p1t1o

I know Im getting this from...ahem...gizmodo :shame: but here you go anyway: http://gizmodo.com/what-the-hell-is-this-beautiful-thing-1794528895

Funnily enough, I almost went with "Worf" to start with but I didnt want to confuse my Klingon tactical officer. ENGAGE GORPDRIVE

Rather than inventing or repurposing portmanteaus, we need a set of fresh new words to represent these directions. I'll get the ball rolling with: Gorp - "prograde" Dorp - "retrograde" Lorp - Normal Zorp - Anti-Normal Porp - Radial Worp - Anti-Radial "Burn 25m/s Gorp"

Strongly against "posigrade" Prefer "Nosewardgrade"

That is unfortunately the long and short of it. However, if it is a simulation you are attempting to build, that does grant you some freedom if your goals are a little flexible. It will be very difficult to write a perfect simulator, you wont be reproducing results from CERN any time soon. But since it is a simulator, and thus by definition, an approximation, you are free to define said approximation as you see fit. Set out known assumptions and set out what you are going to show, and you still might be able to generate some interesting data, even if it isnt the exact solution you were looking for at first. For example: Let us assume that protons are small physically spherical objects Let us assume that one particle labelled "antiproton" will consume another particle labelled "proton" (and vice versa) and will produce X number of smaller particles moving at speed Y from the origin of the collision. Here is what happens when we fire an "antiproton" into a mass of ten thousand "protons". Now this only resembles reality at a very basic level, however some statistical information coming from it might be valid. Such as observing how the number of subsequent collisions increase as a function of the number of "antiprotons" you inject. You wont really be simulating the exact results of using real antiprotons and protons, but you will see the sort of numerical things that happen when you do things with large numbers of particles, it can give a general "gist" of what happens when particles start exploding amongst themselves, that sort of thing. Like when a military simulator cannot properly simulate modern missiles because the technical spoecifics are classified, but you can still get a good/realistic picture of what happens to the air battle when you, say, double the number of available weapons, or aircraft. The specific data might be inaccurate, but the overall picture still gives an illustrative idea. Im not sure if that is clear, see what Im getting at?

What orientation is the H2 molecule in? What frequency is the H-H bond vibrating at? What is the temperature of the system? What is the proton energy state? What are the quark-gluon conditions like within each proton AND antiproton? Is the H2 molecule rotating? Dont forget the Heisenberg uncertainty principle! Precisely what angle and attitude will the collision have? What is the electric and magnetic environment present? Is there an electron involved? What is its energy level? Where is it in its probability cloud? This sh** is COMPLEX, you cant give meaningful answers with such broad starting conditions - and even if you gave precise conditions, a reasonable answer would still be very difficult to guess at without actually knowing how to work out the answer. It seems like I should be able to say "Ooh it will be around the 35% mark or thereabout I would imagine", but you really, really cant do that sort of thing at these kinds of scales, in this realm of physics. There is a reason "they" spend million and millions on enormous colliders - because sometimes to know something you actually have to go and do it. In other words, you need to talk to someone who works with antimatter and individual protons at a professional level, and you may need to go through a large amount of higher education to understand the answer. If it was a classical physics problem, many people on this site would be able to work out a pretty decent treatment of the problem and perhaps calculate accurate and well-characterised answers, or by analogy to a similar known problem, give very illuminating comparisons. But at this scale, in the quantum realm, this cannot be done in the same way. Protons are not solid spheres that bounce and collide in nice predictable ways. Even the concept of them being "particles" is an approximation, they are not actually little round balls in any real sense. If all of that sounds rather negative, hear this - that you even know enough to ask very hard questions is a pretty good starting point

That would explain why I have heard the term "Quark-gluon plasma" to describe the debris produced by an annihilation. How much of the kinetic energy supplied by the cue ball, on average by percentage, does the black ball receive during a break in a game of pool? It can vary wildly depending on initial conditions, which in the context of your question, vary wildly with time. So the answer is "unknown", at least without extensive mathematical treatment. Extensive. It could be zero percent, or it could absorb enough energy to blast it into its constituent pieces. On average over a large number of events? I have no idea. So little AM has been produced and successfully experimented with, that it is possible that this is still an open question. Its not something that you can estimate with classical physics, and quantum things are very hard to make intuitive guesses at.

