Sensei

..and there will be more, if nothing will be done, because weapon manufacturers have to earn money, year by year.. 1) what are the biggest gun making companies? 2) are they listed on stock markets (which one) ? are they private (which one)? are they owned by government (which one)? 3) who are their shareholders? (and in what percentage) 4) if shareholders are e.g. retirement funds, or investment funds, then which one.. ? 5) should not retired-to-be and retired people know in which companies their retirement funds are investing their money.. ? 6) should not they disallow their retirement funds to invest in company in which they don't believe is doing something good for people.. ?

I think the main purpose of buyback program is to take illegal weapons from streets..

Australian's gun buyback program in 1996 took 660,959 firearms out of private hands. https://en.wikipedia.org/wiki/Gun_buyback_program

Regulations to control who can buy gun is not enough to limit mass shootings. There is also needed buyback of weapons available on 2nd hand market. And "do something" with existing weapon making companies. They demand steady (or growing) income year by year for their products. Buyback of their stocks, and then change of their profile, to production of something useful to people? That reminds me strategy used by U.S.Army in Iraq and Afghanistan. American soldiers offered cash for weapons given away by Iraq army after surrendering to everybody who wanted it (to destabilize country, which they actually managed to do anyway).

There is known just a few Argon compounds. https://en.wikipedia.org/wiki/Argon_compounds As it's Noble gas, they're in majority extremely unstable.

It reminded me this: https://www.youtube.com/watch?v=xj4gSMdaaxE The last time I was making woodwork, I made a wine press: Not as pretty as this one.. Very similar project to hot tub of wood, for sauna.

The very long chain of jokes... https://www.youtube.com/watch?v=NxFkEj7KPC0

I see you just mention amount of Hydrogen everywhere, omitting how much you will need Oxygen.. 100 kg Hydrogen = 100 000 grams / 4.3h / 3600s = 6.46 grams of Hydrogen burned/reacted per second. 6.46 grams of Hydrogen requires 51.27 grams of Oxygen, from air, if you don't take it in tank. There is 0.3 grams of Oxygen in Liter of air at sea-level (and less at higher altitude). 51.27 g / 0.3g/L = 170.9 L of air must be sucked in by fuel cells per second. Approximately 10.26 m^3 per minute. Looks quite a lot. Wouldn't it require powerful air compressor.. ?

They are not comparable. In solar panel you invest once, then you can use the next 20-30 years, without significant costs, until it breaks (with tiny decrease of power after many years of usage). Oil you have to buy day by day. One day oil price on stock market is $145.31 per barrel in July 2008, the next couple months it dropped to $30.28 in Dec 2008. Just an example. You can't predict price of oil in couple months/weeks, not to mention period of 20-30 years. It can, and will, go high, when oil wells will be running out of oil, one by one. High demand for limited good results in increased price. I am great fan of solar panels. I would use them everywhere, if I could, and only after exhausting accumulators use regular power supply.

You're mistaken. You're mistaken. Obviously they would exist, without any purpose. Jupiter, and other giant gas planets, accidentally played very important role in Solar System formation. They attracted cosmic dust, comets, to them self. If they would not exist, rock planets would be bombarded by asteroids,planetoids,comets,cosmic dust, much more often, and life could never appear. But don't turn it up-side-down. Jupiter just helped development of life on the Earth, but was not designed to do so on purpose.

You might find this paper interesting https://www.nature.com/articles/s41598-017-04910-3 It's study how presence of Magnesium Perchlorate (which is 0.6% wt, of Mars surface) together with UV rays accelerate the dying of microorganisms.

One of the largest problems with Venus is that it receives ~90% more energy than Earth. Irradiance 2600 W/m^2, instead of Earth's 1370 W/m^2. You can calculate it reversing inverse-square law: [math]E_e=\frac{P_0}{4\pi r^2}[/math] Ee=1370 W/m^2 on Earth at 150 mln km (150 bln m) distance from the Sun. [math]P_0=E_e 4\pi r^2[/math] P0 is total power released by the Sun (energy per second). Then, calculation of irradiance of other planet at distance r' will be possible using: [math]E_e'=\frac{P_0}{4\pi r'^2}[/math]

If we're at subject "musical instruments (nearly) nobody heard about", how about Theremin Yes, the guy is shaking hands in air, without touching it.. Some can call it magic..

Welcome on the board!

