Former NASA roboticist and current webcomic author Randall Munroe takes wacky questions posed by just about anyone and applies his physics expertise and sarcasm to provide answers.  His website xkcd is a hilarious tour of jokes, mathematical modeling, life stories, and the titular answers to just about anything.  In celebration of Munroe’s recently published book What if? Serious scientific answers to absurd hypothetical questions, here are a few of my favorite What If? posts:

Relativistic Baseball – What would happen if you tried to hit a baseball going 90% the speed of light?  This one is cool because the end result would be a ‘hit by pitch’.  However, the plasma explosion that would first disintegrate the batter, catcher, and umpire and a microsecond later level everything within a mile of the ball park makes the ruling kind of moot.

Pile of Viruses – What if every virus in the world were collected into one area?  How much volume would they take up and what would they look like?  Presumably taking into account the average size of a virus, which can range from 5 nanometer phages to the newly identified Pithovirus at 1.5 micrometers (more than 300x bigger than the phage), Munroe estimates that if all the viruses in the world were piled up, it would be the size of a small mountain.  He also posits that it would be the consistency of pus and meat slurry…mmm.  Enveloped viruses would undoubtedly provide lipid fats to the proteinous mountain, so I think he’s onto something with this meat slurry hypothesis.

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?  Munroe takes us on a hilarious journey to describe the mass of 602,214,129,000,000,000,000,000 moles, which he hypothesizes could take up the space approximately of the moon.  This is also the start of many interesting (or missing) citations.  Click on them, they are great.

Glass Half Empty – What if a glass of water was, all of a sudden, literally half empty?  I’m just going to give the punchline here, “The lesson: If the optimist says the glass is half full, and the pessimist says the glass is half empty, the physicist ducks.”  Go read it.  You know you want to.

 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?  Apparently ~195 years.

Extreme Boating – What would it be like to navigate a rowboat through a lake of mercury?  What about bromine? Liquid gallium?  Liquid tungsten? Liquid nitrogen?  Liquid helium?  Mercury: the boat would sit on top, but it would be difficult to paddle through.  Bromine:  smelly.  Gallium: easier to row than in mercury, but avoid aluminum boats as it will be destroyed.  Tungsten:  immediate incineration of you and your boat.  Nitrogen: you would either asphyxiate or die of hypothermia.  Helium:  you’d develop hypothermia and die hearing the “third sound”.  Good stuff, eh.