If there is a planet in our universe that was 2x's the size of earth but proportionate in every other way ?

Question

and it supported life. would the people be two times our size? because our bodies are proportionate to the gravity and the environment we live in. so if this fantasy planet supported life but had 2x's our properties with the same balance as ours, there might be giants living out there.

any takers?

Answer 1

Dinasours and blue whale lived here so microbes.

Same gravity can accomodate many things.Small and big!

Answer 2

Assuming your planet had the same density as the earth and was twice the radius, then the mass would be 8 times that of the earth and the surface gravity would be twice that of the earth.

If you scale a person up to twice normal size in proportion, their bones have four times the cross sectional area, but their weight is eight times that of a normal person. So there will be twice as much strain on their bones and they won't be able to take it.

Most biologists feel that increasing the gravity would cause animals to grow shorter and wider. They wouldn't be scaled up versions of us. They would be not as tall, with much thicker bones to support their extra weight.

Answer 3

NO... just 4x the population... yes 4x not 2x

Answer 4

I think you're postulating a rocky planet about twice the mass of Earth, with around 3/4 of the surface covered in free water, orbiting somewhere in its star's Goldilocks Zone.  And you're wondering if that would encourage things on that planet to grow to twice the Earth-normal size.

I don't think so.  Such a planet would have something close to twice the gravity that Earth has at the surface.  Which means it would take twice the energy to raise anything to the same height.

High gravity would encourage squat, short creatures.

Imagine yourself living under the effect of twice the gravity that you're used to.  Now your heart will have to work much harder to get your blood up to your brain.  If you trip and fall, you're much more likely to seriously hurt yourself.  Just trying to walk around is hard work, as if you were carrying your twin on your back all the time.

Trees will be shorter.  Even mountains will be shorter.  Everything is pulled down.  The atmosphere is thicker, so perhaps winged creatures could still fly, but the hollow bones of Earth-like birds would be crushed far too easily.

If you're trying to build a fantasy planet where giants can easily grow, build your planet smaller than Earth, or at least lighter.  It's easier to reach high when there is less pulling you back down.