Calcutta this week turned into a hub of physics minds probing the universe on the tiniest as well as the largest of scales, their experimental feats and their equations touching even philosophical issues.
Physics Nobel laureate Anthony Leggett has asked the scientific community to put human common sense to the most stringent of tests — determine through appropriate experiments whether a cat can be simultaneously alive and dead.
British mathematician, theoretical physicist and best-selling author Sir Roger Penrose believes he’s spotted the echoes of a universe that existed before the Big Bang, their signatures picked up by a satellite.
Also in the city is Alain Aspect, a French physicist who has performed one of 20th century’s greatest debate-resolving experiments, and who likes to squeeze time away from his lab to explore wine-making in the French countryside.
They are here at an international conference on quantum entanglement to discuss a 75-year old puzzle at the core of quantum mechanics — a bedrock field of physics that emerged in the early 20th century and is best described through complex mathematics.
But that doesn’t prevent scientists invoking analogy to discuss complexity.
IBM information scientist and conference delegate Charles Bennett can pepper complex mathematical talks with a love story — well, a quantum love story. At the conference organised by the SN Bose National Centre for Basic Sciences on Friday morning, Bennett cited patterns created by raindrops falling on the ground to highlight the impermanence of information, linking it to his research at IBM Research Centre near New York.
Bennett, 67, the son of two music teachers, had in the 1980s in collaboration with Canadian scientist Gilles Brassard — also at the conference — developed the first protocol, or a set of rules, for quantum cryptography, a method of hacker-proof information transfer.
Although the emergence of quantum information science has given rise to predictions of quantum computers, Bennett cautioned that the engineering challenges are yet to be fully understood. While there have been some proposals, “people really don’t know what a quantum computer will look like”, Bennett told Metro.
“It’s fascinating to have so many of the top minds from this field under the same roof,” said Urbasi Sinha, a scientist at the University of Waterloo, Canada, who had last year helped perform a high-precision test for a fundamental rule of quantum physics.
“They are the luminaries of this field. Their experiments have created history and are part of textbooks and cryptography protocols,” she said. “This was an opportunity for young researchers here to get face-to-face feedback.”
Aspect, a senior scientist at the Institute of Optics, Palaiseau, France, had in 1982 designed and performed experiments that showed that pairs of particles separated appear to share information instantaneously — the idea of entanglement.
His sophisticated experiments for the first time demonstrated entanglement between individual particles, once and for all settling a philosophical debate that had emerged decades ago between 20th century physicists Albert Einstein and Neils Bohr.
Aspect has moved on to study entanglement in detail but, whenever there’s time to spare, he visits small producers of French wine, watching them at work. “Small producers of wine are also in a sense doing experiments, just like physicists,” Aspect told Metro.
But what Aspect demonstrated with single particles, the British-American 2003 physics Nobel laureate Anthony Leggett has been urging scientists to do with many particles. He wants physicists to design experiments to test quantum mechanics at the macroscopic level.
Some scientists believe such experiments — although performed with only clusters of atoms or feeble currents — will be a test of one of the most audacious ideas of quantum mechanics: that a cat in an appropriately designed experiment may be simultaneously dead and alive.
The few experiments done so far suggest that quantum mechanics is indeed valid in the macroscopic domain — scientists have observed currents, for instance, that are at the same appear clockwise and anticlockwise.
“The question is will quantum mechanics break down at some point as we go to larger and larger macroscopic systems?” Leggett asked.
Penrose, a distinguished theoretical physicist at Oxford University, another guest at the conference, has used mathematics to explore the universe on the largest of scales.
In recent years, he has used geometry to predict that the Big Bang — the cataclysmic event 13.7 billion years ago viewed as the origin of the universe — was preceded by another universe, and that there are cycles of time.
“It’s vital to communicate complicated science to the public,” said Penrose, who has written several books describing advances in attempts to understand the universe, including the 1989 best-seller The Emperor’s New Mind, and Cycles of Time, that explores the era before the Big Bang.
Article source: http://www.telegraphindia.com/1110108/jsp/calcutta/story_13408505.jsp
Category: Security News