Enthalpy

Quantum mechanics explains and predicts observations properly and with an excellent accuracy. What would you call "the nature of reality" ? How would you prove that this so-called nature is a better choice for us than QM? Are there observations, experiments, measures that allow us to tell that "the nature of reality" is better than QM?

Stimulation by implanted electrodes is a known means to prevent seizure. The current must then by DC or ELF, not microwaves. To my very limited knowledge, this is still a topic of (academic and recognized) research, not of broad use. One competing method is transcranial magnetic stimulation, which use very strong pulses of low repeting frequency to induce electric fields and currents in the brains. Apparatus exist and are used depending on each country's laws and habits; what the indications are is still under investigation. There I suggested to use shorter, weaker pulses with a higher repetition frequency to make the apparatus lighter: http://www.scienceforums.net/topic/70203-transcranial-magnetic-stimulation/ I suppose, from corroborated evidence, that a weapon already exists since 1992 and is used to inhibit brain's work for a short lapse over few meters distance, to let people hurt themselves by falling. It should logically produce seizures as well. This one could use low-GHz microwaves.

Entanglement is not an "assumption"... And it can't transmit information easily. The measure at one detector tells what the other observes, but forcing a state at one detector will have no effect at the other. The delay between both detections can be much smaller than light's propagation delay between the detectors (see Aspect's experience) but this does not tranport information, hence no information faster than light.

Agreed with Imatfaal: the induction is very similar to a torus , except when the pitch of the bigger helix is not much smaller than its radius, in which case one may take sqrt[p^2+(2pi*r)^2] instead of 2pi*r, and orient the induction accordingly. N is taken per turn of the bigger helix.

Interesting! I read "with Ni and Cr he made stainless steel. His Pt-alloys surpassed..." which is a less clear statement than "he made stainless steel by using Pt". This would be a new insight, because Cr is understood to make steel stainless through the hermetic oxide layer of the readily oxidized chromium, while Pt resists oxidation through its redox potential, making it useable for electric contacts. If I compare with Co, which resists oxidation the same way as Pt does though not as efficiently, the carbon-free piece of magnetic Fe50-Co50 I put under rain did stain. Much slower than normal steel, sure.

Making an aerostat is nothing easy and demands seriously light construction. No single chance with a bottle. Space blanket is a good start. Build big, use glue rather than adhesive tape. Avoid hydrogen that leaks too easily. Do experiments with flammable gas outdoors.

I use regularly Free Commander for that purpose: www.freecommander.com It's more general than a folder compare: a very powerful explorer. For instance, it can find files within compressed archives in subfolders. So don't axpect a big "Compare" button at the middle: learning to use it does take half an hour. Benefits: - It can synchronize folders, not just compare them. You fully decide the criteria: new files, modified, only left folder to right, etc - The version 2005.09a runs on Win95, at least 2009.02b runs on Win2k.

As you have a brake distance, you could distribute the kinetic energy over it and get a force. Believe it or not, I get 694N too.

Known methods produce thin films on a substrate. Putting a thicker part over thin layers is also known, even with optical quality: glueing, ceramic-to-ceramic seals... The thicker part could have steps like a Fresnel lens to be less thick, but then phase isn't consistent among the faces. And if light must hit semiconductors, these can be put directly at the thin layers. If the filter must be short but cover a wide light path, it may comprise several segments stacked, in parallel or opposing directions, or possibly conical like a Fresnel lens - if the stopband light is extracted or absorbed properly. Two or more filters of opposite angles can make the center frequency less dependent of light's angle, but the frequency response will still be distorted. Depending on the frequency and thickness, some layers can consist of vacuum, a gas like air, foam... Some materials change their thickness or index with the electric or magnetic field, which is a way to tune the filter, while most materials respond to strain and temperature, providing other ways. A strong stopband attenuation needs to minimize stray light, which includes internal reflections. The substrate's shape can help by demanding many reflections, each one made faint, before stray light risks to exit in a direction not desired; or, possibly in addition to that, the substrate's surface itself can be made to absorb light - even before jumping to a different medium, which always leaves some reflection. Radioactivity is known to make glass brown; implantation, possibly by plasma, can damage glass or bring extrinsic colour centers faster and better than radioactivity but keep a smooth transition with the transparent part of the substrate, thus preventing reflections. Diffusion of impurities from the surface would do the same, as well as deep diffusion bonding with a coloured version of the substrate's material. I'd first make all faces opaque at the substrate, and later cut and polish the faces at light input and at the thin layers. Such non-reflective faces can have uses beyond this filter. ----- Many thanks for the corrected title! Marc Schaefer, aka Enthalpy

My bad! Mistaken translation, I meant "evanescent wave", this one: http://en.wikipedia.org/wiki/Evanescent_wave Mea maxima culpa! And I can't even improve the thread's title...

