Physics Discussion Thread

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ArjunPandit
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Re: Physics Discussion Thread

Postby ArjunPandit » 02 Oct 2019 19:24

..yes.. i agree with you on that....but i would want college kids and researches to think on these out of carton box too...esp in desh...to challenge/question...

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Re: Physics Discussion Thread

Postby ArjunPandit » 02 Oct 2019 22:26

https://phys.org/news/2019-10-quantum-v ... nergy.html
Quantum vacuum: Less than zero energy

Energy is a quantity that must always be positive—at least that's what our intuition tells us. If every single particle is removed from a certain volume until there is nothing left that could possibly carry energy, then a limit has been reached. Or has it? Is it still possible to extract energy even from empty space?

Quantum physics has shown time and again that it contradicts our intuition, which is also true in this case. Under certain conditions, negative energies are allowed, at least in a certain range of space and time. An international research team at the TU Vienna, the Université libre de Bruxelles (Belgium) and the IIT Kanpur (India) have now investigated the extent to which negative energy is possible. It turns out that no matter which quantum theories are considered, no matter what symmetries are assumed to hold in the universe, there are always certain limits to "borrowing" energy. Locally, the energy can be less than zero, but like money borrowed from a bank, this energy must be "paid back" in the end.

Repulsive Gravity

"In the theory of General Relativity, we usually assume that the energy is greater than zero, at all times and everywhere in the universe," says Prof. Daniel Grumiller from the Institute for Theoretical Physics at the TU Wien (Vienna). This has a very important consequence for gravity: Energy is linked to mass via the formula E=mc². Negative energy would therefore also mean negative mass. Positive masses attract each other, but with a negative mass, gravity could suddenly become a repulsive force.

Quantum theory, however, allows negative energy. "According to quantum physics, it is possible to borrow energy from a vacuum at a certain location, like money from a bank," says Daniel Grumiller. "For a long time, we did not now about the maximum amount of this kind of energy credit and about possible interest rates that have to be paid. Various assumptions about this "interest" (known in the literature as "Quantum Interest") have been published, but no comprehensive result has been agreed upon.

The so-called "quantum null energy condition" (QNEC), which was proven in 2017, prescribes certain limits for the "borrowing" of energy by linking relativity theory and quantum physics: An energy smaller than zero is thus permitted, but only in a certain range and only for a certain time. How much energy can be borrowed from a vacuum before the energetic credit limit has been exhausted depends on a quantum physical quantity, the so-called entanglement entropy.

"In a certain sense, entanglement entropy is a measure of how strongly the behavior of a system is governed by quantum physics," says Daniel Grumiller. "If quantum entanglement plays a crucial role at some point in space, for example close to the edge of a black hole, then a negative energy flow can occur for a certain time, and negative energies become possible in that region."

Grumiller was now able to generalize these special calculations together with Max Riegler and Pulastya Parekh. Max Riegler completed his dissertation in the research group of Daniel Grumiller at the TU Wien and is now working as a postdoc in Harvard. Pulastya Parekh from the IIT in Kanpur (India) was a guest at the Erwin Schrödinger Institute and at the TU Wien.

"All previous considerations have always referred to quantum theories that follow the symmetries of Special Relativity. But we have now been able to show that this connection between negative energy and quantum entanglement is a much more general phenomenon," says Grumiller. The energy conditions that clearly prohibit the extraction of infinite amounts of energy from a vacuum are valid for very different quantum theories, regardless of symmetries.

The law of energy conservation cannot be outwitted

Of course, this has nothing to do with mystical "over unity machines" that allegedly generate energy out of nothing, as they are repeatedly presented in esoteric circles. "The fact that nature allows an energy smaller than zero for a certain period of time at a certain place does not mean that the law of conservation of energy is violated," stresses Daniel Grumiller. "In order to enable negative energy flows at a certain location, there must be compensating positive energy flows in the immediate vicinity."

