Physics Discussion Thread

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Vayutuvan
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Re: Physics Discussion Thread

Postby Vayutuvan » 11 Jul 2020 04:15

https://www.hpcwire.com/off-the-wire/fermilab-scientists-publish-quantum-computing-course-for-high-school-students/

This will be useful for people to get an overview of QC. I quickly scanned the course content. It looks nice - only 180 pages long with many figures and exercises.

Link to the arXiv paper/course content is here.

[ur]https://arxiv.org/abs/1905.00282[/url]

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Re: Physics Discussion Thread

Postby Vayutuvan » 17 Jul 2020 02:05

https://www.techbriefs.com/component/content/article/tb/supplements/pit/stories/insider/37276

Small enough to fit on a chip, miniature versions of these combs — so named because their set of uniformly spaced frequencies resembles the teeth of a comb — are making possible a new generation of atomic clocks, a great increase in the number of signals traveling through optical fibers, and the ability to discern tiny frequency shifts in starlight that hint at the presence of unseen planets. The newest version of these chip-based “microcombs,” created by researchers at the National Institute of Standards and Technology (NIST) and the University of California at Santa Barbara (UCSB), is poised to further advance time and frequency measurements by improving and extending the capabilities of these tiny devices.


What I don't understand is that how solitons can measure frequency shifts.

@AmberG ji, could you please explain in laypeople language? I understand what solitons are, I think.

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Re: Physics Discussion Thread

Postby Amber G. » 17 Jul 2020 05:03

If there are planets, the star wobbles and Doppler will produce a slight shift in the frequency of the star - light. This is how astronomers were able to detect binary stars (even when the partner was too dim to see directly).. with planets, the shift is smaller, so if one get better and accurate frequency measurements that's very helpful.

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Re: Physics Discussion Thread

Postby Amber G. » 24 Jul 2020 02:57

Another aspect of Mie Scattering .. which we discussed in detail in few posts recently..
With less such particles to scatter the light .. not only we can see Himalayas from Punjab .. Solar output in Delhi is 8% more. From MIT news:.
Covid-19 shutdown led to increased solar power output
- As the air cleared after lockdowns, solar installations in Delhi produced 8 percent more power, study shows.

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Re: Physics Discussion Thread

Postby Mort Walker » 24 Jul 2020 05:30

^^^Here is the actual article that MIT News referenced:
The Impact of COVID-19-Related Measures on the Solar Resource in Areas with High Levels of Air Pollution
https://www.cell.com/action/showPdf?pii ... %2930272-5

The biggest difference was seen from March 21-30, 2020. 8.3+/-1.7%.

Image

Image

Now the two plots taken together are important to rule out something anomalous like someone washing and cleaning the surface of the panel(s).
Last edited by Mort Walker on 24 Jul 2020 05:42, edited 1 time in total.

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Re: Physics Discussion Thread

Postby Vayutuvan » 24 Jul 2020 05:38

I like the second one. It shows that 2019 was an anamolie. in 2017 and 2018, there was no appreciable difference by the time the monsoons arrived which is just about now. Makes sense as the rain cleans air of particulate matter.

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Re: Physics Discussion Thread

Postby Mort Walker » 24 Jul 2020 05:45

Vayutuvan wrote:I like the second one. It shows that 2019 was an anamolie. in 2017 and 2018, there was no appreciable difference by the time the monsoons arrived which is just about now. Makes sense as the rain cleans air of particulate matter.


Yes. If you have more W/m^2, you have to start asking questions as to what is going on which is what the 1st plot shows. What I didn't see is how much more power or energy over that week the panels produced. Commercial solar panels are around 20% efficient in converting the solar flux to power. The panels may already be max efficiency where reduced 2.5ug PM may not make a difference. The study collected insolation data (solar flux) at a PV installation in Paschim Vihar. What they did not collect is the difference in energy produced that week compared to the same weeks in earlier years. That would have been more interesting to show a correlation between lower particulate matter concentration and solar energy production at lower latitude (below 30N) locations.

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Re: Physics Discussion Thread

Postby Vayutuvan » 25 Jul 2020 02:16

There is another effect that has to be taken in to the calculations. Panels need to washed at regular intervals or else dust settled on the surface of the panels reduces efficiency. We were thinking of angel investing a project but the reduction in efficiency due to dust made the idea infeasible.

When it rains, the dust on the panels gets washed off periodically to keep the efficiency up.

