pp 1309-1311 October 2020 Editorial
pp 1314-1314 October 2020 Science Smiles
pp 1315-1317 October 2020 Article-in-a-Box
pp 1319-1337 October 2020 General Article
Freeman J. Dyson, a brilliant theoretical physicist and a gifted mathematician, passed away on 28 February 2020 at the age of 96. A vignette of his outstanding contributions to physical sciences, ranging from the subject of quantum electrodynamics to gravitational waves, is provided in this article. Dyson’s futuristic ideas concerning the free will of ‘intelligent life’ in-ﬂuencing the remote future of the cosmos with ‘Eternal Intelligence’, Dyson tree, Dyson sphere and so on, have also been discussed brieﬂy.
pp 1339-1351 October 2020 General Article
The one person who comes closest to the legacy of Hermann Weyl was Freeman Dyson, who contributed enormously to both Physics and Mathematics. His books and talks are testaments to his proliﬁcity in writing widely on the world at large and on science and mathematics in particular. To name a few of his books, he has (talked and) written on ‘Bombs and Poetry’, ‘Imagined Worlds’, ‘Origins of Life’ and ‘Birds and Frogs’. Remarkably, Dyson contributed handsomely to what is termed ‘pure mathematics’. One would expect a physicist-mathematician to interest himself mainly in problems of an ‘applied’ nature. Here, we take a necessarily brief peek into some of his ‘purely mathematical’ work. The suggested read-ing at the end can be referred to for more details.
pp 1353-1367 October 2020 General Article
One typically disturbs a system from equilibrium and studies its behavior to understand its stability. This procedure gives insight into the dynamics at play. It is one of the few techniques used in all areas of physics, be it Newtonian mechanics, quantum mechanics, or general relativity. We have continued this eﬀort by disturbing black holes. We will see that black hole chimes like a bell when it is disturbed. We will study this chiming mathematically in Schwarzschild black holes.
pp 1369-1384 October 2020 General Article
The article delves into the realm of application of complex numbers and matrix transformations in pentagonal tiling. A basic understanding of the concepts in these two branches helps to plot the tiles in any computer algebra system (CAS). The application of the concepts has been demonstrated for the special case of Type 13 pentagonal tiling.
pp 1385-1397 October 2020 General Article
The objective of this article is to study the speed control of a DC motor using PID controller and understand the Ziegler–Nichols (ZN) tuning method for a PID controller. PID controllers are widely used in many industries such as paper mill, cotton textile industries. PID controller also ﬁnds its applications in drones. The usefulness of PID lies in its general applicability.
pp 1399-1405 October 2020 General Article
Suppose a science teacher expects her students to develop ‘scientiﬁc temper’. How should she orient her teaching? What should be her conception and approach in teaching ‘scientiﬁc temper’?
pp 1407-1417 October 2020 General Article
There have been many proofs of the inﬁnitude of primes since Euclid (circa 300 BC) ﬁrst gave his proof. In this article, I present my contribution to this collection of proofs.
pp 1419-1455 October 2020 Series Article
That the cuckoo lays its eggs in the nests of other species and does not build its own nest or raise its own oﬀspring, is one of the oldest known facts about Natural History and has been abundantly and eloquently immortalised in myths and stories, art and literature, music and poetry, philosophy and morals. Attempts to understand this curious phenomenon in any rational way began just about 100 years ago. With a landmark study consisting of a few simple and elegant experiments that needed no laboratory or funding, Nick Davies and Michael Brooke at Cambridge University in the UK ushered in its modern scientiﬁc study as recently as 1988. In this article, I will describe their experiments and their results and conclusions, accompanied by a running commentary relating their work to the theme of this series and end with some more general reﬂections on the pursuit of the science of animal behavior.
pp 1457-1462 October 2020 Reflections
pp 1463-1466 October 2020 Book Review
pp 1467-1472 October 2020 Classics
pp 1473-1473 October 2020 Information and Announcements
pp 1474-1474 October 2020 Birds in the Backyard
Volume 25 | Issue 11