Even if the matter is somewhat more complicated than previously thought, energy cannot be obtained from nothing, even though it can become negative. The new research results now place tight bounds on negative energy, thereby connecting it with quintessential properties of quantum mechanics.

what i found interesting in the article was
1. Another way of looking at entropy apart from the disorder/chaos in the system
2. Another Indian IIT scientist involved in it
3.Relation between quantum and relativity theories, not that i am clear as to how these 2 are connected through this work...

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Re: Physics Discussion Thread

Postby ArjunPandit » 02 Oct 2019 22:31

https://phys.org/news/2019-10-peek-schr ... rbing.html
Image
Quantum physics is difficult and explaining it even more so. Associate Professor Holger F. Hofmann from Hiroshima University and Kartik Patekar from the Indian Institute of Technology Bombay have tried to solve one of the biggest puzzles in quantum physics: how to measure the quantum system without changing it?

Their new paper published this month has found that by reading the information observed from a quantum system away from the system itself researchers can determine its state, depending on the method of analysis. Although the analysis is completely removed from the quantum system, it is possible to restore the initial superposition of possible outcomes by a careful reading of the quantum data.

"Normally we would search for something by looking. But in this case looking changes the object, this is the problem with quantum mechanics. We can use complicated maths to describe it, but how can we be sure that the mathematics describes what is really there? When we measure something there is a trade-off and the other possibilities of what it could be are lost. You cannot find out about anything without an interaction, you pay a price in advance." explains Hofmann.

During Patekar's month-long stay at Hiroshima University when he was an undergraduate student, the two physicists tried to imagine ways of measuring the system without "paying the price" i.e. keeping the system's superposition or meaning that the system can exist in all states. In order to understand their results Hofmann describes their findings using the well-known physics story of Schrödinger's cat:

Schrödinger's cat is in a box and the scientists don't know whether it is dead or alive. A camera is set up looking into the box that takes a photo from a position outside of the box. The photo taken of the cat comes out blurry; we can see there is a cat but not whether it is dead or alive. The flash from the camera has also removed a "quantum tag" marking the superposition of the cat. This photo is now entangled with the fate of the cat—i.e. we can decide what happened to the cat by processing this photo in a certain way.

The photo could then be taken away from the box and processed on a computer or in a darkroom. Depending on what method is used to process the photo, we can find out either if the cat is alive or dead, or what the flash did to the cat, restoring the quantum tag. The choice of the reader determines what we know about the cat. We can find out if it's dead/alive or restore the quantum tag that was removed when the picture was taken, but not both.

This is only a step forward in our understanding of quantum mechanics. Today its full application remains confined to expert-level systems like quantum computers, although some of its aspects can also be used in precise measurements, and for secure communication using quantum cryptography.

"This is a key part of my research. I really wanted to understand why this quantum weirdness is there. I focused on measurements because that's where the weirdness comes from!" says Hofmann.

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Re: Physics Discussion Thread

Postby tandav » 03 Oct 2019 10:58

https://theprint.in/science/why-the-phy ... ry/116838/

Interest in the IISC breakthrough claims in Room Temp SuperConductivity seems to be have ebbed... Anyone closer to the IISC research team can update us further.

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Re: Physics Discussion Thread

Postby ArjunPandit » 03 Oct 2019 16:09

^^we shouldnt be too harsh on ourselves..these things are part and parcel of the process there have been errors in studies abroad too..remember the faster than light neutrinos..or fusion breakthroughs to enable reactors in next 30 years..for last 30 years...the fact that these guys are trying in desh is a good thing..yes more discipline is required..

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Re: Physics Discussion Thread

Postby Amber G. » 03 Oct 2019 23:50

tandav wrote:https://theprint.in/science/why-the-physics-community-has-lost-interest-in-breakthrough-discovery/116838/

Interest in the IISC breakthrough claims in Room Temp SuperConductivity seems to be have ebbed... Anyone closer to the IISC research team can update us further.

