Physics Discussion Thread

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Amber G.
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Re: Physics Discussion Thread

Postby Amber G. » 09 Apr 2019 05:12

Amber G. wrote:Subir Sachdev (Harvard) along with Dam Thanh Son (UChicago) , and Xiao-Gang Wen (MIT) share the 2018 Dirac Medal for their work on "novel phases in strongly interacting many-body systems."

Congrats! Subir Sachdev was born in India and was at IIT Delhi as a student in late 70's.

Ceremony was just a few days ago. Congratulations!
Image

The video of the ceremony is on youtube and the lectures by Prof Sachdev and others is here for those interested.
(The interesting lecture starts around 45:00 time)
at: https://www.youtube.com/watch?v=2Z2h8t8QtFY&fbclid=IwAR2t2fvaJcbChxtI62yMyTJkSxKg-tbSD_1vAwfEL-hOprhY69yPPfVP5k4

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Re: Physics Discussion Thread

Postby Amber G. » 09 Apr 2019 11:48

Meanwhile - Potential BIG News regarding Gravitational Waves.

Just a a week into the 3rd LIGO Observing Run and first candidate has been posted to GraceDB - the GravitationalWave candidate event database: say hello to S190408an! More info, including a map of its likely sky location, at https://gracedb.ligo.org/superevent

With new and more-sensitive apparatus many think that we may start discovering an even every week.
Hoping LIGO India to come on line.

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Re: Physics Discussion Thread

Postby ArjunPandit » 10 Apr 2019 04:00

Is the image of Blackhole out yet?

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Re: Physics Discussion Thread

Postby ArjunPandit » 10 Apr 2019 04:09

NASA Demos CubeSat Laser Communications Capability
https://www.jpl.nasa.gov/news/news.php?feature=7371

1. Remember I had asked a brief question about interplanetary communications. I think this will have applications there
2. why is it a packet and not a beam. WOnt a packet necesitate an alignment of time, which may be difficult at interplanetary scales due to differences in gravity of sun

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Re: Physics Discussion Thread

Postby Amber G. » 10 Apr 2019 07:39

ArjunPandit wrote:Is the image of Blackhole out yet?

You can watch Wednesday's press conference in English via the European Commission YouTube channel or the National Science Foundation live stream at 9 a.m. ET.

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Re: Physics Discussion Thread

Postby ArjunPandit » 10 Apr 2019 14:28

ArjunPandit wrote:NASA Demos CubeSat Laser Communications Capability
https://www.jpl.nasa.gov/news/news.php?feature=7371

1. Remember I had asked a brief question about interplanetary communications. I think this will have applications there
2. why is it a packet and not a beam. WOnt a packet necesitate an alignment of time, which may be difficult at interplanetary scales due to differences in gravity of sun


further to this post, how is time synchronized at interplanetary level? because of the gravitational field differences. Are they really material esp given the massive fields of sun?

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Re: Physics Discussion Thread

Postby ArjunPandit » 10 Apr 2019 19:04

Image

first Image of blackhole

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Re: Physics Discussion Thread

Postby ArjunPandit » 10 Apr 2019 19:05


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Re: Physics Discussion Thread

Postby sudhan » 10 Apr 2019 19:26

ArjunPandit wrote:
first Image of blackhole


Noice!

Is that an accretion disk? Or just light from behind warping around the massive black hole?

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Re: Physics Discussion Thread

Postby prasannasimha » 10 Apr 2019 20:18


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Re: Physics Discussion Thread

Postby Amber G. » 11 Apr 2019 01:45

^^^ The image shows a bright ring formed as light bends in the intense gravity around a black hole. This the biggest known black hole ( 6.5 billion times more massive than the Sun)

( EHT looks at gas surrounding it- it is image of a shadow. Specifically, they are looking at the event horizon - the limit beyond which light can not escape . The gas in the surrounding area heats up to billions of degrees, creating a silhouette etc . The precise shape of the ring can be predicted by Einstein’s theory of relativity - including lopsidedness of the brightness of the ring. And, of course, Einstein is proven right again.

Incredibly (to me) the magnification, or angular resolution, is equivalent to reading a text on a phone in New York from a sidewalk café in Paris. WoW!

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Re: Physics Discussion Thread

Postby ArjunPandit » 11 Apr 2019 02:48

Why it is not symmetric?

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Re: Physics Discussion Thread

Postby Amber G. » 11 Apr 2019 03:27

ArjunPandit wrote:Why it is not symmetric?

The shape (within the limit of its resolution) fits perfectly with Einstein's theory... Short answer about why one side of the image is brighter than the other:

The "shadow" in the center of the picture against is a backdrop of glowing light - the light that is being pulled in by (so to speak) the black hole’s incredible gravity. We can see/measure the black hole’s orientation relative to Earth. The brighter side is the one rotating toward Earth, meaning the particles are being thrown toward our planet faster on that edge, making them appear to glow brighter.

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Re: Physics Discussion Thread

Postby vimal » 11 Apr 2019 11:25

That image of blackhole is really kinda anti-climactic after watching so many sci-fi movies.

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Re: Physics Discussion Thread

Postby ArjunPandit » 11 Apr 2019 14:22

Thanks Amber G,
now why did we focus on M87 and not the one in our own galaxy? I see two factors at play size of black hole and distance from earth.
I would expect distance to play a bigger factor as intensity varies by inverse square of distance and luminosity would be linear.
M87: ~55Mn from earth and size is 60 light years
Milky way: 26K Light years from solar system, size: 17 light hours
Could there be any other factor at play?
What i could think was that galactic center would be difficult to observe due to rapidly rotating stars around it in high numbers and intermediate star dust possibly causing some transient effects.
Let me know if i am missing anything

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Re: Physics Discussion Thread

Postby Amber G. » 11 Apr 2019 21:44

^^SMBH of our own galaxy will be the next candidate...
It was a VERY long process .. such science takes a long time , patience and determination.

