I have a weight loss tip. Completely free. Ready?

Go to the moon.

Ha, ha.

Oh, you wanted a practical tip?

But really, so many people say they want to lose weight. I know, we are shallow. But there is a small physics lesson here. Technically speaking, what people really want to lose is mass. Mass and weight are different.

Your mass is the same everywhere you go. I am simplifying a bit and pissing off Einstein's ghost, but just roll with me here. Your mass is the same everywhere you go. And it is this mass that you pay your gym membership for.

What about your weight? It is decided by mother Earth. Yes, that planet you always trusted...

See, unlike your mass, your weight actually depends on where you are. Particularly, how big the planet you are standing on, is. Your weight is tied to your planet's size through a simple and elegant mathematical equation.

Whoda thunk it?

(Er...Newton, that's who.)

Every planet has a number that represents its gravity. Bigger the planet, larger the number. Earth's is 9.8.

9.8 what? Doesn't matter. You can think of it as 9.8 kilo-candles or 9.8 cow-patties. Nobody cares. Units are kinda arbitrary anyway. A "meter" exists because we say so. It is all convention. There is no such thing in reality. Don't believe me? Look up the definition of a "meter". Go ahead. I'll wait.

So the earth's number is 9.8.

The moon's number is 1.6, since it is so widdle.

And the sun's number is a whopping 274.

It is this number that you have to multiply your mass by to arrive at your weight. So once again, your mass is constant. For all practical purposes. But to find your weight, you have to multiply.

On the sun, Twiggy would weigh like a motherfucker. On the moon, you could be Elvis Presley sitting in a vat of peanut butter and not give a damn, as long as nobody handed you a mirror.

Since our muscles are uniquely adapted to earth's number, we can do some strange things when on the moon. Like jump about six or seven feet straight into the air. Our muscles are suddenly much stronger, having had to "fight" earth's number all our lives (every time we walk or so much as raise a finger, we are fighting earth's number). So we sneeze at the moon's number when visiting there.

If there were moon-people and if they ever got uppity with the earth people and started a war, they would be so weak compared to us, we could simply slap them to a bloody pulp.

So they better not start a war, wherever they are hiding.

Er...bye now.

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Now for the boring bits. All this stuff above about mass and weight boils down to Newton's Second Law, one of the most important derivations in physics: Force = Mass x Acceleration (due to gravity)

Or, in short: F = ma

Your weight is a downward force acting on the planet. You arrive at it by multiplying your mass by the planet's gravity. The "downward" bit is important since force is a vector quantity, having the same direction as the acceleration due to gravity. Never, ever, mix up your scalars and vectors. Your physics will be all wrong and this will make the sun-people very very mad. And they are very very strong.