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Q & A: Why is only gravity long-range?

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Most recent answer: 03/08/2012
Q:
Well bacicly I was helping my son revise for his test when he asked me why gravity is stronger over long distances than any other non-contact forces. I'm not great at science (dropped out of school at 16) so no Muumbo jumbo, Thanks in advance
- Willow Edmonds (age 34)
England
A:
The basic reason is that the other forces have sources that cancel out on a long range. Electricity, for example, has both positive and negative charges. Positive charges attract negative charges and thus tend to be surrounded by them. That leaves a region that is neutral, as seen from a distance.

Something sort of like that but even more dramatic happens with nuclear forces, although for the strong nuclear ("chromodynamic") force the "charges" are more complicated.

For gravity, the source (mass) is always positive, and it's self-attractive. A positive mass attracts more positive mass, leading to an even bigger source with bigger effects at a distance.

Mike W.

(published on 03/08/2012)

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