78

Paint. /safely compromise that glass/ so I am within the bounds of the question! The robot is relying on a camera that is looking thru a pane of glass. If you cover the glass with paint, or glue, or ketchup and mustard (mixed), or... you get the idea... anyway — the robot won't be able to see. Maybe it has windshield wipers. Good luck with those vs paint....


63

Acid. Crater lake at El Chichon https://www.usgs.gov/faqs/can-lakes-near-volcanoes-become-acidic-enough-be-dangerous-people-and-animals?qt-news_science_products=0# Crater lakes atop volcanoes are typically the most acid, with pH values as low as 0.1 (very strong acid). Normal lake waters, in contrast, have relatively neutral pH values near 7.0. The crater ...


63

Gold would then be completely unsuitable for use as the basis of any currency. It would just be another material with certain physical properties. Assuming the world society survived the screaming madness that occur in the years following the discovery that all their money is, well, not money... The good: Gold is a very inert metal. It does not rust, it ...


55

You would have many problems: first of all, the abundance of mercury it's not that high to realistically be able to fill in oceans. In the solar system it is one of the rarest element, even less abundant than platinum. Moreover, even assuming that you had that much mercury, you would stumble into another, serious issue: the density of mercury is 13.5 $g/cm^3$...


54

As noted, I feel like my answer to a previous question will also apply here. What you're looking for is an emetic: a substance that induces vomiting. Your X threshold remains the point at which a dose becomes lethal, but the Y threshold becomes the point at which the emetic properties kick in and you throw all the poison back up before it can enter your ...


45

Dead water is a misdirection! Why not Acid? Someone else suggested acid - of the stable liquids I believe this is the best choice, however: glass was being manufactured around 100AD, and a small glass canoe could survive the river of acid (Yeah you gotta hike it over a mountain, but they'll find a way, same way they got monastery windows up into the ...


44

You would want the planet's crust to be dense enough to prevent the mercury from going underground. However, denser materials are typically metallic, and would form amalgams with the mercury. However, there is a solution: Make the planet an giant ball of mercury large enough to have its own gravity, and possibly with islands floating on the surface.


40

On the bright side, they've got a few decades of technological development into tech needed to survive the new world Thermodynamics is a harsh mistress and doesn't care about your technological development. If you want to dump heat, you need a place at lower temperature where you can dump the heat, because thermodynamic laws state that heat flows naturally ...


35

Heavy-ish crude oil (not heavier than water). toxic for almost everything. slow evaporation and heavy vapors that don't readily jump over the mountains (and if they do, the worst is the smell) stable for the timespan required rainwater simply sinks into the water body below. Water bodies can even be connected underground with no major ill effects. Bonus: ...


34

Forget chemical. A sea full of radioactive salt is effectively impassable to a pre-flight civilisation, not affected by rain, toxic to all life and will last 40,000 years with judicious choice of isotopes.


31

People need boron, because plants need boron. https://en.wikipedia.org/wiki/Boron Boron is a chemical element with the symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in the Solar System and in the Earth's crust.[11] It constitutes about 0.001 percent ...


26

Looking around my industrial workshop.... First thing that comes to mind is a sandblaster: The sand will scratch the glass, making it opaque. Scratches can be removed from bullet proof glass using wax and elbow grease, but that will take the robot time. Sand also allows for static electricity based attacks if you are an electric elemental or whatever. ...


25

Los Angeles? Salt Lake City? Or maybe even someone local by 1931. The first neon sign in Las Vegas went up in 1928. http://captainhistory.com/wordpress1/2018/02/25/the-first-neon-signs-in-las-vegas-nevada/ If you want there to be some adventure and finagling involved your characters could go on a road trip to Los Angeles, which would be a good contrast ...


25

Two ideas! on a theme: Lava (or at least molten rock) Due to some wierd quirks of geology, the "seas" are molten, slow flowing rock. They don't have to even be completely liquid at all times, just enough to be so hot that any structures you build burst into flames. The gases given off by this should make traversing it very difficult. Conversely, it'...


24

compressors You can always dump heat. With a compressor, you can transport the heat from a cool to a hot environment in oder to keep the cool environment cool. But the cost is high. Living underground lessens the cost, good insulation, too. heat dumps You can also dump your heat underground just by boring a deep hole for your compressor's pipes. It's ...


