jona@nikhefh.UUCP (Jona Oberski) (09/25/87)
What would YOU answer to the following: Question: Which things - common instruments, consumergoods, etc. - would not exist if we would not have Einstein's Theory of Relativity: "ETR"? Some guys want to produce Yet Another Popular Video On Relativity: YAPVOR. It is intended for the general public, the more general, the better. They asked the question and I answered: none; promising to ask you too. I suppose the idea behind the question is clear to you, but let me explain some interpretations of the question, which are certainly NOT meant. U1. To unknow ETR is NOT meant to imply that physical phenomena would actually be different form the known phenomena. U2. To virtually change anything in human history, like ETR, is NOT meant to imply that EVERYthing could be different now (which probably would be the case though). U3. "Things not existing" are NOT meant to point to Philosophical Implications of ETR, except perhaps, if they are determinants of many people's everyday life. I'll be glad with any answer, but please keep in mind these exclusions, since the YAPVOR makers aim to explain things in terms of everybody's common experience. Some answers (and some comments): A1. No nuclear energy, nor bombs. (????). A2. No lasers. (??; hardly common experience). A3. No high-energy physics research (!!!!; no common experience). By the way, do you like the idea: "The only commonly-known physicist's theory is without practical value". Hope to read from you. Bye now. Jona@nikhefh.uucp P.S. Please forgive me my Dutch.
gwyn@brl-smoke.ARPA (Doug Gwyn ) (09/27/87)
If it doesn't help produce beer, television programs, or condoms, it is of no value to "the common man". That doesn't mean it has no practical value to the human race as a whole, however.
smoliar@venera.isi.edu.UUCP (09/29/87)
In article <391@nikhefh.UUCP> jona@nikhefh.UUCP (Jona Oberski) writes: > >What would YOU answer to the following: > >Question: Which things - common instruments, consumergoods, etc. - would not >exist if we would not have Einstein's Theory of Relativity: "ETR"? > >Some answers (and some comments): >A2. No lasers. (??; hardly common experience). Hardly? I think not. Certainly compact disc players have reached a point of abundance where they can count as "common experience." Also, in this country it is getting increasingly difficult to find a merchant that does not use a laser-scanned price code. Lasers have very much become a part of everyday life, to the point that often we don't notice them.
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (09/29/87)
In article <391@nikhefh.UUCP> jona@nikhefh.UUCP (Jona Oberski) writes: > >What would YOU answer to the following: > >Question: Which things - common instruments, consumergoods, etc. - would not >exist if we would not have Einstein's Theory of Relativity: "ETR"? > Very interesting. The first "practical application" of relativistic effects in a "product" was in a Defense Dept navigation system called the "Global Positioning System (GPS)". GPS is currently in service to the US military in "super-accurate" mode and to civilians in coarse mode, like shippers and surveyors, who can pay for a GPS receiver which was $50k three years ago when I last worked on navigation systems. GPS uses a constellation of satellites traveling well-tracked routes and the Doppler effect to let the receiver determine precisely where it is and how fast it is going. GPS is quite an advance in satellite-based nav systems. So where does relativity come in? Well, the satellites are 'up there' a hundred miles where the gravity/acceleration field is different. GPS is so accurate that they need a relativistic correction to the satellite clocks (cesium, I believe) to keep them in sync with terrestrial clocks. First instance, I believe. It's been a while since I thought 'nav'. It would be interesting if anyone out there knew more details of the relativistic correction. Unlikely, I guess, unless there is some other refugee from the Stars Wars universe on this internet. So if you are a sailor or you are out on the high seas looking for oil or sunken treasure, know that Einstein had much to do with how well you know where you are in that big pool of water. -- ------------------------------------------------------------------- Kent W. England | Boston University Network & Systems Engineering Group | Information Technology kwe@bu-it.bu.edu internet | 111 Cummington Street itkwe@bostonu BITnet | Boston, MA 02215 harvard!bu-cs!kwe UUCP | (617) 353-2780 -------------------------------------------------------------------
wyant@eplrx7.UUCP (10/01/87)
In article <391@nikhefh.UUCP>, jona@nikhefh.UUCP (Jona Oberski) writes: > > What would YOU answer to the following: > > Question: Which things - common instruments, consumergoods, etc. - would not > exist if we would not have Einstein's Theory of Relativity: "ETR"? > > Some answers (and some comments): > A1. No nuclear energy, nor bombs. (????). > A2. No lasers. (??; hardly common experience). > ... > By the way, do you like the idea: > "The only commonly-known physicist's theory is without practical value". A1) Despite Eistein's aversion for the oversimplified expression "E = mc^2", two young physicists at the time were stimulated by this expression to consider the release of energy by the transmutation of matter through fission (I wish I could recall their names). They were told that it wasn't feasible by Einstein, but the same concept must have occurred to others. The possibility of the release of atomic energy through fission was openly discussed in the technical literature before WWII, with the war putting a damper on any further discussion. The famous energy and