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Q & A: does gravity come from heat?

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Most recent answer: 05/14/2013
Q:
I think that the earth has gravity because its core is heated.I think so because when your bathroom water is hot when running the shower curtain comes towards it.What do you think?
- Jonathan (age 12)
Trinidad and Tobago
A:
Jonathan- That's a very interesting thought, just the sort of combination of different types of observation that physicists love to do. It turns out not to be correct, however.

All sorts of planets, including ones that are far from the Sun and quite cold, have gravity holding them together and also making other things orbit around them. In fact, it turns out that everything has gravity. We can tell that for big things (galaxies,...) by looking at how things move around. For some smaller things (say lead balls) we can directly measure the gravity between them in the lab, in an experiment first done by Cavendish.

I hope you keep coming up with nifty ideas, and also get a chance to help test them.

Mike W.

(posted temporarily without checking, Lee is galavanting around the world.)

(published on 05/14/2013)

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