Yes. Last I heard was that their patent is in the public domain. ([url]http://www.physics.iisc.ernet.in/~arindam/gold-silver-nanostructure-patent/]<link>[/url] As far as publication in reputable journal (by the IISc Scientists - none.. but their tweeter accounts have "More update soon" for a long time.
I do know quite a few people in IISc and some are good friends and I am in contact with them. I met one (who recently was honored by Padma award from GoI), a friend physicist who gave a key-note address in US without mentioning this. (Many IISc scientist avoid talking about this)

Disclaimer: I am skeptic. I am also too close to people involved in the story (Please read the story linked by Tandav) Prof TV Ramakrisnan was my prof, Prof. Raychaudhuri is a friend (and not really liked by that IISc group as he is also in the same field). My specific technical questions to authors were answered by polite non-answers or were ignored. (Naturally most people, as it happens in physics, in the field are quiet and are in no hurry to judge and will wait till all the results are in.)

There are at least 10 labs in India alone which they can ask or cooperate with to duplicate/validate finding or ask others (even IISc colleagues outside their group) to look through their data/experiment --- In my humble opinion --( I think they can avoid much of the confusion and can still preserve their patent/commercial investment).

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Re: Physics Discussion Thread

Postby Amber G. » 04 Oct 2019 20:53

Okay - The season is near.. here are predictions for 2019 Physics Nobel: (from those discussed in physics dhaga :) )
- Related to Blackhole - (https://forums.bharat-rakshak.com/viewtopic.php?p=2342065#p2342065 etc) This year or next year. For Nobel the cut-off data is February that post was in April. (But work was done for years by those scientists).
- Detecting Exoplanets - Lot of discussion in this dhaga.
- Structure of Neutron stars (Gravitational Waves)
- Superconductivity (new classes of super conductors containing Fe (Hideo Hosono) or Hydrogen (Mikhail Eremets ) - (Proven)
- Quantum Entanglement / Quantum computing / practical application. (People Aspect, Clauser ,Zeilinger) .. Theorist Bell has died so will not be eligible).

Meanwhile, happy to share that Prof Rajesh Gopakumar got Distinguished Alum award from IIT Kanpur this year.

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Re: Physics Discussion Thread

Postby Vayutuvan » 05 Oct 2019 00:54

Since there was some talk on Kelvin-Helmholtz Instability, this paper - as per the abstract - seems to be of interest.

Enhanced GEANT4 Monte Carlo simulations of the space radiation effects on the International Space Station and Apollo missions using high-performance computing environment

Highlights
•A new application simulated radiation through full-sized spacecraft.
•Application implemented new computational detectors including human phantom.
•Simulations of dose for ISS and Apollo 11 matched well experimental measurements.
Greatest contributor to radiation dose for Apollo missions was from GCR.
•Simulations of Apollo 14 showed higher measured dose most likely due to SPE.


Abstract
A significant challenge to current and future manned and/or unmanned space missions is due to deep space radiation. An improvement in more realistic (more accurate) simulation models in predicting the effects of radiation within the spacecraft is required, especially to better predict dose to astronauts, energy deposition within sensitive electronics, and effectiveness of radiation shielding for long-term space missions. The International Space Station provides an invaluable resource for long-term measurements of the radiation environment in Low Earth Orbit (LEO); however, the only manned missions with dosimetry data available beyond LEO are the Apollo missions. Thus the physiological effects and dosimetry for deep space missions are not well understood in planning extended missions.

<snipping how they used HPC with MPI to do Montecarlo etc.>


One quick point is that Van Allen Radiation belt radiation is well studied so that is not of a lot of interest for current missions beyond LEO.

Two points of interest from the above abstract which I highlighted. My comments follow:

Firstly, the greatest contributor is Galactic Cosmic Ray (GCR) radiation as opposed to any other radiation or effects.
Secondly, the only data that is available is from as far back as Apollo 11 through Apollo 14 missions. Probably there was no further research since manned missions beyond ISS did not take place by the US/NASA.

India would have had some data from our people flying on Soviet/Russian space missions. India would have collected some data during CY1 and now possibly from CY-2 and the lander before communication was lost.

Those would certainly help in future unmanned/manned missions.

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Re: Physics Discussion Thread

Postby Amber G. » 05 Oct 2019 03:21

Vayutuvan wrote:Since there was some talk on Kelvin-Helmholtz Instability, this paper - as per the abstract - seems to be of interest...<snip>
.

