Enthalpy

Happy to see that you agree with me. The electrons, even paired, cannot occupy the ground state 5-10eV below, because the bands are full and the exclusion principle applies - so no bizarre story of behaving like bosons. Electrons grouping in pairs, including thoses electrons near the Fermi level, is a part of standard BCS theory. This pairing is to result from lattice deformation. I want to distinguish such a pairing from spin pairing on an available state, which does not make a superconductor, and does not permit electron nor pairs to occupy the same state. BCS explanation of superconductivity does not rely on standard spin pairing.

Processes are reversible, so two photons of >511keV each should make an electron-positron pair, but I have never heard about it - only pairs created by one photon >1122keV. I suppose that the creation by a pair of photons is excessively rare, because it demands to concentrate their energy too much to happen often. Also, pair creation from a single photon happens at the big electric field of a heavy atomic nucleus; two photons would have to coincide at the nucleus, making it less probable.

My answer wasn't very constructive... I hoped someone else would jump in with better proposals. The 13C/12C (and 18O/16O and 2H/1H, but ashes must miss both) proportion vary faintly over the epoch over the timescale you want. Climatologists claim to reconstruct the ancient climate from these proportions. Though, one proportion will hint at several possible periods. http://en.wikipedia.org/wiki/Oxygen_isotope_ratio_cycle Not so good over your short time, because ground water can stay for centuries. http://en.wikipedia.org/wiki/Carbon-13 http://en.wikipedia.org/wiki/Isotopic_signature#Nitrogen_isotopes 13C and 15N seem more sensitive to the kind of organic material than the climate. http://en.wikipedia.org/wiki/Proxy_(climate) http://en.wikipedia.org/wiki/Isotopic_signature Found nothing. I thought an isotopic method was known for timescales shorter than 14C.

Thank you both! My mom had a bottle of pure ether when I was a kid (looong ago, probably removed from sale meanwhile). Sold in pharmacy to remove surgical tape. Hence I noticed how nicely flammable it was, even better than ethanol. On an other forum, someone asked "how to dispose of 5L diethyl ether" and among refined answers, I proposed "burn it" as the result is clean, but apparently this is a swearword for chemists. Hence I wondered if a few peroxide crystals would knock over sand bags, or some other nefarious behaviour by ether.

Did you mean H5O2+? Ions exist in solids and solutions (or in vacuum before they meet matter). In water, H+ is always hydrated many times (I have 3 to 5 times as a mean in memory, could be wrong). So H3O+ is already too short; rather a reminder the some H2O must be accounted if H+ goes in a different compound.

Already used in telecomm demos, nothing straightforward, and only to ensure that the data link has not been tampered. Exactly, you're encouraging speculation instead of development in physics or technology. The resulting answers would bring exactly nothing. Only buzzwords like "wormhole", "dark energy", "metamaterial" used improperly by people ignoring them. The constructive approach - but it's lengthy and not spectacular, and gives less the illusion of a brilliant brain - is to describe work on your disruptive technology, make it feasible, and show or explain how it is feasible. If not, search for a less disruptive improvement - a faster horse if you wish - and tell how your ideas have made it possible. That's already very difficult, and finding one from time to time is an accomplishment. By the way: the people who made disruptive inventions or discoveries also made faster horses. Einstein patented some apparatus of common use.

The field, or rather its source, can be static. If the type I superconductor is cooled once the field is established, when the superconductor passes the transition temperature, it expels the field. This speaks against a result of induced voltage. Zero induction in the superconductor, but the field can be the cause of many things there... This is an other case where things happen at a location where the vector potential A is interesting, while the induction B is not. Electromagnetism is tricky ("not elementary"). Because the induced voltage appears around the induction field B, you get a voltage even if the conductor moves near a place of uniform induction field, provided that the flux inside the loop changes. Or you get a force on a conductor loop, depite the induction field B is constant at the loop, provided the flux in the loop changes. This is the case in a voice coil motor. In such cases where "at" and "within" give bizarre results, the potential A is clearer than the field B - but unfortunately, we have instruments or objects to observe B, which makes B more concrete. Is that more than a buzzword applied to an unrelated topic? I don't understand. I don't understand that neither. Gives me the bad impression of a message formulated vaguely enough to provoke reactions.

