physics 2013 has been declared. This year,The Swedish Academy has chosen to honour “Francois Englert and Peter W. Higgs for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider“. But every one is not happy.
As the scientific community celebrates, as small section of the Indian population continues to crib. These self-appointed custodians of India’s scientific heritage are aghast at the treatment that is being shown to the memory of Dr. S. N. Bose who, they claim is the key figure behind the Higgs Boson. The amount of misinformation goes much deeper and this self-righteous anger is having grave negative impacts. Recently, a reputed newspaper carried an article highlighting the fact that India should rejoice because several Indian institutions played crucial role in the ATLAS and CMS experiments at the Large Hadron Collider which was responsible for detecting the “Higgs Boson”. However, the reaction to this article was rather disheartening. The author was admonished for ignoring Dr. Bose and Indians were accused of basking in undeserved glory.
In this is short article we shall try to dispel the myth surrounding the formulation of the Higgs mechanism and Dr. Satyen Bose’s role in it and we shall also highlight the contributions of some of the research laboratories associated with discovery, i.e., the actual Indian Connection.
While everyone is correct in guessing that the term Boson is named after Dr. Bose yet that is not sufficient to attach his name to the discovery. Why? It is because of the simple reason that Dr. Bose had almost no role in formulating the Higgs Mechanism. Honestly speaking, one does not need to be aware of the latest development in theoretical or mathematical physics to realize that.
The Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism (which for brevity is originally referred to as the Higgs Mechanism) is the theory in question. It had effectively removed a major obstacle to constructing a unified theory of weak and electromagnetic interactions and involves a mathematical formalism known as ‘spontaneous symmetry breaking’, an analogy drawn from the BCS Theory of superconductivity.
The mechanism is essentially a relativistic version of one that operates in a superconductor. Now as they were trying to unify weak interactions with electromagnetic interactions they faced a problem. Since the weak interactions are of short range and very weak at low energies, it was clear that if they were mediated by an intermediate vector boson W, it must have a large mass – an apparent problem, since gauge bosons were believed to be by nature massless, like the photon. Some mechanism was required to give mass to the W while leaving the photon massless. The proposed mechanism was the “Higgs mechanism” which required a spin 0 boson: the famous goddamned particle or the Higgs Boson.
Keep in mind that, a vector boson is a boson with the spin quantum number equal to 1. The vector bosons regarded as elementary particles in the Standard Model are the gauge bosons, which are the force carriers of fundamental interactions: the photon of electromagnetism, the W and Z bosons of the weak interaction, and the gluons of the strong interaction. This will prove crucial later on in the discussion.
The ‘Higgs Mechanism’ was developed independently by three groups within a matter of weeks in 1964. First up were (late) Robert Brout and François Englert in Belgium, followed by Peter Higgs in Scotland, and finally Tom Kibble, along with Gerald Guralnik and Carl R. Hagen in London. However, the entire history of the mechanism includes many other names whose name we shall omit for the brevity of space (See the bibliography for links to a much more detailed discussion on the history of the mechanism).
So where and when does Prof. Satyendranath Bose come into the picture? He comes much earlier.Circa 1924, while Dr. Bose was presenting a lecture at the University of Dhaka, (now Bangladesh) on the theory of radiation and the ultraviolet catastrophe, he chose to focus on how the contemporary theories, were inadequate in explaining the spectrum of a blackbody. During this lecture, in which he had intended to show his students that theory predicted results not in accordance with experimental results, Dr. Bose made an embarrassing statistical error which gave a prediction that agreed with observations, a contradiction. We shall briefly highlight the main conclusion drawn from the lecture by using an analogy of flipping coins.
What are the possibilities of flipping two coins? Two heads/Two tails/One of each. But aren’t the coins distinct? Since the coins are distinct, there are two outcomes which produce a head and a tail. The probability of two heads is one-fourth, not one-third. The arguments given by Dr. Bose on the topic were similar to arguing that flipping two fair coins will produce two heads one-third of the time. The error was a simple mistake that would appear obviously wrong to anyone with a basic understanding of statistics. However, it produced correct results, and Dr. Bose realized it might not be a mistake at all.
The reason Dr. Bose produced accurate results was that since photons are indistinguishable from each other; one cannot treat any two photons having equal energy as being two distinct identifiable photons. By analogy, if in an alternate universe coins were to behave like photons and other bosons, the probability of producing two heads would indeed be one-third , and so is the probability of getting a head and a tail which equals one-half for the conventional (classical, distinguishable) coins. Dr. Bose’s “error” led to what is now called Bose–Einstein statistics.