Approved. The only remote limit is that the friction "coefficient" isn't really constant... Mankind is still in need of a proper theory of friction, and a proper theory wouldn't have just a "coefficient of friction". The brakes are designed to stop the car even if heavily loaded and at maximum speed.

Hello dear friends ! I conceived the following optical filter for improved stopband attenuation. I haven't found it described after a short search; an optics specialist (I'm not) could better tell if this filter is already known. Like an interferential or dichroic filter, it comprises thin layers of varied index over a substrate, so the layers aren't to scale on the sketch, nor are all reflections shown. As an original feature, some layers are coupled by fading waves resulting from the varied refraction indices and from light's angle. The fading layer attenuates light but is thin enough to leave some through, and within the passband only, the following resonating layer(s) restores the amplitude. Fibre optics uses similar filters on chips where fadings waves couple open or race tracks to make bandpass filters, used for instance for wavelength multiplexing in datacomms - but here light is not in a fibre. The frequency behaviour resembles also microwave filters made of coupled lines with their excellent stopband attenuation, and whose theory can be picked, thanks. The fading wave can attenuate strongly, provided resonator(s) near enough restore the amplitude. This improves over a dichroic filter where attenuation results from destructive interferences, whose amplitude must match precisely, and are difficult to achieve over a broad frequency band. The fading wave filter has naturally a strong attenuation everywhere outside the passband. This filter is naturally a bandpass, though it can be made wide enough to act as a high or lowpass over the frequencies of interest. The "reject" output would be a bandstop, but without the naturally high attenuation. Longer waves also pass more easily the fading thickness, enabling a lowpass of limited selectivity. Only the available materials and feasible thickness limit the frequencies, which include radiowaves, THz, IR, visible, UV. The resonating layer(s) can be thick enough to show several resonances, to increase the selectivity when only one resonance falls within the frequencies of interest, or because several resonances are wanted; in an extreme case, this comb filter stabilizes short repetitive pulses, and its strong outband attenuation can help build the macroscopic equivalent of a ring laser, recover a clock signal... A big external Q-factor at the resonating layer is often undesired: it needs precise thickness, angle, frequency, broadens the transmitted ray, can induce loss and a reaction time... But as flexibly as in electronics, several resonator layers (the sketch has only one) in a multipole filter answer that, to combine a big attenuation with a broader passband, as the resonators are more strongly coupled; the superior optical materials ease that. The angle influences the attenuation, especially near the limiting angle, and the passband frequencies. Depending on the use, it's a drawback or an advantage, to tune the filter a bit. Optics can often be split, as in Lyot's coronograph, to have parallel rays for filters at some portion of the path. The filter can also split light in several bands using a uniform layer thickness if light bounces at varied angles, for instance because the first propagating layer is a wedge; for losing very little power, it looks nice at wavelength demultiplexing, and can losslessly multiplex as well, even broad strong rays. With an easily tailored passband, and a strong outband attenuation to reduce the detector noise, this filter has uses even where light doesn't travel in fibres. Impossible to imagine them all: free-space Internet among buildings, communications with and between spacecraft, chemical analysis (methane on Mars!), search for and images of extrasolar planets... Marc Schaefer, aka Enthalpy

MSDS confirm it is a carcinogen, as is almost every non-natural substance. But you have to distinguish the amounts, exposure duration... Which the MSDS don't. Just as one example, you might read the MSDS for ethanol - you know, the poison that so many humans ingest knowingly and willingly: http://www.sciencelab.com/msds.php?msdsId=9927073 http://www.nafaa.org/ethanol.pdf proven carcinogen, proven mutagen, proven teratogen, lethal dose 7g/kg, and so on.

