p1t1o

@Der Anfang You dont know me, or how wonderful, or not, I am But this IS a pretty awesome forum, and it was nice to be reminded of that, and that being a part of it is a pretty cool thing. And hey, maybe that does make me a bit more wonderful. So thanks

There's carbon nanotubes on burnt toast. There are dioxins (a class of extremely toxic compounds) in burnt toast. If I had a 3rd fact about burnt toast it would really round-out this comment.

Are there any of those still flying?

I had a look at your diagrams over on XKCD. I think that there is a fizzle problem, the device is only confined at the ends, the weapon will expand radially until it is no longer critical, this of course happens in every weapon, but without significant radial confinement I suspect it will disrupt itself too quickly to release much energy. In other words, your design would be much more efficient if there were an extention of the confinement, but this would add radius and essentially defeat the object. Compare to the Little Boy device. This was "assembled" explosively, but confinement was due to the tensile strength inertia* of the casing. The casing was very thick and very heavy and produced an inefficient device. I feel like the thickness of casing needed to make your device detonate with a decent efficiency would defeat all gains in reducing radius by making it a cylinder. However, I think it is likely that you were thinking along the right lines, there was a revolution in US warhead design that vastly reduced the radius of fission devices, called the "Swan device" it was an oval-shaped primary, that had a compression system that used clever timing to achieve spherical compression. It is worth noting that the Swan configuration, intended to produce a minimum-diameter device, was usually used entirely without a reflector/tamper/strong casing, as doing so - even though less fissiles would be required, increased the diameter. Ergo, swan devices used rather more fissiles than would otherwise be required, in order to achieve lower radius. Very modern warhead are said to have [details are obviously not available] an actual pit that is oval, or "prolate", using again clever timing and construction to compress, forming a sphere at the right moment. Making a subcritical oval is essentially similar to your subcritical rod design in terms of reducing the radius of your subcritical component. In fact it can be seen as your rod device but with the compression system covering laterally as well, as described above. So the rod idea itself is totally solid. As for using neutron poisons, i dont see why this approach wouldnt work, but I dont see why it is necessary when geometry is already controlling the criticality. You risk poisoning the reaction itself, increasing the proability of a fizzle or even a dud, especially since a mature compression system has to have full coverage (or your plutonium will be squirted out the same gap as your poison, spoiling the criticality). *at the temperatures and pressures involved, chemical-bond tensile strength is meaningless and it is the inertial mass of material which provides the brief resistance to outwards expansion. This is true whether you are considering a Little Boy-like device or the inwardly collapsing tamper of a spherical implosion device, it is even true down in the chemical-energy realm and applies to things like shaped charges and kinetic penetrators. The energies at which chemical bonds become trivial is suprisingly low, in a scientific context.

This seems as good a place as any to ask - Doge Is it "doe-guh" (like "dawg") or "doje"? Soft or hard "g"?

There's a great many things that can degrade concrete, collectively called "rot", I imagine there are even some biological pathways, so literal rot - although a properly formulated concrete for your use should be treated against the major risks. The most obvious is corrosion of the steel reinforcement rebar, as rust takes up more space than the original metal, it expands inside the concrete, causing spallation. One of our major products is a corrosion inhibitor for just this reason.

So I live in West London, UK, and work in Slough about 15 miles away. I am ordering a car from a dealership in Doncaster (about 200miles away) because thats where the best deal is. To kill 2 birds with one stone, and to give it a good burn-in drive, Im having it delivered to my parents house and I will pick it up from there ( the second "bird" is visiting my parents), my parents live much closer to Doncaster than me. I got the financial paperwork to sign, and the address of the head office on the paperwork? Its like 100m away from my office in Slough, I can literally see their building from our windows. Small world huh?

