Hot answers tagged

87

The torch burns quicker. A lot quicker, but you won't get a violent explosion. Fire requires three things - heat, fuel, and oxygen. You've increased the oxygen, but you haven't increase the fuel, so all will happen is that the torch will burn out far faster - if it lasts for 10 minutes, it might not even last for one. The oxygen won't ignite itself. ...


75

Laser beams have straight trajectories in anything other than totally unreasonable gravitational fields (where you won't be using bullets, that for sure). This makes them very easy to aim. Lasers beams propagate at the speed of light. This will be substantially faster than any projectile weapon, and a reasonable amount faster than any particle beam, too. You ...


55

Apollo Fire and Wick Effect I generally agree with Halfthawed, but I had some additional thoughts on the matter. There is one well known and documented incident with fire and people in a pure oxygen atmosphere: the 1968 Apollo 1 accident. The fanatic overexaggerated fear of a pure oxygen atmosphere is rooted in the horrible 1968 Apollo 1 accident where ...


40

The answer depends on a mighty host of factors, including how pointy your projectile needs to be. However, we can put together a pretty reasonable upper bound by looking at reentry vehicles. They are pretty much the fastest manmade things in the atmosphere. Apollo 10 came in at roughly 11km/s. The record fastest reentry vehicle was Stardust, which came in ...


24

At what velocities would the (aerodynamically shaped) projectile just burn up? Only a few km/s. Read up on the Sprint missile, which could reach Mach 10 in 5 seconds (which would be about 3.5km/s, though that slightly depends on the altitude it had reached at that point) which resulted in skin temperatures of 3400 degrees C and needed an ablative heat ...


19

Regarding Oxygen toxicity This is rather an extended comment with some calculations than an actual answer. I'd like to back up the matter with some actual calculations. I presume you mean a $20ft \times 20ft \times 20ft$ room when you say "20ft cube room". That means we have a volume of $V=226.5m^3$. Let our initial pressure be at $p=p_0\approx 100kPa$. ...


10

The torch will burn much faster & hotter. There's a fairly common real-world example of this: the oxyactylene torch used for welding and cutting ferrous metals. Light it with just the actylene turned on, and you get a rather cool yellow flame that smokes a lot (rather like your adventurer's torch). Increase the flow of oxygen, and it burns with a hot, ...


9

Short boring answer: nope. Even a really, really dense gas (tungsten hexafluoride, 12.4g/l at room temperature... actual tungsten gas might be denser, but it would be at a hazardous 6203K) is much less dense than the lightest solids (solid hydrogen, 86g/l, at a chilly 14K or lithium, 534g/l at room temperature). You could cheat by using carefully ...


8

Lasers can be armor-penetrating bypassing Slugs energy goes into the outer layer of armor first. Armor-penetrating bullets are specially designed to get through armor better, but the fact remains that they have to destroy the armor before they can hurt the target. An x-ray or gamma laser is different. Yes, some of the energy is going to be deposited in ...


8

Just as food for thought: Some fraction of c (light speed). First, you fire a laser or something that will ionize the air between yourself and the target (= create a plasma). Think big: Something that ionizes a channel that is between 100 and 1 km wide. Bigger is better. Then you use electronic and magnetic fields to move as much plasma out of the way as ...


7

A falling object has momentum proportional to its mass and velocity ($p = mv$). If a person could magically absorb that momentum, they could decrease it to 0 by reducing the velocity to 0. The object would stop, but at that point it would have no more momentum to absorb. They could then let the object fall again, accumulating more momentum, before harvesting ...


7

Precision Lobbing the battery as a grenade may be more effective in terms of energy transfer to the target, but it also has a habit of transferring that energy into everything around the target. That doesn't work well if there's something in the vicinity you want to preserve, such as a hostage, or a building, or depending on your battery capacity, the city. ...


7

You can use aerogels to imitate a cloud. Aerogel is a synthetic porous ultralight material derived from a gel, in which the liquid component for the gel has been replaced with a gas. The result is a solid with extremely low density and extremely low thermal conductivity. Being extremely low dense, aerogel can be easily lifted to look like it is floating, ...


7

You have a few conceptual problems here. If you have to cover 570 million light years at 0.9999999999c, time dilation will habe a factor of 0.00014141979198682754. You can use this calculator to find out, just multiply your input by 100 because the calculator uses percentages. 0.00014 of 570,000,000 years is about 79,800 years. That's 12 orders of ...


