Enthalpy

The higher octane results from a mix with compounds (iso-octane and many more) just as good as others.

Maybe you could be interested by that one? More astronomy, and more model than fundamental theory - but I suspect it can change many things in astronomy and isn't very difficult. Present models want all elements and isotopes to stay mixed when a cloud of matter collapses to form a galaxy, a globular cluster, a stellar system... But these models presuppose that the virial theorem applies, then "deduce" the equilibrium... My back-of-envelope calculation tells that gravitation's differential effect on just one neutron or proton more in a nucleus is worth hundreds of times kT, so that the segregation of elements and isotopes must happen provided it has enough time during some period of the cloud's evolution - rather early, when the mean free path makes an interesting portion of the cloud's size. http://www.physicsforums.com/showthread.php?p=3439127#post3439127 http://saposjoint.net/Forum/viewtopic.php?f=21&t=2778 http://www.chemicalforums.com/index.php?topic=64466.msg233020#msg233020 I suppose most of the project is to find where and when the proper conditions exist, and then find patience to explain that the common assumption is wrong. Already known observatios go in my direction, for instance oxygen disappears early from the visible part of a newborn stellar system and reappears once thestar gets visible. Then you could look at the many consequences of isotopic segregation on existing astronomical models of many things, because presently they suppose no segregation, and deduce evolution histories from the observed isotopes abundances.

Does such a low octane exist? Or do you mean 98?

Is there any known case where a living organism produces pure carbon? I can't even think of a strict hydrocarbon produced during the life of an organism. Life uses to produce molecules with functions, like acids, amines... that can be managed by tools like enzymes. Then, some organic fibres are excellent. Spider silk is one example that approaches the performance of carbon fibres (but doesn't exceed it, despite newspapers ramblings). Polyamides should fit the capabilites of life and are good when unidirectional, with the aramide variant being excellent, similar to carbon.

The idea of velocity is very unclear and misleading for an electron in an atom. The orbital momentum is more useful. The "orientation" of an orbital is not a simple idea. In each direction, for instance the direction of the external field, an orbital can have a finite set of orbital momenta.

I did, and came to nothing interesting - which is no argument against other people trying. Kinetic energy demands a high speed, which seemingly a rotation attains best. Then the possible kinetic energy is a question of surviving the centrifugal force. A quickly rotating liquid would need a strong container, and is worse than rotating the container alone. I also checked if the unwanted moving air around a solid wheel could provide a dynamic bearing, but it seems worse than a standard bearing of small diameter hence small torque. Similar conclusions with liquid bearings. Well, it's all a matter of cost. if a contained can be cheap (immobile concrete walls in the soil?) and the fluid doesn't loose its speed, fine.

Maxwell-Botzmann supposes non quantification, hence does not deduce it. It's an asymptotic case with big volumes. Smaller volumes need QM which does introduce a minimum kinetic energy. A freely rotating molecule does have a minimum rotation energy. It's this minimum energy, different for ortho- and para-hydrogen, that evaporates liquid hydrogen obtained as a mix of both forms.

Do you mean the momentum E/c? The electrons moving apart to the sides, and slightly forward (versus the gama direction) would conserve this momentum, wouldn't they? Or do you mean an other momentum? The gamma's spin=1 seems to combine nicely with two spin=1/2, doesn't it?

Maybe you could tell more about what topics you like? Something related with particles and strings, or not? Some theories would be very useful in mundane domains: - The perception of sound, especially non-periodic. We have nearly nothing. This can only improve. - Galling. We have absolutely nothing workable. http://en.wikipedia.org/wiki/Galling About every "knowledge" in this field is wrong (including the linked Wiki...) for lack of experimental data. This must really be undertaken from zero, forgetting the existing nonsense, and looking for elementary tendencies. Even simple laws would be very helpful to mechanical designers, who are presently misled by universal errors.

