p1t1o

A chemistry professor of mine once told us that "back in the day" they would demonstrate the nature of t-buli in lectures by squirting a syringe of it over the front row, whereupon it would auto-ignite in air and be entirely consumed before it reached them. One hopes. Of course, "back in the day" they used to mouth-pipette benzene.

Ah I think I remember that! Wasn't it an outer limits episode? I feel like there are several other examples of "fighting a war against an enemy always unseen" floating around, but I cant quite put my finger on any of them. "1984" probably counts, but in a different way. Starship troopers maybe? Didnt that start with rocks coming out of space, and sending rocks right back?

You might notice a lot of rockets are white. Generally speaking, matt white surfaces are actually a lot more reflective than mirrored surfaces, it is just that the light is scattered so you dont see a reflected image, but it looks white from every angle due to the large amount of light being reflected/scattered. Why do they use metalised foils and things as space insulation? Probably because its very thin and light. Another examples is the "anti-flash white" that nuclear bombers used to use back when high-altitude missions were the norm: http://colors.findthedata.com/l/835/Anti-Flash-White Fun Fact - this would also apply to sci-fi "anti laser armour", so when your book talks about "mirror armour" or somesuch, it is a bit of a blunder. Not only would matt white reflect more energy, but a literal mirror would not de-focus the beam, so on reflection it could strike another target.

I dont see why. Contemporary spacesuits are quite bulky and suffer from being "inflated", but it actually annoys me when I see space sci-fi and Im like "Why are they moving around in slow motion just because they're in space? Sorry, I meant: iiiiiiiinnnnnnn spaaaaaaaaaace!!" sometimes this occurs even on-board ship without any spacesuits. Sorry, spaaaaaacesuuuiiiits.

On the topic of error sources, from the conclusion of the AIAA paper: "The nature of the signals observed is still unclear. Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Indeed many more checks remain like studying effects from outgassing, thermal effects from the magnetron, etc. Our test campaign can not confirm or refute in any way the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far. We did find a number of side-effects in the previous setups that indeed can produce large false signals. More work is needed to assess other error sources and the source of the signals that we have observed. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation. We believe that this is a good education project to track down measurement errors and as a worst case we may find how to effectively shield thrust balances from magnetic fields." I also found this interesting from the body of the text: "We were really puzzled by this large thrust from our control experiment where we expected to measure zero." Full source: https://tu-dresden.de/ing/maschinenwesen/ilr/rfs/ressourcen/dateien/forschung/folder-2007-08-21-5231434330/ag_raumfahrtantriebe/JPC---Direct-Thrust-Measurements-of-an-EM-Drive-and-Evaluation-of-Possible-Side-Effects.pdf?lang=en There is also this paper: http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=39772.0;attach=1113532 Which shows that no thrust was detected when the device was powered by an on-board battery instead of an external power supply linked by cable. *Something* is going on, but I wouldnt put my money on reactionless forces, or even some other form of exotic propulsion. I *would* put money on it being a figment of increased instrument sensitivity and incomplete isolation from external influence. They really need to give this thing to those boys that detected those gravity waves with that setup that detected a shift in length of half a proton-diameter, they'll know a thing or two about cancelling out unwanted interference!

7/10 - dropped 3 points because people rationalise their expenses because people are idiots - I *had* to get the seatwarmers, besides, they were *only* £3000. Hey everyone, I have a great idea! Lets eat food! Anyone else want to eat food? I love eating food so much I do it every day, how about you?

2 – As far as I know, grappling hook guns are not a thing. Its all well and good firing a hook over a ledge, but its not guaranteed to catch. And if it does catch, how do you know it will hold your weight? In space you’d have 3 problems, first, firing the gun (any gun) if you are floating freely, would give you an unwanted impulse, which will propel you away from your target, but much worse it may send you tumbling, and you may not have a way to stop. Second, you reallllllly don’t want your hooked projectile to puncture anything. 3rdly, say you fire a hooked cable at something and it catches – when you reel yourself in, you maintain the same angular momentum relative to the destination, and just as the ballerina speeds up when she brings her arms and legs closer to her centre of mass, you will rotate around your target faster and faster as you approach, this can easily lead to you being smacked very hard into something, or even being flung into space. Oh and a hook isnt going to be much use in space, they tend to rely on gravity to catch on anything, so you'd need a kind of "universal" grabby bit, a blob of adhesive might be a good bet, but that has its own problems. No I don’t think any sort of “gun” would be a great way to move around in space. 4 – The same reason that when you inflate a balloon, it doesn’t become a cube.