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Re: Physics Discussion Thread

Postby Mort Walker » 25 Jul 2020 03:02

^^^Were you thinking of investing in India or somewhere else? Accumulated dust on the panels would cause a serious degradation of solar irradiation as opposed to particulate matter in the air.

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Re: Physics Discussion Thread

Postby Vayutuvan » 25 Jul 2020 05:15

India.

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Re: Physics Discussion Thread

Postby mappunni » 19 Aug 2020 08:19

Not sure this video belongs here, Mods please move it to the right thread

True Tesla: "Ideas of the old Vedas and the work of Nikola Tesla"



On the occasion of the 75th anniversary of Nikola Tesla's departure into eternity, as a homage to this our's and world's scientific giant, a special lecture was held on January 18, 2018, at the Ilija M. Kolarac Foundation in Belgrade.
In this really elite place for the promotion and popularization of culture, science, and art, it was pointed out by solid arguments and shown to the world the importance of (lesser-known) Nikola Tesla and the significance of his work, which on this occasion was presented to the public as an even bigger more important and significant scientist than the Great Tesla,
we know and to whom we already give away many well-deserved confessions.

Theme: "Ideas of the old Vedas and the work of Nikola Tesla".
Lecturer: Goran Marjanović, B.Sc.
Moderators: dr. Vladimir Ajdačić, dr. Miloje Rakocevic

Key statements:
Dr. Vladimir Ajdačić: Work of Nikola Tesla is one of the most beautiful topics, to talk about Tesla and his miraculous accomplishments and the depth of his perception of the things we are exploring.

Dr. Miloje Rakočević: Discover the phenomenon, understand the phenomenon, present it, reveal it and create something based on this phenomenon, if you understand it, create a device, create an opportunity for all humanity.
That was Nikola Tesla: scientist, inventor, creator, scientist over scientists. That's how he should be interpreted.

G. Marjanović, BSc: He intuitively came to the realization of how nature works, how this reality works, and he intuitively applied all its principles, not knowing them, nor ever mentioning in his diary any of basic cosmic constants, Pi nor fi, etc., but by his work, efforts, persistence, by endless changes he has reached the perfection of his apparatus - that the application of these constants provides.
And that's true, less known, Nikola Tesla!

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Re: Physics Discussion Thread

Postby Amber G. » 28 Aug 2020 07:34

Some recent discussion from other brf threads which may be more relevant and may have more interest here:
Mort Walker wrote:AmberG,

Yes, having all of those ephemeris on-line is handy. People use to have large volumes of books that contained ephemeris of just the earth and moon. I remember back in the 1980s calling US Naval Observatory in Washington D.C. and giving them mm/dd/yr and lat/lon locations on the globe to get just a particular day's information for janam-kundli accuracy. This was a service they provided free at the time. I hope data, like you acquired, can some day be provided by ISRO for earth, moon, sun and planets. Many of the ancient sages of India made ephemeris that were used by Ptolemy and most likely incorrectly credited to him for developing.

I do like your pictures.

Virtually all good libraries in astronomy department in my graduate student days (eons ago) had those Ephemeris (Thick volume, one for each year for US Naval Observatory). My prize possession (cost me a lot) was Newcomb's tables - Really thick volumes - which were the basis of making all those yearly ephemeris. By 1980 or even beforf that computers completely replaced Newcomb's tables and 13 decimal places log-tables!.
(In 1971 I taught my father who was really interested in astronomy, and some Indian pundits who wanted to learn simpler and more accurate way to kundali - how to calculate Sun, moon, ephemeris using a SR-71 (TI calculator)) ..Anyway this is probably I can still calculate/estimate position of sun and moon, even without a computer :)..

About Indian data - Gauss once estimated, some of our ancient data of people like Bhaskara was based at least another 500 years or older data which they must have had to provide that accuracy.

Anyway, now a days there are plenty of good computer programs, apps which are quite good.

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Re: Physics Discussion Thread

Postby Amber G. » 28 Aug 2020 07:48

Also from CY2 Thread:
Mort Walker wrote:The problem here is that the failure of CY-2 was an engineering problem. There was no problem with the orbital mechanics. The problem comes when you use mathematics to characterize a problem that you don't fully understand when building a spacecraft. Lots of variables you miss and incorrect assumptions. The math isn't wrong, but rather the application is. Think of a furniture carpenter who uses the right tool to make a beautiful cabinet. The engineer must use his/her mathematics tools the same way. A physicist and mathematician will marvel at the beauty of the tool and how it can be used to make other beautiful things.


