Enthalpy

Hi dear friends! Ionizing radiations emitted at Solar flares are said to be a concern for astronauts, say on a trip to Mars. If the rays are parallel enough, and their direction varies slowly enough, here's a possibility to make a shield lighter and more efficient: The (here purple) shield stops most primary rays from the Solar flare, and inevitably creates secondary rays by bremsstrahlung, whose gammas and X-rays are difficult to stop. The trick is to put this shield farther from the craft, at some habitat sizes away (I'd link it mechanically) but keep it just slightly bigger than the habitat. Then, most secondary rays don't hit the habitat. An other shield (here green) is still required againt the remaining secondary rays and against the isotropic cosmic rays. Marc Schaefer, aka Enthalpy

Hi, welcome here! Silica and glass surfaces have a layer of hydrates, typically ending as Si-O-H. The Si-O bond must make this oxygen atom more favourable than in a water molecule for hydrogen bonds with other water molecules.

Search for: platinum catalyst at eBay.com or elsewhere.

Hydrogen is usually not considered a metal (no alkaline oxide, insulator...) but it can become a conductive metal under huge pressure. The periodic table is not periodic, so extrapolating words and properties to its first line works badly.

For my personal information please: A part of the electron's and proton's masses result from their electric field. When the electron and proton are close to an other, the electrostatic attraction reduce their energy (twice as much as the kinetic energy increases the electron's mass+energy). Must this energy change be included in the electron's mass to compute the orbitals? Also: this energy change isn't necessarily located at the particles (...with all subtleties associated with a particle position). This energy change is rather everywhere around the proton and the electron, where the square field (Ep+Ee)2 differs from Ep2+Ee2. Because this energy change can be located elsewhere than the electron's rest mass, its contribution to inertia may not be proportional to the mass+energy change (nor to half the change). Is that included in models for the hydrogen atom? And does it make any sense? Thanks!

1) As no atmosphere evens temperatures out on the Moon, you can't define one temperature. It depends much on the colour and more. Proper life support must bring a good temperature, not the Moon, whatever the daytime is. 2) Cosmic rays don't depend on night and day. Solar rays do. Our terrestrial atmosphere is 10,000 kg/m2 thick and offers a good protection at sea level, so stones or dust 5m thick would be good. Ice would sublimate away. Esa has a very nice demonstrator to sinter regolith and make walls of it 3) Earth's atmosphere loses half its density at 6000m height. The Moon having about the same temperature but 1/6 the gravity, nitrogen would occupy 6*6km "height", and lighter water vapour even more. 4) Same info as Moontanman. 4 bis) While the soil isn't a difficulty, water is. It's not available on the Moon, or only with huge difficulty, and would escape immediately, so it must be confined in some huge dome. The other difficulty is our lack of knowledge for biological cycles: the last attempt, Biosphere 2, failed on Earth. 6) What do you call an H3 reactor? Is it tritium, 3H? Up to now anf for any foreseeable future, no deuterium-tritium reactor is operational. But Sunlight is plentiful on the Moon, better than the clearest desert on Earth. Oxygen exists in stones and regolith, hydrogen doesn't; water ice is said to await explorers in the soil at some polar locations... But in what concentration? Moving tons of soil on a remote celestial body to gain traces of frost looks inefficient.

Hi mattcz450, welcome here! QM is interesting indeed; but the present topic isn't the best introduction you can find about it, as it's in some places more philosophy and rhetoric than physics, so a standard text about QM would be a better read.

Slightly reformulated: If the particle at your detector was observed, then you know that the other particle was observable at the other detector. The polarization orientation etc of your detector doesn't change the statistics at the other detector.

For four decades, computer monitors that use electron beams are being spied through their uncontrolled radiation. Though, I can't tell whether the electron beam radiates during the electrostatic acceleration, or the modulating electrodes and circuits, or something else. X-rays are produced by the electrostatic deflection of electrons at heavy nuclei: what kind of other proof is necessary?

Law does not demand that exposed metal parts of an equipment are grounded.

Acting on one particle does not modify the properties of the other, hence no information transfer.

Is the difference between the English ground and earth only a matter of US versus UK? In other languages it's a physical distinction.