The data (of the picture) was gathered about 2 years ago (2017), the computer program which analyzed the data and produced this picture was, I think was first written around 2007.

There were 8 stations distributed over the globe -- none in India :( About 150 scientists authored the paper. ..
Image
Image
This is quite a good read:
https://iopscience.iop.org/article/10.3847/2041-8213/ab0ec7/

Abstract
When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux ratio gsim10:1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 ± 0.7) × 10^9 M⊙. Our radio-wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.

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Re: Physics Discussion Thread

Postby ArjunPandit » 12 Apr 2019 00:16

Now with this small thing, I am a bit excited, because using multiple micro-satellites like astrosat India can accomplish quite a lot of things. We already have MoM.

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Re: Physics Discussion Thread

Postby Amber G. » 12 Apr 2019 02:59

This may be as good time as any to share Professor Stephen Hawking’s fantastic 16-minute animated explanation of black holes:
https://www.bbc.co.uk/programmes/p03h9y3b

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Re: Physics Discussion Thread

Postby ArjunPandit » 12 Apr 2019 15:25

Just to highlight why blackholes are key to better understanding of world
1. We have a reasonable understanding of how large masses work, i.e., the forces of gravity
2. we have identified the manifestations of the workings at very small scale, i.e., quantum mechanics, and associated models like standard model
what we havent been successful is at combining the two, i.e., gravity and quantum world. There's no "proven" theory of quantum gravity.
The only place where this combination of gravity and quantum world occurs is a black hole where a large mass goes into an extremely small size.
We havent been able to quantize gravity.
Why full understanding of gravity is important? because gravity is the retarding force to humans in travel, esp space travel. Imagine if we are able to modify the gravity in vicinity of a traveling spacecraft before leaving earth and around approaching a planet. Or during interplanetary travel to ensure that minkowski transformations dont kill humans.
Just my thoughts

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Re: Physics Discussion Thread

Postby ranneel » 13 Apr 2019 08:03

Two GW candidate events in a week of blackhole binary merger.
https://twitter.com/LIGO/status/1116610512664403969?s=19

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Re: Physics Discussion Thread

Postby Amber G. » 15 Apr 2019 20:58

^^^ LIGO took 13 years to detect the first gravitational waves.
As I said here, it was being estimated that the upgrade of LIGO will make it so that we may detect 1 every week or so..(After LIGO india comes on line it may be a daily event)..
Anyway ..

The upgraded LIGO has just detected two likely gravitational signals from colliding black holes in the past *two weeks*
(It may take some time before the confirmation that these are real and formal announcement is made)

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Re: Physics Discussion Thread

Postby ArjunPandit » 15 Apr 2019 21:37

Amber G. wrote:^^^ LIGO took 13 years to detect the first gravitational waves.
As I said here, it was being estimated that the upgrade of LIGO will make it so that we may detect 1 every week or so..(After LIGO india comes on line it may be a daily event)..
Anyway ..

The upgraded LIGO has just detected two likely gravitational signals from colliding black holes in the past *two weeks*
(It may take some time before the confirmation that these are real and formal announcement is made)

Amber g, didnt see any other thread for this post. But do you have any channel posting interesting tidbits on social media. Like shiv has one on his areas of interest

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Re: Physics Discussion Thread

Postby ranneel » 26 Apr 2019 15:31

Another GW candidate of a binary neutron star merger on 25th April.
Unfortunately, this happens to be "single instrument detection" with only instrument at Livingston detecting it.Instruments at Europe could barely detect this and at HanFord was offline. This unfortunately increases the search zone for electromagnetic counterparts.
Anyone interested in the chatter for the EM search can look at https://gcn.gsfc.nasa.gov/gcn3_archive.html#tc1

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Re: Physics Discussion Thread

Postby ArjunPandit » 03 May 2019 16:28

this one comes straight from marvel comics
https://timesofindia.indiatimes.com/ind ... 157260.cms

The Laser Interferometer Gravitational-Wave Observatory (LIGO) and the European-based Virgo detector have signals they think were from an event that saw a black hole and a neutron star merger—basically the neutron star was consumed by the black hole.

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Re: Physics Discussion Thread

Postby Amber G. » 25 May 2019 04:24

Murray Gell-Mann, a giant from my generation passes away.

Caltech Mourns the Passing of Murray Gell-Mann (1929–2019)
Murray Gell-Mann, Caltech's Robert Andrews Millikan Professor of Theoretical Physics, Emeritus, and a winner of the 1969 Nobel Prize in Physics, passed away on May 24, 2019. He was 89 years old.

Gell-Mann helped bring order to the field of particle physics in the 1950s and 1960s—a time when a bewildering array of new particles was being found in "atom-smashing" experiments. He devised a new method for sorting the particles into simple groups of eight, based on their electric charge, spin, and other characteristics (Israeli scientist Yuval Ne'eman also came up with a similar classification scheme). Gell-Mann termed his method the "eightfold way" after the Buddhist Eightfold Path to enlightenment, and for this research and related work he was awarded the Nobel Prize in Physics.

