Physics Discussion Thread

Amber G. · Post by **Amber G.** » 23 Sep 2011 21:16

May be of interest to some:

Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

(Some how, this story got quite a bit of exposure in many main-stream news sources.. eg)
Faster than light measurement shocks physicists

ramana · Post by **ramana** » 23 Sep 2011 22:39

So what does that mean to Einstein's law?

Amber G. · Post by **Amber G.** » 23 Sep 2011 23:04

^^^ We have to wait and see, but I am doubtful if the results will stand. (Its about 60 ns difference,or equivalent to about 20 meter with path of several hundred kilometers - difficult to measure exact distance through earth)

Meanwhile, major LOL ... following I-phone messages going between our two sons and us.

Younger son: (An engineer, at present in China) "He orders a drink (An Italian neutrino walks into a bar in Geneva) - Is it really true?"

Older son: (A physics PhD who at present is at CERN Switzerland): " I don't think so. ..

Btw, the neutrino is Swiss, and visits Italy."

Younger son: "Nope, it's Italian and visits Geneva. Remember, it's going faster than c"

ramana · Post by **ramana** » 24 Sep 2011 00:17

Mort Walker · Post by **Mort Walker** » 24 Sep 2011 07:37

I haven't been following this too closely, but I personally believe this to be a measurement error that will be corrected with following experiments.

http://public.web.cern.ch/public/

SaiK · Post by **SaiK** » 24 Sep 2011 09:54

Simply put, it appears that they have now N that is faster than C.

Now, how much faster is neutrino > speed of light?

CERN reported that a neutrino beam fired from a particle accelerator near Geneva to a lab 454 miles (730 kilometers) away in Italy traveled 60 nanoseconds faster than the speed of light. Scientists calculated the margin of error at just 10 nanoseconds, making the difference statistically significant.

--->>it is a tiny delta!.. any measurement errors?

http://timesofindia.indiatimes.com/home ... 089574.cms
so, ToIlet can talk phyjix too.

negi · Post by **negi** » 26 Sep 2011 06:30

Doesn't Neutrino by definition have non zero mass ? And yet they were found to be travelling faster than light ?

Rahul M · Post by **Rahul M** » 26 Sep 2011 10:14

it might well be a measurement error.

Amber G. · Post by **Amber G.** » 26 Sep 2011 20:43

negi wrote:Doesn't Neutrino by definition have non zero mass ? And yet they were found to be travelling faster than light ?

I don't know what you mean "by definition" but people have wondered about its mass. Actually standard model assumed that neutrinos are massless, although one can (ad did) add massive neutrino's to framework. In early days one, experiments told us that either they are mass-less, or has very small mass. Phenomenon of neutrino oscillation (which was experimentally observed in 1990''s) requires neutrinos to have nonzero mass. The upper limit is less than eV...

Any way, even assuming the upper limit of mass, the difference in velocity due to effect of mass of (a 17Gev) neutrino would be something like 10^(-19) - 10 billion billionth!

negi · Post by **negi** » 26 Sep 2011 20:52

^ This is what puzzles me so does it mean that one can consider a neutrino to have mass or no mass depending on the situation ? Even if it has zero rest mass; theoretically won't it's max speed will still be limited to 'c' (as per the mass energy equivalence ) ?

Amber G. · Post by **Amber G.** » 26 Sep 2011 21:46

^^^In physics, one goes by what one can measure. All we know that neutrino mass is less than a eV or so. Whether its mass is zero or very small the effect on its max. velocity is small - very small. The difference measured is about 60 ns, mass component will contribute much less than millionth of that.

(We have seen neutrion's from supernova far away and seen photons and neutrino's arriving at (virtually) the same time --BTW if those (super nova) neutrinos traveled as fast as the recent claim, one would have seen them about a year or more before photons - but we have not seen that - but we also know the big difference - that CERN neutrinos have much higher energy)

Since neutrinos are very hard to detect/study we know very little. Sudarshan has talked about tachyons (faster than light particles) and some have talked about tachyonic neutrinos.

Few post above, I talked about a lecture I heard (about topological insulators) about Majorana fermions... well some say (no one knows for sure) that neutrinos may be Majarana fermions (in contrast to regular elections, protons etc which obey Fermi statistics and are fermi-fermions).