Well what we can say with a high degree of confidence is that the total mass-energy of the system before and after annihilation will be conserved, as will the total charge of the system. Im not sure if neutron embrittlement would be a limiting factor, there are larger worries present. Possible that the high temperature environment would "anneal" any neutron embrittlement, but whether or not this is true is non-trivial to work out. As for some kind of 4th-gen enhanced radiation warhead, again, its too complex to say "Combine uranium with antiprotons will liberate more neutrons than a thermonuclear device of comparable mass" or the opposite. But if its for sci-fi, and you aren't going fully 100% "hard" sci-fi, then I suppose its vaguely plausible, to create this device with antiprotons and uranium. Since practical research with AM is very limited, who can say you are definitely wrong? For details about neutron embrittlement of an AM reactor, I would just look into how it is dealt with in real-life fission reactors, and modify that context to your needs.

I feel like the question is far too simple for the physics that it relates to...

Pictured: a better airport design

"Spaaaaaaaaaaaaaaaaaaace"

You've got it right in that an anti-proton wants to react with a proton. But the specifics of actual "anti-atom" annihilating with each other I think would be far less clear-cut. For example, one the positron has annihilated one of the helium's electrons, does it release enough energy, in the appropriate manner, to eject the other electron? If there is still an electron present around the helium, it will strongly repel the remaining anti-proton. And if the anti-proton manages to interact with the helium nucleus, the remaining particles will likely be flying in all directions seperately, it is not likely that a complete tritium nucleus will be left over, and if it were, it is unlikely to still have the leftover electron bound to it. If I recall correctly, there are proposed propulsion mechanisms that are similar to the method you propose, ie: using magnetic fields to direct the high-energy products of annihilation reactions as an exhaust, but it isn't the perfect energy source that we might sometimes imagine - a significant amount of energy produced by annihilation comes in a form that cannot be directed (uncharged particles, gamma rays) and so cannot contribute to propulsion, the engine will also be intensely radioactive, which means heavy shielding amongst other complications. As always, head on over to project rho for a decently up-to-date skivvy on proposed propulsion methods, and a decent primer on antimatter propulsion: http://www.projectrho.com/public_html/rocket/enginelist.php On which this interesting link, amongst others, can be found: http://www.dtic.mil/dtic/tr/fulltext/u2/a160734.pdf

Reminds me of that article that talked about "molecules of light" which will definitely allow us to build lightsabers.

Not to use less water, but to eliminate less. But not like "less"-less, its more that in normal, urban day-to-day life there is more excess to play with. So its not like a huge "Im aclimatised to heat now, fear me!" but just a sort of fitness for hot weather. People who are obsessed with drinking a lot of water in day-to-day life though, can get in trouble very quickly in hot places for this very reason, if there is no preparation, and as you say, they are taken off-guard by how much water they need.

The flavour/nutrient brain connection must be very powerful because, no joke, I have heard it so often from vegetarian or vegan friends and acquaintances... "I do miss bacon though." "If I went back, it would be for bacon." "Say? Do you have any bacon I can smell?" *edit* If you think too long and too hard about what exactly we do to pigs, it is like, the gruesomest horror movie...

First off, this sort of thing can be dangerous, so much so that "excessive beer drinking" is listed as a cause of hyponatremia. But you do have to do it to extreme excess. Like I said there is a lot of variability. Its not pure water for starters, so its osmotic potential is less than that of just water, then there is the urination which counters it a lot, then you may just possibly be a bit overweight if you enjoy chugging gallons of beer at a time, giving you a larger volume to dilute. And probably a million other details as well. Its not a hard line though as in "drink a certain amount then you die", probably at some point you start feeling like poop which will hopefully discourage you from chugging too many more gallons of beer. It may even be responsible for a part of some hangovers at a low level, manifesting as low blood sugar and low electrolytes. I would imagine that a severe drop in blood sugar/salts does contribute to some alcohol poisoning cases. Umami is "meaty" and is related to certain amino acids I believe, so its a telltale for delicious, delicious protein, another staple for survival! Now combine umami with fatty and you have the reason why bacon is so...so good. So good. Honey glaze?! Forget about it!! Ok now I am hungry for real. Oh I didnt mean intentionally reducing your water intake whilst in hot place. I mean training your body to eliminate water less rapidly before you go. Of course they take a lot of water because they will lose a lot in said hotness. If they didnt acclimatize beforehand though, they would need significantly more, and thus be at even more risk of stones/dehydration. Mind you, Id wager that folk of this ilk are probably not the sort to give much credence to the "8 glasses" myth and probably dont have much aclimatising to do, esp. if they travel to hot places regularly. PS: who drinks less water in hot places? Is that a thing?