6

International laws and agreements In real life there are lots of ways of bringing an enemy to their knees, but they are unnaceptable due to humanitary reasons. See the UN's Convention on Certain Conventional Weapons for banished weapons and Protocol I of the Geneva convention for banished practices. You can't, for example: Blind people with lasers; Bomb ...


6

Any interesting battery material for a laser gun would be more usefully deployed as an explosive warhead. I don't think this should be treated as a universal assumption. After all, the gunpowder or cordite used in modern-day firearms and artillery pieces is plenty interesting, but it's hardly a good material for an explosive warhead -- and even artillery ...


6

The technique to do this is similar to that used in constructing stellar models. You know some of the properties of your object - in this case, it look like the mass and radius. You want to figure out the internal structure of the planet, including the central density and pressure, as well as the density and pressure profiles as functions of radius. The best ...


6

It is an ineffective weapon for capturing slaves on many levels Lack of Range: When you launch an arrow, there is a lot of resistance from inertia, but once it's up to speed, there is very little drag to slow it down in atmosphere. This is why a bow and arrow can pierce a target from far away with little more energy than you would need to thrust the arrow ...


6

Temperature is not a coordinate like position, velocity, time, or rotation. Symmetries on those coordinates lead to conservation of momentum, special relativity, conservation of energy, and conservation of angular momentum. Symmetries of those values are aspects of the entire system, while temperature is an aspect of each part of the system. Absolute zero ...


6

A violent, rather sudden death. When you are unsuspecting, you usually do not hold a torch with the burning end as far away as possible. You hold it in a comfortable position, so it will be maybe half a meter away from your head. It's dark and unsuspecting Kleeber wants to see, so he summons that torch, in a normal, comfortable position. The room was ...


6

Nothing of Note, Sorry. Thus far almost everyone has been mesmerised by the Red Herring of oxygen toxicity. Given the time constraint of the query and given the chemistry of the experiment, I'm sorry to say that every answer, including the accepted, that involves toxicity is going to fail a reality check. Rationales: Let us not forget that Kleeber the ...


6

Real-world example: Operation Plumbbob Cort's answer to this question is pretty great, but makes two faulty assumptions. One, the reentry vehicles aren't the fastest objects humans have ever made, and two, they're interacting largely with the top of the atmosphere. As evidenced by the host of other answers, the theoretical side of things is difficult at ...


5

Apparently, the amount of energy needed to shield Mars from the solar wind is less than one might think. There was a proposal to build a device that could project a magnetic field that would deflect the solar wind from Mars, potentially allowing a terraforming project to take place. In a nutshell, the device would be placed in orbit at the L1 point between ...


5

You don't even need to drink superfluid: you already would become covered in thin film of superfluid both outside and inside a few moments after you opened container holding it. Dependenig on fluid composition it can (optionaly): suffocate you - it will cover you lungs inside for sure. If it has large molecules ("not superfluid water") it will prevent ...


5

In hard-scifi you can't. And reason is not only "Routledge's Law", but range. Laser weapon has very limited range compared with slugs. You can shoot slugs from Moon to Earth with common modern howitzer and case some damage (to city-size target), but you will never be able to do it with reasnoble laser even utilizing futuristic technology. It doesn't means ...


4

There's ongoing work to develop a mechanical counterpressure suit, which uses stretchy materials to squeeze the occupant, with only the helmet needing to be pressurised with some suitable gas or fluid. Helmets can more easily be made rigid and so not have issues with volume changes. (MIT Biosuit) Filling a suit with water might be tricky, due to its ...


4

When Perdita falls beyond a certain distance, the belt activates, using Aethyr to create a magical bubble around her. When she hits the ground (or any solid object larger than the average bird,) the Sphere of Meteoric Conversion converts all her kinetic energy and the kinetic energy of the surface pushing back against her (that is, the equal and opposite ...


4

There are a lot of options, some better than others. Since you did not specify the tech level, I'll assume modern technology. Solar and LED-lights Slap some small, robust solar panels to the flat side of the blade, put a rechargeable battery into the handle and place LED's all over the sword. Might looks more like a Cyberpunk sex toy or cos play implement ...


4

I'm surprised a real world system that is currently being used hasn't yet been discussed. Lockheed Martin has developed a laser system to overheat drones and missiles to thus shooting them out of the sky. A laser is an ideal system for this since it can track targets with erratic paths much better than conventional slug throwers, it can also frequently ...


4

Clouds have a charge. Normally, the top part of the cloud has excessive positive charge, while the bottom accumulate a negative charge. Lightning is produced when the two balance out temporarily. So, what you can try doing is Establish some clouds / physical conditions which have charge accumulation in such a manner (top surface positively charged) Build ...


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