## A piano from a plane

What happens if you throw a piano from a plane? Would it be dangerous?

I think we should ban people throwing pianos out of planes!

Exactly, what would happen if you threw a piano out of a plane? Are you sure it would be dangerous?

Well, you say it’s obvious, but let me ask you some questions and then let’s see if you are so sure.

• How long will it take to fall? Will it be 10 seconds? One minute? Two minutes? Oh! you need to know how high the plane was flying before you can tell me how long it will take to fall? What what range of times will it take? What if the plane is only just above the ground – would that be dangerous?
• Will it break apart as it falls? Pianos are not known for their aerodynamic efficiency. So could the wind actually tear it apart? Well yes, it might. It could easily loose a lid, and some internal parts.
• How dangerous would a falling piano be? Very dangerous? Well doesn’t that depend on where it fell? And in how many pieces. And the range of speeds of those pieces. And of course, there are many types of piano.

So based on this we conclude that you want a blanket ban, but you don’t know exactly how long it would take to fall – that would need further research. And low altitude falls -from  say 1 metre would probably not be dangerous. You don’t know how many pieces it would break into – that too would need research. And you don’t know exactly how fast each part would be travelling when it hit the ground. And you would need to know where the piano exited the plane in order assess the likelihood of damage.

So without further research you can’t be sure that de-planing of pianos would definitely be dangerous. And yet you want a complete ban?

Is a blanket ban appropriate? Yes! Because despite the detailed uncertainty, we all know that one way or another the piano will hit the ground and damage whatever it happens to hit.

And it’s the same with putting 35 billion of tonnes of  carbon dioxide in the atmosphere every year. Lots of the details are uncertain, and much of the argument against actually doing something exploits this uncertainty. But the end result is simple to calculate.

As surely as a piano thrown from a plane will hit the Earth, carbon dioxide emissions will warm it.