A number of people have commented on this LA Times op-ed by Steve Giddings about what physicists expect to come out of the Large Hadron Collider. It includes a nice list of possible particle physics discoveries plus a few things that will annoy Peter Woit, and also includes the obligatory note about spin-offs:
All this may seem like impractical and esoteric knowledge. But modern society would be unrecognizable without discoveries in fundamental physics. Radio and TV, X-rays, CT scans, MRIs, PCs, iPhones, the GPS system, the Web and beyond — much that we take for granted would not exist without this type of physics research and was not predicted when the first discoveries were made. Likewise, we cannot predict what future discoveries will lead to, whether new energy sources, means of space travel or communication, or amazing things entirely unimagined.
This is not by any means the main thrust of his argument, which is basically that we should build the LHC because the fundamental science it will uncover is really, really cool. And that’s a good thing, because the practical impacts of the LHC are likely to be totally insignificant. The list given above is a great argument for funding Bell Labs, but not the LHC.
I’m not denying that those technologies came out of fundamental physics research, but take another look at that list: “Radio and TV, X-rays, CT scans, MRIs, PCs, iPhones, the GPS system, the Web and beyond.” There is exactly one item on that list that originates in the era of billion-dollar accelerators, and that’s the web. The fundamental science behind the others all dates from before the founding of CERN in 1954.
The direct practical impact of the large accelerator era is pretty much negligible for the simple reason that you need a really big accelerator to observe the phenomena they study. All you need to generate X-rays is a couple of pieces of metal in a vacuum tube, and a current source. If you want to make a Z boson, you need many millions of dollars worth of gear. You’re almost certainly never going to see practical technologies based on the Higgs boson, because it takes a billion dollars worth of particle accelerator to make one.
Now, sure, the Web is a spin-off from particle physics research, though that seems to be as much an accident of history as anything else. It’s not like nobody else would ever hit on the idea of sending more than plain-text messages over the Internet, if there hadn’t been particle physicists. And it’s possible that dealing with data from the LHC will lead some Berners-Lee 2.0 to develop, I don’t know, full sensory holographic information transfer protocols, and twenty years from now we’ll all be struggling to remember what mere local physical reality was like. But really, if that’s what you want, you’d be better off splitting the $10 billion among a thousand computing and neuroscience labs, and letting them work directly on the problem.
In the large accelerator era, I wonder if we don’t need to make a distinction between “basic research” and what we might as well call “fundamental research” (though that term kind of bugs me for other reasons). What goes on in high-energy labs these days is so far removed from everyday energies that it might as well be astronomy, as far as practical impacts are concerned. You wouldn’t try to sell the Hubble Telescope to the public on the basis of potential spin-offs in imaging technology, and I’m not sure it makes any more sense to try to sell the LHC on the basis of possible spin-offs in computing technology (or whatever).
This is not to denigrate the study of basic physical principles, though. Basic research done at energies achievable on a reasonable scale is incredibly valuable, and leads to all sorts of unexpected technologies. Where the large accelerator era of particle physics has given us the web, the contributions of a basic research facility like the old Bell Labs are far greater. I don’t know if anyone has ever calculated the ultimate economic impact of all the devices invented at Bell Labs versus the amount of money spent operating it, but I bet they come out ahead of CERN, even if you use one of the more fanciful estimates of the worth of the Web.
If you want practical technologies to transform everyday life, what you want is Bell Labs working on devices that can be produced in large numbers and run off ordinary electrical lines, not the LHC which is necessarily a one-of-a-kind instrument. There are huge gains to be made from the study of basic physics at human-scale energies (high-temperature superconductivity, say), but nothing practical is likely to be based on TeV-scale physics.
Now, as I said, the spin-off argument is not the main argument put forward by Giddings, and it hasn’t been the primary line pushed by the particle physics community, probably because it failed so miserably with the SSC, back in the day. The organizations responsible for the LHC have done an outstanding job of selling their instrument on the basis of the way-cool things it will discover, to the point where their worst PR problem is not the cost of the device, but the infinitesimal probability that it will somehow destroy the Earth. And that’s as it should be– if we can spend hundreds of billions of dollars saving idiot financiers from their own incompetence, we can afford a few billion for the LHC, which is of infinitely more value to human civilization.