Ha! It specifies "internet gaming" (yeah, you know, that term we all use: "Anyone up for some internet gaming?"), all my gaming is 100% offline, so I must be safe. *** Anyhoo, random science facts. Here's some stuff I learned when starting to work for a company that makes concrete and cement related construction products: You cant dispose of a body at a building site by dumping it into wet concrete/cement. It is never (or hardly ever) poured in layers thick enough to submerge a body, usually only a few inches at a time (or a continuous process with a few inches of wet concrete). And anyway, void formation is a known and undesirable phenomenon, and the huge void caused by a decomposing body would be quickly detected by quality control procedures and would never be allowed. There is a special recipe of concrete specifically for rocket launch pads. There are concrete recipes that float in water. Concrete continues to "mature" for a great many decades, and its compressive strength increases as it does so. Concrete and cement do not harden as it "dries", the curing reaction is started by water. Some of the water is consumed in the reaction but the concrete/cement can still be wet/damp when fully set. Concrete and cement can cure underwater. The most produced/used/consumed material in the world, is water. The second is concrete.

Wow, good way to make me feel old. "You know that game you like? Since you've been playing it, these people have passed through entire life stages full of bright colours, opportunity and excitement! Whereas you've just...aged. " XD *** This looks well presented, you obviously know what you're doing, kudos, and good luck!

I thiiiiiink this is the aircraft I was thinking of, seems to fit the drawn profile quite well, if you stick some hardpoints on the wings. https://en.wikipedia.org/wiki/Saab_105 Its Swedish so I dont know what it'd be doing there but someone mentioned an airshow nearby? You often see strange aircraft flying when that happens. Saw an F-22 whilst working near Farnbrough in the UK once (It might be the "AppleMac" of fighter aircraft, but dang it made a pretty noise! Reminiscent of the "Vulcan Howl".)

Could it have been something similar to examples shown here? https://blog.aopa.org/aopa/2015/08/11/special-mission-aircraft/ A business jet used as a some sort of testbed/flying lab, with podded instruments? Its not all that uncommon, as a further example, the RAF used to operate these (below) for multiengine training but also for naval anti-air training with radar simulator pods on the wings. Another guess: https://en.wikipedia.org/wiki/FMA_IA_58_Pucará Or this? https://en.wikipedia.org/wiki/North_American_T-2_Buckeye Or even: Thers another aircraft that matches the drawing that I can imagine, but I cant for the life of me remember any identifying details about it and cant find it anywhere.....

I cant, but then imgur is blocked here too.

All true, but they do reduce drag I believe the "bulge" was extended specifically to take advantage, and the anti-shock bodies which house flap actuators are far wider than they would otherwise be. "One interesting outcome of the area rule is the shaping of the Boeing 747's upper deck.[9] The aircraft was designed to carry standard intermodal containers in a two-wide, two-high stack on the main deck, which was considered a serious accident risk for the pilots if they were located in a cockpit at the front of the aircraft. They were instead moved above the deck in a small "hump", which was designed to be as small as possible given normal streamlining principles. It was later realized that the drag could be reduced much more by lengthening the hump, using it to reduce wave drag offsetting the tail surface's contribution. The new design was introduced on the 747-300, improving its cruise speed and lowering drag, with the side effect of slightly increasing capacity on passenger flights."

On the topic of supersonic airliners: Could an airliner reach Mach 1? Yeah sure, but so can a rock, doesnt mean you'd want to fly one. Take a look at a supersonic fighter jet. Look at the horizontal stabilisers. They are slab-like, all-moving affairs, ie: there is no seperate "elevator" flap. This is because in the transonic region, shockwaves are set up across wing surfaces. These shockwaves interfere strongly with the airflow over the trailing edge, almost completely removing all control authority from elevators, and in the early days of supersonic research, there were many "unexplained" incidences of aircraft falling out of the sky for no apparent reason. Only later was it discovered that this (amongst other things and other incidents) was the likely cause. Combine this with the "Mach Tuck" phenomenon (and a 0.85Mach-rated airliner may not have the capacity to alter its centre-of-mass enough to compensate even just for that) and aircraft have to be carefully designed to operate in/around the trans/supersonic regime. Modern airliners are however designed with transonics in mind, many obvious design features are there to improve performance in the transonic region, but there are many features appropriate to the supersonic regime that are conspicuously absent, eg: the all-moving slab tailplanes. I certainly wouldnt bet my life on any airliner surviving anything other than a brief foray to just above the sound barrier. Gross structural integrity should not be ignored either, the dynamic pressure on the front surfaces of the aircraft will rise significantly with speed. With the square of speed, even. As will temperature, which will in turn, also affect structural properties. FunFactTM: the "bulge" at the front of a 747 actually reduces transonic drag by smoothing cross-sectional area changes, just like wasp-waisted fighter jets (see: area rule). Same goes for those aerodynamic bodies you see under the wings.