You implicitly suppose, in spherical symmetry, that a particle (or worse, two particles; not a "single quantum" here) is described by one single wave. This is not the case, for instance with entangled photons, who can be of linear or circular polarization; a single wave does not explain the correlation both in linear and in circular detectors. If you properly describe the spherical symmetry as a spherical distribution of possible waves, then these individual waves have the proper spin, polarization and so on.

Saw on Youtube an experiment in a university class. A paperboat floating over an invisible "sea" of SF6. Fun. Also, at a German source of sparkling water, where dioxide accumulates in a part of a cave: soap bubbles floating on the dioxide. Zeppelin airship: I made some toys. A 3m long one with glued space blanket filled with helium. Just thin shopping bags filled with natural gas float also (do this outside please! Preferably with an anchor and without wind). But carrying any significant weight demands a huge volume, and Zeppelins are slow as well, explaining why aeroplanes replaced them. For local uses, for instance sightseeing tours or as cranes, you may consider my regenerative buoyancy control: http://www.scienceforums.net/topic/70114-aerostat-buoyancy-control/

Maybe you could detail more in which sequence cold, tension and annealing are applied, and what the conditions are? For instance, anealing CrNi17-7 at 700°C suppresses the hardening benefit of previous cold-rolling, but tempering at +200°C makes it more resilient AND improves the yield strength a bit. I can't tell if the Russian Gost make a difference between CrNi18-10 and 17-7. Anyway, some suppliers do cold-work even the CrNiMo18-12, despite it hardens less quickly; for instance Bulten prefer this alloy for their screws (originally for submarines), which are non-magnetic and resist seawater corrosion.

The interference pattern has a deterministic prediction, but its observation is statistic. One particle is detected at one place (in the traditional experiment) and shows no pattern at all because it gives a single point, many particles make fringes more recognizeable but always noisy. Interferences exist with a single aperture as well. It's called diffraction, and limits the angle resolution of telescopes for instance. Light interferences were computed before Feynman by summing complex amplitudes - that is, including the phase - over all possible paths; there was no need then to add: paths "of the particle". QM added that other particles behave that way, and Feynman (or someone else?) that this holds if the particles transform meanwhile. To the formulations "the particle can take any path" or "we ignore which one it has taken", I prefer "the particle takes them all" and "indetermination appears when the context forces a particle to decide" for instance at a detector. I'll change my opinion if reading of an experiment that needs it.

The incentive to replace hot filaments with cold spikes is huge! To make a display with one electron flow per pixel and colour, filaments are impractical while everyone hopes field emission would enable the option. This is a many-billion market. The only difficulty is that field emission isn't useable; the weak current would probably have solutions, but sensitivity to residual gas not, and this is a no-go.

Hi EVM, I had not encoutered it before, so mechanical design can live without it... http://en.wikipedia.org/wiki/Critical_resolved_shear_stress It looks like one more attempt to deduce mechanical properties of materials from their crystal structure, and, how to say, such attempts fail with a high regularity. I wouldn't invest too much time searching for such theories. Young's modulus can be more or less explained, but deformation and ductility aren't predicted usually. Anyway, single crystals are an exception in mechanical design; I know of nickel-alloy turbine blades, which are grown single-crystal. Even for them, crystallography make inaccurate predictions - and grain boundaries define much more how polycrystals behave.

Hi EVM! Never encountered the name before because it's a Russian designation, apparently for plain X12CrNiTi18-10, among the most common austenic stainless steel: http://www.steel-grades.com/Steel-Grades/Heat-Resistant-Steel/12x18h10t.html EN equivalents would have a bit less carbon, like <0.06% in X6CrNiTi18-10, which improves the corrosion behaviour of weld seams. The "temper" and "HRC" data is the previous link look nonsense. I can't help more... - I don't see a reason for cryo with this steel. Other stainless (PH15-7 maybe?) use cold to finish the martensitic transformation. Some benefit from cold to obtain work hardening using smaller deformations, typically to make rocket tanks, but CrNi17-7 would be better than 18-10 and is preferred then. - On annealing, the CrNi18-10 family uses to forget all previous treatments, so why use cold before? - I don't understand "what research method applies" - You could look at the websites of Carpenter, Boehler, Allegheny... They often explain much about the heat response of their alloys. Search for 18-10 alloys with titanium and without molybdenum.

