Physics Current Affairs - 2019
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Globally renowned physicist, academic and higher education reformer Professor Yash Pal passed away in Noida, Uttar Pradesh. He was 90.
He was known for his contributions to the study of cosmic rays, as well as for being an institution-builder. He was also one of the leading science communicators in India.
About Yash Pal
Yash Pal was born in 1926 in Jhang in then British India (now in Pakistan). He had graduated with a master’s degree in physics from Panjab University in 1949 and earned PhD degree in Physics from the Massachusetts Institute of Technology in 1958.
He had started his academic career at Mumbai’s Tata Institute of Fundamental Research (TIFR). He had served as the first Director of the newly set up Space Applications Centre, Ahmedabad, in 1973.
He was a member of the ‘cosmic rays group’. He was appointed by the government to several school and higher education reform committees. Government had also roped him as chair of National Council of Educational Research and Training after it had started work on the National Curriculum Framework.
He also had served as chairman of the University Grants Commission (UGC) from 1986 to 1991. In 2009, the Union Ministry of Human Resources Development had set up a committee on higher education (known as Yash Pal Committee) chaired by Yash Pal to look into reforming higher education in the country.
He was awarded the Padma Bhusan (1976), Padma Vibhushan (2013). He also has received the Kalinga Prize (2009,), awarded by UNESCO for the popularisation of science.
Researchers’ team from Tata Institute of Fundamental Research (TIFR) have discovered that bismuth semi-metal in bulk form becomes a superconductor.
The team was lead by Dr. S. Ramakrishnan of the Department of Condensed Matter Physics and Material Sciences at TIFR, Mumbai.
What researchers have discovered?
They have discovered that when temperature of bismuth semi-metal in bulk form is lowered to 530 microKelvin (about -273 degree C), it becomes a superconductor. It acts as superconductor at temperature three orders of magnitude higher than the theoretical prediction.
- This landmark discovery challenges the conventional understanding of superconductivity based on Bardeen-Cooper-Schrieffer (BCS) theory.
- It cannot explain the superconductivity seen in bismuth as it only explains superconductivity in most low Tc (critical temperature) superconductors.
- The discovery demands a new theory and a new mechanism to understand superconductivity in bismuth.
- It provides an alternative path for discovering new superconducting materials which are very different from the conventional superconductors.
What are Superconductors?
Superconductors are materials that conduct electricity with no resistance whatsoever. In order to achieve superconducting state, the element should have mobile electrons, and these electrons should come together to form pairs, known as Cooper pairs.
Unusual phenomenon in bismuth
Unlike other elements in the periodic table, bismuth has unusual phenomenon. Bismuth has only one mobile electron per 100,000 atoms. Whereas, the metallic superconductors have one mobile electron per atom. Since carrier density of bismuth is so small, it was believed that bismuth will superconduct. Thus, superconductivity in bismuth is puzzling.