Enthalpy

Yes and yes.

Mix of water with glycerine, erythritol or xylitol is cold to the hand, so if your thermometer doesn't show it, just forget any thermometer. And ethanol with ice produces something like -40°C so it's not a matter or hypersensitive instruments. Ethanol, methanol : yes, that's it.

I'd suggest to decide whether you build a satellite or a launcher. That's not the same activity. Opportunities exist to put your small satellite as a secondary passenger on a big launcher. This would be accessible to a single person, and already more than difficult enough. For a single individual, the maximum complexity I imagine is to supply with a primary battery for a couple of days, design to work over a wide temperature range, not stabilize the orientation - and then find some excuse to launch the thing. Maybe you could test some reentry technology like an inflatable heat shield.

Camera pixels are huge as compared to present-days components because they need to catch much light. I see no production reason preventing to make them much smaller, say 50nm*50nm. Performance would be very bad, but such pixels would be 300*300 atoms big. If the wavelength is absorbed only by dopant atoms, then it's easy to have only ONE absorbing atom per pixel - except that some pixels will have zero dopant atom and some 2 or more. Also, some optics experiments are made using a single atom. Sinc decades, so it's not very exotic now.

Energy, for instance of the photon pair, creates a gravitation field just as the electro-positron did.

Nuclear pulse propulsion is as unfeasible as you imagine, yes. More feasible, but nothing desireable to my eyes, would be radioactivity. Coat big (seriously big) light panels with a really thin alpha emitter, so that alpha particles and decay atoms can exit the layer freely, and you get half the decay recoil. The energy density is similar to nuclear fission, though not quite as high. And of course, it's dirty.

As there is zero commercial fusion reactor, six billion people are familiar with all of them.

Welcome here! Mix of water with glycerine, with erythritol, xylitol http://en.wikipedia.org/wiki/Erythritol http://en.wikipedia.org/wiki/Xylitol available commercially, used in food for the "refreshing" effect in contact with mouth water. Water ice can also be mixed with ethanol, or methanol, to produce cold. Beware methanol is a poison (and ethanol as well, in fact).

http://www.webelements.com/chromium/ and it's the most common and useful alloying element to harden steel (besides carbon, silicon, manganese present in "unalloyed" steel).

The electron has a kinetic energy (this half you're searching for) and possibly a net momentum, depending on the orbital. This results inevitably from the electron being a wave and being concentrated around the nucleus by the electric attraction. You can write the wave as a weighed sum of simpler wave functions, for instance plane waves; concentrated, or localized, implies that short waves are summed in the electron wave, and these short waves have a big momentum and energy. Just because the kinetic energy increases as the electron gets smaller, the electron won't concentrate indefinitely. When the added kinetic energy cancels out the electric energy lost, the orbital is optimum and won't shrink more. This is how QM explains that matter has a volume. Some orbitals (typically S orbitals) are symmetric enough that all momenta brought in the weighed sum cancel out (but kinetic energy sums up). Other orbitals (P, D, F...) are less symmetric, for instance have cylindrical symmetry, and can have a net angular momentum. One trick by quantum mechanics is that wave functions are complex. By letting the phase rotate around the nucleus, but keeping the magnitude of the wave uniform along the rotation, QM achieves to give the orbital a net angular momentum without letting a "probability bump" rotate around the nucleus. So to say, the electron moves for some aspects but stands for others. This avoids the electron to radiate on such orbitals but still have an angular momentum and an orbital magnetic momentum.

Back to the title question: "rays" are just as wide as light is... That is, if light was emitted by a galaxy 1 billion light-year away, its light is more than one billion light-year wide. Though, one single pixel of the detector in the telescope may detect this light, and even, the photocurrent can be (and often is) measured as individual electrons. That's why physicists (old Albert in fact) introduced the photon. It says essentially that light can be very widespread but its absorption possibly very concentrated and quick.

It stays that x1 acts on x2 but x2 still doesn't on x1. If it's a question of particles, then these two scalar variables should interact. Conservation of momentum: I mean in the interaction of x1 and x2, independently of the external F. If the coupling shall conserve momentum, then it must act symmetrically on both x1 and x2.