Great physicists in the past were puzzled by this analogy and wanted electromagnetic waves to be the vibration of a support: http://en.wikipedia.org/wiki/Luminiferous_aether but the search for this support gave a decidedly negative result http://en.wikipedia.org/wiki/Michelson-Morley_experiment even with theoretical refinements like aether drag. For over a century, this quest is abandoned in favour of Relativity, which succeeds since then in each and every test, and far more convincing to me, is used daily by millions of engineers and physicists to make correct predictions. Frankly, any attempt back is vain.

Strength or hardness is a property of molecules (and condition and more), not of atoms. For instance diamond isextremely resistant to compression while graphite is not. Or pure iron is extremely soft (even if body-centered cubic) while steel can be hard. Conversely, silicone rubber is extremely soft and weak while silicon and carbon can be very hard.

If you remove heat from a gas, the pressure will decrease too. In a monoatomic gas like argon, under reasonable conditions, the internal heat is just the kinetic energy of the molecules. Heat given to or taken from this gas at constant volume changes just this internal energy; but at constant pressure for instance, or under different conditions, the internal energy would share the change with other forms of energy. Polyatomic gases also store internal energy in other movements ot state changes. Take nitrogen: the atoms can rotate around their common center or mass, which is kinetic energy, but without a global movement of the molecule's center of mass. Or bromine: the bond is elastic enough to elongate or contract even at room temperature due to shocks against among molecules, so the bromine atoms not only move with the molecule's center of mass, they also rotate around it like nitrogen does, and they also vibrate around it, which adds more kinetic energy and deformation energy. Somewhat stiffer molecules like carbon dioxide vibrate a bit at room temperature and more at heat, while light ones like hydrogen or stiff ones like nitrogen vibrate little even at heat. Pressure is the shocks of molecules against the walls, yes. Temperature is the amount of energy in each movement (or state) capable of storing some energy, among others in each translation of the molecule's center of mass. So a warmer temperature means that the molecules translate faster and hit the walls with more energy and moment, pushing them stronger: more pressure. But at the same pressure, more molecules hitting the surface per time unit also push the surface stronger, so temperature isn't the sole cause of a gas' pressure; density is one other. Or written differently, the volume of a unit amount of gas, for instance a "mole" of gas - but that's nothing more than the reciprocal of the density, moles per volume unit versus volume per mole. Gasses fortunately happen to give a very simple relation between temperature, volume and pressure, under reasonable conditions: just P=R*T/V where R is measured as 8.3145J/mol/K and V is the volume of a mole, a mole being 6.022e23 molecules - chosen as the number of carbon atoms that weigh 12g.

It's all a matter of size. The proton and electron attract an other very strongly, but because they're waves, they can't become arbitrarily small, since a too small wave would have increasingly more kinetic energy, to the point where this increase is worse than the benefit from the particles of opposite charge being closer to an other. This is what defines the atom's volume: so to say, the nucleus and electron(s) have already collapsed together, down to the most favourable size. Bigger objects like a gas cloud don't have this minimum volume resulting from their wavelength, because a wavelength the size of the cloud would mean a negligible kinetic energy. So this reason does not prevent the collapse of a cloud. Other reasons can prevent or brake the collapse, especially the central pressure; the usual theory tells that some heat radiation mechanism must allow the cloud to cool down, hence reduce its central pressure, to go on contracting despite this contraction heats it. [Maybe someone will model that nuclides must be distinguished in that process, and that heavier ones can coalesce by expelling lighter ones. Or maybe I'm horribly wrong. No established science now, in any case.] Under extreme density resulting from gravitation, the weak force can make neutrons out of protons and electrons; the necessary conditions differ a lot from a contracting gas cloud.

Proton-Boron is a well-studied reaction, generally given as an example of aneutronic fusion - but it produces three alphas so one could call it fission as well... I'd say: more energy comes from the strong force than the electric repulsion, hence fusion. This reaction is a remote hope to produce heat without the neutrons that make the surrounding materials radioactive. Though, I know no single reaction that relies solely on accelerated particles and has a chance to release net energy. This reaction is considered in plasmas instead, with Z-striction leaving a tiny hope, laser not being considered a candidate in a planned timeframe, magnetized target being about exluded and tokamaks hopeless. If any fusion released net energy; the conversion to electricity would be a lesser difficulty... Vapour turbines work! Direct electric conversion to several kV has been demonstrated with alpha and beta radioactive sources, but is less efficient and convenient even than thermoelectric elements - which should be replaced by a thermal engine anyway, a turbine rather than a Stirling. Charge carriers multiplication has been demonstrated and even used also: a radioactive material coats a photocell, where silicon takes 3.5eV to make a carrier pair harvested at 0.45V - the serious limit is the deterioration of the Solar cell, whose semiconductor properties are more fragile than a metal's mechanical performances.