Thanks for the article - Okay got curious.. where in BRF someone talked about this fluid dynamics aspect and found that there were posts about solar wind in CY2 thread. :)
...
Some comments:
(Kelvin-Helmholtz instability is relevant in understanding dynamics of corona (solar atmosphere) - which produces solar flares)
Greatest contributor to radiation dose for Apollo missions was from GCR.

This is not surprising - actually what everyone thought all the time. (Most "radiation" from SPE will be stopped by hull of the space-craft). GCR has much higher energy than solar wind particles. (GeV vs KeV).
- One of the *main* scientific measurement Apollo astronauts did was to measure "solar wind" -- as it is difficult to experiment on earth - due to the fact that earth has magnetic field and it rotates you get shielded from it -

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Re: Physics Discussion Thread

Postby Amber G. » 05 Oct 2019 04:26

For those who are interested quite a few resources, like this one:
https://srag.jsc.nasa.gov/SpaceRadiation/What/What.cfm

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Re: Physics Discussion Thread

Postby UlanBatori » 05 Oct 2019 07:12

The Abdsurdity of the Nobel Prizes in Science: The Atlantic

The very first prize in medicine was awarded to Emil von Behring in 1901 for the discovery of antitoxins, but not to his close collaborator Shibasaburo Kitasato.

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Re: Physics Discussion Thread

Postby Vayutuvan » 06 Oct 2019 10:02

Nobel prizes are political; almost all of them.

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Re: Physics Discussion Thread

Postby Amber G. » 06 Oct 2019 22:19

This week Nobel Prize in Physics will be announced, so here is a photo challenge for BRF..

There are many great physicist in this picture. At least three are world renowned and widely known. Can you identify them and tell us when and where this photo was taken.

Recently Nobel Committee released the name of all nominations (from 1901-9166) including those who did not win the prize. There is one in the picture who was nominated 8 times, another 4 times and the third, the most famous of all, was a polymath, physicist, biologist, botanist and archaeologist, and an early writer of science fiction but is perhaps best known as an Electrical Engineer.

Image

(Photo Credit: American Institute of Physics - Segre Archive)

How many can you identify?

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Re: Physics Discussion Thread

Postby Vayutuvan » 06 Oct 2019 22:56

Jagadish Chandra Bose in the center - polymath, invented the radio before Marconi did.
SN Bose - second row second from the left.
Last edited by Vayutuvan on 07 Oct 2019 01:35, edited 1 time in total.

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Re: Physics Discussion Thread

Postby Amber G. » 06 Oct 2019 23:25

Vayutuvan wrote:Jagadish Chandra Bose in the center - polymath.p, inventor of radio before Marconi.
SN Bose - second row second from the left.

Yes! Satyen Nath Bose was nominated 4 times for Nobel Prize - according to recently made public report. Boson (like photons etc) are named after him. Bosons follow "Bose-Einstein Statistics". The other kind of particles are Fermions (like electrons, protons, neutrons etc) which follow "Fermi-Dirac Statics".

Here is another, on of my favorite, photo of Dirac and Bose.
Image
(Photo Credit: SN Bose Archive)

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2019 01:19

Interesting read, focusing on the discoveries and less on personalities. The Nobel Prize in Physics: The papers
***
The 386 people who were eligible for the prize but didn’t win tell as much of a story as the 109 who did...
From India, Bhabha, SN Bose, and MN Saha did not win. CV Raman did win.
Nice read:
Physics Nobel nominees, 1901–66

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Re: Physics Discussion Thread

Postby Vayutuvan » 08 Oct 2019 05:23

What about ECG Sudarshan? Was he ever nominated? Kapany?

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Re: Physics Discussion Thread

Postby Rishi_Tri » 08 Oct 2019 07:01

Vayutuvan wrote:Jagadish Chandra Bose in the center - polymath, invented the radio before Marconi did.
SN Bose - second row second from the left.


Meghnad Saha, left of Sh JC Bose!.. That's at least three Nobels in there - in the same frame. Testament to the fact that Nobel missed the most prominent Indians, continues to do so, and deliberately.