I should not to get into the either-or old argument (e.g pointing out it is not a zero um game etc.etc.). I just wanted to point out that any project of the magnitude of the LHC can be viewed as a large collection of individual engineering and computing projects, many of them never attempted before. So the possibility is spin-offs useful for all kinds of other engineering and computing goals, which have nothing to do with producing and investigating elementary particles, is very real. I would add to that also the training aspect: there is a large number of young people that will start their computing or engineering careers with a good challenging project.
This is a very fair point. While I don’t think the spinoffs are that important it is interesting to look at the data processing side of the LHC. If we did just give the money to computer scientists they would, quite rightly, go off and look a lots of interesting little problems. What the LHC does is to focus a large group of people on a very difficult problem. And then all the cascading problems that come with it. It breeds a level of cooperation you don’t normally get in academia.
If necessity is the mother of invention then they have the mother of all necessities. The processing requirements of the LHC are nothing short of spectacular. Perhaps just another way of looking at it.
Mainly the LHC is just really really cool.
Interesting that you mention Bell Labs. If it weren’t for their perfection of certain ideas like the semiconductor field, or even communications theory, we wouldn’t have the internet, computers, iPhones, iPods, or what have you.
The loss of Bell Labs is going to be felt for a very long time.
I would point out that there actually are industrial accelerator applications, and the advances in accelerator science used to find the Higgs will filter down into better, cheaper, safer, more efficient industrial accelerator technology.
The October issue of Symmetry was focused on this sort of thing. Here are some of the articles, for those who are interested in reading about them.
http://www.symmetrymagazine.org/cms/?pid=1000749
http://www.symmetrymagazine.org/cms/?pid=1000757
http://www.symmetrymagazine.org/cms/?pid=1000753
should not to get into the either-or old argument (e.g pointing out it is not a zero um game etc.etc.). I just wanted to point out that any project of the magnitude of the LHC can be viewed as a large collection of individual engineering and computing projects, many of them never attempted before. So the possibility is spin-offs useful for all kinds of other engineering and computing goals, which have nothing to do with producing and investigating elementary particles, is very real. I would add to that also the training aspect: there is a large number of young people that will start their computing or engineering careers with a good challenging project.
Sure, but by the same token, you could imagine lots of other large-scale engineering and computing projects that would also develop new and useful techniques, while also producing something of more immediate tangible benefit for society. And there are many projects and programs that can train young scientists and engineers in fields with more concrete applications than high-energy particle physics.
I would point out that there actually are industrial accelerator applications, and the advances in accelerator science used to find the Higgs will filter down into better, cheaper, safer, more efficient industrial accelerator technology.
Enh. I am dubious.
Looking at those Symmetry articles, they’re talking about accelerators on the MeV scale (at least, the only numbers I could find were in MeV, or even lower), which are very different beasts than the LHC (a millionth of the beam energy, for starters). We have one in the basement of the Science and Engineering center at Union, which we use for undergraduate labs and thesis projects. I really doubt that the issues involved in producing and controlling a beam at LHC energies are going to lead to dramatic breakthroughs in the production and control of MeV-scale particle beams. Especially since people have been working with MeV-scale beams for what, eighty years now?
Let’s look at it a little differently.
The LHC would not exist without Bell Labs.
To which we should add Texas Instruments, low temperature research into the properties of matter in the solid state, and the accelerator and detector innovations developed to do nuclear physics (CERN started out doing nuclear physics), but mostly we have to give credit to the basic research into semiconductors NOT basic research into the origin of muons, for those discoveries.
And the application of X rays was predicted when the basic physics discovery was made. The time lag between discovery and application was measured in weeks (maybe months) of the distribution of the photograph of Roentgen’s wife’s hand.
The sort of hubris we see in that op-ed piece is just what led to the cancellation of the SSC in Texas. You don’t get other physicists to support your basic research if you belittle what others do (who else remembers Leon Lederman’s attack on Rustum Roy) and don’t give credit where credit is due.
I think ever balloning costs and a poor communication about its benefits killed the SSC.
Those examples from Symmetry magazine are all based on devices developed to do nuclear physics or even atomic physics.
Good guess concerning 8 decades. Lawrence’s cyclotron and the van de Graaff were in 1931 and the Cockcroft-Walton in 1932, but MeV energies came a few years later.
BTW, that research was all privately funded!