If the emission of an electron is the only goal, then one doesn't need too detailed models of the conductor. All models for the emission http://en.wikipedia.org/wiki/Field_electron_emission http://en.wikipedia.org/wiki/Thermionic_emission suppose only some sort of work for the electron to leave the metal http://en.wikipedia.org/wiki/Work_function and optionally a kinetic energy for the electrons in the metal. Though, condensed matter is interesting in itself. By the way, field emission is often done by one single atom at a tip (LaB6, tunnel microscopes...) but people boldly apply models of bulk materials (as far as I know) combined with field concentration at the tip. Maybe a better model, where the tip atom is not treated as bulk, could bring something.

The thin sheets of hard material than make the flow calmer can't make strong weld seams, that's why I wanted to obtain big single-part sheets, but they can be soldered together - even stainless steel if nickel-plated - or glued. So sheets of commercially available size fit the task, including as skins for a sandwich, or as stiffeners.

Do I properly imagine that, when a gamma ray produces an electron-positron pair near a nucleus, the photon interacts with a virtual pair to give it energy and make it real, and then the nucleus' electric field separates the new particles? And that pair creation by photons without a nucleus, which has been hard to observe, is rare because the electric field of photons uses to be much weaker than that of nuclei?

An electric, magnetic or electromagnetic field can exist far from any charge, and even after the effect of the charge can be felt locally, for instance if the emitting star has become a black hole. This field stores energy: the one that the camera feels when seeing the light emitted by the then alive star. And even before this light is detected, standard physics tells it contains energy, whether an electron feels it or not. It's convenient to say so because the energy lost by the emitter's radiation is retrieved at the absorber. In these cases, the field stores energy (0.5*eps*E2, 0.5*B2/mu) without a charged particle to create it nor a charged particle to feel it. Then you have the gravitational effects of light. Negating that the EM field contains energy woud let one run into trouble.

Education systems vary too much among the countries, I can't give a sensible opinion. ---------- Cost of energy: even to produce electricity, which is a minority use, coal is the cheapest by far. Gas follows, then oil. Which isn't surprising: just dig it, set one fire. Presently, electricity from wind is more expensive than hydrocarbons, slightly less than from nuclear plants as long as you don't need to store it - which it still to be done. Then, you have solar thermal electricity, more or less affordable, also built in big size, and which stores energy from day to night. Beyond that... Geothermal energy looks perfect (available anywhere when needed, small footprint) but isn't developed enough to assess its cost clearly. Photovoltaics is expensive, probably the worse in that limited list. Organic cells might improve it. Then you have other forms of energy besides electricity, for which renewables exist as well - but fossil hydrocarbons are so cheap. Things like biodiesel, vegetable oil or bioethanol compete only because their bear very light taxes as food, while vehicle fuels bear heavy taxes. Nothing nice to write for a renewables enthusiast like me, but that's the hard reality. The best step to take right now may be to store electricity obtained from the wind; renewable fuels are a farther goal.