He is perhaps best known for developing the theory of "quarks," indivisible components of matter that make up protons, neutrons, and various other subatomic particles. He famously named quarks after the exclamation, "Three quarks for Muster Mark!" in James Joyce's novel Finnegans Wake. Quarks are never seen individually, nor can they be dislodged from the larger particles they inhabit. They also possess charges of -1/3 and 2/3, an attribute originally thought to be a physical impossibility. Later experiments confirmed the existence of quarks, and these objects now form the basis for our physical understanding of the universe.

"Murray Gell-Mann was a seminal figure in the history of physics," says Caltech president Thomas Rosenbaum, the Sonja and William Davidow Presidential Chair and professor of physics. "A polymath, a discerner of Nature's fundamental patterns, and, as such, an expositor for the connections of physics to other disciplines, Murray helped define the approaches of generations of scientists."

"Murray was one of the great theoretical physicists of his time, and a fixture in the theory group at Caltech. He left his mark on generations of students and postdocs," says Fiona Harrison, the Benjamin M. Rosen Professor of Physics and the Kent and Joyce Kresa Leadership Chair in Caltech's Division of Physics, Mathematics and Astronomy.

Gell-Mann was born in New York City on September 15, 1929. His father, Arthur, was born in Austria and later moved to Manhattan to find work, securing a variety of jobs; he counseled children at an orphanage, worked on Wall Street, did German correspondence for a toy-importing firm, and opened a language school. Arthur married Gell-Mann's mother Pauline, who was also born in Austria, in 1919. In an oral history for the Caltech Archives, Gell-Mann noted that his mother "always had dreams for me, of doing great things," and that her dreams were realized when he tested into a private grammar school with a full scholarship. He ended up skipping several grades.

Gell-Mann described his broad interests in his oral history: "My principal interests were all in subjects involving individuality, diversity, evolution. History, archeology, linguistics, natural history of various kinds—birds, butterflies, trees, herbaceous flowering plants, and so on—those are the things that I loved. Plus mathematics. Plus all sorts of other things—art, for example, and music," he said.

He received his bachelor of science degree in physics from Yale University in 1948 and a doctorate in physics from MIT in 1951 His father persuaded him to choose physics as his major at Yale. Physics, according to Gell-Mann, was "the only course in which I did badly in high school, and hated it." But his father told him he would love quantum mechanics and relativity. "So I took physics, and after a while I got to like it. And I found that my father was right, in fact—uncharacteristically, he was quite right. Quantum mechanics and relativity were marvelous."

In the 1950s, fundamental physicists had increasingly powerful ways of probing short distances using particle accelerators.In high-energy physics, examining smaller scales offers ever more fundamental elements of the universe. An issue, however, was translating the experimental evidence provided by these particle accelerators into a cohesive understanding.

"Dr. Gell-Mann had this clear vision and penetrating insight to look through the large amounts of data that were coming from experiments and make sense of it," says Caltech's Hirosi Ooguri, Fred Kavli Professor of Theoretical Physics and Mathematics and director of the Walter Burke Institute for Theoretical Physics. "He opened a new paradigm in particle physics."

From the 1950s through the 1970s, Gell-Mann played a leading role in helping to create the standard model of elementary physics. In 1951, he was a postdoctoral fellow at the Institute for Advanced Study and, from 1952 to 1953, he served as a visiting research professor at the University of Illinois at Urbana–Champaign. After serving as a visiting associate professor at Columbia University and then an associate professor at the University of Chicago from 1954 to 1955, he joined the Caltech faculty as an associate professor of physics. He came to Caltech with his first wife Margaret Dow, whom he had met at Princeton and married in 1955. Dow passed away in 1981. Gell-Mann became professor in 1956, and Millikan Professor in 1967.

"Gell-Mann was one of the great theoretical physicists of the second half of the 20th century," says Mark B. Wise, the John A. McCone Professor of High Energy Physics at Caltech. "He is best known for his contribution to the physics of strongly interacting particles, bringing order out of chaos through his discovery of an approximate flavor symmetry that organized the masses of all these particles into almost degenerate multiplets, and for his discovery of quarks as the fundamental constituents of these particles."

The idea of quarks (which was also independently proposed around the same time by a former Caltech professor George Zweig (PhD '64)) was a part of Gell-Mann’s body of work to classify the elementary particles and their interactions, for which he received the Nobel Prize. Among other concepts he introduced are "strangeness," which governs how some families of particles decay, and "color charge," which relates to the grip exerted by the strong nuclear force to hold protons and neutrons together within atomic nuclei. Working with others, he later developed a quantum field theory of quarks, called quantum chromodynamics, which accounts for nuclear particles and their strong interactions.

From 1974 to 1984, Gell-Mann championed the work of John Schwarz, who is now Caltech's Harold Brown Professor of Theoretical Physics, Emeritus. At the time, Schwarz was working on an upstart idea known as string theory—which was not very popular with the physics establishment.

"It was a time when the standard model of elementary particles—which Gell-Mann established—was developing rapidly. Everyone was working on that, so superstring theory wasn't popular. But Dr. Gell-Mann saw that this research that Schwarz was doing was very important and supported him for 10 years," says Ooguri. Gell-Mann secured funding to support Schwarz as a research associate at Caltech until his major breakthrough in 1984, when he and Michael Green of Cambridge discovered a way for superstring theory to explain the weak interaction of electrons.

"It's rare to support someone whose research is not very popular. He had to believe in what Schwarz was doing, and he had to trust his judgement in supporting it," Ooguri says. "It made Caltech a very special place in the world of theoretical physics, that he had that kind of foresight."

