How would a giant look like, according to Square/Cubed Law?

[Ragenaut]

Let's scale up a man who is 6 feet tall and 200 pounds. Let's make him twice his height, 12 feet tall. This would scale his surface area up by the square of two, and his volume would be cubed. Assuming the volume of someone is their weight, it would be 200 cubed, or an unbelievable 8 million pounds! I believe this is extremely unbelievable, and using the BMI would be more reasonable, at merely 800 pounds.

Now, for you sciency folks out there, I have two questions. What is the proper way to use the square cubed law, and how would someone of such large size look like?

 

[Nilum]

We have a case for this, actually! In the real world!

Robert Wadlow!
Height: 10 ft, 9 inches. (Over twice as tall as the average American at the time!)
Weight: 491 Pounds.

Dude. Was. Huge.

He also had issues moving about the world. He required a cane and leg braces simply to walk. Because humans were not made to be at that size--didn't stop his body from adapting, though.

The issue with SCL in determining the height/weight of organisms is that it doesn't account for biological redistribution of resources. That is, SCL just scales an organism up flatly--it doesn't account for adjustments in the internal structure of the organism, such as in how much of that weight goes to bone, muscle, tissue, organs, et cetera. A perfect example can be found in the cardiovascular system--ie: Lungs, bloodstream, heart, et cetera.

The larger an organism, the more powerful its heart must be, the larger its lungs have to be, and so on. This is because an organism which uses oxygen to fuel itself (eg: insects) need to be able to metabolize and distribute that oxygen across its body. Some of it lies in environment. For example: Oxygen levels. The more oxygen is in the air, the larger the insects you can theoretically have, because the more oxygen you can acquire per breath than otherwise.

Scientifically speaking? The theoretical threshhold for an organism is dependent on gravitational forces, the ability to get resources in and around the body in time to keep fuelling it and waste matter out before it poisons it, the total mass of the creature in question, its structure, and so on.

You could, theoretically, have giant people. You'd need to find a way to make their bone structure stronger, so they don't suffer structural deficiencies, and you'd need to find a way to strengthen the heart muscle so it could pump blood harder and faster throughout the body to account for the larger size, but the rest can be coped with.

You can also simply take a page out of fantasy, and that is to ask your audience to suspend disbelief so you can tell a more compelling or exciting story.