What’s your first impulse when its raining hard and you don’t have an umbrella? You run for cover.

But my high school physics textbook touted it didn’t make a difference.

Whether you ran or walked, the number of raindrops hitting you would be the same.

I was stumped.

If you heard something similar, your head no doubt started doing all kinds of philosophical gymnastics, as did mine. But this seemingly ‘simple’ — whatever that means — problem, isn’t so ‘simple’ after all.  Here are some alleys of thought this stumper sends our minds down…

1)     “That’s frigging impossible!”

The above approach solves it by leaving containers in the rain and ‘showing’ they acquire more water with time. When this container is on a cart that can be moved, the slower it moves, the more water it acquires.  (The mathematical proof there goes through a lot of trouble just to establish this.)

2)    What about the wind?

We think of everything natural as chaotic and unpredictable. So the wind is ‘spoiling’ an  ‘ideal’ situation. Hypothetically, if there was no wind, and it was raining hard enough, then maybe it wouldn’t make a difference.


The above approach imagines what it would be like to be able to take a ‘photograph’ of each and every ‘moment’ one spends in the rain. Then, reducing the volume of space the runner  covers into cubes of the same volume. Then counting the number of raindrops inside of each cube at any moment, and calculating how  the number changes between photographs.

I didn’t find it as convincing. Mathematically, it was a valid argument. But is there more?

Is it really about the number of raindrops? Is the problem really about how wet you get?

I remember sitting by the window as a high school student, watching the rain, contemplating… then  suddenly, I thought of Neo.

Remember the scene in the Matrix, where Neo goes to visit the Oracle, and runs into this bald kid?

Spoon Bend...or Mind Bend?

Spoon Bend…or Mind Bend?

Bald kid: Do not try and bend the spoon. That’s impossible. Instead… only try to realize the truth.
Neo: What truth? 
Bald kid: There is no spoon. 
Neo: There is no spoon? 
Bald kid: Then you’ll see, that it is not the spoon that bends, it is only yourself. 

Remember when Neo finally figures out what the kid meant?


Imagine doing the same thing to the rain what Neo does to bullets.  You just see a curtain of rain, frozen, hanging there. And realize it makes no difference whether you run or walk. The same number of drops will hit you regardless.

It’s not difficult to guess  the philosophical counter arguments to this approach, but the arguments are more concerned with themselves than the underlying truths such thought experiments reveal.

I remember staring at the never ending curtain of rain as a high school kid, and wondering if math really made complex things more simple, or simple things more complex.

2 thoughts on ““FLY YOU FOOLS!”

  1. David Shultz says:

    So do more raindrops hit me when I run or not???
    One of my friends in college was given an assignment to model the optimal angle of a windshield such that it would contact the fewest number or raindrops at different speeds and raincloud densities. Just the fact that he was given the assignment makes me think it does matter how fast you’re going, but I don’t remember what he concluded.

    • joykrit2013 says:

      In the real world, yes. If moving at the speed of light, no.

      The point of the matrix thought experiment was to show that motion is a just sequence of photographs. Wasn’t really about the number of raindrops That’s why I linked to the earlier post that is ostentatiously about Philip K Dick. If you haven’t seen the water and sound video already, I highly recommend it.

      The best angle for a windshield or any surface to be hit by the fewest number of anything falling perpendicular to it is obviously 90 degrees. Under ideal conditions. The best statistical bet is 45 degrees since there is no way to predict wind directions. So that sounds more like a statistical problem than about counting the number of raindrops. Like most mathematical problems.

      The raincloud density will vary because of the wind, but assuming it doesn’t. if the windshield moves by a distance of dx, the change in dy would be the shift in raindrop pattern.

      Only way to graph it out is to have a working holographic video imaging device that can record everything inside a given space, and then reduce the space to a number of cubes and track the change of number of raindrops inside each cube over an extended time. And see if a pattern emerges. Everything in nature is fractal so the raindrop patterns are bound to be regular as well.

      I don’t think the windshield angle would make a difference, unless of course it has to do with the stress/strain ration of the material that suspends it.

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