"Murray Gell-Mann was a great scientist, and he was very important in my career," says Schwarz. "During the 10-year period from 1974 to 1984, when I and a few collaborators were developing superstring theory as a possible framework for a unified quantum theory of all fundamental particles and forces (including gravity), with very little encouragement from the rest of the theoretical physics community, he recognized that this approach might turn out to be correct. Murray was an advocate for preserving endangered species, and he said that I fell in this category."

In later years, Gell-Mann became interested in the issues of complexity at the heart of biology, ecology, sociology, and computer science. He co-founded the Santa Fe Institute in Santa Fe, New Mexico in 1984 to study such complex systems, and authored The Quark and the Jaguar, published in 1994, to present his ideas on simplicity and complexity to a general readership. He married his second wife, Marcia Southwick, in 1992 and retired from Caltech in 1993.

Ooguri recalls Gell-Mann returning to Caltech's campus in 2013 for a symposium marking the 50th anniversary of his quark model. "He was a warm person, and curious about people. He was also extremely generous with his ideas. He was not like the lone genius; he was very open, and generous to other people."

"It would be hard to overestimate the degree to which Murray dominated theoretical particle physics during his heyday in the 1950s and 1960s. He contributed so many deep ideas that drove the field forward, many of which are just as relevant today," says John Preskill, the Richard P. Feynman Professor of Theoretical Physics at Caltech. "Murray was extremely kind and supportive when I was a young Caltech faculty member. He'll be sorely missed. This is a very sad day for Caltech and for the world of physics."

Gell-Mann also served as University Professor at the University of New Mexico and the Presidential Professor of Physics and Medicine and Professor of Medicine and Physics and Astronomy at the University of Southern California.

Gell-Mann was a member of the National Academy of Sciences and the Council on Foreign Relations; a foreign member of the Royal Society of London, the Pakistan Academy of Sciences, and the Indian Academy of Sciences; a fellow of the American Physical Society and the American Academy of Arts and Sciences; and an honorary member of the French Physical Society. He held honorary doctorates from Columbia University, the University of Cambridge, the University of Oxford, the University of Chicago, the University of Florida, the University of Illinois, the University of Utah, Wesleyan University, Yale University, and the University of Turin.

Gell-Mann was a director of the John D. and Catherine T. MacArthur Foundation from 1979 to 2002 and was a board member of the Wildlife Conservation Society from 1994 to 2006. He served as chairman of the board of trustees of the Aspen Center for Physics from 1973 to 1979; was a Citizen Regent of the Smithsonian Institution from 1974 to 1988; and served on the U.S. President's Science Advisory Committee (1969–72) and on the President's Committee of Advisors on Science and Technology (1994–2001).

Among numerous awards and honors, Gell-Mann was the recipient of the Albert Einstein Medal of the Albert Einstein Society (2005), the Ernest Orlando Lawrence Memorial Award of the Atomic Energy Commission (1996), the Franklin Medal of the Franklin Institute (1967), and the John J. Carty Award of the National Academy of Sciences (1968). In 1988, Gell-Mann was listed on the United Nations Environment Programme's Roll of Honour for Environmental Achievement. He also shared the 1989 Ettore Majorana "Science for Peace" prize.

He is survived by his children Nicholas Gell-Mann and Elizabeth Gell-Mann; and stepson Nicholas Southwick Levis.

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Re: Physics Discussion Thread

Postby sivab » 26 May 2019 10:47

https://www.thehindu.com/sci-tech/scien ... 246496.ece

Finally, IISc team confirms breakthrough in superconductivity at room temperature

Putting to rest all doubts and criticism, a team led by Prof. Anshu Pandey from the Indian Institute of Science (IISc), Bengaluru confirms that their material exhibits major properties of superconductivity at ambient temperature and pressure. A material is said to be a superconductor if it conducts electricity with nil resistance to the flow of electrons. Superconductors will help build very high efficient devices leading to huge energy savings. Till now, scientists have been able to make materials superconduct only at temperatures much below zero degree C and hence making practical utility very difficult.

Superconductivity at ambient temperature has been a holy grail in physics for about a century. This is where IISc’s work becomes particularly important. A revised article has been posted on May 21 in arXiv, a pre-print repository.

The material that exhibited superconductivity is in the form of nanosized films and pellets made of silver nanoparticles embedded in a gold matrix. Interestingly, silver and gold independently do not exhibit superconductivity.

The team examined 125 samples, of which 10 showed a drop in resistance signaling the onset of superconductivity. They attribute the unsuccessful results in the remaining 115 samples to oxygen exposure at the time of sample preparation and when the samples were taken for study.

“If this [result] is correct, it would be the greatest work done in India since the discovery of Raman effect,” says Prof. T.V Ramakrishnan, leading condensed matter physicist who is a distinguished Associate with the Department of Physics at IISc. “The material they have made is unbelievable — a tiny sphere of gold, placed 10-20 tinier spheres of silver inside it…This [material] they found shows a sharp drop in resistivity [reflecting superconducting state]. This is potentially amazing,” he adds.

Identical noise
The initial version posted in the repository on July 23, 2018 by a two-member team of Prof. Anshu Pandey and Dev Kumar Thapa attracted criticism, raising doubts about the data and hence the study. The reason: the presence of identical pattern of noise for two presumably independent measurements of the magnetic susceptibility. Noise, by its very virtue, will be random and so finding nearly identical noise in measurements made under different conditions is highly improbable. Dr. Brian Skinner, a physicist at the Massachusetts Institute of Technology, Boston was the first to notice this.

