Way on down

How much do you weigh? … if that question isn’t too impertinent.

Actually the question is a bit open ended because it doesn’t specify where you are when you measure your weight.
That’s a detail that could become important in the near future when the Musk-Bezos-Branson Bazillionaire space race really kicks off.

You could, in all honesty, hop on the bathroom scales here on Earth and read, for example, 120kg, then divide that by six to get your weight as it would be on the Moon.

Then, when some rude colleague asks how much you weigh, you can tell them truthfully that you weigh 20kg.
You’d only need to provide the pesky Moon detail if you are too slow getting out of the lunch room or if they are quick enough to notice that your great lumbering frame weighs plenty more than the equivalent of a water-cooler bottle.

When you think about it, by asking your weight they are sneakily asking about your mass. And that’s not the mass favored by people in religious circles, or even pentagrams (let’s not be shapeist).

This mass is the one popularised by your high school science teacher.

Einstein’s famous equation, E=mc2 means that if you take a bit of mass, say half a gram, and multiply it by a very, very big number, you get the amount of energy it contains.

For half a gram of stuff, that’s equivalent to the energy of an atomic bomb.

When someone asks about your mass, they are sneakily trying to get you to admit to how much stuff your body is made of.

Which is a dumb question because they are looking at your stuff (or stuffing) when they ask it.

But amazingly, mass isn’t just the stuff you are made of but mainly the energy that is holding it all together.
And that brings us back to Einstein and how mass is really energy. But we just don’t have the space … or the time … or the energy.