Schrödinger's hat

Please reword this last bit. I do not understand.

One problem I see in a near-total collapse (where raiding and fighting is prevalent) is that any such facility will be valuable. You could arm yourselves to defend it, but presumably there will be other groups equally well armed. Fortifying such a facility would only increase its value attracting more raiders/looters. If you were then powerful enough to fend/scare off anyone who wanted what was inside then you would be powerful enough to start enforcing laws and laying down civilisation immediately.

I suppose you could do something with CO2 and some kind of pumping. Find a way to attract CO2 into a small chamber which has a glass window to another gas which emits photons at one of the IR transition energies of CO2 (N2 or O2 might work, too. I don't remember their spectra off hand). You'd need some kind of selective filter to pull it out from the air. It would essentially be a CO2 laser with the lid off. You'd also need to examine how long the state existed for, it may not be possible to get CO2 out of anything before it decays back to ground state. (maybe something phosphorescent involving spin pumping would work better, but then you'd be emitting exotic molecules). For the flame shape to form at all you'd need the gas to be fairly hot (and thus would cause expansion of the surrounding air), but with sufficient damping in the machine below, it could be fairly quiet.

Umm, not sure what you mean here. RFID chips are usually microchips that are powered by an external field. I do not see how this could relate to a virus or synthetic biology. One could, perhaps, use one to activate a container that had a sample of a pathogen? Then there is the problem of getting the container into the person (much harder than, say, an airborne virus. Any wholly created organism is going to be a bit like the new kid in a school full of bullies. With a little more technology I suppose could engineer a virus from scratch (but why bother, when there are so many that work quite well already?). Incorporating an rfid chip in any type of cell would be difficult, as they need to be large enough for an antenna (I cannot think of a way of making an antenna for anything that will penetrate skin that is much under 1 mm).

What I gather from that story, is that if you do not accept the axioms of logic, then you are not forced to accept an argument's conclusion from its premises.

I say rather than large facilities which will get looted if anything really bad happens, the most durable approach is redundancy. Similar to the rosetta project. http://blog.longnow.org/category/rosetta/ Why not lobby governments to store information in/on coins. I know some coins use diffraction to add colour, so small scale features are not out of the question. This would double as an anti-counterfeit measure. Instructions for building a microscope and the necessary lenses could be included in a visible font size with the rest of the information at a smaller scale. Further details could be etched on the inner surfaces of two or more disks which could then be joined together to protect from wear and oxidisation. Another approach would be to attempt to get high durability archives of the most important knowledge (archival quality paper? or possibly some other material) into people's homes. This could have educational benifits as well. A similar technique of large scale features for simple information and smaller for more detailed. This approach is limited in the amount of information that can be stored in each home, (even a font size of 50 micron would limit you to gigabytes -- I think this is very much on the smaller limit of what would be possible, and would require etching on glass or metal) but numerous editions could be released, possibly with the same large scale educational and instructional content.

Well I meant relatively unreactive compared to say, bleach. I should pick my words better. I was under the impression that arsenic (and most heavy metals) are toxic because they will substitute in reactions where other elements (ie. phosphorus) are required for the organism to function.

It depends on where or what exactly you're talking about. There's a neat theorem from calculus that says any spherical arrangement of sources for a 1/r^2 (like gravity) field will act as a point source from the middle. Providing you are outside the shell. If you are inside it all cancels out and you don't feel anything. So in a low curvature limit (such as a planet) a spherical shell acts like a point in the middle. and if you were outside the planet then it would just be proportional to the mass. You could also add it up as a vector field (find the magnitude and direction of the gravity due to each part, vector add them, then the total would be the same as a point mass in the middle). You will still feel lighter on a larger planet of the same mass (you are further away from the middle). If parts of the planet were moving very quickly relative to one another it would get a little more complicated. You could still work out the individual contributions and add them up as vectors, but you would need to consider gravitomagnetic effects, depending on your choice of guage. You would not be able to add up rest masses, or inertial masses, and your relative velocity would change the force. If you want to consider high curvature effects (neutron stars/clusters of black holes or something else exotic) then I am afraid it is a little bit beyond me. I would hazard an answer of: If you were sufficiently far away then the net gravitational effect would be proportional to the net energy in the system. But if there were a lot of spin things get weird, and I do not understand frame dragging sufficiently well to answer your question. It depends on where or what exactly you're talking about. There's a neat theorem from calculus that says any spherical arrangement of sources for a 1/r^2 (like gravity) field will act as a point source from the middle. Providing you are outside the shell. If you are inside it all cancels out and you don't feel anything. So in a low curvature limit (such as a planet) a spherical shell acts like a point in the middle. and if you were outside the planet then it would just be proportional to the mass. You could also add it up as a vector field (find the magnitude and direction of the gravity due to each part, vector add them, then the total would be the same as a point mass in the middle). You will still feel lighter on a larger planet of the same mass (you are further away from the middle). If parts of the planet were moving very quickly relative to one another it would get a little more complicated. You could still work out the individual contributions and add them up as vectors, but you would need to consider gravitomagnetic effects, depending on your choice of guage. You would not be able to add up rest masses, or inertial masses, and your relative velocity would change the force. If you want to consider high curvature effects (neutron stars/clusters of black holes or something else exotic) then I am afraid it is a little bit beyond me. I would hazard an answer of: If you were sufficiently far away then the net gravitational effect would be proportional to the net energy in the system. But if there were a lot of spin things get weird, and I do not understand frame dragging sufficiently well to answer your question.