Is there such a thing as a "free" quark? If yes, is there anything especially noteworthy about them? Any properties worth mentioning? If no, why not?

That...rings a bell...I do believe "Crius" was a planet in the (rather excellent) game Privateer II: The darkening, starring Clive Owen (young!), John Hurt and Christopher Walken no less!

Declare Martian independence.

I flipping LOVE how X-McXFace is a thing now XD

There are some complexities to the terms here, I think I made the same mistake, a critical mass is not necessarily a nuclear detonation. The demon core incidents were "criticality" incidents in that they were pushed to a "critical" state where the power output (and neutron production) was rapidly increase dot a high level. A nuclear detonation is a "supercriticality" which is what we recognise as a runaway chain reaction, which is only halted by the destruction of the device. The exponentially rising "supercritical" state requires somewhat more severe conditions than those created in a laboratory experiment in order to release the sort of energies involved in a detonation, but a steady criticality can be obtained and brief supercriticality will result in the apparatus dismantling itself. Enclosing a sub-critical mass in a neutron reflector changes the conditions present and makes sub-critical mass into a critical one, this will reach a steady, critical, state of high power output, and if it is rapid enough it will explosively deconstruct and halt the reaction. Almost the entire structure of a fission device is designed to contain the reaction for long enough, and to make the reaction proceed fast enough, at the exact right time, that a significant amount of energy is released before the destruction halts the reaction. That is why you could never get a true nuclear detonation merely from creating a critical mass by enclosing a subcritical one [with a neutron reflector]. The "Lady Godiva device" (essentially used for the same experiments as those performed with the demon core) - The 3 parts form a critical mass, note: no neutron reflector required. Before and after a criticality incident, the right picture shows the damage caused:

Oh it hypothetical for sure, what I meant was that "electric armour" has been seriously considered as a possibility, as far as made-up supertechnologies go, its more plausible than some. It doesnt require free neutronium for example

Well the "Fat Man" device was 1.5m in diameter, almost all of it weapon, and its yield was roughly 20kt. Its not a simple question at all to try and extrapolate that up to 2.5m, but you get an idea of the ball park - its not going to be a Megaton, we can say that much. Reasonable guess would be anywhere within a range from 30-100kt, gut feeling. Just for reference, in 1959 the RAF deployed a very large fission-only device that was about the same size as Fat Man but with a 400kt yield, and a modern thermonuclear warhead can do 475kt in a device 21inches across (but a bit longer) - it is said that the diameter [of modern thermonuclear weapons] is largely set by the diameter of the fission primary, which will have (very roughly) 5-10% of the final yield.

Well first off, you kinda answered your own question, of course it would work. Its just a question of magnitude and whether it could be made to be sufficiently practical for use. You've mixed up magnetic and electric charges there I think, and magnets wont work as well because all (non-exotic) magnets have to have both poles, but a negatively charged bullet would be repelled by a negatively charged tank, and there is a magnitude which would produce enough force to stop a bullet for sure. But it might also have many other, less desirable effects. Your version probably isnt practical, but its not a ludicrous idea at all: https://en.wikipedia.org/wiki/Reactive_armour#Electric_reactive_armour **edit** Now that I think about it, there IS a magnitude of charge - theoretically - that could stop a like-charged bullet, but Im not sure if it is possible to GIVE an object that much charge. The only way I know to charge a physical object is to manipulate the population of electrons present in some manner or other. Strip some off to give it positive charge, squeeze some more in to give it a negative charge. But electric repulsion or attraction is very powerful. At some point, the negative charge is enough that electrons themselves are repelled and they just...ping off. Similarly, strip enough away, give something enough of a positive charge, and it will simply rip electrons off surrounding materials.