With momentum p=0 the wavelength is not zero but infinite. An "immobile" particle would need to be perfectly delocalized. This is an idealized case.Particles being more or less localized, they have a minimum of momentum and energy, as a consequence, just because they're waves. Hi Heisenberg. The frequency of a particle is not absolute - which I find disturbing. It is exactly as relative as energy is. Depending on if you include the rest mass or not, the frequency change. But you may also neglect or not its potential energy within Earth's gravitation, its potential and kinetic energy within our Sun's gravitation field, our galaxy's field which isn't known, and so on. If the particle has a charge you may want to include an electrostatic energy, but electric potentials are relative, not absolute. And maybe there are forces we still ignore, so we neglect up to now some energy in this unknown field. Only energy differences are observable and do matter - and so for particle frequencies.

It's done with big pressure and some heat. You obtain "industrial diamonds" (search keywords), which are small and impure, but reasonably hard, so they can be used in cutting tools. At an even smaller scale, nanocrystalline films of diamonds are routinely deposited with semiconductor processes, for instance as electron emittors, in attempts to make flat display screens.

Supposing that human fellows are stupid is often a loosing bet... But the hope to find better solutions than the rest of Mankind has up to now is also a pre-requisite in the psychology of an inventor, which does bear consequences, hi bro. Hydrogen fusion is easy. Fusors for instance do it: http://en.wikipedia.org/wiki/Fusor But to harvest more energy from fusion than was invested - say in the acelerating field - the material must be held warm enough and dense enough for a time long enough: keywords "Lawson's criterion" http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/lawson.html http://www-fusion-magnetique.cea.fr/gb/fusion/physique/lawson2.htm This criterion is really hard and makes fusion energy very difficult - far beyond thick metal and concrete. Temperature is in the many-million K, so if containing the matter, it can't be with engineer's materials; the one method up to now is a magnetic field, and then you end with a Tokamak or its Stellarator variant http://en.wikipedia.org/wiki/Tokamak http://en.wikipedia.org/wiki/Stellarator or you don't contain the matter, but then it's a very short process that needs higher P and T according to Lawson. Current designs are laser fusion http://en.wikipedia.org/wiki/Laser_fusion Z-pinch machines http://en.wikipedia.org/wiki/Z_machine and at intermediate time scale, magnetized target fusion http://www.generalfusion.com/ All are damned difficult. My suggestion would be to play a bit with Lawson's criterion and check its technological implications. One more worry: the easiest reaction is D-T but Tritium is not available and can't be produced in proper amounts elsewhere, so a fusion reactor would have to regenerate it, but this needs a step of neutron multiplication, which is about as polluting as uranium fission to produce the same energy http://saposjoint.net/Forum/viewtopic.php?f=66&t=2450 the least improbable approach to run without tritium instead would be the Z-pinch. I've stopped thinking at fusion. Renewables are easier and we'll have them before. ----- Why do you suggest a plutonium wire? Any wire can be exploded by a current surge to produce heat and pressure within, say, a piece of D-T ice. If you hope to start plutonium fission, it takes more than heat. Plutonium can combine well with deuterium (and possibly lithium) to ease a combined fusion+fission reaction, but - You'll end with currents similar to the Z-machine if putting the proper figures, I bet - The whole game of hydrogen fusion is to avoid the polluting fission products... People who develop tritium regenation at ITER know perfectly that the neutron multiplier of choice is plutonium, followed by uranium... And they stick to lead because Pu and U would be a fission reactor - most heat would be made by fission, not fusion, and the reactor would require as much scarce uranium as presently. Is there more in this proposal?

That's nothing more than my spontaneous gut feeling, but the factor epsilon models a coupling force between directions 1 and 2. If you replace this action from 1 on 2 by an interaction between 1 and 2, you should solve simultaneously the conservation of momentum (which is violated presently) and of energy. Once this is done , a new main direction, obtained by a rotation somewhere between 1 and 2, will allow you to write the pair of equations as on acceleration+oscillation, plus a trivial one without movement on the perpendicular direction. In case 1 and 2 are not geometric directions, the geometric analogy is still a guide to the mathematical operation.

This would first need to measure an ohmic value at a moving component. Maybe through an electromagnetic field, but the related effects must be split among propagation and local changes. Could you choose clearer thread titles?

If hitting at the tip, the handle would retainor even gain speed. Not only unhealthy, it would also be suboptimum. Same for a tennis racket: not only should the ball hit the centre of the strings; masses must also be balanced so that this point coincides with the minimum shock at the handle.