24

One possibility would be a mixture of a poison that binds to a cell receptor and a lower concentration of a non-poison that binds more strongly to the same receptor (i.e. an antagonist with higher affinity). With a small dose, the non-poison only binds to a fraction of the receptors; the poison binds to the remaining ones and the target dies. With a large ...


24

The straightforward answer is "carry some fire with you". Wikipedia calls the devices uses for this purpose "fire pots". More ritualistically-inclined versions of the device are found in the form of censers and thuribles, which would seem to be ideal for the use of magically-inclined folk, but the underlying principle is prehistoric. ...


21

Liquid Nitrogen If you freeze something solid, you can hit it and shatter it much more easily. See https://www.youtube.com/watch?v=QbAH65Iqj_M Your hero would have to spray the head for a bit to cool it down which could be more difficult but the fog created would help to hide him. Frost built up on the glass would also help blind the robot so it might work. ...


21

Bullets Bulletproof glass is designed to stop/catch a bullet... once. However, this wrecks the glass. You can't see through it after. Typically, it is a sandwich of regular glass and 1/2" thick polycarbonate. The polycarbonate catches the bullet. The glass is there because glass is better at resisting ordinary service wear and tear - scratches from ...


20

Lithium, like boron (covered in another answer), is relatively rare because few processes have produced it since the Big Bang created a tiny percentage -- but it's useful both as a chemical and as a component of one of the "easiest" pathways to nuclear fusion -- including aneutronic fusion of lithium and deuterium, which is likely to be very ...


20

dilute radium-226 bromide solution. The radium (half-life 1600 years) would decay into radon-222, a radioactive gas with a half-life of 3 days. The water would be highly radioactive, boiling hot and bubbling radioactive, toxic and corrosive gasses. the gasses would decay quickly and not make it out of the 'dead canals'. It would also generate bromine, helium ...


20

If your goal is just to have a planet with liquid metal oceans, not specifically mercury, you could go with gallium. Its melting point is just ~30°C (~85°F), so a little warm but still perfectly survivable and even comfortable for humans. And it's much more common than mercury. Not sure about the feasibility of covering an entire planet in gallium seas, ...


19

With no starting tools this is a big undertaking for your loner, but with the right skill set you could do this with the natural elements you would expect to find almost anywhere in India. In any such suvival setting, you will first want to make some basic stone tools: an axe, a chisel and a hammer. This will involve a lot of time spent at the river or beach ...


19

Bacteria-infested water. Yes, it should be toxic to every known form of life. Your civilization probably hasn't developed biology enough to know what bacteria are, so they are not known forms of life. Long ago, the water was flowing uninterrupted, life was plenty and free. Then the ridges were raised, which also raised the sea floor in between, with no ...


18

All cooling involves dumping energy somewhere The laws of thermodynamics essentially mandate this. There ain't no such thing as a free lunch. As such, you can shift the thermal energy around but you can't just make it go away. Air conditioners blow hot air out one end and cold air out the other. The basic principle is adiabatic expansion and this is why ...


17

Any life as we know it can't exist on the planet. Nor volcanoes. You can't have a sulfur cycle In addition to L Dutch points, an ocean of mercury can not exist on any planet with a sulfur cycle. Any biological processes that produce hydrogen sulfide (sewer gas) or natural volcanic systems (sulfur dioxide) putting trace amounts of sulfur in the air will cause ...


15

I can imagine a solution, but it's gross. The poison can have two effects. One mild effect if that it will cause very mild nausea. This effect kick in quite fast, in the first minutes. The second effect is the lethal effect (paralysis of the lungs, for example, or any other), but the substance provocking this second effect is hard to digest, and it doesn't ...


15

Mercury It is quite toxic. It will be liquid, and stable as long as the mountains don't interact chemically with it. Since they were put there by intelligent beings with unlimited budget, that might be the case. Any water raining on it will stay on top, because mercury does not dissolve in water and is way much denser. Since the mountains are artificial or ...


14

Hasn't been mentioned yet, but beryllium has a rather low abundance, and is a remarkably useful metal due to a number of unusual properties it exhibits, namely: Despite being an alkali-earth metal, beryllium is actually remarkably non-reactive. It doesn't even form oxides in regular atmospheric conditions unless you heat it to high temperatures. It has an ...


14

This paper talks about combustion It is the fact that combustion properties of large-scale crude oil pool fire have great significance for security design and firefighting of current crude oil reserves. Burning rate, the flame shape and radiation intensity are the most important parameters for fires properties. And this is an image of a fire on an oil ...


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