GOTO is essential instruction in machine code/assembly.. JMP (JuMP to absolute address) and BRA (Branch Relative Address given as offset). GOSUB is nothing different from JSR (Jump to Sub-Routine absolute address) or BSR (Branch to Sub-Routine relative address given as offset).

Sorry, I have not read entire thread carefully, but I only see you mentioning Hydrogen, and completely ignoring Oxygen issue. On sketches there are just Hydrogen tanks, and you're providing liquid Hydrogen calculations. Am I correctly expecting that Oxygen will be taken from air? If so, should not you make calculations also for Oxygen.. ? And show how, and how fast, Oxygen will be taken from air on various altitudes.. ? You mentioned 17 km altitude in post #16. If we use this calculator with 17000 m http://www.altitude.org/air_pressure.php "At 17000m, the standard barometric pressure is 10 kPa (75 mmHg). This means that there is 10% of the oxygen available at sea level." Let's assume that at standard conditions there is 0.04464 mol/L 21% is Oxygen, and 10% of that is at 17km. So it gives 0.04464 mol/L * 0.21 * 0.1 = 0.00093744 mol/L of Oxygen O2. To split 1 molecule of water to H+ OH- there is needed 1.23-1.5 eV, so for 2 Hydrogen atoms (1 H2), it's 2.5-3 eV. Multiply by e and it's 3.94e-019 J. Let's assume that it'll be given back in reverse reaction, without loses. In post #8 you mentioned motor has 86 kW = 86000 J/s Divide 86000 J/s / 3.94e-019 J = 2.1827e23 Oxygen atoms reactions per second. /2 = 1.09137e23 O2 /Na = 0.1813 mol O2 needed per second. 0.1813 mol / 0.00093744 mol/L = 193 L per second needed. In post #16 there is mentioned 127 MW. And it would be 285000 L of air needed per second.

The best is to start with activity diagrams, with arrows. https://en.wikipedia.org/wiki/Activity_diagram

HTML, AJAX, MySQL are not computer languages. Albeit it's worth to learn them. ps. You forgot Java. My list in priorities to learn: C/C++,Java,PHP,JavaScript.

Reaction of Lithium with water: Lithium floats on the surface of water, so it has smaller area contact with water than if it would sink. Comparison of alkali metals video https://www.youtube.com/watch?v=HvVUtpdK7xw

You ca You can build whatever you like. At the end, if it will be working, you could... sell them for $24k per unit.. Probably you will earn plentiful more than on "purple gold".

On eBay/Alibaba/etc? http://www.ebay.com/bhp/vacuum-furnace

Well, there is huge, deistic god won't reveal himself/herself to humans, so scientists can't make any experiment with him/her. To start making experiments, scientist has to have some revelation of phenomena. Humans wouldn't know about magnetism if there would be no natural magnets, and any other way to magnetize objects. Humans wouldn't know about electrostatics if there would be no way to charge objects by rubbing them.

I have better news for you. Bonobo builds a fire and toasts marshmallow The problem with "constructions" is that they are typically made of material easy to process. Animals use wood, early humans also used wood. And nothing remained to our time. Beavers are building dam from wood. If they would extinct, prior human, nobody now would believe that they could build dams..

That should be banned! It's mistreat with cruelty poor chimp..

One of the best examples of spin IMHO is radioactivity. Say we have radioactive isotope with even quantity of protons and neutrons, f.e. Uranium-238 has 92 protons, and 146 neutrons. Both even. So it's composite boson with spin 0. It's decaying: U-238 -> Th-234 + He-4 + 4.267 MeV To Thorium-234, which has also spin 0. Helium-4 has also spin 0. So decay is immediate. And decay energy is split immediately to Th-234 and He-4. Appropriately to their masses to conserve both energy (E=mass of uranium-238 nucleus * c^2) and momentum (initially 0). But if radioactive isotope is fermion, it has fractional nucleus spin. f.e. Uranium-235 has 92 protons, and 143 neutrons. Spin 7/2 It's decaying: U-235 -> Th-231 + He-4 + 4.86 MeV Th-231 has 90 protons and 141 neutrons, spin 5/2. 7/2 dismatch 5/2 obviously. So there is needed gamma photon to be emitted by excited nucleus after decay.. Excited nucleus has more mass, and more total energy, than in ground state. So alpha particle is accelerated to smaller velocity, and has smaller kinetic energy, and smaller relativistic mass than like it would be in 1st case with U-238.