# Tag Info

107

Not with the time constraint given. Let's start with the most destructive thing we've got: nukes. There are about 15,000 nukes worldwide, of varying yields. Sources: World Nuclear Weapon Stockpile, Plougshares Fund, 2018 Federation of American Scientists, 2018 Assuming an average yield of 200 kilotons, which is what most US nukes have, we could assemble ...

104

Back in the day before portable electric lights, carbide lamps were used: A mechanism dripped water onto carbide, which then gave off acetylene gas, which burned in a controlled fashion. This was used for headlights on cars and bicycles and for miners' lamps, even for lighthouse lamps. Hence, this is an obvious answer to your question. Another option is to ...

69

an atmosphere that is lethal if you get a breath or two but won't burn your skin off or poison you anyway when you walk out the door without your moon suit? take our atmosphere and remove all the oxygen, replacing it with an inert gas like nitrogen. Asphyxia will ensue after a couple of breathes. Asphyxia or asphyxiation is a condition of deficient ...

62

No. Most of the preceding responses have overlooked one relatively-recently identified home for life on the planet; within the crust itself. Researchers have found bacteria up to 4 kilometers down in continental crust and 2 km beneath oceanic crust. Recent estimates are that up to 70% of the microbial life on the planet is, in fact, in the deep biosphere. ...

55

It's physically possible. Put a spherical object in a geostationary orbit, make it rotate about its own axis at a rate suited to your own visibility/non-visibility requirements, and make a portion of it have very low albedo. Staying at a single point in the sky, the object will only be visible while the higher albedo portion is facing the planet and ...

53

My suggestion: 60% Xenon 20% Oxygen 15% Nitrogen 5% Carbon dioxide Why Xenon? Xenon is a noble gas. It has very few common chemical reactions, and is frequently used in situations where air is too reactive to be safe. It's safe to touch and even safe to breathe. It's also a very effective anesthetic. Present-day doctors in Europe use it because it is ...

49

Yes, but not in the way you are thinking. One way this could happen is if some killer fungus starts growing unchecked throughout the planet, on land and sea. By killing all plant life it would destroy every other ecosystem, so it would wipe out all mammals. It would also practically wipe out all other members of the animal kingdom. This is part of the plot ...

47

No. The mass of a proton is about $1.67\times10^{-27}$ kg. Therefore the total maximum energy released by its annihilation with an antiproton is $2mc^2= 2\times1.67\times10^{-27}\times9\times10^{16} = 3\times10^{-10}$ Joule. This is not much. Even if all this energy would be deposited inside the victims brain, it is a very small amount. But it would not. As ...

47

On September 28 2003, Italy experienced a nation wide black out. After three hours, energy was restored in northern regions. Electricity was restored gradually in most places, and in most cities electricity was powered on again during the morning. Energy was restored first in the northern region because there is where hydroelectric plants are located, ...

38

Yes, they could. You "just" need a large mirror to concentrate sunlight on a boiler to produce the steam. Power plants that use this principle are in use today: Ivanpah Solar Power Facility The first problem you have is with economy. Burning coal is just way too cheap if you have it available, and it's much easier to get a few megawatts of heat out of ...

35

Disclaimer Because my answer below throws a bit of shade at the other existing answers, and because I'm going for a bit of a flip, humorous, and somewhat defiant tone, I feel that I should point out that I'm a real life physicist and most certainly not a crackpot :-P Rant All the naysaying in the other existing answers, e.g. "This universe is ...

35

The obvious retro answer would be to use carbide lamps which work by dripping water onto a chamber of calcium carbide producing acetylene as was used on the original versions of the Model T Ford: Copyright Royce CaC2(solid) + 2H2O(liquid) -> C2H2(gas) + Ca(OH)2(aqueous) However, since the Calcium Carbide is made using an electric arc furnace, there may be ...

30

The mass of the Moon is 7.342×1022 kg. One ton is 103 kg. How much is thousands of tons? Let's say you have thousands of thousands of tons. That's one million tons, or 109 kg. This is still ten thousands times a billion less than the mass of the moon. (source: Diego Delso) Just as a comparison, one of the largest mines that ever operated on Earth, ...

28

Short answer is yes, they would. Longer version as follows. I've filled out more detail to accommodate the hard science tag. A rocket engine basically works through gas expanding and being thrown out the back of the engine at high speed. What that means in practice is that as the gas expands as a result of the fuel being burned, it pushes out in all ...