Anyway, what a photograph. Truly For the Ages.

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2019 07:06

Vayutuvan wrote:What about ECG Sudarshan? Was he ever nominated? Kapany?

The list is public only up to 1966. Saha, SN Bose, Raman, Bhaba's work was in 20's 30's 40's etc..
(Not secret that Sudarshan's name was nominated quite a few times as the people who nominates can sometimes let it know)

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2019 07:25

Rishi_Tri wrote:
Vayutuvan wrote:Jagadish Chandra Bose in the center - polymath, invented the radio before Marconi did.
SN Bose - second row second from the left.


Meghnad Saha, left of Sh JC Bose!.. That's at least three Nobels in there - in the same frame. Testament to the fact that Nobel missed the most prominent Indians, continues to do so, and deliberately.

Anyway, what a photograph. Truly For the Ages.

The people are:

(Seated, L-R) Meghnad Saha, Jagadish C Bose and Janan C Ghosh. (Standing L-R) Snehamoy Dutt, Satyendranath Bose, Debendra M Bose, Nikhil R Sen, Janendra Nath Mukherjee and Keshab C Nag.

Saha was nominated for Nobel 8 times, SN Bose 4 times. (Bhabha 5 times, Raman 12 times (won in 1930))

The picture is Presidency College (I am pretty sure).

Saha and Satyendra Nath Bose (of Bose–Einstein fame) were classmates at Presidency College, whose faculty included the well-known chemist and entrepreneur Prafulla Chandra Ray, the great Jagadish Chandra Bose (in middle), and famous mathematician Devendra Nath Mallik. Saha and Bose are also famous as they translated Einstein’s and Minkowski’s famous papers on relativity and made available in India in English translation- from German( Meghnad Saha and Satyendra Nath Bose that book is known to all physicists in 50's 60's)

This group is also *very* famous for their work to promote nationalism - worked very closely, for example with Subash C. Bose, translating old Indian science books and to revive ancient India’s intellectual past.

***
Interestingly just a few posts above are about "solar wind".. Megnath Saha is credited for radiation pressure due to solar winds (and solving the mystery of the comet’s tail pointing away from the Sun remained unanswered).

***
Here is another picture from the archive. SN Bose with the great Neils Bohr (whose birthday is today!)
Image

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Re: Physics Discussion Thread

Postby Vayutuvan » 08 Oct 2019 10:02

Amber G. wrote:
Vayutuvan wrote:What about ECG Sudarshan? Was he ever nominated? Kapany?

The list is public only up to 1966. Saha, SN Bose, Raman, Bhaba's work was in 20's 30's 40's etc..
(Not secret that Sudarshan's name was nominated quite a few times as the people who nominates can sometimes let it know)

you know ecg sudarshan personally, IIRC. also cv Raman's family. you said this before in brf.

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Re: Physics Discussion Thread

Postby Prasad » 08 Oct 2019 14:04

Tangential but have to ask. What did all these amazing people setup in their lifetimes to continue and expand study in their respective fields? CV Raman was involved with IISc afaik. Others?

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Re: Physics Discussion Thread

Postby ArjunPandit » 08 Oct 2019 18:40

Three scientists have been awarded the 2019 Nobel prize in physics for groundbreaking discoveries about the evolution of the Universe and the Earth’s place within it.

The Canadian scientist James Peebles has been awarded half of the 9m Swedish kronor (£740,000) prize for his theoretical discoveries about the evolution of the universe. A Swiss duo of astronomers, Michel Mayor and Didier Queloz, will share the other half of the prize for their discovery of the first planet beyond our solar system.

James Peebles was rewarded for laying a foundation for modern cosmology, including his realisation that the faint microwave radiation that filled the cosmos just 400,000 years after the Big Bang contains crucial clues to what the universe looked like at this primitive stage and how it has evolved over the subsequent 13bn years.

Mayor and Queloz have been recognised for their joint discovery in 1995 of the first exoplanet 50 light years away in the constellation of Pegasus. The planet, 51 Pegasi b, is a gaseous ball about 150 times more massive than the Earth and with a scorching surface temperature of 1000C.

