Things in nature often move in complicated ways. You have probably
watched the way a butterfly moves. The molecules of the air that you
are breathing move in a similar way. This type of motion we call a
random walk. You can also take a random walk.
What you need:
• A coin to flip
• Open space
Try This:
Go out to a large open field and mark a spot on the ground. Take with
you a coin like a nickel or a quarter. Stand on the spot and flip the
coin. If the coin comes up heads, turn to the right and take a large
step. If the coin comes up tails, turn to the left and take a large
step. Keep doing this many times and see where you end up.
What’s going on?
If you flip the coin 25 times you will probably be about five steps
away from where you started. This is because five times five equals 25.
How far would you expect to be if you flipped the coin 100 times? A
random walk is not a very fast way to get anywhere!
When you try this, you will notice that sometimes you go much farther
than you expect and sometimes you end up very close to where you
started. But if you repeat it many times or get several of your friends
to do it with you with coins of their own, the average distance should
come out as expected. In science we can often predict what will happen
on the average even when the process is random.
