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Contradictions Accepted As Valid?

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RadCap

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Can you explain why you think light is accepted as a contradiction? My understanding is that the ideas that light is a particle and that it is a wave are just models that help describe light's behavior. Nobody literally believes that light is actually both a wave and a particle, rather it is something else that has some aspects of both. The apparent contradiction occurs because we don't really know what that something else is, so we are stuck using imperfect models until we know more.

I would agree that the vast majority of today's physicists hold a sort of "model" view somewhat along the lines that you mention. But most people do not talk to today's physicists; rather they get their views from popularizers in the field. These popularizers tend to focus on some of the more overly-dramatic and bizarre interpetations, because these often sell well. So, for instance, they will read in Gribbin's wildly popular In Search of Schroedinger's Cat that "[t]he complete break with classical physics comes with the realization that not just photons and electrons but all 'particles' and 'waves' are in fact a mixture of wave and particle." It is not too difficult to discern how such a reader walks away with a sense of identity contradiction.

And, in fact, part of the blame lies with the very founders of quantum theory, people such as Born, Bohr, and Heisenberg. Bohr's physics/philosophical foundations grew out of his Hegelian "attempts at "analysis and synthesis" which explictly replaced causality with his notion of "complementarity." But, Bohr's writings are well-known for the obscurantism of a Kant, and his "complementarity" gained an almost mystical sense around it. In John Archibald Wheeler's magnificent compendium of original papers, Quantum Theory and Measurement," the great Leon Rosenfeld remarks (in his commentary prefacing a paper by Bohr):

"Complementarity is no system, no doctrine with ready-made precepts. There is no via regia to it; no formal definition of it can even be found in Bohr's writings ... Pragmatic Americans have dissected complementarity witht the scalpel of symbolic logic and undertaken to define this gentle art of the correct use of words without using any words at all.... [bohr] often evoked the thinkers of the past who had intuitively recognized dialectical aspects of existence and endeavored to give them poetical or philosophical expression."

(It is interesting to note, as Mara Beller, science historian, points in a September 1998 paper in Physics Today, "The Sokal Hoax: At Whom Are We Laughing," Bohr's obscurities are so great that a reprint of a paper of his in the Wheeler compendium I mentioned above, is printed out of sequence and, though often referenced, hardly any notice is ever given to the page sequencing mistake.)

The overall point here is, without going into great depth, that it is to the credit of today's physicists that they have extracted the mathematical and experimental value from the Copenhagen founders and have largely replaced the underlying Copenhagen philosophy with more practical concerns. Nevertheless, one sees in popularizations the Copenhagen ghost, often enhanced in a flowery manner with reference to some current philosophical darling who has no real grasp of the physics involved. It is not surprising that those who get their physics from today's popularizers, and those who with scholarship read the historical record of quantum development, arrive at much different views of the status of quantum physics then do many physicsts today who have adopted a more practical view.

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Almost no one in the field of gravitational physics expects Gravity Probe B to provide results that are not consistent with general relativity. Researchers in the field would love differing results (since that would indicate new physics), but few expect that.

What is this project? I haven't heard of it.

General relativity has withstood predictive verifications of light deflection,
Here's a question.

The formula for gravitational pull between two objects says it's the product of their masses and the gravitational constant divided by the square of the distance between them. But in the case of a photon, one of the masses (and therefor the final value) is zero. So according to my understanding of classical physics, photons should completely ignore gravity.

So why do planets, black holes, etc. have an effect?

As far as LIGO is concerned, I am quite familiar with the system. No one expects any significant results out of LIGO,

Gee, thanks. That's my job you're talking about, there. :(

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Here's a question.

The formula for gravitational pull between two objects says it's the product of their masses and the gravitational constant divided by the square of the distance between them.  But in the case of a photon, one of the masses (and therefor the final value) is zero.  So according to my understanding of classical physics, photons should completely ignore gravity.

So why do planets, black holes, etc. have an effect?