The discovery heralded a new era of astronomy, with astronomers having since found more than 4,000 exoplanets, with an incredible range of sizes, forms and orbits. Learning about these strange and varied world’s beyond our solar system has transformed our understanding of how planets formed and given new focus to the question of whether there could be alien life is out there somewhere.

Peebles is also credited with developing the theoretical tools that allowed scientists to perform a cosmic inventory of what the universe is made from, showing that ordinary matter makes up just 5% of its known contents, with the rest being dark matter and dark energy.
https://www.theguardian.com/science/201 ... anets-2019

“We still must admit that the dark matter and dark energy are mysterious,” Peebles told the Royal Swedish Academy of Sciences on Tuesday. “There are still many open questions...What in the world is this dark matter?”

Looking back over his career spanning half a century, Peebles, who is Albert Einstein professor emeritus of science at Princeton University, said that he never set out with a grand plan. “I could think of one or two things to do in cosmology. I just did them and kept going,” he said. “The prizes and awards, they are charming, much appreciated, but that’s not part of your plans. You should enter science because you are fascinated by it.”

Prof Goran Hansson, secretary-general of the Royal Swedish Academy of Sciences that chooses the laureates, said the three had made “contributions to our understanding of the evolution of the universe, and Earth’s place in the cosmos.”

Prof Sir Martin Rees, the astronomer Royal, described Peebles as the world’s “most
influential and respected leader of empirical cosmology with a sustained
record of achievement spanning half a century”.

“The study of exoplanets is perhaps the most vibrant field of astronomy. We
now know that most stars are orbited by retinues of planets; there may be a
billion planets in our galaxy resembling the Earth (similar in size and at
a distance from their parent star where liquid water can exist),” Rees added. “This takes us a step towards the fascinating question of detecting evidence for life
on the nearest of these exoplanets.”

On Monday, Americans William Kaelin and Gregg Semenza and Britain’s Peter Ratcliffe won the Nobel prize for physiology or medicine for discovering details of how the body’s cells sense and react to low oxygen levels, providing a foothold for developing new treatments for anaemia, cancer and other diseases.

The Nobel prize for chemistry will be announced on Wednesday, two literature prizes will be awarded on Thursday, and the peace prize comes on Friday. This year will see two literature prizes handed out because the one last year was suspended after a scandal rocked the Swedish Academy.

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2019 20:22

Amber G. wrote:Okay - The season is near.. here are predictions for 2019 Physics Nobel: (from those discussed in physics dhaga :) )
- Related to Blackhole - (https://forums.bharat-rakshak.com/viewtopic.php?p=2342065#p2342065 etc) This year or next year. For Nobel the cut-off data is February that post was in April. (But work was done for years by those scientists).
- Detecting Exoplanets - Lot of discussion in this dhaga.
- Structure of Neutron stars (Gravitational Waves)
- Superconductivity (new classes of super conductors containing Fe (Hideo Hosono) or Hydrogen (Mikhail Eremets ) - (Proven)
- Quantum Entanglement / Quantum computing / practical application. (People Aspect, Clauser ,Zeilinger) .. Theorist Bell has died so will not be eligible).

Meanwhile, happy to share that Prof Rajesh Gopakumar got Distinguished Alum award from IIT Kanpur this year.

So, not too bad a guess..:)This year’s #NobelPrize in Physics rewards new understanding of the universe’s structure and history, and the first discovery of a planet orbiting a solar-type star outside our solar system. The discoveries have forever changed our conceptions of the world
Image

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2019 20:45

Physics Laureates Michel Mayor and Didier Queloz have explored our home galaxy, the Milky Way, looking for unknown worlds. In 1995, they made the first discovery of a planet outside our solar system, an exoplanet, orbiting a solar-type star, 51 Pegasi...Posting a nice image.
Image

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Re: Physics Discussion Thread

Postby ArjunPandit » 08 Oct 2019 20:59

what i find interesting is the way first exoplanets were discovered by the wobbling of stars..very crudely said thats nothing but another application of newton's third law and the gravitational force..

