Seriously, WTF is up with surface area and volume limiting how big things can grow??

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Disclaimer: I did see a previous question touching on something like this but what I’m confused about was NOT addressed so hopefully this is allowed.

They say that the surface area volume ratio limits how big things can grow because surface area scales as a square while volume scales as a cube, so the ratio of volume to surface area goes up as you get bigger. Fair enough. BUT: how is this not just a matter of what units you’re using?

For example, a 1x1x1 ft cube has a surface area to volume ratio of 6sq. Ft to 1 cubic foot, so 6:1. A 1x1x1 meter cube has a ratio of 6:1 too but the units are meters. Couldn’t you always define your units so that you have a 6:1 ratio with any size of cube?

To bring it back to the actual question, wouldn’t your ratio be essentially the same no matter how big your object is? Imagine you expanded everything in the universe by the same amount but kept your unit of measurement the same, you wouldn’t suddenly hit some limit where it stops working right? Does it have something to do with the size of molecules and proteins etc? Please help I am so confused

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Anonymous 0 Comments

> For example, a 1x1x1 ft cube has a surface area to volume ratio of 6sq. Ft to 1 cubic foot, so 6:1. A 1x1x1 meter cube has a ratio of 6:1 too but the units are meters. Couldn’t you always define your units so that you have a 6:1 ratio with any size of cube?

This number is not *unitless*. So it’s arguably not accurate to even call it a *ratio*. Your process of reasoning only works if you can cancel out the units on both sides. But when you have “6 square meters : 1 cubic meters”, the best you can do is cancel it to “6 : 1 meter”, or “6 *per meter*”. (Indicative, in this case, of how much extra area you’re getting per specific depth of tissue)

Somehow along your argument you seem to have omitted this unit without justification, which is the reason for your confusion.

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