Collecting the water that impregnates firn may not be so difficult. A machine inspired from these that dig trenches for cables is much cheaper than the park of wind turbines. It shall dig trenches down to the compact ice. Advancing in snow at 50mm/s only during daytime of summertime, it digs 300km per year. That's about the size of the meltwater reservoir. Then you can cover the trench with snow to prevent water from freezing there. Water is to seep from the snow walls and run on the ice bottom, possibly in a man-made half-pipe there. Maybe a permeable cover protects the half-pipe from collapsing snow. The trench can be renewed regularly if necessary. An additional possibility is to let the trench open to cold air, so that seeping water freezes in the trench and makes it impermeable. Combined with the slope of the hard ice below, this would accumulate water where it shall be pumped. It isn't easy to move wind turbines, but fastening them in ice is easier than in soil. If they can be moved from time to time, then water needs to be collected just locally. At favourable locations, pumping may not be necessary. An impermeable full pipe might accept water accumulated by the impermeable trenches and carry it by gravity to the surface of lower locations where it shall freeze. Marc Schaefer, aka Enthalpy

I've recently seen images from a sea sonar with cm resolution. This sonar operates at 1MHz, and consequently, has very few meters range. The range and image sharpness must be worse in soil, because soil is less homogenous than seawater. An other reason is that a fossil is a stone like an other. Sometimes a flat print on a stone, sometimes a 3D organ or organism turned into stone, but its acoustic properties must differ little from the surrounding soil, so the fossil will not be obvious. The human eye should be the best analyzer for the sonar images. If you want to try it: - The sonar having a limited range, I feel important that its transducers can be moved quickly. Though, near 1MHz, an excellent contact is mandatory. This point needs attention. - Signal processing can help you. Not to recognize a fossil, but to remove echoes from the surface, deep layers... This is well developed (at lower frequencies and longer ranges) for oil and gas exploration. - It could be easier over the bed of the Ocean or a lake. Sound transfer from a moveable transducer is easier there. ========== Got 8 million hits (and nice pictures) with the searchwords sonar archaeology but these side-scan sonars picture only the seabed and the objects on it, they don't penetrate the underlying soil.

Earthquakes making electric fields in advance in the atmosphere: this has been investigated many times; I didn't follow the state of research. But electric power lines would be an excellent place to detect them, sure. Instead of corona discharges, which are badly reproducible, you could measure the voltage on the line and extract the information by signal processing. Preferably, do it at several distant power lines, to discriminate a local quake from a global aurora borealis. The general impression of the linked Pdf is that is lacks numbers - because numbers that fit distinguish a good theory: - If possible, how strong is the field, the resulting voltage induced in the power line, the possible corona effect. Very difficult for Earth science, sure. - Or observation over some time, in Greece/Japan/California... See how often quakes and coronas are correlated, and how often each appears without the other. Correlated coronas with the weather as well, which is a bigger cause. With Solar flares as well.

In addition to entanglement transporting no information: - Light and radiowaves propagate much faster than the plasma emitted by a flare, so observing or transmitting with normal means suffice - Who cares about Solar flares? The proper response is not to detect it and disconnect the power lines, but to put protective components at the power lines. This is done for decades, and since then no blackout resulted from a Solar flare.

G is the prefix to Giga, that is 109.

A non-trivial question. Devices connected to the power grid can have their metallic housing connected to Earth. If some insulation malfunctions and a power line touches the housing, the Earth wire evacuates the current, so people don't get in contact with the line. In addition, "differential" circuit breakers feel that some current that goes in the device at one line doesn't come out at the other (as it flows through the Earth line), and this sign of malfunction lets the breaker go off. Law in many countries demand such an Earth connection, depending on varied conditions. A lightning impact will find Earth whatever you do. Providing a good path to Earth means that the current there isn't destructive. A connection to Earth avoids the accumulation of static charges. ---------- Then, in electronics... It gets more complicated, opinions vary among people and depend on each case. A typical LW or MW wire antenna is single-ended; its current flows to an Earth contact. Both at the transmitter and the receiver. Among various equipments, which ones should connect to Earth? It depends. Connecting them all is often a good beginning, but not with big currents and smal voltages at low frequencies, because then, the return currents flow in part through all Earth connections, and this lets the various ground potentials differ, so some people prefer to connect only one point to Earth. It's much a matter of personal experience.