Let’s see, according to Giddings, the LHC is going to explain dark energy (and it’s well-known that vacuum energy may someday be an energy source powering our civilization), it will discover dark matter (thus, according to a talk by a well-known physicist I heard last week, possibly creating a whole new technology based on new stable massive particles), it will “open new frontiers in the understanding of space and time”, and produce black holes (this will cause wormholes that allow us to time-travel as well as travel to other parts of the multiverse, according to some CERN physicists).
And you folks are arguing about whether it really will, as Symmetry magazine argues, help with the technology for sterilizing medical supplies?????
More worrisome might be the possibility that several years of LHC research will lead to respectable advances in our understanding of HEP, but nothing like what has been advertised to the public, creating a massive credibility black hole down which future funding for several areas of physics research will disappear…
Huh? Lawrence was a Berkeley professor, and the major cost of the cyclotron development was his salary.
The hardware costs were negligible and probably mostly out of lab stocks.
Similarly Cockroft and Walton were at Cambridge.
More worrisome might be the possibility that several years of LHC research will lead to respectable advances in our understanding of HEP, but nothing like what has been advertised to the public, creating a massive credibility black hole down which future funding for several areas of physics research will disappear…
I think there’s only a very narrow range of possible results that would really lead to a credibility problem for high-energy physics, at least based on what the LHC may or may not find.
As I understand it, things would need to be really dramatically weird for them not to find the Higgs, and that alone would be a significant enough development to justify the LHC (or to be sold as justification for the LHC, which is probably more relevant). Absolutely anything else that they discover would be the biggest particle physics result since forever, and again, ample justification for the LHC.
So, the “credibility black hole” situation is really only in play if they fail to find anything at all. Or if something does go horribly awry leading to the destruction of the Earth, which is only slightly less likely than the nothing-at-all case. Of course, the credibility black hole in the destroy-the-Earth case wouldn’t last very long…
I wonder to what degree understanding of condensed-matter physics details, phonons in particular, depends on techniques developed more recently than 1954 to understand quantum problems provoked by HEP investigations. Condensed-matter physics, of course, underlies every recent advance noted, one way or another, along with improvements in treating electromagnetic problems.
We could reasonably suggest that handing the LHC money to condensed-matter and applied electromagnetic physicists would produce overwhelmingly more important results.
One role of HEP/large accelerators projects seems to be ignored in this discussion; it is not just that HEP physicists themselves invent new items, such as many HEP experimentalists going into industry created or worked on
– detectors for medical imaging, based on HEP detectors,
– magnets for MRI from experience in designing accelerator magnets,
– software for breast cancer detection, based on cluster-finding algorithms used for finding clusters in calorimeters,
– software for radiation dose calculations in radiation oncology,
– proton or ion beams for radiation oncology,
– lower-energy electron beams for many applications, and so on;
it is also that these projects provide the first and most demanding customers for high-tech industry, and can create a new industry, or transform an existing one;
e.g. Fermilab’s Tevatron was the first large-scale user of superconducting magnets,
http://www.symmetrymagazine.org/cms/?pid=1000677
Before, you could order superconducting wire, but only in small quantities and with long delivery times, after the Tevatron, there was the industrial capacity to produce it, and suddenly there was a small industry in superconducting wires, magnets… and superconducting magnets appeared and became feasible in many applications (such as NMR magnets).
The stricter alignment requirements in the construction of accelerators probably also helped getting Laser alignment tools accepted in geodesy.
So there is a symbiotic relationship between HEP and high-tech industry; both HEP and industry benefit.
Of course, there is always a tension on how best to allocate limited research funds, and having many small projects may look more attractive; but if there were no LHC, would there indeed be more money for other projects?
I remember the chairman of another physics department telling former critics of the SSC something like ‘now that the SSC got canceled, you should have plenty of money for your [non-HEP] research from the money saved’ (After Congress cancelled the SSC in 1993, it decided to build another aircraft carrier, which the Navy didn’t want [high operating cost constraining future budgets]).
P.S. More on ‘The LHC meets industry:’
http://www.symmetrymagazine.org/cms/?pid=1000360
(Still more work done on fabricating superconducting wires and magnets, helping in the development of a superconductor industry)
I know that graphic tablet technology came from particle detection research. There were a number of interesting technologies back in the 70s using radio, ultrasound and capacitance, but they had all originally been developed for detecting particles at various labs. I found the ultrasound tablet to be physically painful and seriously nauseating. I nearly puked at the demo. I’m not sure of the energy levels of the accelerators, but this was around the time of the J/Psi, but well before the top and bottom quarks.