Hydrogen and fuel cells carry more energy per kg, which increases an aeroplane's range. This example combines ATR 42's short body (even the tail?) with ATR 72's wider wing to carry the <4000kg fuel cells providing 4000kW electricity. 7000km range (not the limit) at 554km/h and mean 2*1400kW with 60% *95% efficiency take only 1574kg hydrogen carried in 4 tanks under the wings. A geared motor eases the overall design. I prefer to spread the fuel cells among the tanks and distribute only electricity. In a new design, consider several bodies like Rutan's Voyager had. The chimera ATR 72-42 frame shall take-off at 22500kg but weigh 12100kg empty. Minus 4000kg fuel cells but plus 300kg from lighter electric motors leave 6700kg. Four tanks built as previously take 1484kg. Hydrogen for the full range and two pilots leave 3.4 t transport capacity. London - Dubai - Hong Kong or Tokyo - Anchorage - New York - Amsterdam at 554km/h here is too long for passengers but parcel or freight companies can like the improved flexibility or fuel savings over airliners' hold. A fast business aeroplane would also benefit from hydrogen's range. Marc Schaefer

In what kind of observation, please? What is the experiment that makes a difference between no rest mass and a mass too small to distinguish? For the neutrino, the doubt lasted for very long. What should make the photon different? Is there some reason that necessitates a photon without a rest mass, say for the consistency of a theory, or is it just the usual photon's model within the theory? For the neutrino, "no rest mass" and "too small to observe" was not the same to people's taste, and after several decades efforts, an answer exists.

In case you want to reduce hysteresis losses hence braking force, and can choose the wall material, then Armco sells very pure iron that is cheap and has a tiny coercive field. It's a horror to machine, though.

Carbon dioxide is the limit. The maximum concentration is known. Please check: I have in mind a mole proportion of 3.5% dioxide in the air breathed out, so this would be one absolute maximum proportion in the air breathed in. The throughput of carbon dioxide per person is known as well, as a function of the activity. This can be converted from and to the power (mostly heat) produced by this person if the proportion of C, H, O in the food is known; I'd take a sugar as a typical composition of usable food components, in a first approximation. Sports medicine uses to measure the dioxide output to evaluate the power produced.

- I don't see how to accelerate a neutron. It has a magnetic moment, but that would be a very inefficient method. - How do you obtain thermal neutrons? Neutrons in usable amounts are usually created by fission, at several MeV, and must be braked in most reactor designs, quite the opposite. - Why should you prefer fast neutrons for fission? At least uranium prefers slow ones. Do you have other elements in mind?

Never heard of. Elements heavy enough contain a higher proportion of neutrons than fission products, and some excess neutrons use to fly away early: within some ps of the fission for most neutrons, about 1s later for 1-2% of them. The remaining neutron-proton unbalance in fission products evens out through beta minus radioactivity. Worse: fission neutrons are needed to sustain a chain reaction, provided this is the intent. Without the chain reaction, for instance through proton bombardment; fission needs more input energy to proceed than is extracted from. Some reactors (like Rubbia's design) claim to work from a proton accelerator, but still rely on neutron emission for 99% of all fissions, protons making only 1% (which makes stability not so obvious...). Even then, the necessary accelerator's power has never been achieved up to now.

Is there any reason why photons should have no rest mass and move at c, instead of having a tiny one and move imperceptibly slower? I ignore it. Exactly the same question remained open long enough for the neutrino. Please don't answer "because of equations" or "because of model". If they're massive, adjust said models a little bit and keep c for the asymptotic speed. What is well observed is that photons from very remote sources arrive at the same time, so their energy doesn't influence perceptibly the propagation speed. But this holds for neutrinos as well... ngosh@india, could you choose more detailed thread titles?