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130 votes
Accepted

How to survive the heat death of the universe?

Get out I mean, literally. As in "get out of the universe". The heat death of our universe is by definition not a survivable event. That's the bad news. The good news is that it takes a very, ...
aroth's user avatar
  • 2,422
125 votes

What could be the right powersource for 15 seconds lifespan disposable giant chainsaw?

Giant coiled spring. It would uncoil itself and drive the chain. It would provide loads of power on demand. Storing that kind of energy as a coiled spring is dangerous, but I see that as a positive ...
Willk's user avatar
  • 304k
114 votes

How to monetize free energy without revealing its existence?

You could use your invention to power computer hardware to "mine" a cryptocurrency like bitcoin. "Proof of work" cryptocurrencies like bitcoin deliberately waste enormous amounts of energy generating ...
bjmc's user avatar
  • 790
100 votes

How to survive the heat death of the universe?

No. By definition the heat death is the state where you could no longer do anything. Any actions you do before it only makes it come sooner. Best strategy: Sit still, do absolutely nothing. (I kinda ...
SE - stop firing the good guys's user avatar
86 votes

What would be the ideal power source for a cybernetic eye?

Batteries can be made quite small today, and batteries can be recharged wirelessly by magnetic resonance. So feasibly, the battery could be implanted in the temple near the eye and be recharged by ...
Klaus Æ. Mogensen's user avatar
79 votes
Accepted

Justifying the use of directed energy weapons

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 ...
Starfish Prime's user avatar
78 votes

How to survive the heat death of the universe?

Hard physics answer I think the question is fundamentally ill-posed. As long as there are humans alive somewhere, the universe is millions to the power of millions of years away from the "heat death" ...
semi-extrinsic's user avatar
70 votes
Accepted

In a post-fossil fuel economy, what could natural gas pipelines be used for?

They can used for underground power and communication lines, as a replacement for overhead lines. The reason why overhead lines are still prevalent in America is due to the initial cost of ...
Giter's user avatar
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69 votes
Accepted

How can Elsa's power fuel my Industrial Revolution?

One option is to use stirling engines. They work just as well on cold as on heat. Or rather, they work on a temperature gradient. One of these toys will work if you place it on a cup of hot water ...
Luke's user avatar
  • 3,423
69 votes

Consequences of an Earth-size object hitting the Sun?

Fzzt. The sun is big. Source It's not the biggest thing out there by a long shot: ... but in our neighborhood, it's the biggest fish in the pond by far. Heck, the Sun belches bigger than us: (...
KeithS's user avatar
  • 6,421
66 votes

How can Elsa's power fuel my Industrial Revolution?

Don't Look for Energy - Go for Infrastructure The problem with freezing powers is that they actively suck energy out of wherever they are used. The movement of the energy itself could be useful, ...
GrinningX's user avatar
  • 8,181
65 votes
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Would using carbon dioxide as fuel work to reduce the greenhouse effect?

It is technically possible to burn carbon dioxide, but not in a practical way. The reason burning carbon produces energy is that the total potential energy of carbon and oxygen is minimized by the CO2 ...
Cadence's user avatar
  • 37.5k
58 votes

What are the safety margins for destroying a planet from space?

Well, at best you're depositing in the planet (or the powdered remnants thereof) energy equal to its gravitational binding energy. According to Wikipedia, the one true source of truth, the ...
Mark Olson's user avatar
  • 14.3k
58 votes
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What would be the ideal power source for a cybernetic eye?

Although I like the classic cyberpunk concept that states that nanomachines build a small turbine generator in one of your biggest veins (like the inferior vena cava), I understand you want something ...
Stormbolter's user avatar
  • 2,611
54 votes
Accepted

If magic is programming, then what is mana supposed to be?

In this cosmology, envisioning mana as akin to the computational resources - CPU time, RAM, or other crucial system components - that a sentient program or a fragment of the universe's architect can ...
intro's user avatar
  • 846
53 votes

What is the best way to use my two portals?