In one of his tweets in August 2018 Dr. Skinner said: “…They [IISc team] are really not backing down from their claims. They emphasize that they are focused on providing validation of their data…” And that is precisely what the IISc team has now done — provide validation of their data. On May 22, 2019, Dr. Skinner tweeted “…I am gratified, to say that least, that it is a scientific story now, and not a story about social scandal.”

Interestingly, the plots of magnetic susceptibility versus temperature in the new data still show the repeated “noise” in some instances. However, the researchers have clarified that the magnitude of the noise is well above instrumental resolution. “This suggests a possible physical origin related to the sample as opposed to instrument artefacts,” they write.

Referring to the “noise”, Prof. Arindam Ghosh from the Department of Physics at IISc and a co-author of the revised article says: “This is the data that we got. Further studies have to be done to understand this.”


The proof
“Two of the most important properties of superconductivity are dimagnetism and zero resistance. These two were seen in the material we studied. They seem to suggest that the material becomes superconducting below a certain temperature (286 K or 13°C). And it can go up to 70°C,” says Prof. Ghosh.

“At 286 K we have seen clear transition from a normal state to a superconducting state. This is more than anyone has reported,” Prof. Ghosh adds.

The revised version has provided the recipe for preparing the material, which was not included in the version post in July last year. The revised version also has plenty of data on the calibration of the setup. Besides retesting superconductivity, the authors tested it on another superconducting metal — lead. “[Unlike in the case of the original material] we did not see repeated noise,” Prof. Ghosh clarifies.


Researchers critically evaluating the revised version have raised some concerns. Prof. Pratap Raychaudhuri from the Superconductivity Lab at Tata Institute of Fundamental Research (TIFR) Mumbai has raised concerns that while the drop in mutual inductance is fairly sharp, it is at a lower temperature compared with resistance. “In superconductivity when the resistance goes to zero the diamagnetic drop should coincide with resistance drop. Here the resistance drops to zero at 175 K but the diamagnetic drop is at 165 K. This kind of difference [between resistance and diamagnetic drop] is unusual,” say Prof. Raychaudhuri.

Responding to Prof. Raychaudhuri’s observation on the sharpness of fall in mutual inductance Ghosh says: “We think there is long penetration depth (the depth to which the magnetic field penetrates inside the material) and so the change in mutual inductance can be very small.”

And about different temperature at which diamagnetic drops and resistance goes to zero, Prof. Ghosh explains: “We don’t have full clarity on this but there have organic superconductors where such discrepancies have been seen before.”

Soon after Dr. Skinner raised a red flag, there was criticism that authors were not sharing the samples with their peers for evaluation. “Our samples are extremely sensitive to environment. Samples degrade very rapidly and so measurements have to be made immediately after sample preparation,” Prof. Ghosh says, explaining why samples could not be shared with others. “We have now found a way of protecting the samples for a long time, which allowed us to do measurements over the last few months. Once we develop a protocol for better protection then we will be engaging and collaborating with other groups in India and abroad.”

Prof. G. Baskaran, a SERB Distinguished Fellow at The Institute of Mathematical Sciences, who works on the theory of superconductivity, was quick to provide a theory soon after the preprint was posted in 2018. In his theory, monovalent character of silver and gold and repulsion among electrons could produce room temperature superconductivity under certain restrictive conditions. Prof. Baskaran is excited that the Thapa-Pandey system precisely provides such conditions. “This looks like a case where granular superconductors play a role. I am excited that the key first step in this challenging field has been brought about by a systematic and detailed effort.”

The manuscript has been sent to a journal for publication and the first level of reviewing by editors has been completed. It is currently undergoing technical review by peer-reviewers. “We hope it will be published soon,” Prof. Ghosh says.


Will be one of the most significant discovery when confirmed.

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Re: Physics Discussion Thread

Postby chaitanya » 27 May 2019 03:42

^ Very exciting! RT superconductivity has so many applications... if proven, GOI should dump money into these labs and protect the IP. This way India can be ahead of the curve and the rest of the world

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Re: Physics Discussion Thread

Postby Amber G. » 28 May 2019 01:49

I have to be careful in commenting regarding the above news story. I am not an expert in this field but I do understand basics and have friends who are experts. I have read the paper (actually the original much debated ArXiv article posted few months, that article was never published or retracted. This new one seems to be the revised article of the same paper - still not published). I have also read a lot of questions posed by other scientists and there is lot of discussion going on about this on many different platforms - including some social media).

Anyway allow me to post some of my perspective. As said before, I may turn out to be wrong but this is what I think at present. These concerns are being shared with the authors and if I will hear from them or some new update I will post them here. This , of course, assumes that this thread does not get derailed by our familiar troll as it was done before.

(I will only use initials for scientists, as people in the field will know who they are. Again let me make it clear, PLEASE TAKE IT FOR WHATEVER its worth. Criticism of any scientist or institution described here should NOT be taken seriously as these are my views only - based sometimes on speculation. I will be happy if parts, which turns out to be wrong, are corrected).

It may seem unfair as I am posting anonymously here in a thread with possibly one sided arguments - Only thing I can say here that I will correct anything posted here which I thing turns out to be wrong. Meanwhile I ask you to remember what I post here is true to best of my knowledge but I may be wrong in repeating something.