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Re: Physics Discussion Thread

Postby Amber G. » 09 Oct 2019 00:51

ArjunPandit wrote:what i find interesting is the way first exoplanets were discovered by the wobbling of stars..very crudely said thats nothing but another application of newton's third law and the gravitational force..


Yes, this is still one of method used.

This method to find a planet is called the radial velocity method; it measures the movement of the host star as it is affected by the gravity of its planet

Image

Another is transit photometry.

Along with variations in radial velocity, transit photometry is now used when searching for exoplanets. This method measures changes in the intensity of the star’s light when a planet passes in front of it, if this happens in our line of site.

Image

(There are a few other methods, but the above 2 counts for 99+% of the discoveries. Direct imaging is very rare but now has been used)

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Re: Physics Discussion Thread

Postby Amber G. » 09 Oct 2019 01:26

Prasad wrote:Tangential but have to ask. What did all these amazing people setup in their lifetimes to continue and expand study in their respective fields? CV Raman was involved with IISc afaik. Others?

For interested, there is lot of material out in libraries. (Check out their biographies).

The amount of service, for Indian science, and India is *VERY* high.

Bhabha (and CV Raman, Chandrasekhar etc too) had good relationship with Nehru and TIFR, Atomic Energy, BARC are just a few examples. Bhabha died (and Nehru too) so the momentum was gone, but if he survived a few years, IIT Kanpur would have been a world class center for Nuclear Engineering.

Saha & SN Bose - (Who was close to Subash Bose and thus was not favorite of Nehru/Congress, but still did a lot), apart from inspiring a *whole generation* of people like us, providing extremely good textbooks - some of them were like bibles - and premier Institutes (and learning centers) like Institute of Nuclear Physics in Calcutta (Now Saha Institute of Nuclear Physics) - which was inaugurated by Nobel laureate Irene Curie. His student Basanti Dulal Nag Chowdhuri (with Ernest Lawrence in Berkeley) constructed the first cyclotron at the University of Calcutta.

But most important, IMO, his contribution to Planning Commission in India was to oversee irrigation in UP and other practical things.

Saha was a true nationalist.
Let me give one nice reference: https://physicstoday.scitation.org/doi/10.1063/PT.3.3267

The JC Bose's students (see picture) - all of them - were true nationalists.

ArjunPandit
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Re: Physics Discussion Thread

Postby ArjunPandit » 09 Oct 2019 01:49

^^i was talking to an oxford grad in physics sometime back and he mentioned about SN bose and mentioned that he was beyond BEC his contribution was not much.

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Re: Physics Discussion Thread

Postby Amber G. » 09 Oct 2019 02:43

ArjunPandit wrote:^^i was talking to an oxford grad in physics sometime back and he mentioned about SN bose and mentioned that he was beyond BEC his contribution was not much.

Really! Apart from physics his contribution in mathematics (many well known papers in pure math) , chemistry, biology, mineralogy, philosophy, arts, literature, and music (he played esraj masterfully) are quite noteworthy. He was fluent in Bengali, English, French, German and Sanskrit a poet.
He won gold medal - highest marks, second was Saha.
BES would be enough but his work/contribution in - just a very few items - Einstein’s Unitary Field Theory and experimental physics (eg X-ray spectroscopy, X-ray diffraction etc.. with Saha, Raman) were top notch.

The recent documents released from Nobel committee also names Oskar Klein the referee rejecting him for the prize. (Not surprisingly)

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Re: Physics Discussion Thread

Postby Vayutuvan » 09 Oct 2019 03:07

Why "Not surprisingly!"? They are not working on the same thing, right?

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Re: Physics Discussion Thread

Postby Vayutuvan » 09 Oct 2019 03:14

ArjunPandit wrote:what i find interesting is the way first exoplanets were discovered by the wobbling of stars..very crudely said thats nothing but another application of newton's third law and the gravitational force..


It is all measuring accuracy of the instrumentation dependent. Most of the research is in building measuring devices with the required accuracy. Lower the M_p/M_s ratio (masses of the planet and star) the smaller the wobble. Also there could be many planets of different masses orbiting the star (or rather center of mass of the multibody system). One has to solve an n-body problem (or rather an inverse problem).