The most likely problem with Vikram - as most were afraid of before and many in the know suspect - is to do with simple "stability" of orientation in the critical moment... may have resulted in computer overload or something like that when they tried to resolve it only to make more systems fail..

One problem I discussed here in Brf a few times - "tennis racket theorem or intermediate axis theorem" was a cause of instability /failure of more than a few sats. Gimbal lock at critical time made Armstrong's Apollo 11 a near disaster - good thing he was a very good pilot. (I remember Collins (or some one else), when asked for a Christmas wish wanted a "fourth Gimbal lock."

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Re: Physics Discussion Thread

Postby Amber G. » 29 Aug 2020 00:27

This is quite interesting and this could be huge!.

(Scientists from IIT Bombay proposed a novel setup to carry out quantum information processing at room temperatures. This study is funded by Government of India's Department of Science and Technology. Reputed institute and people involved. India has very heavily invested in Quantum Computing R&D)

May be some other thread be more appropriate..
A new approach to quantum information processing at room temperatures

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Re: Physics Discussion Thread

Postby Mort Walker » 29 Aug 2020 01:08

AmberG,

Good discussion. Should have come here more often and the math thread where you guys had solutions to interesting polynomials. :)

Amber G. wrote:Virtually all good libraries in astronomy department in my graduate student days (eons ago) had those Ephemeris (Thick volume, one for each year for US Naval Observatory). My prize possession (cost me a lot) was Newcomb's tables - Really thick volumes - which were the basis of making all those yearly ephemeris. By 1980 or even beforf that computers completely replaced Newcomb's tables and 13 decimal places log-tables!.
(In 1971 I taught my father who was really interested in astronomy, and some Indian pundits who wanted to learn simpler and more accurate way to kundali - how to calculate Sun, moon, ephemeris using a SR-71 (TI calculator)) ..Anyway this is probably I can still calculate/estimate position of sun and moon, even without a computer :)..

About Indian data - Gauss once estimated, some of our ancient data of people like Bhaskara was based at least another 500 years or older data which they must have had to provide that accuracy.

Anyway, now a days there are plenty of good computer programs, apps which are quite good.



I didn't know there was a TI SR-71. I knew there was a TI SR-50. I had the opportunity to play with an HP9100 scientific calculator found in a garage sale in the early 1980s. It was built in the late 1960s and had nixie tubes for the numeric display.

Ephemeris books can still be purchased on Amazon and I had a colleague who bought a few 6-7 years ago as he needed data of sidereal time. He was correlating solar noise getting into a sensor in the microwave frequencies. He wanted to calculate that if it was indeed solar noise when the sensor was oriented toward a particular azimuth and elevation and not microwave interference from other sources. Computer programs and apps could have been used, but the fellow didn't trust what source material s/w developers were using. :lol: B.Sc. EE, MS & Ph.D. high energy physics. My approach to the same problem was that a FFT (Fast Fourier Transform) of the noise could be done automatically on test equipment, with sufficient bandwidth, to characterize the interference because it is most likely from a communications device that would fall into a communications modulation scheme, or spurious noise from oscillators and intermodulation. Everything else that wasn't random noise would most likely be solar noise. About a year ago I did a similar test where a real-time spectrum analyzer not only did the FFT, but thing also decoded the IP address of a communications device which was broadcasting below -80 dBm (10 pico-Watts)!

I did not know about Gauss making such a statement. History of science education seems to be lacking.

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Re: Physics Discussion Thread

Postby Amber G. » 29 Aug 2020 04:45

^^^ My copy of ..1968 Ephemeris .. Also Newcomb tables (Vol 6 shown here) published in 1898 which were the basis of *all* US Naval Observatory Ephemeris for next many decades ..(1968 there was first revision for the tables' constants .. than again in 1980 or so and little later, Newcomb's parameters no longer considered standard and tables were produced by computers with newly defined standard parameters etc..

In 1967 unit of time "second" was no longer defined from ephemeris (Newcomb's table were used to define the unit of second before that ) but from Atomic standard of Cs atom.