***

With that disclaimer, I think DOUBTS and criticism of Prof AP's team (and IISc) is not put to rest. Far from it. At least I have doubt.

sivab wrote:https://www.thehindu.com/sci-tech/science/finally-iisc-team-confirms-superconductivity-at-room-temperature-pressure/article27246496.ece

Finally, IISc team confirms breakthrough in superconductivity at room temperature

Putting to rest all doubts and criticism, a team led by Prof. Anshu Pandey from the Indian Institute of Science (IISc), Bengaluru confirms that their material exhibits major properties of superconductivity at ambient temperature and pressure. A material is said to be a superconductor if it conducts electricity with nil resistance to the flow of electrons. Superconductors will help build very high efficient devices leading to huge energy savings. Till now, scientists have been able to make materials superconduct only at temperatures much below zero degree C and hence making practical utility very difficult.

i
The manuscript has been sent to a journal for publication and the first level of reviewing by editors has been completed. It is currently undergoing technical review by peer-reviewers. “We hope it will be published soon,” Prof. Ghosh says.


Will be one of the most significant discovery when confirmed.


The arxiv paper, for those who are interested, is here:
https://arxiv.org/pdf/1807.08572.pdf

My doubts/questions/comments:

- This paper seems to be just an updated version of the old (much criticized) paper. The old paper, which I thought would be retracted by IISc, did not get retracted (but it wasn't published either). This new version, it seems, at least to me, does NOT answer some of the questions others asked, it represents the same data + some additional data. The "raw" version of old data - requested by other scientists (including Indian Scientists) is still not there (just the graphs). No one, at least AFAIK, has been able to "reproduce" the data.

- It seem STRANGE to me, that for a feature of the data that is so controversial, they didn't just take new data. (Why not present new measurements of the magnetic susceptibility? Looks like they were not able to replicate it.

- They try to address a bunch of potential issues with the old measurement, such as current going around the voltage probe in a way that could mimic the sudden drop in voltage. but to me, and some other people who know more than I do, the arguments are not completely convincing.

- The authors have added a lot of new data, (many new pages and additional authors) . along with a summary of the performance of 125 (?) samples - only 10 of them looked like superconductors. More details, I think is needed on their method and interpretation of data.

Biggest thing is there is still "repetition" of pattern in random noise.. very unlikely. This is still there in newer graphs too. (If you zoom on the graph - as I don't have the raw data - some parts looks like they have been duplicated. This was caught almost right away wrt to their previous paper.

****

To me strangest part was the author's and their supporters conduct. For those who do not know here it is briefly - (from what I Know/heard)

- Just after publication of the first arXiv, BC (US physicist) Noticed a "strange" repeating pattern in the random data noise. (Remember at that time some of the scientists I know here is US dropped everything and started looking at it, as IISc is a very prestigious institute and Room temperature SC is very exciting - In fact there was flood of activity and excitement in physics world).
- The authors took that into notice, and said they will look at the data and try to see why it is.
- PR (An Indian Physicist) looked into it, and became even more interested - as the time went by things became even more strange. Authors became non-communicative.
- Meanwhile some of the physicists who were discussion this received an email form a renowned Indian Physicist (TVR) - telling them, go easy of IISc's scientists (authors) in their criticism. (I Know TVR - he was one of my professor many decades ago). TVR is one of the most well known and senior most scientist in India.
- This "email" looked strange - TVR is not that kind of person so someone called him - It turns out that he never sent that email, The email was sent from a fake account mimicking TVR. Some one went through LOT of trouble for that email. ( They found that the fake email account was strangely, was created July 7. That's 16 days before the paper appeared on the arxiv.). ( I don't know if the story got widely known in general public in India but it was fairly well known among many Indian scientists )

- The story then got extremely weird as more and more people started investigating. Even some fake twitter/facebook/email account were discovered who were contributing to this back and from IISC's authors and others.

****

I think IISc should, If it has not already done so, REALLY check this thing out well and wait before going so gung-ho. I have not heard from TVR but others (Like PR) are actively discussing this. At present everyone is looking at data. RT superconductivity is a BIG deal, so let us wait till we are sure before publicizing it through newspapers.

Hope this is helpful.

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Re: Physics Discussion Thread

Postby Amber G. » 28 May 2019 02:32

Here is an example of why many are questioning the above data - (The pictures below is from BC's write up)
From the older (original) paper:
Image
Look closely at zoomed in part - look at the green and blue data points here - 10/ They have the exact same pattern of random noise. The blue data points are clearly identical to the green ones; they have only been shifted downward by a constant amount.

These are supposed to be two independent measurements, separated in time and in the value of certain parameters. An exactly duplicated pattern of noise is not something you would expect.

(I am still studying the paper - and yet to see if authors explain this - Will let you know when I know more)
These weird pattern seem to be present in the newer paper too. (Pointed by a US reader of the paper)
Image
Still weird noise offsets, sometimes vertically (two green plots), sometimes shifted (yellow and black).

As authors have seen these, if they reply or I learn more .. I will post it here.


Okay -Updated later .. Strange --

The first graph, is still there in the new (revised) paper. Did not notice it because they changed the color ( :D ) but still have have the same data points.. They do acknowledge the weird repetition but give no explanation . ...

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 21:37

Not a physicist but I can't tell the difference or repetation that you claim from that graph. That appears to be baseline. I would assume the upward curve and then plateauing is where the real meat is and that is different. I think it is OK to criticize data but this is borderline claiming fraud. A lot of western scientists do not have a good idea of Indian science and think everyone there is cooking up data. We need to be careful and not add to the noise.

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 21:44

I looked at the green dots and blue dots again. The y-axis is clearly different. As I would assume that it is the baseline hence very little difference. Now if it is the opposite then one can claim that not even negligible difference is seen. Not a copy paste.