I would alter the temperature by making your oobleck with cold water, or refrigerating it for a time. Heating it up too much will change it chemically. (Also be sure to control the amount of water present as precisely as possible between measurements. I would recommend stirring frequently, don't handle it with your hands too much as they absorb water and try and keep time scales short to avoid evaporation. To give you an idea of how quickly the viscosity can change, I have had blobs that are barely thick enough to be picked up, even with very fast motions go hard in 2 or 3 minutes) Being able to change the depth without the required impact changing is a good sign that this is not an important factor (although I would try a slightly wider range of depths to be sure, maybe go up to 8 or 10cm and down to 2 or 3 if possible. Bear in mind that having too narrow a container could have a similar effect) I was saying I'd be more inclined to think energy was the determining factor over impulse, but it's more likely somewhere in between constant energy and constant impulse (or possibly some m^x*v^y where x and y could be anything). In my experience the thickening is related to the initial shear rate or directly proportional to the velocity of the in coming object which would lead one to think of momentum. However, I have only played with objects that have a force behind them (such as my hand or foot, or a rod). We can do a thought experiment: Consider a small object coming in at high velocity, this will tend to bounce (although not quite well enough to play handball on a tub of oobleck, we tried) Where as a very large object moving slowly will sink. These can easily have the same momentum. So momentum alone is not a factor. You have controlled reasonably well for this effect as your objects are all moving quite fast. So they will be imparting their momentum in a time span of roughly how long it takes a sound wave to travel through your oobleck (providing they stop, and the oobleck does not deform too much). So you are effectively comparing different (average) forces applied for a set time. The one other factor to take into account is distance (how far does the oobleck deform in this time). The further the object goes before it stops, the more the oobleck shears. If we continue with the assumption of roughly constant time then distance travelled over constant time gives us a shear rate (shear/time, but time is const so only shear). Shear rate is related to viscosity in a dilatant, which is what will give us resistance force The more I think about this, the less sure I am that it will be either constant momentum or constant energy. I am thinking there may be limits for both of those, as well as just velocity. Consider a very massive object such that it has more of both momentum and energy than the objects you dropped, but it is dropped from very close so it is moving slowly. The oobleck will not thicken and it will not stop (or even be resisted). So first we need to find the shear rate at which we would consider the oobleck solid. Only once that is exceeded can any assumptions about near constant time be validated and impulse or energy be examined. Only one thing can save us now... SCIENCE!!! Do you know how viscosity is usually tested? http://en.wikipedia.org/wiki/Viscometer

Well if it smells bad, chances are fairly good that something is eating the organic molecules so you probably want to preserve it for the sake of the experiment as much as keeping the smell away. Biology is not my strong point so take any suggestions I make with the utmost scepticism. A removable coating could be effective, stopping oxygen from getting to them will slow decay and a barrier will stop the smell from getting out. A wax (something like paraffin, as it is amorphous one would assume piezoelectric properties would be weak) might work, or possibly something water soluble -- presumably re-washing the bones is acceptable. If it is something water soluble it may be important to ensure it dries properly. I know collagens will leech out of bone into water (esp hot water -- mmmm soup). If handling them is not too much of a problem, you could go for something near-universally toxic, but unreactive, such as arsenic or mercury. Or something based on a specific chemical mechanism (a specific antibacterial compound and a fungacide). Many general-purpose preservatives are quite reactive (I know alcohols denature larger proteins, I do not know how they effect smaller molecules). Again, freezing comes to mind. I believe it does not harm proteins much, and if the bones are already quite dry then you shouldn't have to worry about water doing damage as it crystalises. One thing that may help and is quite simple is to keep the humidity down. Buy a tub of silica beads and place it in the container. The less water in the environment, the fewer things that can live. This is about as much help as I can give, other than suggesting you ring a nearby museum.

Activated charcoal is used as a filter to absorb things (such as odour molecules) that pass through it. I do not know how to fix your odour problem, but things you could try are: Filter the air (I do not know how well charcoal works as an air filter, but if it were useful, this would be where). Keep the bones very dry and/or cold. This tends to reduce the amount of volatile substances that can enter the air (I do not know how this will effect the bones for the purposes of your project). Many substances such as sodium bicarbonate (baking soda) will react with many molecules that smell bad to us. Leaving a tub of this present in the area with the bones (or filtering the air through it) may reduce the odour. What properties of the bones need to be maintained? Treating them with a preservative, or coating them with something may be an option.

Hi Blaze, Just missed you in IRC it seems. This is great reasoning for a highschool project, but oobleck is tricky stuff. The depth will matter, although it is difficult to say how much. Temperature is important from my experiences with oobleck as well. Hypervalent Iodine tells me you've controlled for surface area, which is great (adjusting pressure rather than impulse, which is more important) but there are time domain things to take into account as well. Assuming you are using a rigid object, the only thing that will give will be the oobleck, so that will help control things to some extent. Although -- without spending hours with the equations, and not being an expert in fluid dynamics -- I would think that energy would be slightly more important. You could test this distinction by using a light object at higher velocity, and a heavy one at low velocity, I would be surprised if the thickening was constant at constant impulse. (But by all means, surprise me if I am wrong ) By far the most important factor would be the ratio of corn starch to water (if this is the type of non-linear fluid you are using). This needs to be kept within as precise bounds as possible as changes of a few percent can have a large effect. This includes settling (the corn starch will settle to the bottom of the mixture over time). Back to your question of depth -- I apologise for the stream of consciousness -- this will tend to be a factor. In a shallow dish the oobleck will need to shear (slide against itself) a lot more than in a deep dish to get out of the way, and so will more easily thicken (Have you noticed that you have to move very slowly to push your finger into the drops and dribbles that you spill near your work area?). The easiest way to rule this out as a factor is to increase (and decrease) the size of your bowl repeatedly until you find the domain in which the amount does not change. Anecdotally (I have done no precise measurements) I would think that once you get over 50mm deep it would not matter much for a small object.