Image

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Re: Physics Discussion Thread

Postby Mort Walker » 29 Aug 2020 05:12

Amber G. wrote:
In 1967 unit of time "second" was no longer defined from ephemeris (Newcomb's table were used to define the unit of second before that ) but from Atomic standard of Cs atom.


That late as of 1967? I would have thought the atomic standard would have been adopted quickly after 1958 when NIST first got atomic clocks. The USN Observatory historically had emphemeris for navigation purposes. BTW, if you're running a lab, then Cs and Rb time/frequency standards are quite affordable from a few manufacturers in the US.

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Re: Physics Discussion Thread

Postby Amber G. » 29 Aug 2020 23:10

FYI:
Harvard course on "Quantum Phases of Matter" starts on September 2, and the lectures are Mon, Wed, Fri, 3:00-4:00 PM, Boston time. Lectures will be publicly viewable.
(Of course, only registered students from Harvard/MIT will be able to interact during the lecture but others can watch the live or recorded lectures for which no registration required.)

The links can be obtained from their website, but if there is an interest here let me know - I can post a YouTube link at the start of each lecture - I am told that all the lectures could be watch later at those links.
(and access the lecture notes and problem sets ,information on readings and references will also be posted on the web site - and for, I think no registration is required)

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Re: Physics Discussion Thread

Postby Mort Walker » 30 Aug 2020 02:24

^^^Yes. Please post the links. Are the lectures from their condensed matter group or atomic physics. Also, I assume these are undergraduate lectures or a general type like Richard Feynman did?

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Re: Physics Discussion Thread

Postby Amber G. » 30 Aug 2020 22:38

^^^ Reason I shared the above widely was due to the fact that the professor (Sachdev) is world class, and *excellent* teacher whose popular lectures are just amazing. We may be looking at the next desi Nobel in Physics.

I might have made a slight error in initially understanding the scope/background of the course. (I just got informed by an email about his lecture - he gives lectures to general public, and introductory level too - and I have enjoyed his explaining style).

I will still post the direct links (when available).. but the pre-requisite are " graduate courses in quantum mechanics and statistical mechanics, including familiarity with second quantization and path integrals." (Honestly did not see before I posted it here).

I might as well cut and paste the "description" which is now on the Harvard's site (look for PHYSICS 268R)
(The youtube links will be posted pretty close to the date of the lecture - just see their page - which I will copy/put link to here)

Quasiparticles: Fermi liquids, superfluids, and solids. BCS theory of superconductivity. Interacting bosons. Fractionalization and the Z2 spin liquid. Quantum Ising models and gauge theories. Quantum liquids in one dimension. Kosterlitz-Thouless transitions and dualities. Berry phases and band topology. Emergent gauge fields. Quantum liquids in high magnetic fields. Deconfined criticality. Kondo effect. The SYK model and correlated metals.
Notes: Given the pandemic, we are open to rescheduling the class time, depending upon student constraints.

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Re: Physics Discussion Thread

Postby Mort Walker » 31 Aug 2020 07:33

^^^It appears the audience is intended to have a working knowledge of graduate level of statistical mechanics, though watching the initial few lectures may still be useful. Professor Sachdev is in the theoretical condensed matter group at Harvard.

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Re: Physics Discussion Thread

Postby Amber G. » 31 Aug 2020 22:53

^^^Yes, of course.

One of the side benefits of this pandemic is that there are many more courses which are now available to public viewing and/or being shared to other school's students. IIT's in India, (and schools like MIT, Caltech etc in USA) have *many* such excellent courses -- now not only available to students to other colleges but general public viewing..

Worthwhile to check their sites for anybody who is interested - all sorts of subjects, excellent teachers and no tuition fee.

Another course got my attention, is about Hight Temperature Super Conductors by Juven Wang, also of Harvard.

(What was cool that Juven Wang used perfect Hindi for Subir Sachdev's initiative .. "प्रोफेसर सुबीर सचदेव का हम हार्दिक स्वागत करते हैं!" .. remember long ago my getting used to English in IIT's where lot of people spoke it .. now Hindi could be heard when you visit a MIT campus or a Google cafeteria..:) )

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Re: Physics Discussion Thread

Postby Amber G. » 31 Aug 2020 23:12

Mort Walker wrote:
Amber G. wrote:
In 1967 unit of time "second" was no longer defined from ephemeris (Newcomb's table were used to define the unit of second before that ) but from Atomic standard of Cs atom.


