Humans need gravity. This much is known. What is not known is how much gravity. For this reason it would be quite convenient to be able to simulate different levels of gravity. If we could, we might be able to understand the effects of gravity on humans over time, but is such a capability possible and/or practical?

It is often noted that rotating habitats have a size limit based on the structural material used, but this is not really the whole story. Rotating habitats can be bigger (much bigger) than commonly cited, and all it takes is a decoupling.