mass expression is one consequence of ETR. It is likely that the release of atomic energy (bombs, reactors) would still have been realized, even if E=mc^2 wasn't around for conceptual guidance, through the work of Rutherford et al. A2) Einstein did contribute to an understanding of the laser, but not through special relativity. Einstein developed a simple model for electronic transitions in atoms (for those specialists, recall the Einstein A and B coefficients) which provides a good description of the lasing process. Again, my memory fails, but there is a good book available by a philosopher/sociologist of science which argues that special relativity is not a theory of physical interactions but rather a theory of measurement. Newton's physics assumed and left unstated the procedures by which measurements on physical systems are made (recall the absolute reference frame which is implied by Newton). Einstein merely clarified the procedures by which measurements on physical systems are conducted, and their limitations. From this understanding of how measurements are made, all sorts of consequences for how physical theories must be constructed and the effects can be demonstrated (e.g., speed of light limits, time dilation, etc.). In carefully specifying the limitations of measurements for classical physical systems, special relativity has had a profound effect on practicing physicists since the 1920's. All particle accelerators have been designed assuming that special relativity is rigorously correct. Patrick Wyant Engineering Physics Lab E.I. du Pont de Nemours Wilmington, DE *!uunet!eplrx7!wyant
willner@cfa.harvard.EDU (Steve Willner) (10/01/87)
In article <391@nikhefh.UUCP>, jona@nikhefh.UUCP (Jona Oberski) writes: > Question: Which things - common instruments, consumergoods, etc. - would not > exist if we would not have Einstein's Theory of Relativity: "ETR"? It's hard to separate any development that came after relativity from the influence of relativity. Quantum mechanics, for example, is not directly dependent on relativity, but I believe the prime developers were greatly influenced by Einstein's approach. However, I'll assume that your question means what if the Schroedinger equation were known but not the Dirac equation. (If the Schroedinger equation goes away, so do transistors and integrated circuits, among other things.) Without the Dirac equation, I don't believe we would understand nuclear magnetic resonance (NMR) or be able to use the phenomenon in analysis. (I'm not very knowledgeable in this field, so experts please correct these comments.) NMR has been used for many years in organic chemistry and more recently in biochemistry to determine molecular structures. While we would certainly have some sorts of plastics without NMR, I doubt we would have anything like the vast number and variety tailored for specific properties that we have today. Nor would we have most of the synthetic fibers or products like Teflon, Tyvek, and lots of others. I'm not sure about application to pharmaceuticals, but I suspect that many drugs would not exist and the biochemical actions of others would not be understood. NMR has also been used for a few years now for medical imaging. (It's referred to as "magnetic resonance imaging" or "MRI" to avoid negative public reaction to the word "nuclear"). It probably saved my brother's life a couple of years ago, when doctors were able to use MRI to find soft tissue problems that didn't show up on X-rays or CAT scans. Another application that comes to mind is X-ray diffraction analysis, which is widely used for studying crystals of all kinds. Studies of semiconductors and viruses probably have had the greatest practical effects, but I'm not really sure how important the relativistic corrections are. Finally, if you are willing to accept intangibles, how about the reassurance that the Sun will not become a nova or supernova? Relativity is crucial in understanding the processes that actually cause novae and supernovae, and we now know that these processes are not important in the Sun. > By the way, do you like the idea: > "The only commonly-known physicist's theory is without practical value". No. -- Steve Willner Phone 617-495-7123 Bitnet: willner@cfa2 60 Garden St. FTS: 830-7123 UUCP: willner@cfa Cambridge, MA 02138 USA ARPA: willner@cfa.harvard.edu
willner@cfa.harvard.EDU (Steve Willner) (10/02/87)
In article <391@nikhefh.UUCP>, jona@nikhefh.UUCP (Jona Oberski) writes: > Question: Which things - common instruments, consumergoods, etc. - would not > exist if we would not have Einstein's Theory of Relativity: "ETR"? Certainly no particle accelerators of any sort. Particle accelerators are now being used for medical treatment. And aren't synchrotron light sources used to make masks for VLSI circuits? If so, no personal computers or modern telephone switching systems. No nuclear reactors (suggested in the original posting) is almost certainly right. (Though they might conceivably be developed entirely empirically.) If so, no radioisotopes. These are used in medicine and are also widely used as tracers in both plant and animal physiology. We would certainly not understand photosynthesis, for example. Wouldn't this have an effect on modern farming? -- Steve Willner Phone 617-495-7123 Bitnet: willner@cfa2 60 Garden St. FTS: 830-7123 UUCP: willner@cfa Cambridge, MA 02138 USA ARPA: willner@cfa.harvard.edu
ins_atge@jhunix.UUCP (Thomas G Edwards) (10/02/87)
what would the state of microelectronics be without etr? would we have transistors (i don't think there is a direct link)... light emitting diodes would probably be a better guess. we sure would not have squid's. -thomas g edwards "artificial life lives!"