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 23:18

I looked at the data again. It seems to me now that the rise and top of the curve is the real thing. There is noise at the baseline. Why is noise at the baseline so important while all you need is the rise and top of the curve is not clear to me.

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 23:18

As regards them getting this in some samples only maybe the process is not very efficient YET and they need to work on it.

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 23:25

No self-respecting scientist will share raw data unless the journal where it is being published asks for it or there is evidence of fraud in which case the journal themselves ask for it or they ask the institute to enquire.

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 23:27

I hope they are not pressurizing the group in order to prevent them from publishing in a good journal. Specially if it is a breakthrough as they claim. In turn the group needs to be extra careful as they are claiming something big.

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Re: Physics Discussion Thread

Postby Amber G. » 28 May 2019 23:34

^^^ Thanks for comments - Please put these comments . I am very interested in further developments.

I hope that IISc and the authors can sort that out and before publishing can make sure.. It is a big thing so IISc's reputation is at stake .. (either way - if this turns out to be wrong).

At present I have virtually everyone (some real experts) I know is doubtful. - Mainly because the concerns about the data was shared with the authors (some who raised the concern are very prominent scientists - both Indian and Foreign) - and authors still have not answered the concerns .. Like many I am also reading the paper, it will take time for final judgement. I will share here, what I and others think. I can understand IISc and Authors concern for giving more details (about materials etc) but they could very easily have shared the data ("noise" part) at least with some other Indian (but outside of their group) reputable scientists to get the feedback.

Meanwhile two incidents really concern me. Both PR and TVR are mentioned in that Hindu Article. Both of these guys I know a little. TVR was my prof once, an excellent no- nonsense fellow. By all accounts one of the most respected Condensed Matter Physicist in India. PR is also in the field, a well known TIFR scientist.

Let me post a post from PR written some time earlier:
https://www.facebook.com/pratap.raychaudhuri/posts/10155731690888601
(The post is for public view and has already been out so sharing it here. I am also quoting the post for convenience)
Pratap Raychaudhuri
August 13, 2018 ·
Today something very strange happened.

1. I receive a mail from my very respected senior colleague Prof. T. V. Ramakrishnan (TVR) asking me not to criticize Thapa and Pandey on social media and be patient. The mail contained trailing mail with Anshu Pandey asking him his reaction on unfortunate developments and Anshu Pandey's supposed response.

2. I wrote a rather strong response to Prof. T V Ramakrishnan requesting him at the end not to form opinions based on second hand sources. Since the e-mail address Prof. Ramakrishnan wrote was not his usual e-mail address, I assumed he is visiting some place abroad and also included his usual yahoomail address while responding.

3. I receive a call from TVR asking if I have time to talk. I was on my way to my son's school, so I tell him that I will call him later.

4. I call him. He tells me he was sad seeing my mail, but then...he saw the trailing mails. HE HAD NEVER WRITTEN ANY SUCH MAIL! He does not have any other e-mail address other than the one he normally uses.

5. We talk on the phone for a while, and then I send him a mail profusely apologizing for the unkind words I wrote. Then I check the mail again.

TVR's impersonated mail was sent from protonmail server. A check on Wikipedia tells me that this is a end-to-end encrypted mail-server (unlike Gmail and Yahoo) based in Switzerland. What baffles me who would have an interest in crafting a careful and highly credible mail thread, send it through an encrypted e-mail server only to dissuade me from writing on Facebook?

If anyone has received any similar mail impersonating TVR please alert. The email address I received from is, TV Ramakrishnan <wileslicher@protonmail.com>

Edit 1: The e-mail address should have rung a bell. But the mail and the thread was highly credible, I saw the name of the sender and did not check the e-mail address it came from very carefully (while initially responding).


There were further questions - "wileslicher@protonmail.com" had few more avatars (later closed those fake accounts)...writing/tweeting/Youtubing to support the IISc story..

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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 23:39

There is a lot of politics in science. So it is not pertinent to get into which Prof said what or who sent e-mail to whom. This appears to be an attempt to create doubts. If I were a physicist I would have gone into the paper. They should stick to the science of the data and answer queries when sent for publication. This is a big claim and needs to be thoroughly done. That is only what counts.

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Re: Physics Discussion Thread

Postby Amber G. » 28 May 2019 23:46

Supratik wrote:No self-respecting scientist will share raw data unless the journal where it is being published asks for it or there is evidence of fraud in which case the journal themselves ask for it or they ask the institute to enquire.

That one can understand but interestingly normally graph files in preprint are in vector graphics (so one can "zoom" in and not loose detail).. In the august paper these graphs were bit-maps - which is, as anyone will tell you, is quite unusual for a pre-print paper.

In anyway I will wait till the paper is published and the data behind the graphs are available.

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Re: Physics Discussion Thread

Postby Amber G. » 28 May 2019 23:51

Here is a story from Scientific American published few months ago ...some may find it interesting,
(This essentially documents some of the points I was making here)

A Superconductor Scandal? Scientists Question a Nobel Prize–Worthy Claim

The discovery would change the world. From power grids that never lose energy to magnetically levitating trains, finding a material that is superconductive at room temperature would bring a range of fantastical technologies to life. And it is not as far-fetched as it sounds. Although superconductors—materials that can transmit electricity with zero resistance—exist only at extremely frigid temperatures today, there is no physical reason why they cannot also work at room temperature. It could simply be that no one has stumbled upon the magical formula yet. But that might be about to change. In a study posted to the arXiv in late July, Dev Kumar Thapa and Anshu Pandey, two scientists from the Indian Institute of Science, suggest a concoction of gold and silver nanoparticles achieves the Nobel Prize–worthy goal. The finding, from a reputable team, was initially met with both excitement and skepticism as physicists cautiously took a closer look. But the story has since prompted disbelief and even a little drama.