That late as of 1967? I would have thought the atomic standard would have been adopted quickly after 1958 when NIST first got atomic clocks. The USN Observatory historically had emphemeris for navigation purposes. BTW, if you're running a lab, then Cs and Rb time/frequency standards are quite affordable from a few manufacturers in the US.

Yes. Historic perspective of definition of time is quite interesting. After centuries of having earth-spin as a standard, (dividing "mean solar l day" in 24*60*60 seconds).. only around 1940's (or may be little later or sooner) people realized that earth-spin is not that stable as it's motion around the sun. And standard definition of second ("ephemeris time) depended on those "NewComb's" tables.
Definition changed again in 1967 when the accuracy of atomic standards become official.
This standard may still change, as we are having more stable clocks than Cs..

As you say Rb (and may be some more) standards are quite affordable. (I am not running a lab :) .. Who knows, they may become part of our hand-held GPS or common lab equipment like we have quartz crystal to day) -- interestingly I can use my GPS and sat's atomic clocks to calculate fairly accurate time which is even cheaper) I do know there are many Indian companies/institutes are also working on finding better/affordable/stable standards/clocks for navigation needs).

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Re: Physics Discussion Thread

Postby Mort Walker » 01 Sep 2020 02:56

Amber G,

Many parts of academia were putting courses/lectures on-line as the trend had started, but the pandemic accelerated it. I've watched a little of Kip Thorne's lectures and they're fascinating. There is also a lot of tutorials/lectures coming on-line from industry too. Lot's of good stuff.

---------

Your hand-held GPS is getting a satellite lock from 3 or more sats which have Rb clocks in them. Our mobile phone network and internet servers with Network Time Protocol (NTP) are also using Rb clocks, though some are using Cs.

The reason for having Rb or Cs clocks is not just for accurate timing, but to have excellent phase noise (noise amplitude vs. offset frequency from carrier) and jitter (noise amplitude vs. offset time from standard). For an experimental physicist or engineer, a time and frequency standard allows you to distinguish very low level signals without the need to super-cool electronic equipment. Like Penzias and Wilson did for radio receivers at Bell Labs in 1964 for CMB. Frequency stable clocks and modern signal processing will allow you to see below the thermal noise floor relatively easily when working in the electromagnetic spectrum.

Both CY-1, CY-2 and MOM have an on-board Rb clock for accurate timing and detection of signals from its sensors. India's NavIC system uses Rb clocks supplied by Spectratime from the EU which failed on IRNSAA-1A in 2017. It had 3 Rb clocks which failed. ISRO has replaced these Rb clocks on further satellites from another manufacturer domestically or from a US company.

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Re: Physics Discussion Thread

Postby Amber G. » 02 Sep 2020 21:09

Rumors of big a announcement coming from LIGO was correct - This is a Breaking News (or announcement of an event happened many months ago but is now officially confirmed. ):

On 2 September 2020, the LIGO Scientific Collaboration and the Virgo Collaboration announced the discovery of GW190521, the most massive gravitational wave binary observed to date. The two inspiralling black holes had masses of about 85 and 66 solar masses, and resulted in the formation of a black hole remnant of 142 solar masses. This remnant provides the first clear detection of an "intermediate-mass" black hole.
Image

#GW190521 detection was more of a "bang" (or a low frequency "blip") than a "chirp" as the signal was "audible" in detectors for such a short time.
Image

Here is Nice infographic:
Image

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Re: Physics Discussion Thread

Postby Amber G. » 09 Sep 2020 21:11

Saddened by the passing away of Professor Govind Swarup- The Father of Indian Radio Astronomy. Many of the astronomy community had the pleasure of closely interacting and learning from him.

His legacy lives on in the form of large indigenous & international state-of-the-art major scientific facilities like the GMRT and ORT on Indian soil. Professor Swarup took keen interest in, and had been very encouraging and supportive of the LIGOIndia (gravitational wave observatory under construction). We feel inspired by him to continue this legacy which has paved the way for upcoming mega-science projects like LIGO India.


-Prof. Tarun Souradeep of LIGO India.


Image

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Re: Physics Discussion Thread

Postby Amber G. » 10 Sep 2020 21:58

I am delighted to hear that a Special Breakthrough Prize has been awarded to Steve Weinberg. Congratulations.
$3 MILLION SPECIAL BREAKTHROUGH PRIZE IN FUNDAMENTAL PHYSICS AWARDED TO STEVEN WEINBERG

Also Congratulations, to Urmila Mahadev , recipient of the 2021 Maryam Mirzakhani New Frontiers Prize "For work that addresses the fundamental question of verifying the output of a quantum computation." A breakthrough result indeed!