In any case, interesting times ahead .. Not too many think that neutrinos are faster than light (even the authors of the paper are skeptic) but we are sure to learn more about neutrinos (Sudarshan may get his Nobel)

Bade · Post by **Bade** » 26 Sep 2011 21:46

Reasonable doubt

If MINOS were to confirm OPERA's find, the consequences would be enormous. "If you give up the speed of light, then the construction of special relativity falls down," says Antonino Zichichi, a theoretical physicist and emeritus professor at the University of Bologna, Italy. Zichichi speculates that the 'superluminal' neutrinos detected by OPERA could be slipping through extra dimensions in space, as predicted by theories such as string theory.

Ellis, however, remains sceptical. Many experiments have looked for particles travelling faster than light speed in the past and have come up empty-handed, he says. Most troubling for OPERA is a separate analysis of a pulse of neutrinos from a nearby supernova known as 1987a. If the speeds seen by OPERA were achievable by all neutrinos, then the pulse from the supernova would have shown up years earlier than the exploding star's flash of light; instead, they arrived within hours of each other. "It's difficult to reconcile with what OPERA is seeing," Ellis says.

http://www.nature.com/news/2011/110922/ ... 1.554.html

Amber G. · Post by **Amber G.** » 26 Sep 2011 22:10

^^^ Thanks, very nice link.

...Most troubling for OPERA is a separate analysis of a pulse of neutrinos from a nearby supernova known as 1987a. If the speeds seen by OPERA were achievable by all neutrinos, then the pulse from the supernova would have shown up years earlier than the exploding star's flash of light; instead, they arrived within hours of each other. "It's difficult to reconcile with what OPERA is seeing...

I mentioned this in my previous post.. one non-trivial difference being mentioned is that energies of CERN neutrinos are much higher than 1987a supernova.

SaiK · Post by **SaiK** » 26 Sep 2011 22:58

It always confuses me on how does one measure something that does not have mass and dark in nature?

Nandu · Post by **Nandu** » 27 Sep 2011 05:02

Amber G. wrote:^^^ We have to wait and see

Are you sure? Maybe we should check the archives, instead? The confirmation might have been posted int the past.

Amber G. · Post by **Amber G.** » 27 Sep 2011 08:50

Anujan · Post by **Anujan** » 27 Sep 2011 10:50

The bartender says "we dont serve your kind here".

A Neutrino walks into a bar.

Amber G. · Post by **Amber G.** » 27 Sep 2011 22:42

Power Point presentation of the CERN talk is worth watching. I am sure it's on cern's website, but if there is interest, I can put the link to a copy I have.

One who has seen the original talk/presentation, told me that the authors are quite cautious. In Q&A period, they wanted and divided the questions along ideas about statistical error / ideas about systematic errors / what they might have missed etc and request that no questions be asked for theoretical implications. They checked / rechecked everything for last 6 months before going public.

Meanwhile, it is quite impressive to see the sophistication of the measuring devices, and I am sure there will be many side benefits.

BTW the last line of the PP slide is:

We do not attempt any theoretical or phenomenological interpretation of the results

gakakkad · Post by **gakakkad** » 28 Sep 2011 08:47

^ post the links...

Amber G. · Post by **Amber G.** » 28 Sep 2011 09:21

^^^ Here is a pdf copy (google docs)
Measurement of the neutrino velocity with the OPERA detector in the CNGS beam - Dario Autier PP

Amber G. · Post by **Amber G.** » 29 Sep 2011 09:08

Meanwhile - Tevatron is closing.

Mort Walker · Post by **Mort Walker** » 29 Sep 2011 09:16

^^^Yep. Its absolutely shameful on the Ombaba administration when they couldn't gather up $35 million to operate the tevatron through 2014. Just cut $35 million aid to Pakistan and give it to the DoE. I get the feeling that this administration is hostile to the mathematical based sciences. Meanwhile DoE is dumping good money after bad with solar energy that costs $1.50 KWHr. Even if KWHr prices could be brought down to $0.50, that would still be too costly.

gakakkad · Post by **gakakkad** » 29 Sep 2011 16:24

Mort Walker wrote:^^^Yep. Its absolutely shameful on the Ombaba administration when they couldn't gather up $35 million to opete the tevatron through 2014. Just cut $35 million aid to Pakistan and give it to the DoE. I get the feeling that this administration is hostile to the mathematical based sciences. Meanwhile DoE is dumping good money after bad with solar energy that costs $1.50 KWHr. Even if KWHr prices could be brought down to $0.50, that would still be too costly.

its even hostile to biological sciences ..

