The classic invocation of Murphy's Law in today's world is that of buttered toast falling and landing butter side down. It turns out that we, as bipeds, are doomed to forever have this happen.
Toast has a tendency to land butter side down because it does not have time to flip over. This spin is from the gravitational torque (twist) placed on the bread as it falls over the edge of a table (at about 1 meter (3 feet) high) cannot bring it to make a complete 360 degree flip. Now, if tables were taller (about 3 meters tall) this wouldn't be as much of a problem because the bread would have time flip before it hit the ground.
Why are tables only 1 meter tall? This has to do with our build as bipeds. It is convenient for us. Other animals can get much taller because they fall over less often. As bipeds we are notoriously unstable compared to, say a horse or elephant or whale. At taller than 3 meters (9 feet) if we fell we would shatter our heads. This is generally considered to be a 'bad' thing.
So because we can't reasonably be much taller than 2 meters (6 feet) before problems start occurring this places a maximum height of a table, and thus the tendency for bread to fall and land butter side down.
There are some ways to correct this.
- Work from tables about 3 meters tall. This gives bread falling from such a height the time necessary to flip to butter side up. This was confirmed in a series of tests that showed that toast falling from normal tables landed butter side down 62% of the time, while landing from tables 8 feet up only landed butter side down 47% of the time.
- Always put toast butter side down on the table. This implies a very clean table and non-stick surfaces with regards to butter, peanut butter, and jelly (also vegamite if you are from down under). As any parent knows, such a non-stick surface does not exist with regards to these surfaces.
- Eat very small squares of toast (about 5cm (2 inches) on a side). When these flip over the side of the table, it takes less torque to get them to spin. There is an optimum sized bread for every height table.
- Tie the toast butter side up to the back of a cat. The cat will always land on its feet and the butter side will be maintained. Note: this may cause the cat and toast to spin and form a perpetual motion machine.
Likely the most practical method is to minimize the time that gravity has to act and apply torque. To do this one must move the bread away from the edge and let it fall normally. Toast dropped from any height with no spin
on it will tend to land in the same orientation that it was dropped from. In the case of a edge of a table this means getting the toast away from the edge by pushing it off the table
. For a tray
, one would move the tray rapidly down (faster than the toast was falling) and then to the side so the toast does not flip.
Face it, the toast will land butter side down more often than not, and Murphy works with the fundamental nature of our existance.
European Journal of Physics 16 172-176 1995