2021 New Horizons in Physics Prize "for calculating the quantum information content of a black hole and its radiation" recognizes remarkable recent progress achieved by @AlmheiriAE
, Netta Engelhardt, Henry Maxfield and @quantum_geoff.

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Re: Physics Discussion Thread

Postby Amber G. » 24 Sep 2020 20:05

Dr. Sekhar Basu, former Secretary of the Department of Atomic Energy, an unassuming thinker of keen insights, a problem solver, a committed scientist- technologist and a big hearted cheerful man passed away.

He leaves a rich legacy and a wide imprint that will always be remembered . He worked on several mega science projects and many Indian and international scientists had privilege of knowing/working with him

You will be missed Dr. Basu.

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Re: Physics Discussion Thread

Postby Amber G. » 06 Oct 2020 03:02

Physics Nobel Prediction:
Aspect and Clauser - quantum entanglement
Bennett and Brassard - quantum information/computing
Zeilinger

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Re: Physics Discussion Thread

Postby Vayutuvan » 06 Oct 2020 05:39

You mean Bennett (Physicist) and Gilles Brassard, a Comp. Scientist? Wow. That would be a first, AFAIK.
Last edited by Vayutuvan on 07 Oct 2020 05:24, edited 1 time in total.

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Re: Physics Discussion Thread

Postby Amber G. » 06 Oct 2020 19:00

^^^ Okay, it is not quantum information/computing/entanglement but another favorite Black Hole!

Congratulations to Roger Penrose, Reinhard Genzel and Andrea Ghez.

Wow! who would have thought that a song in Brf would inspire the Nobel Committee!
Bol, bol, bol mister golmatol
just how massive is a big black hole?
half the radius divide by G
and multiply by square of c.
:)

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Re: Physics Discussion Thread

Postby Vayutuvan » 07 Oct 2020 22:53

what is perplexing is that Penrose and Hawking were collaborators and equally famous and collaborators. why did Hawking not get a Nobel? I never understood that. Hawking was a theorist only, so is Penrose.
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Re: Physics Discussion Thread

Postby Amber G. » 07 Oct 2020 23:30

FWIW - Given that Nobel committee does not always listen/agree/etc to me :) .. ..
No doubt Stephen Hawking was brilliant but (so their argument goes -) ' he never got a Nobel Prize because "no one has proven his ideas" was he was alive. Here "proven" means experimentally demonstrated in the mind of Nobel committee."

Penrose's/Hawkins theory most "convincing" was demonstrated - again some will argue (i do not agree with this) - only recently with LIGO (gravitational waves) and recent direct observation(s).. some 50-60 *years* after that work.

Of course, *many* INCLUDING Penrose are voicing this - Penrose himself is quite unhappy that Hawkins is not recognized for the work which they both should have gotten the credit.

Unfortunately there are many such cases .. George Sudarshan is one case (where they actually given Noble to someone else for the work *he* did). Chandraskehar' Nobel came DECADES later. (mainly due to what I think racist lobbying of Eddington)

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2020 05:04

^^^ About Hawkins and Penrose ..
UK Nobel physics laureate pays tribute to snubbed Hawking
Nobel physics laureate Roger Penrose on Tuesday said his late colleague Stephen Hawking richly deserved a share of the prize after the British scientists conducted pioneering research into black holes.

"...the two individuals who have done more than anyone else since Einstein to deepen our knowledge of gravity".

"Sadly, this award was too much delayed to allow Hawking to share the credit with Penrose,"

Penrose said a Nobel prize for Hawking would have been "well-deserved" but was possibly held back by the committee's desire to honour observable, rather than theoretical, science. { This is what I commented in my post, but also see below.. as I think evaporation of older black holes ought to have been good enough }

Nevertheless, he said evidence to back up Hawking's theories of radiation emitting from the evaporation of older black holes, even from a previously extinct universe, was "extremely strong" and would likely be vindicated in time.


BTW .. Einstein never got his Nobel for Relativity ... he got it for Photo electric effect.

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2020 05:27

Vayutuvan - More I think about it, (and many others are also saying this) it almost seems cruel - Both Penrose and Hawkins ought to have gotten it in Hawkins life time.