Perhaps Donald Trump had a point after all , when he questioned Om-Baba's brains and wondered how he got into Harvard/Columbia

..

Amber G. · Post by **Amber G.** » 02 Oct 2011 00:58

Yes Tevatron is closing but Fermilab will still have an accelerator and it will have an upgraded intensity (Nice name: Project X

)

Meanwhile, a new book some may find interesting:

More at WPost story:
New book about Feynman

Amber G. · Post by **Amber G.** » 02 Oct 2011 02:50

^^^

It is a sad fact — an endlessly rehashed symbol of just what is wrong with America — that we make heroes of athletes but not mathletes, that we write comic books about men with capes but not real men with calculators, and that “Dancing With the Stars” has never tapped Andre Geim or Konstantin Novoselov, who — oh, admit it, you had to Google them — were last year’s winners of the Nobel Prize in physics.

The Link to Feynman comics:
http://www.amazon.com/gp/product/159643 ... 1596432594

Mort Walker · Post by **Mort Walker** » 02 Oct 2011 09:58

The Fermilab Tevatron was/is capable of 1 TeV and Project X is 8 GeV energies. A big difference I would say, although both are for looking at different things.

Amber G. · Post by **Amber G.** » 04 Oct 2011 09:19

Saul Perlmutter, Brian Schmidt and Adam Riess .. wins Physics Nobel.

Amber G. · Post by **Amber G.** » 04 Oct 2011 20:35

Interesting anecdote about Perlmutter, (this year's winner) ...people who knew and worked/(got taught by) him became objects of tons of insults (and even threat of lathi-charged) in BRF. Even his thesis adviser (Muller) and mentor, whom I have quoted multiple times in nuke-dhaga (and who might be the first person to coin "banana equivalent dose") got mocked by a few "experts" here in brf.

Amber G. · Post by **Amber G.** » 06 Oct 2011 03:40

Popular article about this year's Nobel
Why Einstein Was Wrong About Being Wrong

Rudradev · Post by **Rudradev** » 07 Oct 2011 07:16

parsuram wrote:Rudra Guru:

Would gladly send you a copy to any email you provide.

Parsuram ji,

Sorry, I just saw this... I don't look in the Purdah forum very often.

My email is rudradev DAWT brf ATT gmail

Please do send me your essay at your convenience, thanks.

Amber G. · Post by **Amber G.** » 10 Oct 2011 07:48

Amber G. wrote:^^^
It is a sad fact — an endlessly rehashed symbol of just what is wrong with America — that we make heroes of athletes but not mathletes, that we write comic books about men with capes but not real men with calculators, and that “Dancing With the Stars” has never tapped Andre Geim or Konstantin Novoselov, who — oh, admit it, you had to Google them — were last year’s winners of the Nobel Prize in physics.
The Link to Feynman comics:
http://www.amazon.com/gp/product/159643 ... 1596432594

Had a chance to spend some time with the author. Interesting concept to have a comic book ("graphic book").. for such a subject.

Also the Chemistry Nobel this year was more physics...

gakakkad · Post by **gakakkad** » 10 Oct 2011 20:36

^^^ the guy will consider himself lucky..to pocket the 1.5 mill all to himself...if he was given the physics prize he would have to share it it rest of them...

Amber G. · Post by **Amber G.** » 10 Oct 2011 21:14

^^^ Actually more lucky according to a friend of mine, who told me that the prize should have at least been shared with his thesis adviser, who was the real pioneer in that field....

Amber G. · Post by **Amber G.** » 10 Oct 2011 21:38

gakakkad wrote:^^^ the guy will consider himself lucky..to pocket the 1.5 mill all to himself...if he was given the physics prize he would have to share it it rest of them...

Reminds me of the time when I was at a party to celebrate Physics Nobel given to one of our guru. It was late, most people left except for a very few guests. One of them (I think he had quite some wine) who was acting quite friendly to the guy asked,

"So buddy, how much (dough/money) have you made?"