Heat can be internal to a system or exchanged between several ones. Enthalpy doesn't consist only of heat. Depending on the transformation of a gas, the enthalpy change can give the heat or the work exchanged with the rest of the world, or a mix of both. If the system is not just a gas, the exchange can be something more general. Enthalpy is not fully contained in the system considered. In H = E + PV, only E is stored in the system. For instance if water accelerates in a nozzle from a pressure drop, its E does not change, its PV does and is converted into kinetic energy, but the body that provides this "pressure energy" is not the accelerated water, it's somewhere else - for instance a compressed gas that pushes on water. Though, and that's something very useful from thermodynamics, enthalpy can be computed just from the state of the system (for instance water's pressure), despite not being stored fully in the system. To compute water's speed, we don't even have to know if a gas or a piston and spring pushes on the water. And if the system is a gas, or a vapour-liquid equilibirium... E changes together with PV, but the exchanged heat and work can still be computed, by making some assumptions - for instance that little heat is exchanged and losses are small, and then T and W can be computed from the pressure before and after.

This expansion is not adiabatic. Energy provided by expansion is converted to heat at the porous material (in a nozzle, it would first become kinetic energy, then possibly heat depending on the surroundings). This heat stays in the gas, so some W converts to Q. As an energy (find which one) is constant, so does the gas' temperature, meaning as well that the porous material absorbs no heat. Or turn the reasoning an other way. As pressure was lost but no work extracted, something has been lost: the ability to provide future work with the available heat. No energy was lost but the entropy has increased.

1) What do you obtain by hydrogenating 1-pentene? 2) Can you find a series of transformations, each having a known heat, which is equivalent to this hydrogenation: same beginning, same end? Can you then combine the individual heats? Don't forget the additional H2O. Keep in mind: there is a gross and a net heat of combustion (translation to other languages may not be direct). One makes liquid water at rooms temperature, the other gaseous water at room temperature. The difference is big and is a very frequent source of mistakes. Always check the consistency of the heats of combustion. -285 kJ/mol is liquid water. Added warning: heats of formation are often measured by burning the compounds. It's universal and apparatus exists for that purpose BUT the combustion heat of hydrocarbons exceeds vastly their heat of formation, so that a slightly imprecise heat of combustion reults in a botched heat of formation or hydrogenation.

There I suggested an alternative algorithm on complex numbers to obtain the same kind of result as atan2(): http://www.scienceforums.net/topic/69084-suggest-a-topic-for-master-thesis/#entry711886 beware I haven't tested it. While I've an excellent feeling that it works, whether the computing time and accuracy are interersting remains to be seen. And anyway, your purpose may not be to program an numerical algorithm if Atan2() is available!

Normal and dark matter are very dilute, at the scale of a galaxy; in addition, dark matter interferes very little with normal one, as a hypothesis. Put both together, one doesn't expect an observable effect.

I'd add: the biggest publicly known since Tunguska. Because this huge event would pass unnoticed over the Pacific, the Southern Atlantic, the Antarctic, and many more locations. An other meteorite crashed over central Cuba one day before or after and nobody knows even its path. Surveillance networks exist for infra-sound (initially to detect aerial nuclear explosions) and for earthquakes, but these networks don't use to go public for an event that would be minor if away from a city. Over the southern Pacific one unexplained event made the loudest noise observed to date. A meteorite is one possible explanation, then it would have been big. I'm a bit wary about the 18 miles/sec. Russians give lower figures, like 18 km/s. Wait and see what they tell. Nor did the object explode at one precise altitude; much more, it lost matter over the whole atmospheric path, and some quick big parts reached the ground.

The edible fig tree can be male or female, and its flowers are of three different sexes, depending on the tree's sex. Trees do not grow and reproduce like humans, and are extremely varied, so any transposition would lead to wrong conclusions. Male and female "fruits" are reported to exist on some pepper trees... There, in an agriculture thesis http://projets.cirad.fr/content/download/4787/29542/file/Marion%2520Avril-Ethiopie.pdf but are these really fruits, or rather some edible flower? In pine trees the so-called "fruits" are not fruits. To botanists, apples, pears, quinces... are not fruits but false fruits, as they don't form from the flower. http://en.wikipedia.org/wiki/False_fruit