Classical Physics is different from Modern Physics.

Light bends because of the curvature of space-time.

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What is this project? I haven't heard of it.

The ironic thing is that the project is older than you, but was stillborn until last April. It is a very sophisticated space-borne experiment designed to test certain aspects of general relativity. It was originally conceived back in the 1960s but it finally became a full reality in the past few years. Here is a pointer to a web site on the project.

(Interestingly, it appears that one aspect that Gravity Probe B was designed to detect, the Lense-Thirring effect, may have been scooped recently by a much more modest re-evaluation of previous data by another group. If this analysis turns out to be correct, then this other group gets the credit for first detecting the effect, though everyone still awaits Gravity Probe B's confirmation, which will be to a far greater degree of precision.)

Here's a question.

The formula for gravitational pull between two objects says it's the product of their masses and the gravitational constant divided by the square of the distance between them.  But in the case of a photon, one of the masses (and therefor the final value) is zero.  So according to my understanding of classical physics, photons should completely ignore gravity.

So why do planets, black holes, etc. have an effect?

The formula you refer to, Newton's law of gravitation, has been known for some time not to be able to account for a great deal of gravitational phenomena. That fact was part of the motivation for Einstein to develop his general relativity. When some of this phenomena was discovered, such as the Newtonian discrepancy in the advance of the perihelion of the planet Mercury, attempts were made to modify Newtonian theory, including some who tried to lend an equivalent weight to light. These were all ad hoc attempts at corrections and they all resulted in abysmal failures. In general relativity the stress-energy-momentum tensor is the source of gravitation, not simply the mass of Newtonian theory. Thereby general relativity not only accounts for the anomalous advance of the perihelion of Mercury, but it successfully predicted a whole array of new phenomena, including the gravitational deflection of light. (It might interest you to know that in general realtivity two parallel beams of light do not affect each other gravitationally, but anti-parallel beams do. An interesting prediction of general relativity.)

Gee, thanks. That's my job you're talking about, there. :yarr:

I was referring, of course, to detection of gravitational waves. But, in what way is that your job? Do you work on the LIGO project?

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The ironic thing is that the project is older than you, but was stillborn until last April.
Heh. Better late than never, I suppose. :yarr: Thanks.

I was referring, of course, to detection of gravitational waves. But, in what way is that your job? Do you work on the LIGO project?

Indirectly. Two of the physics professors here at Loyola are involved with LIGO, and I'm a student research assistant for one of them. I don't yet have the physics expertise to even understand the science involved, but I am quite good at programming. Hence my job is basically to take some of the raw numbers that some of LIGO's instruments spit out, sort them, crunch them and turn them into useful graphs.

I think that technically I just work for my professor, not for LIGO itself (even though I'm payed out of his LIGO grant money). I'm not 100% sure on that, though. I'd have to ask.

The really sweet part of the deal is that the time I spend studying science and mathematics related to the job counts as work hours. Now if I can just get a similar deal for computer science and engineering course to go along with that, I'll be in great shape. :D

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Two of the physics professors here at Loyola are involved with LIGO, and I'm a student research assistant for one of them.  I don't yet have the physics expertise to even understand the science involved, but I am quite good at programming.  Hence my job is basically to take some of the raw numbers that some of LIGO's instruments spit out, sort them, crunch them and turn them into useful graphs.

Then you are probably not too far away from the Livingston facility. Let's see ... McHugh or Whelan? ... I'm guessing ... Whelan. :yarr:

LIGO is a great project to be associated with. A real theoretical and technical marvel, yet it is a learning process. The test bed for LIGO II that I saw was even more incredible. I think that the really significant results will be forthcoming when LIGO II comes on. Enjoy the work you are doing there.

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Then you are probably not too far away from the Livingston facility.

Within driving distance, I believe, although I've never been there (yet).