28

Pure nitrogen is harmless -- except that it won't support life. A breath or two will do no harm, but you won't even notice you're suffocating, because the carbon dioxide will clear from your blood as if you were breathing air -- but you won't be gaining any oxygen. You'll fall over unconscious after three or four breaths, and you'll die in four minutes (...

25

Black body radiation The Sun is, approximately, a black body. That means that the light it emits follows a particular spectrum according to Planck's law, with the shape of the spectrum determined solely by the Sun's surface temperature. In particular, the wavelength of peak emission can be found through Wien's law, which is also a function of temperature. ...

23

Of course, it's possible, a Kardashev type II civilization will have it quite easy. This is a healthy star, like our: And this is a super healthy star (even when scientists says it's a failed star!): Our objective is the second image. Now, let me explain everything. How is a normal star Normal stars, like our star or the star from the first image, have ...

23

You can have a binary star, and the planet in a Trojan position in the same orbit as the smaller of the two stars. Basically, the two stars describe one side of an equilateral triangle, and the planet occupies the third vertex, in either L4 or L5 position. One such configuration is presented here (figure 2, on the right). Wikipedia gives stability ...

23

If by single pathogen you mean a strain of virus or bacteria and not a single specific bacterium or virus, then Yes. We already have an existing example - Rabies. Rabies only affects mammals. If your strain is easier to transmit via multple methods (air, water, soil) and harder to kill (e.g. boiling water will not kill it) with widespread travel ...

22

people who can do magic aren't common Pragmatic answer: defend yourself against the common threat. Most people you meet won't be able to blast through your armour, so just wear the best that you can get, and you'll be largely OK. Maybe you'll meet people who didn't follow this rule, and you'll find yourself a fair bit more resilient than they will be. Even ...

22

Yes it could The Wikipedia article on the subject is quite detailed and offers the exact answer to your question. The L4 and L5 points are stable provided that the mass of the primary body (e.g. the Earth) is at least 25 times the mass of the secondary body (e.g. the Moon). The Earth is over 81 times the mass of the Moon (the Moon is 1.23% of the mass of ...

21

Your issue is right here It seems pretty straightforward to just deposit the waste heat into the black hole Unfortunately this isn't true. The problem is that heat isn't something you can just dump into a black hole. To be clear, heat is just the random motions of atoms and molecules inside substances. There isn't a way to just "move" that into ...

20

No. Positron emission tomography is regularly used to scan brains. PET detects gamma rays created when positrons, emitted by an injected radio tracer undergoing positron emission decay, annihilate with electrons in the patients tissue. For example, a brain scan using 18F-FDG has an effective radiation dose of 14 mSv [1], which is on the order of the ...

18

If they have a lot of desert space, perhaps they could build solar updrift towers? It's basically a large area covered by a greenhouse roof and a high chimney in the middle. The energy output is proportional to the area times the chimney height. They were invented in 1896, so they use only technology available at that time.

18

Well, the one thing that life needs on Earth (and pretty much anywhere else depending on how extreme your xenobiology is) is water. Now, we're not trying to boil the ocean here but... No wait. That's exactly what we need to do. Let's start with how much water that is to boil. We're talking about 1.26 x 1021 litres of the stuff. That's a lot and is going ...

17

Let's get empirical. The good news is research into martian concrete has been done. Researchers think regolith on Mars could serve as a replacement for concrete components. The Mars rovers have used gas chromatography, mass spectrometry, and laser spectrometry to determine the composition of martian soil. Mars regolith is mostly silicon dioxide and ferric ...

17

A geostationary satellite follows an orbit which keeps it over the same point on the Earth. https://www.skyandtelescope.com/observing/how-to-see-and-photograph-geosynchronous-satellites/ The streaks are stars which are elongated by the rotation of the earth and the long exposure. The satellites are rotating with the earth and so they look like dots. I ...

17

No Within a month period is impossible. The only event realistically capable of wiping out all life that quickly is a meteor strike and you can't get to any asteroid big enough in that time frame let alone get it moving and back to Earth. Scientists estimate it requires something of at least 100km diameter for an extinction level event. The Chicxulub ...

17

This is actually easy to calculate. There is no "gravity", so you just sum your starting velocity with your launch velocity. This makes your launch vector a straight line. Here's what makes it confusing: While someone from space would see a straight line, an observer on an adequately large cylinder world would see an apparently normal ballistics curve. ...

Only top voted, non community-wiki answers of a minimum length are eligible