Oh I have a question - is there a formal definition of "gunpowder era"? When I think "gunpowder era" my mind goes to flintlocks and muzzle loading cannon, so like around 1600ish? But cordite was not invented until 1889 and some sources have mentions of gunpowder-like things dating back to like 500AD. Thats a wide period. It is going to be easier to build a nuke in 1888 than in 1088 after all. 1888 only predates nukes by a handful of decades, easily within a single lifespan. In fact, the "gunpowder era" ends after the invention of high explosives, so a legit nuke could (if some key research was done just a single generation earlier, much of the groundwork was already present by this time) have been built technically within the gunpowder era. Its not that much of a stretch to imagine a Manhattan-style crash project could have been pulled off just a few decades early. Its not quite as romantic as lobbing spiked, cast-iron tac-nukes with a trebuchet (gonna need to up-rate those...) but still.....one could have had a cowboy with a nuke on his back, how's that? Or Sherlock Holmes (first appearance 1887) could have had one in his basement.

What about muzzle velocity? Did a bit of searching and the velocity was only about 300m/s, that's achievable with gunpowder right? If you have a solid sphere of a critical mass, it has already detonated. The challenge is creating a weapon that is sub-critical when not in use, and super-critical on command. *** Critical mass is dependant on geometry, a critical mass when a solid sphere can be made sub-critical by forming it into a hollow sphere - this is a dangerous design (but WAS used in several service weapons) however, as accident could easily make it critical. Modern weapons use a solid sphere of sub-critical mass, which is compressed violently enough to crush the sphere to a denser crystalline phase, thus pushing it into a smaller, super-critical sphere. Some compact designs are rumoured (thats all we've got) to use a "prolate" or "lozenge-shaped" core using a more advanced implosion system.

The range of assumptions and conditions needed to bring this about without exporting a fully-realised 20th century knowledge base and the required materials is....a stretch, but I'll go with it Whether or not you could get enough energy from a gunpowder explosion is one for the mathematicians - but it does seem doubtful, the speed of detonation is very much slower than a true high explosive and the energy density much lower. It is very possible that it just takes too long for gunpowder to explode for it to even "fizzle" (a nuclear, but incomplete, detonation) and you'll probably just get some shrapnel and a hot ball of plutonium. The gross design concepts of a implosion fission device are not that esoteric, but there are difficulties that are not at first obvious: The timing of the detonations around the sphere must be very exact to the microsecond, its very unlikely that this could be achieved with gunpowder fuses. The explosives are not just "in layers", in an implosion device there are two types of explosive, with tow detonation speeds, and blocks of the two types are machined into precise shapes (often termed "lenses" as the geometry focuses a wave) so that the outwardly expanding spherical shock fronts from all of the seperate detonation points smoothly merge into a single spherical, inwardly converging shock front. The precision required to manufacture this (and the mathematics required to figure it all out) are very probably beyond gunpowder era technologies. An implosion device is a precision made machine, with very many parts and many esoteric operating principles. The general diagram - fissile core, layers of explosive, casing and fuses, is elegant for sure, but deceptively simple. Even the core, in a mature device, has many seperate components, to maximise efficiency/yield and minimise chance of failure (for example, your design omits a tamper and an initiator). A modern, fully-featured weapon is among the most highly advanced pieces of machinery on the planet. A poorly built device with insufficient precision could have any effect from a totally non-nuclear detonation of just the explosives, to a "dirty" explosion which spreads fissile material, to a "fizzle", a partial nuclear detonation which could have a yield almost anywhere in the range from 0% to 100% intended. With gunpowder-era precision (and, well, gunpowder) I would wager it is strongly skewed towards the first example (non-nuclear). This is why there is little danger in declassifying the gross details of a fission devices design - its not the physics or the design which is prohibitively difficult, its the manufacture and acquisition of the materials. A gun-type device is much easier to build, and seeing as little-boy was fired with cordite (essentially modern gunpowder) I dont see why you couldnt build one to use gunpowder if a similar barrel velocity can be obtained. Precision requirements are far less. There are some details about the design of the core they'd need to know, but the main design parameter is barrel velocity, there is a minimum that needs to be met to avoid a "fizzle". Not sure about that though - anyone know the differences in performance between cordite and gunpowder?