Since the prize was shared, he answered. (It was a few thousand dollars).

The person who asked the question couldn't hide his surprise and blurted out:

"So why such a big deal ... I make more than that every year"

(He was a surgeon , a faculty member in the same university but making much more money than a physicist)...

BTW in those days...On the east cost ... starting salary of an assistant professor in Physics in City University of New York was less than starting salary of a sanitation worker ... both being hired by the City of New York) ...

gakakkad · Post by **gakakkad** » 11 Oct 2011 17:08

^^ lop-sided are the ways of the world..smartest get the least dough ...Though in a decades time i predicts docs will be joining sanitation workers...thanks to ombabacare , and mba's and the useless wall street that might well be transplanted to pakistan..

the 2009 chemistry winner , Ventak raman Ram krishnan studied in Baroda , Gujarat ..for some time he was my dads neighbour... Though dad never remembered him..the guy won the nobel in 2009..dad could not still remember the chap... An year or so ,ago he visited baroda and was felicitated by his alma mater , The MS University... dad being in the Univ senate was invited... they had a brief converstation.. dad learnt that the guy does not own a car.. And part of his nobel prize money would go in paying some loan.. that emailed me the whole coversation.. felt quite said...

Amber G. · Post by **Amber G.** » 11 Oct 2011 21:33

^^^Interesting anecdote about Ventakraman Ramkrishnan.. BTW the story about the party I told about happened at the same institute where VR was a grad student (or post doc?) around the same time (or within a few years).

To me, your story is even more remarkable because, I believe VR's *both* parents taught at university in Baroda (MS University) ... anyone connected with the university should have known the parents at least, as there were not that many scientists in biochemistry..and rarer still where *both* parents are in the same field.

BTW, well known story about VR (he himself has told it) is that he did not get into IIT or the Medical School of his choice...so went into physics (his PhD was in physics) and later moved into biochemistry/medicine .

Bade · Post by **Bade** » 12 Oct 2011 21:53

That smartest gets the least dough....is proof enough that money alone does not guarantee high productivity. Medics are overpaid beyond most professions in most places and often are found wanting. Even a close friend who turned from physics to medicine, claims it is all about drug peddling sanctioned by authority.

ramana · Post by **ramana** » 12 Oct 2011 22:10

Not really. He is being cynical. If he truly beleived it why isn't he back in physics.

Medics do save lives in the end.

Bade · Post by **Bade** » 12 Oct 2011 22:17

They do save lives as in extending the life-span, but there is definitely a collusion with pharma interests too. In fact surviving in physics with a career is even more difficult than in the medical profession, even when paid low.

Amber_G or Alok_N can definitely say for sure as they seem to have been in the field for very long.

The attrition rate is quite the opposite for the two fields. Less than 1% physics professionals (with MS/PhD) continue in academics doing physics, just because there really are no toe-holds to remain in the field doing research following a post-doc if not converted to a faculty position during your post-doc years. Almost 99% medics continue in the field, since there are many options and specialties.

gakakkad · Post by **gakakkad** » 13 Oct 2011 08:36

" Medics are overpaid beyond most professions in most places and often are found wanting."

IMHO , lawyers and mba's are overpaid beyond most professions...\physicists and other researchers are the most underpaid profs.. in comparison to docs... most docs are paid ok...some are overpaid ..some underpaid..(primary care)
In fact I do agree with ramana.... tragically societal pressures and money play a larger role than talent or interest in deciding ones occupation...especially true for Indians...

In finland univ prof's and school teachers are the highest paid profs...I dont know if it would be practical for US or India to have that system...

anyone connected with the university should have known the parents at least, as there were not that many scientists in biochemistry..

vr's dad had briefly taught my dad... in fact only when the local newspapers mentioned his dads name and photograph dad realised who he was...though I did not get an opportunity to meet him , I was told he his a nice chap..quite introvert...

That he failed to get into IIT/PMT shows ,how badly the Indian system needs to change for good...

In 1940's Jack Kilby (father of Integrated circuit , Nobel physics 2000) failed to get into MIT... I imagine the American system in those days was pretty much like that of India today...only thing is that things in India are resistant to change...