Initially his paper, titled, “Planck’s Law and the Hypothesis of Light Quanta“, was rejected by the Philosophical Magazine. It was their contention that he had presented to them a simple mistake, and Bose’s findings were ignored. He wrote to Albert Einstein, who immediately agreed with him and loved the idea. Prof. Bose and Prof. Saha had earlier translated Einstein’s paper on General Relativity from German to English and on Dr. Bose’s request, Einstein himself translated Dr. Bose’s seminal paper and ensure that it was published in Zeitschrift für Physik.
Einstein adopted the idea and extended it to atoms. This led to the prediction of the existence of phenomena which became known as Bose–Einstein condensate, a dense collection of bosons (which are particles with integer spin, named after Bose), which was demonstrated to exist by experiment in 1995.
This was the basis for the Bose Einstein statistics. Now, the Bose–Einstein statistics apply only to those particles not limited to single occupancy of the same state—that is, particles that do not obey the Pauli’s Exclusion Principle restrictions. Such particles have integer values of spin and are named bosons, after the statistics that correctly describe their behaviour.
Now how does the two add up? You may recall that the vector boson W has spin 1 and the Higgs boson had spin 0, i.e.,integral spin and hence is called a boson. While Higgs et all put forward their mechanism, Satyendra Nath Bose was continuing into retirement and was occupying a chair in the University of Dhaka. (He finally died in 1974). Thus the works of Bose and Higgs and his colleagues were all on different topics at different point in time, beautifully connected by the rules of mathematics.
So, we have a whole class of particles named after an Indian scientist. Every school children know about a boson; no, not the Higgs but the Photon. One does not hear people grumbling that the Photon is not called something like the Photo Boson or the fact that Tata Photon dongles do not acknowledge S. N. Bose’s “great contribution”. But, I digress.
Well, this is perhaps just a reflection of our post-colonial mentality. Indians may feel that Dr Bose do not get sufficient attention in the international arena but it is not so.The Nobel Prize in Physics 2001 was awarded jointly to Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman “for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates”. In the Nobel Lectures/Speeches, Bose was fully acknowledged.
It is also interesting to note that it was one of the Gods of the quantum pantheon, Paul Dirac who named the particles Boson (and not something like “Einsteinion” or so). Though it is an entirely different issue as to why Bose was not given a Nobel during his lifetime but attaching a great name to one of the biggest discovery in particle physics just out of sentimental reasons should not be encouraged. The media should also be reprimanded for sensationalizing news items.
SINP (Saha Institute of Nuclear Physics) at night!
We, as Indians, should take more pride in the fact that Bose had made contribution in one of the most fundamental areas of Physics, having a whole class of particles named after him. Scientists themselves do not seek credit and we are pretty sure they would not like their names to attach to the wrong place! But our cause for celebration does not end here. We, as Indian, did have a role in the ‘discovery of the Higgs Boson.’ The physicists working at various research laboratories across the country had worked in the design of the detectors and also in analysing the data.
Scientists at Kolkata’s Saha Institute of Nuclear Physics (SINP) and Variable Energy Cyclotron Centre (VECC) played a big role in the successful CERN experiment than we have been given to understand. They had a contribution in setting up two major detectors at the LHC tunnel – the Compact Muon Solenoid (CMS) and the ALICE.
A chip that played a vital role in providing clues about the immediate aftermath of the simulated Big Bang therby helping the experimentalists detect the boson was designed at Saha Institute of Nuclear Physics.
In the LHC, within microseconds of the high-energy proton beams striking each other, the MANAS chips or the Multiplex Analog Signal Processor recorded the exact time, location and duration of each collision. It measured the charge generated at each collision point and converted them into voltage to measure the charge. MANAS records the time, positional coordinates of the collisions and the quantum of energy produced. This information aided the experiment and was stored in the chip. Scientists later accessed the data and analysed them to arrive at conclusions. The MANAS chips were conceived and created by Swapan Sen and Sandeep Sarkar of SINP. Each of the 80,000 chips used were mounted on muon detectors – that have been designed at SINP as well. The two-member team has been working on the chip for 11 years, the first prototype of which was developed in 1997.
Also part of this grand experiment was Hyderabad-based public sector undertaking, Electronics Corporation of India Limited (ECIL). For the Large Hadrons Collider (LHC), CERN, Geneva, ECIL supplied 70 nos. of Breaker Control Modules, 5500 nos. of Quench Heater Power supplies and 1450 nos. of Quench discharge Local Protection Units. These systems play an important role in LHC operation like Energy Extraction in Quench protection (with a breaking capacity of 13 kA) and quenches the superconducting magnets in case of magnet malfunction. ECIL also contributed in terms of Installation & Commissioning these systems through supply of Human resources. (Source, The Times of India)
The Times of India article goes on to state that: “While India did not contribute money, it provided expertise and also manpower that was said to have been valued at 34 million Swiss Francs, according to the Raja Ramanna Centre for Advanced Technology (RRCAT), Indore which was designated as the main laboratory for the purpose of coordinating with CERN. The Indian contribution was supply of equipment, components and devices which were designed and developed by Indian laboratories and agencies, according to RRCAT.