The measured Young is wrong. It's 210GPa for any ferritic steel, unless heavily alloyed -and no alloying element would bring steel to 290GPa. There is no lower limit to the yield strength of mild steel. As steel gets purer iron and is well annealed, the yield strength drops and drops. For instance Armco steel (it bears a different name in their catalogue) is extremely soft; it's a cheap iron core for electromagnets, relays, and is horrible to machine. So you may experience difficulty measuring an elastic behaviour while your steel is essentially plastic. By the way, mild steel is one example of a centered cubic crystal that is very ductile.

X rays are emitted by high voltage through corona discharge, which does always happen until proper and non-obvious measures are taken, and uses to waste most electric power. With several watt at 500kV, X-rays ARE a serious worry.

From what I read, current density from nanocrystalline diamond films only outperforms other cold emitters but is very far from a hot filament. You can be pretty sure that a breakthrough in 1992 would result in widespread use in 2013. As for sensitivity to residual gas: vacuum obtained by pumps in electron microscopes is excellent - no hope to outperform it in a tube with a getter. If this were the key to field emission, all users of microscopes would already have improved pumps, since field emission would bring so much to them: tiny emission zone and interesting current at the same time. Alas, it's unuseable. Better devices with electron beams: academic research hunts more uses than audio amplifiers. First where electron beams are still not replaced: electron colliders, powerful radiowave transmitters, X rays sources... and then for uses where they might outperform semiconductors, say in the upper GHz frequency domain - maybe. One very strong incentive are displays with one electron beam per pixel and colour. Many research papers use cold cathodes as these suffice for half an hour experimentation, but up to now, all commercial devices have a tungsten filament or a LaB6 or SrB6 warm spike.

And this representation of chemical bonds is wrong and misleading: - Orbitals are not orbits - The eight electrons together make little sense - Valence electrons are shared across the whole crystal, not just neighbour atoms

The fields of two simple permanent magnets (like ceramic, neodymium, or samarium) simply add, with the only subtlety that magnetic fields have a direction. No electric current flows through air due to the permanent magnetic field, and two magnets instead of one have no special effect. ---------- Only a type I superconductor carries a current in reaction or the permanent presence of a magnetic field. This current prevents the flow of the magnetic field through the type I superconductor, up to a limit which is weak, for instance 20mT. A hole in the superconductor permits the magnetic field to pass through there; for instance the center of a coil is such a hole. A type I superconductor expels also a static magnetic field, if the field preexisted and the material is cooled after. So it's not only a consequence of induction in a lossless loop. ---------- This current can be useful. In a so-called Squid, it gives measureable effects which are extremely sensitive to the magnetic field. Squids make fantastic sensors for many things, like gravity. Though, if one tries to obtain a power from this current - which a Squid does not - then the current brakes and stops. This holds for type I and type II superconductors as well as for metals, semiconductors, plamas. To obtain durable power from the induced current, the flux of magnetic field through the loop must vary, so that new current (and voltage) is induced as the old one vanishes. This is done by varying the field strength quickly (for instance 50 - 60 - 400 times per second in a transformer) or its orientation (in an alternator). This implies that only magnetic fields changing over time make electric power. This change requires itself power if electricity is obtained: power coming from a shaft in an alternator, or from a primary electric circuit in a transformer. It also implies that the created current varies over time in most machines: just alternating current in simple machines; those that provide direct current normally have a rectifier or a commutator. ---------- In contrast, a permanent current makes a permanent magnetic field. And while a magnetic field contains energy, it does not demand power to perpetuate. A permanent magnet alone consumes and produces no power, a type I superconducting coil neither; normal conductors waste power in that task only due to their imperfection, not by the nature of electric and magnetic fields. But without something else, like a movement that introduces power, no electric power is obtained from the magnetic field. ---------- "Elementary electromagnetism"... If only it could be! After several decades of non-trivial electromagnetic designs, I wouldn't call it "elementary".