daver@sci.UUCP (Dave Rickel) (10/02/87)
In article <695@cfa.cfa.harvard.EDU>, willner@cfa.harvard.EDU (Steve Willner) writes: > In article <391@nikhefh.UUCP>, jona@nikhefh.UUCP (Jona Oberski) writes: > > Question: Which things - common instruments, consumergoods, etc. - would not > > exist if we would not have Einstein's Theory of Relativity: "ETR"? > > Certainly no particle accelerators of any sort. Particle > accelerators are now being used for medical treatment. And aren't > synchrotron light sources used to make masks for VLSI circuits? Umm. If i remember rightly (which is a big if), cyclotrons stop working because of relativistic effects; so cyclotrons, anyway, would still be around. I doubt that synchroton radiation is used in any commercial mask manufacturing step, so nobody would miss it (yet). > > No nuclear reactors (suggested in the original posting) is almost > certainly right. (Though they might conceivably be developed > entirely empirically.) If so, no radioisotopes. How do they get the Americium that is used in ionic fire detectors? Time for the old CRC...it says something about Americium being produced by intense neutron bombardment of Plutonium. So, fire detectors, by kind of a circuitous route. david rickel decwrl!sci!daver
sarge@thirdi.UUCP (Sarge Gerbode) (10/03/87)
How about keeping the discussion to sci.physics? Seems like sending to five newsgroups is cluttering things up a bit. -- "Absolute knowledge means never having to change your mind." Sarge Gerbode Institute for Research in Metapsychology 950 Guinda St. Palo Alto, CA 94301 UUCP: pyramid!thirdi!sarge
howard@cpocd2.UUCP (Howard A. Landman) (10/09/87)
In article <756@elbereth.rutgers.edu> cje@elbereth.rutgers.edu (Cthulhu's Jersey Epopt) writes: >Beg pardon? Is our understanding of photosynthesis really so recent that it >depended on radioactive tracers? I'm not disputing this; it's just that the >claim comes as quite a surprise to me. Yes. Melvin Calvin got the Nobel Prize for this. The technique was essentially, you have some algae photosynthesizing in a flask, through which is bubbling CO2. You introduce some radioactive CO2 into the stream, wait 5 seconds, and dump the algae into a vat of alcohol and dry ice, which kills them and stops the reaction. Then you spend a few weeks determining what all the radioactive carbon compounds you found were. When you're done with that, repeat the experiment, but this time wait 10 seconds. Then 15 seconds. Then ... Variations with radioactive oxygen, strobe lamps instead of continuous illumination, algae in the dark or exposed to different wavelengths of light, etc., give you some of the boundary conditions. Don't forget to use several diferent kinds of algae to confirm your results. A few hundred or thousand experiments like that, and you know exactly what's going on, and even how fast. If you want an even better example of how radioisotopes are used in biology, take a look at radioimmunoassay. Especially the sensitivity figures. -- Howard A. Landman ...!{oliveb,...}!intelca!mipos3!cpocd2!howard <- works howard%cpocd2%sc.intel.com@RELAY.CS.NET <- recently flaky "Unpick a ninny - recall Mecham"