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Re: Physics Discussion Thread

Postby ArjunPandit » 09 Oct 2019 06:44

vayutuvan g, thanks for your perspective
why I find it interesting is because of my cbse book class IX CBSE/ncert book. When it introduced the three laws of motion and the law of gravitation. In the gravitation chapter a side box was about does the earth get attracted to the apple and does it reach out to the apple or the other way round? Then the explanation was that the mass of earth is much higher compared to the apple and thats why the apple moves with acceleration due to gravity.
That kind of hard wired this into me and most who studied along with me the fact that orbiting bodies with small mass can have any material impact on the body around which they orbit.
Yes it makes sense to me now but the breaking of acccepted wisdom and the simple fact that blocking of light until i read about the real application in detecting plans(we all did the angle calculation with the coin blocking the sun/moon in XI trigo, again very crude simplification).
That coupled with your point above of the instrumentation accuracy, which to a layman like me is more of an engineering problem (please correct me if i am mistaken), fascinates me of the possibilities of how we take many no s for granted. This fascination also gets manifold when i read more about LIGO precisions or the super komikonde precisions..
and that's why i really enjoy the creativity of ulanbatori ji and wisdom of Amber G.
I have not followed your posts that rigorously till now

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Re: Physics Discussion Thread

Postby Vayutuvan » 09 Oct 2019 09:41

Arjun pandit ji.

I am somewhat abashed. there are vpmany physicists and mathematicians and other science and Engg. people in our brf forums who are senior to me - age as well as knowledge.

but thanks for your vote of confidence. I am more of an applied mathematician/computer scientist/numerical analyst/algorithmicist.

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Re: Physics Discussion Thread

Postby Rishi_Tri » 10 Oct 2019 19:16

I know this is perhaps not the best place to ask.. but don't know where to ask.. but since the topic came up .. asking nevertheless.. who are the prominent indians to have not been awarded nobel.. I can think of the following:

- Meghnad Saha, JC Bose, SN Bose, Homi Bhabha, EC George Sudarshan, Jayant V Narlikar (Sciences),
- Upendra Nath Brahmachari (discovery of treatment of Kala Azar - Medicine)
- Baba Amte (fight against leprosy), Sunderlal Bahuguna (leading chipko leader) bindeshwar pathak (sulabh shauchalaya).. members of indian freedom movement (peace prize)
- (Literature) - Innumerable .. don't know about other languages but for hindi definitely Harivansh Rai Bachchan, Maithili Sharan Gupta, Ramdhari Singh Dinkar

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Re: Physics Discussion Thread

Postby Amber G. » 13 Oct 2019 22:25

Scientific American -- About Jim Peebles’ award which honors modern cosmological theory.


A Well-Deserved Physics Nobel

vijayk
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Re: Physics Discussion Thread

Postby vijayk » 15 Oct 2019 01:49

http://blogs.discovermagazine.com/d-bri ... t-gravity/
The Case Against Dark Matter


What do BR experts think?

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Re: Physics Discussion Thread

Postby ArjunPandit » 15 Oct 2019 03:38

vijayk wrote:http://blogs.discovermagazine.com/d-brief/2018/05/08/dark-matter-emergent-gravity/
The Case Against Dark Matter


What do BR experts think?

Vijayk g,
Not an expert by any means, and more of a string theory person (so please factor in my biases before that). Given that this is an unresolved question in physics, or a type of redlight where Amber Red card, mongolian yak herder and wolf can honk/howl with whatever equipment they've got
here's my howling, AFAIK, this question is closely interwined with the point of unification of fundamental forces,
the question that new theory or explanation should work out is
1. what happens at black hole singularity
2. why is gravity weak in our 3 dimensions
3. is there any limit on dimensions and the explanations of the constants we observe c, G, h, epsilon etc.
4. Unification of gravity
5. Should be provable as well :mrgreen: :mrgreen: :mrgreen:
as per current studies, DM/DE have been an important influence in even how the galaxies and galactic clusters are structured and string or to be precise M theory has been able to rest except DM/DE.


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