I wouldn’t underrate the value of shoving a whole pile of physicists together and getting them to work on some project or another. It barely matters which, and it doesn’t matter if they succeed or not. They’ll still come up with all sorts of neat stuff and spin off companies to market it.
In the context of this post, I find it particularly amusing that one of the main stated goals of the LHC seems to be finding Higgs. Let’s see. To the best of my knowledge, the Higgs mechanism was in fact understood by Anderson some years before Higgs. (Anderson did it in the context of superconductors, where the Higgs mechanism manifests itself through the Meissner effect: a photon acquires a mass inside a superconductor.) A Higgs boson itself was discovered back in 1981 by Littlewood and Varma, once again in the context of superconductors (Phys. Rev. Lett. 47, 811, 1981). The Higgs boson turns out to be not such an exciting particle, but this is beside the point. The irony, of course, is that all three — Anderson, Littlewood and Varma — were employed by *Bell Labs*, not CERN, SSC, Fermi Labs or whatever preceded those. Hence even from the pure physics point of view Bell Labs could give LHC quite a run for the money. The best the LHC crowd can claim now is that they are looking for the Higgs at *their preferred* energy scale (since it has already been found at ours). Could someone please remind me why their energy scale is so superior? Infinitely more expensive, yes. But does it mean we can necessarily draw a superior understanding of basic physical principles there? If anything, the history of the Higgs casts some doubt here.
Re the internet and the Web: I’m curious – what findings in basic physics promoted these technologies?
The Wikipedia doesn’t mention any basic physics in the History of the Internet article. And while Sir Tim Berners-Lee created the Web, his physics background appears to be accidental (as you say). Hypertext predated the internet, and Berners-Lee’s main insight was to implement the hypertext inside the internet.
As for bailing out incompetent financiers (as if you or anybody else could’ve done any better) – most economists think that shouldn’t have been done, either. But, as you say – if the West is so damn rich, why not indulge in economically unsound projects?
What baffles me is the HEP community’s steadfast unwillingness to back basic technological research on advanced accelerator concepts. For relatively small amounts of money (in HEP terms) we could find out whether these concepts were practical or not. If they were, then we could advance the energy frontier without having to build an accelerator the size of France. And I bet there would be a lot more interesting scientific and technological spinoffs from learning to control wakefields than from building gargantuan versions of the same old tech.
Certainly the Web, or something similar to it, would have been developed had CERN not existedâthere had been research on hypertext since the 1960s. However, I think the point is that CERN made a practical implementation of networked hypertext, one that worked on multiple platforms and under different operating conditions. It was developed for a specific use and we’re still suffering from design choices made for its specific environment, but it has been generic and flexible enough to grow spectacularly. However, I do not think merely piling money on CS departments would have created the Web. CS researchers do basic research as well, in their area. So, while the underlying ideas for the Web had been developed at CS labs, it required an actual real-life environment for them to be put together in a real-life-usable way (and note that this was some 25 years after the original tests of hypertext started).
So, on one hand the LHC may or may not produce usable spin-off effects unrelated to particle physics, but on the other hand the basic research done there may well give researchers ideas for doing sub-atomic things that do not require large accelerators, or allow us to make smaller accelerators, or come up with completely different ways of generating, say, Higgs bosons, and those ideas and products may not be obvious descendants of LHC technology and you might then thirty years down the line wonder if anything good came out of the LHC.
@18 what steadfast unwillingness? Wakefield and advanced accelerator concepts are backed by SLAC and other accelerator labs, and as soon as the engineering is ironed out we’re eager to start putting it to work. I’ve heard talk of using it in the ILC if the more ambitious forecasts about the proof-of-concepts bears out.
As far as gargantuan versions of the old tech, keep in mind LHC funding was first approved in ’95, before wakefield had begun to mature. There’s also the issue that funding agencies are notoriously adverse to “lets try this new idea in our machine” without lots of proof-of-concept work.
Or a particle accelerator!!!
” However, I think the point is that CERN made a practical implementation of networked hypertext, one that worked on multiple platforms and under different operating conditions.”