Congratulations! You've solved the energy crisis! Place Portal B some distance above Portal A. Now place a turbine blade in between the two of them. Slowly insert a steady stream of water, stopping ...
HDE 226868's user avatar
  • 101k
52 votes

How to monetize free energy without revealing its existence?

Seed money So you've got a device which can increase the temperature of water in an arbitrary location far from the actual device. A 10 million pound version of this device is basically a weapon of ...
Murphy's user avatar
  • 26.4k
50 votes

Could a species evolve a special organ that stores pure energy & allows it to control its own magnetic field?

Storing Energy Surprisingly, most creatures already do this! Fats built up on the body contain Chemical potential energy, as does glucose molecules in cells. This definitely isn't storing lightning in ...
ATaco's user avatar
  • 460
50 votes
Accepted

How do I store enormous amounts of mechanical energy?

Pneumatics or Springs If you're just storing energy locally, a flywheel or pumped hydro is your friend, but if you want to move energy around in physical storage "batteries", then your best ...
jdunlop's user avatar
  • 31.3k
48 votes

How to monetize free energy without revealing its existence?

Consider looking into what and where power is needed, on demand, and people are willing to pay for it. Take for example Electric Car charging points. If you can install one of these with a payment ...
ECiurleo's user avatar
  • 1,579
45 votes
Accepted

How to harness Jupiter's gravitational energy?

There's plenty of ways to extract energy from Jupiter's gravity. The problem is how do you do so without lowering your house's orbit? Tidal Flexing? (probably not worth it) When two objects interact ...
Schwern's user avatar
  • 30.1k
44 votes
Accepted

Is a food chain without plants plausible?

If phytoplankton count as "not plants", and you want a non-oceanic environment, then the answer is quite straightforward: just take the phytoplankton out of the ocean. You could have a planetary ...
Logan R. Kearsley's user avatar
43 votes

In a post-fossil fuel economy, what could natural gas pipelines be used for?

It is actually a trick question, in a fully renewable energy economy natural gas pipelines will continue to transfer natural gas produced from renewable sources. Natural gas normally comes from ...
Josh King's user avatar
  • 24.8k
43 votes
Accepted

What would a life-form be like if it's antimatter-based

Potentially, it would be very similar to life made out of matter. Antimatter is expected to have the same chemistry as normal matter, so any lifeforms would work the same way with the exception that ...
SurpriseDog's user avatar
  • 3,883
43 votes

Is there anything about photons and/or space-time that would allow the detection of an energy-based attack from a distance of ten light seconds?

Since it is hard-scince question - the answer is NO, defending ship can do nothing to detect incoming laser attack from enemy ship it does not see. Argumentation is obvious: speed of light is the ...
ksbes's user avatar
  • 9,913
42 votes
Accepted

What are the safety margins for destroying a planet from space?

Well, Mark Olson and Samuel provide some very respectable math that winds up with the world destroying shot being taken from about 1 AU or the distance from Earth to sun. Yes, yes; it seems very ...
Willk's user avatar
  • 304k
42 votes

How can I heat my buildings without fire in a low-fantasy setting?

Frame Challenge: The blind can use fire perfectly well, and should You are searching for a solution that itself is looking for a problem. Respectfully, everything listed is a non-issue. Housing: ...
automaton's user avatar
  • 2,537
40 votes
Accepted

How can I heat my buildings without fire in a low-fantasy setting?

Housebarn Have you ever slept in a tent? When you wake up, the inside of the tent is warmer than the outside. Steam issues forth when you unzip the panel, and you go "AAaah!" when the chilly ...
Daron's user avatar
  • 66k
39 votes

How to survive the heat death of the universe?

Hack the Universe The universe is just a simulation running on a super computer somewhere. Exploit a bug so that you can get more energy/matter.
Eric Johnson's user avatar
  • 1,518

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