With the repeated showings on British TV of the 2003 film, The Core, questions about what the centre of the Earth might really be like emerged – again. We know more about the surface of other planets than about the inside of our own planet.
We had a phone call: what happens to gravity inside the Earth?
I’m surprised Weightwatchers don’t realise that gravity is zero at the Earth’s centre. All they have to do is open a branch there – find a cave and a long staircase – and all their members will weigh nothing! It’s not magic. The force of gravity comes from the attraction of matter – the more matter, the more gravity. The warping in space comes into it too since Einstein said gravity is where space bends around masses. So as you dig deeper inside the Earth there comes a point, thought to be around 2900 km, where there is sufficient mass above and around you to decrease the net pull downwards until at the centre the net pull of gravity is zero.
Since weight = mass times g then weight = 0. Problem is that when you come back to the surface your weight is heavy once more, although if you actually climbed those stairs you’d have burnt off a heck of a lot of calories, and the Core sauna room would have melted you too!
Speaking of gravity it is amazing how many people think there is no gravity on the International Space Station and shuttle craft. Their distance from the centre of the Earth is only around 1/30th of the Earth’s radius and so the gravitational pull on the ISS is only about 10% less than on the planet’s surface. But they are in free fall as they orbit and it is this that creates weightlessness.
Back to fiction – and it’s off to AltFiction in Derby tomorrow. Yeay.