1
How many radioactive bananas would you need to power a house?
I heard that bananas are radioactive. If they are radioactive, then they radiate energy. How many bananas would you need to power a house?
What If? (xkcd)
Could I cool down the Earth by capturing a comet and dropping it in the ocean, like an ice cube in a glass of water?
- Popular posts
- 15
- Total points
- 1,174
- HN comments
- 551
- Rank
- #1,759 personal
Visit what-if.xkcd.com → RSS feedOn Hacker News Jul 2012 – Jun 2024
2
Can you use a magnifying glass and moonlight to light a fire? (2016)
A magnifying glass concentrates light on a small spot. As many mischevious kids can tell you, a magnifying glass as small as a square inch in size can collect enough light to start a fire. A little Googling will tell you that the Sun is 400,000 times brighter than the Moon, so all we need is a 400,000-square-inch…
3
Earth-Moon Fire Pole
My son (5y) asked me today: If there were a kind of a fireman's pole from the Moon down to the Earth, how long would it take to slide all the way from the Moon to the Earth?
4
When (if ever) did the Sun set on the British Empire?
It hasn't. Yet. But only because of a few dozen people living in an area smaller than Disney World.
5
What happens when a basebal goes at nearly the speed of light (what-if.XKCD)
What would happen if you tried to hit a baseball pitched at 90% the speed of light?
6
Safe to swim in nuclear spent fuel pool?
What if I took a swim in a typical spent nuclear fuel pool? Would I need to dive to actually experience a fatal amount of radiation? How long could I stay safely at the surface?
7
Droppings
If you went outside and lay down on your back with your mouth open, how long would you have to wait until a bird pooped in it?
8
Everybody Jump
What would happen if everyone on earth stood as close to each other as they could and jumped, everyone landing on the ground at the same instant?
9
Hubble
If the Hubble telescope were aimed at the Earth, how detailed would the images be?
10
FedEx Bandwidth
Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway. –Andrew Tanenbaum, 1981
11
A Mole of Moles
What would happen if you were to gather a mole (unit of measurement) of moles (the small furry critter) in one place?
12
Flood Death Valley
Since Death Valley is below sea level could we dig a hole to the ocean and fill it up with water?
13
Orbital Speed
What if a spacecraft slowed down on re-entry to just a few miles per hour using rocket boosters like the Mars-sky-crane? Would it negate the need for a heat shield?
14
Laser Pointer
If every person on Earth aimed a laser pointer at the Moon at the same time, would it change color?
15
Lethal Neutrinos
How close would you have to be to a supernova to get a lethal dose of neutrino radiation?