I maintain electrons are paired in most materials. I just want to point out that the usual "paired hence boson hence condensed" is too short an explanation. There must be something else in Cooper pairs. Cooper pairs can't neither be all in ground state. As electrons in a metal have 5-10eV energy above the lowest available state, the transition would give hugely more heat than is observed. And anyway, several electron pairs in any material don't occupy the ground state: not in an atom, not in a molecule, not in a metal. Two fermions can occupy the same state, say an orbital. Other pairs, despite being bosons, can't occupy the same state. The BCS theory is certainly something else.

3 x 1012 J is only the energy that boils 1300t water, a cube of 11m side. Wasting power is also easier than producing it. The liquid oxygen pump of an Rd-171 rocket engine absorbs 129MW in a D=409mm impeller: http://www.lpre.de/energomash/RD-170/index.htm so one D=10m impeller would absorb 77GW - have more impellers rotating faster to increase the power, and just dissipate the liquid pressure or speed through turbulence. 77GW are 3 x 1012 J in 39s, intuitively more power than the tornado. I've done my part, know you find out how to catch the tornado's power... ----- Some directions to reduce tornados or their damage: - Paint the city white. Clearer than the surroundings. - Seed convection before the tornados arrive. - Have a permanent convection point outside the city - Spread the city with cold water? White cold sand? I'm pretty sure much has already been tried.

The linked description of a reactor for rocket propulsion avoids to tell a few things (which I was too lazy to search elsewhere), like: - How is americium plasma confined, but not hydrogen despite being a plasma as well - What hydrogen pressure is compatible with the reactor, and whether this pressure fits gas flow in a rocket engine(this is a basic limit in any thermal rocket engine, I found lucky to have one operation domain for my Solar one) What happens to beryllium oxide, how quickly. How to test on Earth and clean the mess.

"break wire" : do you want to stop the electromagnetic field, in which case the Faraday cage is the answer, or the voltage spike induced in wires by the field? Blocking the overvoltage is done much like a protection against lightning. Depending on how strong and near the pulse is, protection against an EMP can be more difficult than lightning. About all military equipment is designed to survive an EMP, so such protections are almost universal and rather well known - I suppose it's public knowledge in many countries.

Is the original question about renewables or about biofuels? Not quite clear. Geothermy hasn't yet been mentioned. Available when and where needed (no geyser required), perfect for heating, can produce electricity at the same time. Small land area, looks cheap. Solar electricity should not be confused with photovoltaics. Conversion through heat is cheaper, more efficient, and can store energy for the night or a cloudy day. Plants work in Spain and elsewhere. Brazil drives using bioethanol (actually a mixture with gasoline). Cars and gas stations have adapted. Works, cheap - and the air is clean!

The cables of flexible printed circuits can carry more than 5Gb/s in each lane. For instance 20Gb/s would just halve the maximum distance between repeaters. Crosstalk voltage increases as the front steepness, nothing tragic with two ground planes. Accepting a reduced wave impedance, thinner insulating layers reduce crosstalk, or permit signal lines closer to an other: the resulting narrower cables would permit narrower boards at the 8M nodes hypercube. A supercomputer draws a huge current that induces ground noise. To protect itself, the asymmetric transmission can for instance connect its cable ground at the transmitter side, let it float at the receiver side where it receives just the line terminations, and have the receiver detect the difference between the signal and the cable's ground. Package inductance is always a worry. Asymmetric transmitters pollute their internal ground when many outputs make the same transition. With one ground contact per signal output, ball grid array packages look numerically good at 20Gb/s. Optical cables would be fantastic... The current technology is Vcsel emitters at 850nm, multimode 50µm/125µm fibers, GaAs detectors. 5mA*2V let transmit >10Gb/s to 300m. It's just that connectors for a single fibre are still as big as a finger, and presently, people try to develop hardware, including collective connectors, for twelve (12) fibres at once. As soon as one can have 500 signals in a transmitter, connector, cable, connector, receiver - all that for 10,000 cables, shooting horizontally from the boards, 10mm thin - they'll be perfect. Marc Schaefer, aka Enthalpy