Perhaps most importantly it wasn’t a proprietary walled garden like AOL or Compuserve, but used a bunch of free standards that anyone could use.
I have no problem with the use of conventional tech on the LHC–clearly advanced concepts weren’t ready then because they’re not ready now. But there seems to be no urgency to getting them ready as soon as possible (or proving that they won’t work) even though they would have game-changing implications (and could be ruled in or out with relatively modest sums).
What I mean by “steadfast unwillingness” is that every time I read a story about physicists getting together to figure out what to ask for after the LHC they always discuss conventional accelerator designs and never talk about waiting to build new machines until we know whether we can do this better and cheaper using new technology. We keep hearing about proposals for conventional accelerators that aren’t as powerful as the LHC but will still cost huge amounts. If you draw out a decision tree, this behavior does not look very rational.
The amount of money going into proving or disproving the advanced concepts is derisory, which makes the results obtained to date somewhat more impressive. But without a full-court press for technology studies, we’ll be right back in the same place in five or ten years, planning conventional accelerators because advanced concepts are still unproven.
@10: That was my point. Those projects were privately funded, although Lawrence did not pay for the 184″ cyclotron out of his salary. IIRC, that came from private donors and federal funding for his research did not appear until WWII.
@13 and @21: Thanks for some more examples of hubris. Those accelerators used for cancer treatment grew out of nuclear physics research back when particle physicists were still climbing mountains or going up in balloons. Ditto for energy loss curves at MeV energies. Please stop pretending that high energy particle physics can take credit for everything done in nuclear and atomic physics. Further, I believe commercial laser alignment devices were developed to lay sewer pipe, not survey a circular ring.
It is true that FNAL created a market for superconducting wire and refrigerators that helped make research in other fields more affordable, but that has not helped push superconductors into the commercial power transmission market. That requires a higher operating temperature that will only come from condensed matter research. Similarly, the greatest advances in magnet technology have been in small permanent magnets where cost and weight matter.
And if what is found at the LHC exposes some physics that can be explored without high energy accelerators, as was suggested @19, that means you could make the discovery without a high energy accelerator. Some examples were alluded to by Chad in the past.
@16 “The best the LHC crowd can claim now is that they are looking for the Higgs at *their preferred* energy scale (since it has already been found at ours).”
Please tell me no one is this stupid. What you found were goldstone bosons. To not understand this (and the differences with the higgs) is staggering.
Well, I would really hate to descend to the level of calling people stupid, but @25 is apparently this arrogant… or ignorant… or, wait, what was that word he/she used? You got it…
At any rate, I suggest you check a paper by Varma: “Higgs Boson in Superconductors” Journal of Low Temperature Physics, 126, 91 (2002) or cond-mat/0109409, which give a nice and rather pedagogical account of this issue. In particular, its reference 6 states that “It was pointed out by Y.Nambu and P. Higgs that the modes derived in Ref.[5] were the equivalent of the Higgs Bosons for superconductors. See, Comments by P.Higgs,
page 509 and by Y. Nambu page 514 in ‘The Rise of the Standard Model’, Edited by L.Hoddeson, L. Brown, M.Riordan and M. Dresden, Cambridge University Press (Cambridge 1997)”
Now, reference [5] is the original Littlewood-Varma paper I have mentioned earlier.
It’s just getting to the point where we can speculate if any mass-producible benefits to society will come out of LHC research. So the field is wide open to imagination, which is why (I guess) you can get dozens or hundreds of comments on it in a blog article.
I think the main point is that the LHC people did a pretty good job of selling the idea by sticking to the idea that what it will do is worthy of the investment in its own right.
They recognized that research funding doesn’t have to come as a result of investors seeing the end game before you start. They took a risk based on the idea that people also love really big projects that go after huge deep questions such as “what really happened at the very instant the universe was born?”
So I’m thinking that it was on the level of “let’s put a man on the moon”. NASA didn’t have to tell everyone that we would see vast improvements in the quality of green cheese as a spinoff of putting men on the moon. The idea was so big and so cool, it could sell itself.
The LHC people took that risk, and it paid off. Of course there were some delays and cost increases, but everyone already knew that was going to be the case with any huge engineering project, and of course it didn’t work perfectly on the first day it was fired up, but again, no one who had a good understanding of the project was surprised by that either.