Fun Fact - If you could build a ship with a drive that can accelerate your ship at 1G indefinitely (A fantasy of course, but this is a thought experiment) you could pilot the ship and circumnavigate the entire observable universe in about 100 years of ship-time, due to extreme time dilation. Many billions of years would pass for people not on board the ship, however.

lulz, this made me think of this: A pair of criminals have raided a weapons laboratory and stolen a lump of plutonium. They see a pair of policemen walking towards thier apartment and think they are going to get caught. "Quick, how do we get rid of this plutonium? Its too big for the toilet!" "Lets try and make it smaller, its solid metal so we'll have to use these explosives!" "I've got all this lithium deuteride as well, chuck that in the box too!" "We are SO smart!"

I'd say it is sometimes a good idea for a government to do this, because if it does turn out to be a game-changer, you get a strategic advantage. And as for the NHS, at least you get a lot of homeopathy for your money, and if it placebos a few thousand people out of the emergency room/GPs office, then all the better. Having said that, I did see one study which tested homeopathic remedies against a placebo...and the placebo performed better!! Probably a statistical anomaly, but hilarious!

Hmmm? Its a broken dream.

*siiiiiiigh*

The amount of modifications you would need to do to get this to work is enough to warrant calling it "building an entirely new spacecraft". Modifications would be needed even to the warheads themselves. If you just detonate a nuke behind an ICBM bus, the propellant is going to be...bits of the ICBM bus.

It is? Then what is all this hoo-haa about? This I can believe, science reporting in general is quite terrible.

Its also weird that the video purports to "explain the science" behind the emdrive when no one knows how it really works yet...

You know what they say: the right man in the wrong place...

I assumed that "elevation" references angle to the ecliptic, now Im not sure.

I thought #14 was a trick question with the answer being zero - both orbits are stated as co-planar, it is stated that the probe cannot be launched into a different elevation than the launching ship and no inclinations are given for any orbit or object...

Simple. Google every question. Google "L4 lagrange" to find out the relationship between earths orbital radius and the radius of the L4 point. Google "orbital velocity calculator" and find an online calculator that will give you orbital velocities based on masses and altitudes. Google any variable to find its relationship to known quantities. Catch my drift? Hint: playing KSP will help immensely in the understanding of all of these variables

All that stuff is the exact reason I have an open mind and havn't entirely dismissed it as a scam. On the other hand, one reason I am skeptical is because this is not the first time (remember the faster-than-light neutrinos?) this has happened and won't be the last.

I try and keep an open mind but the 3rd option seems more and more likely the longer it takes...to figure out if anything is even happening... I would have thought that if violation of conservation of momentum was possible (which if it turns out to be the case, *has always been* possible) that no sign of it has ever even been suspected up until now. Would be extremely happy to be proven wrong of course

Challenge issued - find a research paper involving fluorine that *doesn't* also include an explosion **edit** More fodder - what happens if you stick your head in a particle accelerator: https://www.wired.com/1997/12/science-2/ NB - spot the hilarious-in-a-physicist-sorta-way mistake

I know, I know, and I've been trying really hard with the emdrive, but it has been quite a long time for nothing much to come from something that supposedly violates conservation of momentum.

Unless Im way off, it should be possible to get significant savings, fortunately we both come equipped with a simulator perfectly suited to this problem! I know, I know. Its a huge pain, but I guess we'll just have to play some more KSP...

Im not sure, but IIRC one of the most prominent tests did try the test with the thruster upside-down....and measured a force in the same direction as right-side up....