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Asked by 232grak26 to Daniel, Hannah, Maggie, Ry, Scott on 14 Nov 2017.
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Maggie Lieu answered on 14 Nov 2017:
I would say that gravity is the strongest force in nature because its strong enough to keep the planets in orbit around the sun. The strong, weak and magnetic forces aren’t strong enough to do this, they are only strong on very small scales like in particles
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Ry Cutter answered on 14 Nov 2017:
In truth, we don’t know.
We think at some point in the very early universe (like right at the start), all the forces were combined. They split off one at a time and not in even amounts.
Some scientists think gravity was a smaller split than the other forces. We’re trying to come up with a theory that puts them all back together, but gravity is being very difficult!
Great question!
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Scott Melville answered on 15 Nov 2017:
Great question! It’s actually an active area of research 🙂
There are a few ways to go about answering this, depending on what gravity we’re thinking of.
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In Newton’s picture of gravity, it’s a force just like any other force, but there’s a small number (Newton’s constant, G) that appears in the force law. Put another way, gravity is so weak because… It just is. It’s what we measure, and why Newton wrote down the equations that we did.
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In Einstein’s picture of gravity, this is related to how ‘stiff’ space is. Moving through space and time is a lot like swimming through water – we make ripples (gravity waves). Gravity waves are so small because, unlike water which is nice and gloopy, space is really stiff and doesn’t wobble very much.
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From a modern point of view, the strength of gravity is related to the ‘graviton’ particle. We’ve never found a single graviton on its own, so they must be REALLY small. This is essentially why their force is so small.
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In future, people think string theory might take over as our picture of gravity. Then, the weakness of gravity is more like a prediction (the “weak gravity conjecture”), which is related to properties of black holes!
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