A mission to Jupiter's moon Europa, where wild scenarios put a water ocean below the ice crust http://en.wikipedia.org/wiki/Europa_(moon) benefits from the improved role sharing among the solar and chemical engines, but weaker sunlight there needs time. The already described improved Earth departure sends 7932kg to Jupiter - though I'd have nothing against Venus, Venus and Earth flybys. The probe arrives with asymptotic 5643m/s. The chemical engine brakes by 803+618m/s at 670.9Mm from Jupiter's center - Europa's orbit radius - where the escape speed is 19431m/s. This leaves 5810kg with 10000Mm apoapsis nearly in Europa's orbital plane. The solar engines lower the apoapsis from 5073m/s to 541m/s over Europa's (approximately) circular orbit. Eighteen D=4.572m concentrators push for 3 days around the periapsis so the process takes around 3 years; make science meanwhile. The long push is 80% efficient, so 3683kg head to Europa. Gravitational assistance by Jupiter's four big moons should have brought observations and saved time and mass, but isn't easily accessible to hand computation. The chemical engine brakes by 73+144m/s at 100km over Europa's surface for capture, or 1661km from the center, where the escape speed is 1963m/s. This puts the apoapsis at 10Mm, below the Lagrangian distance, with the preferred orbit inclination, leaving 3512kg. The solar engines circularize the orbit. They provide 431m/s in three months, leaving 3392kg at 100km over Europa, better than 899kg previously http://www.scienceforums.net/topic/76627-solar-thermal-rocket/page-2#entry769456 This includes all the propulsion (about 800kg). The mass can comprise an orbiter, a lander and a diver. ---------- The concentrators have uses beyond propulsion, at Europa and elsewhere, not only as a radiocomm antenna or to warm the spacecraft. Each concentrator catches 827W, or together 15kW. Filters can direct the best frequency band to each use; consider my evanescent wave filter http://www.scienceforums.net/topic/74445-evanescent-wave-optical-filter/ Concentrated filtered light can pump a laser for data transmission and an other to analyze the surface of a celestial body (besides a hydrogen gun). Solar cells get efficient with strong light that doesn't heat them unnecessarily; varied semiconductors would get each the best frequency band. 40% conversion from small cells would already provide 6kW electricity, nice for a radar and for radiocomms. A turbine would deliver more http://saposjoint.net/Forum/viewtopic.php?f=66&t=2051 ---------- More moons deserve their own space probe, like Saturn's Enceladus. http://en.wikipedia.org/wiki/Enceladus_(moon) Weaker sunlight there would make the circularization really long, but some answers exist. The concentrators can make electricity over the whole orbit, stored in a big battery, used at periapsis in the solar engines in a hydrogen resistojet mode. Not very good at Jupiter, but interesting at Saturn. The solar engines can trade efficiency for strength. More concentrators, or even (gasp) a lighter probe. Moon flybys are probably the key to success. The solar engines bring the fine orbit correction and the capacity to adjust the periapsis and the inclination. Marc Schaefer, aka Enthalpy

Or you can compare with the value of goods the rockets may destroy (or even, with lifes). This reduces to the mundane observation that destroying is easier than building. Obvious to engineers and many more people.

The blue and red cards in envelopes would still be reasonable outside quantum theories, as their state would be pre-defined. The way two entangled particles isn't especially disturbing: it can be the polarization of an intermediate state of the radiating molecule that produces two photons. QM becomes weird because experiments show that the common state of both particles is not defined before observation. Presently people often say that the observed state is just a choice at detection, a state common to both particles, so it doesn't need the particles to exchange a signal. Though, I could live with some sort of underlying instantaneous communication channel between the particles, because this channel isn't available to the particles' observers. Maybe I can reformulate that two entangled partices are not more weird than a single particle in that aspect. When a wide particle gets detected at one location, it becomes instantly unavailable elsewhere - though the particle's spread may take years to span at light speed. In that sense, the collapse of the wave packet is the tricky observation; whether the wave describes one or two particles changes little.

[Responding to my: "Then the electric field of a charged particle stores energy, whether an other charged particle feels the field or not."] Well, that's absolutely standard electromagnetism. The volumic density of electrostatic energy is 0.5*E2/eps.

Hamas' rockets (of which some are of standard military type provided by other countries) are unguided hence not very effective, because people are scarce even a in city. Iron Dome intercepts something like 3/4 of the incoming rockets considered important. When an incoming rocket threats a less important zone, it's not targeted. 3/4 is of course a big relieve for the potential victims, but would not be enough against, say, a nuclear warhead. Presently, Iron Dome seems to have the biggest success ratio among antimissile defences.

An electric field has energy even in the absence of anything else. For instance light emitted by a distant star stores energy, possibly after the star's death, until our detectors receive it. Energy in the electric (and in the magnetic) field is the proper means to conserve energy, a useful idea since it's restored in the same amount that was consumed. This electric or magnetic energy creates gravitation just as rest mass does. For instance gamma radioactivity carries mass away. Then the electric field of a charged particle stores energy, whether an other charged particle feels the field or not. This energy is a part of the particle's rest mass, in the absence of any other particle. Physicists are so much convinced of it that they were very bothered because the energy of a charged point particle is infinite, and introduced virtual electron pairs near the point to limit this electric energy to a finite amount.