Let's see ... McHugh or Whelan? ... I'm guessing ... Whelan.  :D
BZZZZT! Sorry, no. I'm Dr. McHugh's wage-slave. But tell him what the consolation prize is, Bob! :P

Out of curiosity, what made you guess that it was Dr. Whelan? Do you know them?

LIGO is a great project to be associated with. A real theoretical and technical marvel, yet it is a learning process.  The test bed for LIGO II that I saw was even more incredible. I think that the really significant results will be forthcoming when LIGO II comes on. Enjoy the work you are doing there.

I like it so far, although for some reason the computer I work on seems to have it in for me (I #$%ing HATE LINUX!). I would probably be able to appreciate what a "great project to be associated with" it is if I understood more of it, but I suppose that will come with time.

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Within driving distance, I believe, although I've never been there (yet).

BZZZZT!  Sorry, no.  I'm Dr. McHugh's wage-slave.  But tell him what the consolation prize is, Bob! :P

Out of curiosity, what made you guess that it was Dr. Whelan?  Do you know them?

Whelan was just a pure guess. I do not them personally, but I know of them as part of the collaboration through LIGO at Caltech and I have read some of their work.

I like it so far, although for some reason the computer I work on seems to have it in for me (I #$%ing HATE LINUX!).  I would probably be able to appreciate what a "great project to be associated with" it is if I understood more of it, but I suppose that will come with time.

Yes, but the fuller understanding will come just in time for you to start a new project! :D

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Whelan was just a pure guess. I do not them personally, but I know of them as part of the collaboration through LIGO at Caltech and I have read some of their work.

Yes, but the fuller understanding will come just in time for you to start a new project!  :P

stephen,

I am curious.....what exactly do you do?

i.e. I know you are a "research scientist", but e.g. are you a member of a university faculty?, do you do any teaching?, or are you a researcher in a private or government facility?

As I say, I am just curious and will not be offended if you tell me this is none of my business. But as one reader in awe of the science thread (and your science posts in particular :D) I think there may be others who are curious too!

Brent

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stephen,

I am curious.....what exactly do you do?

I recently retired from Caltech where for almost 15 years I had the greatest job on campus. I started out working on a part of the human genome project, but I quickly evolved, along with another, into forming the Center for Computational Biology at Caltech. Most biologists are not well-trained in mathematics and physics, so through the Center I acted as a sort of consultant to various labs on campus, using mathematics, physics, and computers. Basically I was able to constantly work to solve the most challenging and interesting problems. Previously I worked for several research firms acting as consultants to groups like the Defense Nuclear Agency. I did a lot of classified work on nuclear research. Prior to that I was vice-president of an 800 man consulting firm, but, as you see, I left the business end because I much preferred the technical work. I am now working on a book about relativity, and, though I have not formally taught before, I am also thinking about teaching. I enjoy the process of explaining physics and mathematics to others.

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I recently retired from Caltech where for almost 15 years I had the greatest job on campus.  I started out working on a part of the human genome project, but I quickly evolved, along with another,  into forming the Center for Computational Biology at Caltech. Most biologists are not well-trained in mathematics and physics, so through the Center I acted as a sort of consultant to various labs on campus, using mathematics, physics, and computers. Basically I was able to constantly work to solve the most challenging and interesting problems. Previously I worked for several research firms acting as consultants to groups like the Defense Nuclear Agency. I did a lot of classified work on nuclear research. Prior to that I was vice-president of an 800 man consulting firm, but, as you see, I left the business end because I much preferred the technical work. I am now working on a book about relativity, and, though I have not formally taught before, I am also thinking about teaching. I enjoy the process of explaining physics and mathematics to others.

Thanks very much! That is interesting.

Actually, my wife is a biologist turned high school teacher. And her Masters is in "Biological Computation" from the University of York in the U.K. She did this in 1979-1980 (a one year taught Masters in math and computer programming for biologists) when biologists who could multiply and divide were a rarity and most of them wore garlands of garlic and carried sharpened oak staves if they had to pass through the computer room :angry: !

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