Which raises the question - why bother putting a cap on and not making it aerodynamic? Unless aero resistance is like really insignificant.

My immediate skepticism is tempered by statements like: [emphasis my own] "behaved as if it had negative mass" "A negative effective mass.." "...whose dispersion features a region of negative effective mass." "...managed to get a fluid of superchilled atoms to act as though it has negative mass" Accelerating in the opposite direction to applied force can cause paradoxes including perpetual motion and infinite free energy, so I think its best to hold off a while on statements like "negative mass has been created". If a truly groundbreaking form of matter has been found, we will have it strongly confirmed in due course. *edit* ninj'd slightly by @Steel

Ooh, I have a fact! Your kidneys are quite efficient. It is said that half a kidney can keep a person almost as healthy as 2 whole ones (not literally cut in half, obvs) that is how much spare capacity they have. Presumably a result of the many different types of environment we evolved in. If you drink a lot of water, say the mythical "8 glasses", then in order to maintain your water balance, your kidneys have to remove a fair amount of water and they get used to doing this over the long term. This means that a person who drinks 8 glasses a day *needs* 8 glasses a day. If you drink less, you need less. There is no detriment. Professional people who go to very hot places with little water (like a remote desert or whatever), will prepare by intentionally reducing their water intake in the weeks/months leading up to the trip, this reduces their kidneys tendency to eliminate water, otherwise, a significant amount of water is lost from your body just by urinating. You do not need to "flush" your body with large amounts of water to "remove toxins", as mentioned previously, your kidneys are very efficient at doing this already. Your kidneys are capable of producing quite a concentrated urine (precisely to conserve water) and anything less than this means you are getting enough water. Barring any dysfunction of course. That they eliminate more water when you drink more, is because you are drinking more water than your body needs, or in other words *too much water*. It *is* possible to overwhelm your kidneys with water and poison yourself, and though this is quite difficult to do, people have died from this. You can produce an LD50 or a lethal dosage for water, but the variability of circumstances is great. In general, drinking 2-3 litres of water in one go/in a short space of time can be harmful, but in practice this is pretty hard to do, and if you were already dehydrated/ing, the amount increases.

Yes I've heard that if you can stick it out for just 3 or 4 cups without sugar, you never take your coffee sweet again. Its our damned efficient evolutionary history. We have been conditioned to find calories tasty, no matter where they come from, its no mystery why fatty and sugary foods are so tasty to so many, because back in the day, calories = survival, and being able to taste which foods had them was a great advantage. I mean, I presume...

@sevenperforce ah well there you go! /thread

Atmospheric drag is not the biggest difficulty facing rockets going into orbit, after the first couple of hundred thousand feet vertical, aerodynamics dont matter any more, the mass of an aerodynamic cap (and the danger of colliding with it after jettison) probably outweigh the gains.

I have been looking at this in terms of soft drinks too, with regard to dental issues. Every single soft drink on the shelf has at least 10% by weight of sugar....10%! Even fruit juices with no added sugar are the same, and they are worse because they can be very acidic. Now, I H-H-H-H-HAAAAATE the taste of sweeteners. Diet drinks taste like swill to me, I honestly dont know how people can drink them. And now some non-diet drinks enhance their sweetness with added sweetener! Of course yes, I drink plain water sometimes, but I am a middle-class child of the 90's and am spoiled ok? I like my soft drinks, and I like them not to taste like garbage chemical sweeteners. I have only found a sparse few drinks that dont have sweeteners and fall significantly below the 10% by weight mark. The only one I can remember off the top of my head now is "Purdey's" which has something like 5% sugar. Its also very tasty. https://www.purdeys.com/

Im not an actual rocket engineer, but it sounds like a completely new engine to me. Almost everything important to the design of a rocket engine would change, necessitating changes elsewhere. The nozzle design affects chamber pressure and temperature. Chamber pressure/temperature affect injector design and turbopump properties. Fuel injection factors affect other upstream plumbing. Etc. There are not actually that many things that are easier to "convert" to something else than to build new from scratch. Many times it would be more difficult and expensive to do this.

Well I tried my hardest when I was a student, but it didnt take.