One thought about particles being or not permanent points... In a hydrogen atom (because we know algebraic solutions for that one), a nucleus supposed immobile gives 1/2000 error. One has to compute the orbitals using the center-of-mass of the electron and nucleus, and a reduced electron mass. This implies a difference between the spectra of protium and the heavier deuterium, which is observed, fits the mass ratios, and not the magnetic interactions. Particle representations where the electron is permanently a point tell here that "when" the electron is at x, the proton is at -x/2000, done (only "when" is abstract here, since the electron has all positions at the same time). On the other hand, as I say "the electron is the wave", is seems harder to let the proton work as a counterweight of the immobile and centered wave. So is that an argument for the permanent point and against the naked wave? I now believe not. The trick is that QM writes a single wave for both particles: Wave(xE, xP) * phaseW( t). Then, if Psi(xE) * phaseE( t) is a solution for the electron around an immobile proton, we can write the solution with a proton of finite mass like: Wave(xE, xP) = Psi[xE*(1+mE/mP)] * Psi[xP*(1+mP/mE)] * Delta[xE*mE+xP*mP]. Delta is here Dirac's function and positions refer to the center of mass. What remains is QM's abstract idea that two particles can have undefined positions, all over the time (orbitals are stationary), but both positions would correlate if they were measured: the proton being at -x/2000. This uneasy and fundamental idea is necessary in every representation of particles, and at least to my personal taste, permanent points being everywhere do not ease it as compared with naked waves. Please keep in mind that the permanent point is the most usual representation (but I'm far from alone). What do you want to call a particle "real"? Both particles are routinely observed individually. It's not a matter of colliders or huge physics lab: engineers see both with a perfectly banal setup. Both particles are waves. This tells why matter has a volume. Both particles can be created and can disappear. Individually and under common conditions for the photon, only with MeV energies and together with a positive particle for the electron. Where do you feel a big difference?

Flying with little power means flying slowly. For a given lift-to-drag ratio, and little more than the weight of a human, it takes a minimum propulsive force; then the available power limits the speed. If you compare this speed with wind's speed, it tells that human-powered flight demands good weather conditions. Then, a good lift-to-drag ratio results from the very elongated wing shape. Gliders do it, human-powered or solar powered flight exaggerates it. But as weight must be minimum, this results in fragile aeroplanes. Complete crews, instead of one single human with excellent power-to-weight ratio, would improve, as: - A team aligned in the wind has little more drag than a single person but multiplies the power; - People spread in multiple nacelles along the wingspan would improve the wing elongation but keep the wing's bending load bearable. Up to now, humans pedal to fly, sometimes with the arms as well (recent helicopter). Rowing may fit human possibilities better. This may combine with an ornithopter better (or not) than with propellers by avoiding a movement transformation. Though, instead of flapping the wings, I'd consider moving two vertical fins, like a steering oar. Encasing fixed horizontal fins can improve the end vortices.

Ammonium nitrate IS dangerous stuff alone. Even without a fuel, it's a strong explosive, though not very sensitive. A little bit of fuel making it sensitive to heat locally can make the reste detonate. Many metals, even not efficiently reducing ones, act as catalysts to start its decomposition. And just heat can make pure ammonium nitrate sensitive.

http://webbook.nist.gov/cgi/formula/C5H11NO2 Nist lists 38 compounds and doesn't claim to be exhaustive http://en.wikipedia.org/wiki/C5H11NO2 Wiki has only 5

Eeeh? Back to measuring gravity: a pendulum works, scientists and navigators did it on Earth centuries ago, and observed the variation from 9.77 to 9.83m/s2. This could be done on other planets and moons. But why? Presently, we have accelerometers much more robust and convenient than an accelerometer. Better: we send space probes passing by celestial bodies or orbiting them before we send probes landing on them, and orbiting gives a measurement hugely more accurate.