Despite physicists’ hope, those in the field know that numerous previous claims of warm superconductors have all fizzled out. So many initially worried that Thapa and Pandey’s find would turn out to be one more erroneous report—dubbed a USO or unidentified superconducting object. But that natural skepticism transformed into suspicion when Brian Skinner, a physicist at MIT, found something unnerving. In one of the paper’s figures, which shows how well the superconductor repels different magnetic fields at various temperatures, he noticed that the data for two different values of the magnetic field have the exact same pattern of noise, albeit slightly offset from each other.* Every time one pattern veers up or down, the other follows—perfectly in sync. But noise is random by definition. It should not repeat itself on separate trials done under different magnetic fields.

That correlation is alarming alone. But it also echoed one of the biggest scandals in modern physics. In the early 2000s, scientists discovered that prominent physicist Jan Hendrik Schön, who also worked on superconductors among other topics, had falsified data from several experiments. It was a move that eventually stripped him of his doctoral degree and led to the retraction of several papers. And, yes, the discovery was sparked when scientists noticed that the noise pattern within one of his published graphs looked eerily similar to the noise pattern within another.

It is a story that scientists know extremely well. “It’s sort of like a bedtime fable,” Skinner says, told to teach students to be scrupulously honest. And it made Skinner hesitant to publish his finding. He knew that the repeated noise pattern would bring Schön to the forefront of everyone’s minds—making his claim sound like an accusation against Thapa and Pandey. Skinner deliberated for more than a week, pulling other scientists aside—from technicians to senior experimentalists—to ask whether this could be an honest mistake. Although that is still possible, everyone agreed that the noise patterns had no obvious explanation. Skinner knew he had an obligation to go public. So, in a short note published to the arXiv, he pointed out the repeated noise pattern and asked for an explanation, without suggesting the data were fraudulent. And Peter Armitage, a physicist from Johns Hopkins University, agrees it was the correct move. “I think that’s a really important observation and he’s done a true service to the field by not only pointing it out—but having the nerve to do so publicly,” he says.

Despite Skinner’s careful attempt to not accuse the team, his finding caused quite the debate. “When I looked at Skinner’s paper and I saw the curve, I thought ‘game over,’” says David Muller, a physicist at Cornell University. “It’s not hard evidence … but I know which way I would take a bet.” The original paper’s authors have not addressed the noise correlation, and say they are waiting for outside validation of their results. Pratap Raychaudhuri, a physicist at the Tata Institute of Fundamental Research in India, set out to find the most plausible explanation for the correlation. After much thought, he argues that the noise is not noise at all but a signal that arises from the natural rotation of particles within a magnetic field. The signal simply looks random and therefore masquerades as noise. What is more: this pattern can repeat itself after independent runs—thus explaining why the two curves match. Although Raychaudhuri admits that he does not fully believe his rationalization, he says it can be easily tested at any professional lab—should the authors send their samples along.

The issue is that Thapa and Pandey have done no such thing. “This kind of silence from the authors is not a healthy practice,” Raychaudhuri says. “It is against the spirit of science.” And while Pandey insists that his results are being validated by independent experts, that brings no comfort to Raychaudhuri, who worries the checks cannot truly be independent. “Getting this validated by your friend, by your next-door colleague and so on, is not independent validation,” he says. He and others in the field would like the team to send their superconducting material to outside labs that can test the results.

In the meantime, the story has taken a wild turn: In August, Raychaudhuri received an e-mail that appeared to come from T.V. Ramakrishnan, a physicist at the Indian Institute of Science, asking him not to criticize the authors on social media. (Raychaudhuri had posted his findings to Facebook.) But Ramakrishnan never sent such an e-mail. It did not take long before the two realized that a fake e-mail address had been set up in Ramakrishnan’s name. “The purpose of the e-mail seems to be to stir up discord between him and me,” Ramakrishnan says. But the odd events do not end there. The same name attached to the encrypted e-mail address is also attached to a Facebook profile that attempted to befriend both Skinner and Raychaudhuri shortly after the e-mail scandal. The profile has zero friends and the timeline reads: "Remember: Julius Caesar went too far!"

Both the e-mail address and the Facebook profile have been deleted. Some suspect that it was the work of a disgruntled student, but Raychaudhuri thinks it is far too early to venture a guess. At the moment, he is surprisingly thankful that so much scientific discourse has happened over social media. Not only did Raychaudhuri post several Facebook posts last week, but Skinner also posted a Twitter thread—events that brought the scientific process into the public sphere. “This is a very good thing, because it connects people,” Raychaudhuri says. “The research community is normally very esoteric and detached from society at large.” He is even optimistic that no matter what happens—whether Thapa and Pandey’s results hold up or their work turns out to be incorrect—that the events will help the public understand this is how the scientific method works to verify (or reject) claims in order to slowly inch forward.

*Editor's Note (8/20/18): This sentence was edited after posting. The original erroneously stated the noise pattern appeared in the data for two different temperatures.


Last edited by Amber G. on 28 May 2019 23:58, edited 1 time in total.

Supratik
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Re: Physics Discussion Thread

Postby Supratik » 28 May 2019 23:55

I have no problem if there are scientific problems with the paper and it gets rejected. But from what you have posted I see an effort to create doubts and suspicion around the work bordering on claims of fraud. That is not a good idea to begin with unless proven otherwise.


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