So I think we can’t tell what the spinoffs will be, just as we couldn’t tell in 1905 what the spinoffs of general relativity would be. Maybe by the end of the 21st century we see what the spinoffs will become.
It’s true that right now, it takes a huge billion dollar machine to make a higgs particle. But this can be countered by two possibilities: 1. there may be benefits of the research that don’t depend directly on making your own higgs particles, and 2. it’s possible there will be more efficient ways to make them with smaller machines in the future. In the 1950s, for example, no one thought that gigabytes of processing power would by given away to poverty-stricken kids in Nigeria, who would be able to do computing tasks with only a few weeks a of training. In those days, you needed a facility that cost millions of dollars to make a computer, and surely schoolkids in Nigeria don’t have that kind of capability, right?
So I think that shows the flaw with the argument that “it costs too much to make one”, because in 80 or 100 years, that may not be the case. We simply don’t know yet.
But, as the LHC development team was so savvy to argue, the fact that we don’t know that stuff now is not important. What is important is that it takes us a level deeper into attacking some of the really big and deep philosophical questions about the universe, which is what drives people to be interested in science in the first place.
So I respect that they made the decision to just go for promoting it on its own merits.
Why the emphasis on the LHC’s economic return? Not all human activities need to be directly beneficial to the functioning of society as defined by capitalist economics. Painters obsessively reworking their forms, gardeners tending their beautiful flowers, children playing hide and seek, lovers kissing; these are all worthwhile activities. Economics is not an end unto itself – our lives are incomplete without meaning. For more on this refer to any of a number of distopian movies that envision a future whose primary value is consumption (you might start with “THX-1138”). Discovering the nature of the universe is as essential a human activity as an infant studying its own hands to determine that it has causal influence in the world.
As somebody who worked with accelerators, albeit a small 3 MeV dynamitron, the main spin offs for the LHC or the SSC was in the amount very high tech, high quality components needed. Beamlines take miles of tubing, valves, vacuum pumps, gauges, sensors and a host of things that make the rest of the high tech world possible. It could be compared in some ways to the auto industry as a generator of blue collar and white collar jobs that actually create tangible objects and require skill to make. Keeping the PhD’s off the streets so they don’t go inventing exotic financial instruments like derivatives is a side effect.
LATEST FUNDAMENTAL PHYSICS DISCOVERIES.
My comment is on your sentense, “In the large accelerator era, I wonder if we don’t need to make a distinction between “basic research” and what we might as well call “fundamental research” (though that term kind of bugs me for other reasons)”. Money spent for this work was very limited that is for a Gamma ray Spectrometer, radioisotopes and XRF sources. Anyone who does fundamental research has to devote several years. The research study lasted nearly 21 years from the begining (1988) to publishing (March 2010.
The website
http://en.giswiki.net/wiki/User_talk:Raomap
is a key ro explain what are the Six Fundamental Physics Discoveries in the paper published in a peer reviewed journal:
PADMANABHA RAO, M. A.. UV dominant optical emission newly detected from radioisotopes and XRF sources.
Braz. J. Phys. [online]. 2010, vol.40,
n.1, pp. 38-46. ISSN 0103-9733.
[doi: 10.1590/S0103-97332010000100007.] [1]
http://www.sbfisica.org.br/bjp/files/v40_38.pdf
1. The FIRST EXPERIMENTAL DISCOVERY : UV dominant optical emission from radioisotopes present as radiochemicals.
2. The SECOND EXPERIMENTAL DISCOVERY : UV dominant optical emission from XRF present as salts.
3. The THIRD EXPERIMENTAL DISCOVERY : UV dominant optical emission from metals at room temperature when present as radioisotopes or XRF sources.
4. The FOURTH DISCOVERY : Bharat radiation (predicted).
5. The FIFTH DISCOVERY: Bharat radiation causing a new class of Atomic Spectra of solids (solid radioisotopes and XRF sources) at room temperature.
These Atomic Spectra of solids could be significant breakthrough in the history of atomic spectroscopy.
6. The SIXTH DISCOVERY: Previously unknown atomic phenomenon explaining how Bharat radiation, the first generation of gamma, X-ray, and beta, and UV dominant optical emission the second generation takes place from from one and the same excited atom in radioisotopes and XRF sources.
M.A. Padmanabha Rao, PhD
Former Professor of Medical Physics, New Delhi, India
raomap@yahoo.com