Also, in my opinion, this is also lopsided ... Penrose discovered his topological singularity theorems single-handedly, Discovery of the MBH at the center of our galaxy is the very definition of a team effort. Yet only two people are recognized which is sort of strange.

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Re: Physics Discussion Thread

Postby Mort Walker » 08 Oct 2020 08:43

The Nobel Prize in Physics is generally for experimental physics. Theoretical physics takes years until the technology is available to demonstrate the phenomenon is correct.

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Re: Physics Discussion Thread

Postby Amber G. » 08 Oct 2020 09:25

Probably around 2/3 Nobels in Physics have gone to experimental Physicists. Maria Goeppert-Mayer (Nobel in Physics in 1963 - and only woman in Physics who won a noble after Mme Curie), when asked who does she think will win the Nobel that year said some thing to the effect " As a physicist she is good in puzzle solving, but 'of puzzles created by nature' not by the mind of man.” .... so the puzzle of who will win this year’s Nobel Prize in physics, your guess is probably as good as anyone else’s."
(Small tid-bit which I still remember - Maria Mayer visited IIT Kanpur in late 1960's) and one of her student was a faculty member for many years)

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Re: Physics Discussion Thread

Postby Amber G. » 09 Oct 2020 03:54

Along with Hawkins - there are two names - AK Raychaudhuri and CV Vishveshwara, among others.

Some of the foundational work on black holes was done by Indian scientists AK Raychaudhuri and CV Vishveshwara, among others.

Vishveshwara was cited in the first paper reporting gravity waves from black hole mergers (which won a Nobel Prize in 2017). And Penrose and Hawking gave the Raychaudhuri equation its name. Hawking and Raychaudhuri are no longer alive, and the prize could have been different had they been.
Image

One Nice Story: The 2 Unsung Indian Scientists Who Laid The Foundation For 2020 Physics Nobel Prize

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Re: Physics Discussion Thread

Postby Prem » 10 Oct 2020 04:15

https://www.msn.com/en-in/news/in-depth ... pf?ocid=st
Nobel for black hole physics

The speaker that day was none other than Roger Penrose, the hugely popular, now 89-year-old, theoretical physicist, mathematician, science philosopher and bestselling author who, on Tuesday, was rewarded with the Nobel Prize in Physics for his work on black holes. Penrose won half the Prize. Nandi of IISER, Kolkata pointed to the contribution of Indian physicist Amal Kumar Raychaudhuri in the work of Penrose and Hawking on black holes. Raychaudhuri, based at Presidency College in Kolkata in the 1950s, had produced theoretical results while working on general relativity and come up with an equation that is named after him. That equation, and his results, proved critical in the work Penrose and Hawking later produced.
“In fact, when I first asked Penrose if I could attend one of the courses being offered by him, he asked me where I was from. And when I told him I had come from Presidency, Kolkata, Penrose asked whether I was related to Amal Kumar Raychaudhuri. I told him I was not, but I had been taught by him. Hawking too was in the room,” recalled Somak Raychaudhury.

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Re: Physics Discussion Thread

Postby Amber G. » 10 Oct 2020 10:56

^^^ Intersting and glad that AKR (As Raychaudhuri is popularly known in Physics circle)'s story has been picked up by many Indian Newspapers ..

To add for those who are interested:
Raychaudhuri's equation played a key tool in Penrose's work for this year's prize. From what I know, "Raychaudhuri Equation" name was coined by Penrose or Hawkins. Raychaudhuri is fondly remembered and credited in Penrose's writing.

(From an article in 2018 - Photo of Hawkins & AKR)
Image

A good review article, written by Witten is given below for interested:
It is a nice introduction to causal properties of General Relativity,
Raychaudhuri equation, singularity theorems of Penrose and Hawking, the black hole area theorem, topological censorship, and the Gao-Wald theorem....

https://arxiv.org/pdf/1901.03928.pdf

(Ref in the above article (8) mentions Vishweshwara's work.. He was the first to identify what is now called a "black hole quasinormal mode" - this was measured by LIGO which won the 2017 Nobel).

(Like many physicist of my generation I have attended Penrose's lectures/seminars multiple times..He is well known in Mathematics, Philosophy, Art etc.. Among his brothers, one is well known Chess Grandmaster. There are many eminent scientists, artists among his brothers/uncles/parents/grandparents..)


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