The major contributions to the LHC include 50,000 litres Liquid Nitrogen tanks,superconducting corrector magnets including Sextpole (MCS) and Decapole and Octupole (MCDO), Precision Magnet Positioning System (PMPS) Jacks, Quench Heater Protection Systems (QHPS), Integration of QHPS units into racks, Control electronics for circuit breakers of energy extraction system, Local Protection Units (LPU), SC Dipole magnet tests/measurements, expert support, LHC Hardware commissioning of cryogenics, power converters, protection systems, controls,Data management software upgrade, data analysis software/documentation projects, development of JMT-II software, Software development – slow control of industrial systems of LHC, design and calculations for vacuum system for beam dump line and analysis of cryo-liner jumper and magnet connections.”
But it does not end here. We quote a portion of an article that appeared in journal of the Indian Academy of Sciences, Resonance, by Prof Gagan B Mohanty, TIFR: The most eye-catching contribution here has been the precision magnet positioning stands. All together 7080 of them, they precisely hold the LHC magnets leading to the phrase “The LHC sits on the Indian shoulders”. On the experimental front, eight Indian groups, led by TIFR, Mumbai, have taken – and continue to do so – an important role within the Collaboration. Starting from the detector building, reconstruction softwares to physics data analysis, the India-CMS consortium has made its presence felt in a significant way within a 3000+ strong international collaboration.
The TIFR group along with Punjab University,Chandigarh has made a substantial contribution in the design and construction of the hadron calorimeter (a detector component that helps in identifying the Higgs decay channels characterized by hadronic jets or missing neutrinos). A joint effort of BARC and Delhi University together with the Bharat Electronics Limited, Bangalore has led to the development of silicon milli-strip detectors (preshower) that are placed in front of the electromagnetic calorimeter. The primary goal for these detectors is to help in discriminating single photons (e.g , the ones coming from the Higgs decay) from two overlapping photons of a pi 0 decay. TIFR is also hosting a large data storage and computing centre – one of the 50 such centres operating worldwide. Looking to the future,the Indian groups are pulling their resources together to actively take part in the planned upgrades of the CMS detector.
In conclusion, the truth of the whole incident is much more than what meets the eye. As Indians, we should take pride in knowing that it was Dr. Satyendranath Bose who gave a theory that control half of the members of the sub –atomic parlour and at the same time we should rejoice that Indian scientists continue to be in the forefront of cutting-edge science. We do have a reason to celebrate but let us just ensure that we do so for the right reasons.
Bibliography and Suggested Reading
- Discovery of a Boson at CERN and Indian Connections, Gagan B. Mohanty,TIFR: http://bit.ly/GNAp8A
- India has reason to celebrate with Higgs and Englert winning Nobel prize for physics; The Times of India: http://bit.ly/15kSEuw
- Kolkata role in CERN test not highlighted enough: Scientists, The Times of India: http://bit.ly/19Al5Ch
- A working (mathematical) understanding of the Higgs Mechanism can be found in this link. It has been explained using semi classical arguments mimicking the basic field theory concepts, assuming the validity of a symmetry principle in the expression of the energy of particles in a classical field: http://bit.ly/Mh4U1t
- On The Higgs Mechanism (for laymen): http://bit.ly/WZWaY
- On the Electroweak Unification and The Higgs (for laymen): http://bit.ly/1an55FQ
- More about vector bosons: http://bit.ly/5Gs6S1
- Even more about the W Boson: http://bit.ly/1g0g67o
- Technical Article on Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism (history): http://bit.ly/ximVIb
- Technical article on Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism: http://bit.ly/fOkhw2
- Rants of people and Phys.org, it couldn’t have been better than this: http://bit.ly/Mea26H
- An article on Dr Satyendranath Bose and his statistics from Dr Lubos Molts’ blog: http://bit.ly/GNBrl4
- Related Wikipedia Articles on:
- Vector Boson: http://bit.ly/GH06qO
- Bose–Einstein statistics: http://bit.ly/qhKKmW
- W and Z bosons: http://bit.ly/7dTern
- Spin Statistics Theorems: http://bit.ly/cJRGlZ