All engineering projects bring some unexpected results, hi colleague; it is more the size of the consequences that increase with the size of the undertaking... This liquid water just impregnates snow that is partially compacted ("FIRN"), so removing it shouldn't let the snow collapse. To my understanding, there are further 3,000m ice below the water reservoir, which must stop at the depth where snow is compacted to ice. So geothermy - which would have ruined the attempt - is not the cause of liquid water there. The authors suppose that fresh snow at the end of Summer insulate this water from cold air.

You are right. Saturation of alkenes by 1,4-cyclohexadiene needs a catalyst like palladium that the OP wanted to avoid.

The well-preserved old knife contains certainly much carbon (or at least hardening elements), as pure ferrite wouldn't stay any sharp. So there's an other reason.

Two bows experiment: I don't have my violin here - I left nearly everything in my country. Other people shall experiment that. There is no good way to improve the highest notes of a piano. Strings just don't fit the task. They can't be longer or they'd break, can't be thicker to be strings, so they store little energy; and high frequency couples them well into the sounding board, plus increases the air drag, so the sound is extremely brief. Hammer alignment and material won't improve that. Piano makers have just exaggerated beyond the capabilities of strings.

You are a wise person, and I followed your advice there: http://www.scienceforums.net/topic/80823-no-bose-einstein-condensate-in-bcs-superconductor-theory/

Hello you all! The Bardeen-Cooper-Schrieffer theory (BCS) makes nice explanations and predictions for the behaviour of traditional superconductors. It relies on electrons making pairs at cold - and pairs of fermions are bosons. Some texts about BCS claim that the electron pairs build a Bose-Einstein Condensate (BEC); other texts don't. Hyperphysics yes, en.wiki yes, de.wiki yes, es.wiki no, fr.wiki "some analogy", it.wiki no, pt.wiki no - textbooks diverge as well. So I wanted to check whether the original BCS theory did include the BEC of electron pairs. Here are the Nobel lectures by Bardeen, Cooper and Schrieffer: NobelLecture1972BardeenCooperSchrieffer.zip which can also be found on the Nobel website: http://www.nobelprize.org/nobel_prizes/physics/laureates/1972/bardeen-lecture.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/1972/cooper-lecture.pdf http://www.nobelprize.org/nobel_prizes/physics/laureates/1972/schrieffer-lecture.pdf The clearest part about this point is from Schrieffer on page 105: So the BEC, which was part of previous superconductor theory, is explicitly excluded by BCS. Because the pairs are big and close to an other, they don't condensate as bosons into a single state. And even: this is necessary to the theory.

Hello responsible citizens, perspicacious scientists, and megalomaniac engineers! A research team has found much liquid meltwater 5-50m below ice surface between the ice particles in Greenland's ice sheet: http://www.bbc.co.uk/news/science-environment-25463647 http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2043.html Observed over 70,000km2, this reservoir could represent 140*1012kg/yr meltwater, or 0.4mm/yr sea level rise, half the contribution of Greenland, provided it does flow into the Ocean now or later, which is still unclear. Human technology may prevent this contribution to sea level rise. Collect this water, bring it to the surface when the air is cold, leave it there to freeze. This goal is at grasp: the Dutch achieved a similar one when they reclaimed land from the sea, without our present technology. How to collect the water in 1,200 wells over the area isn't clear to me - ask a specialist. How much power does it need? Only mean 870MW to bring the water amount from -20m to the atmosphere. If wind is reasonably favourable there (to be checked), then 1,200 land wind turbines of present 3MW technology suffice, spread over the reservoir area equivalent to Ireland. Or find a different energy source; the temperature difference between this water and the atmosphere is a big power difficult to exploit. How expensive? A park of peak 1,800MW - half the power, but offshore makes it twice as expensive - was bought for 2.5G€. http://de.wikipedia.org/wiki/Siemens_SWT-6.0 At this price, we avoid 2cm sea level rise in 50 years. Marc Schaefer, aka Enthalpy