Let me give you an answer that doesn't read like an ad for a mattress brand.

Zero Gravity Foam is nothing more than a marketing term for foam that provides support without pressure, giving you the illusion of weightlessness. Which, all foams would fall into this category. Latex is the least pressure relieving foam, as rubber deflects energy, bouncing it back at you like a spring. Memory foam would be the most pressure-relieving. Latex is good as it is less toxic, but if you keep a good protective, waterproof but breathable protector on any good quality foam bed, your foam will last a long time.

If you are looking for pressure relief, just avoid coil mattresses, as steel coils put pressure on your body. You can lay on a latex bed and on a foam bed and feel the difference.

Zero Gravity is a term used by pure LatexBLISS to describe total muscular relaxation. A state that allows you to fall asleep easily and stay in a deeper sleep longer. Latex is the only type of foam that lasts for decades. Memory and poly foams are very short lived. There are different types and qualities of latex foam. The pure LatexBLISS Talalay Latex has been considered the best available for the past 60, or so, years. Here is a link to their line: Pure LatexBliss

"Zero Gravity" is a buzzword now used in marketing adjustable bases. The only way it could logically apply to foam is , that to a certain extent, you can get relief from pressure points with various products (ie memory foam or latex) It is more logically applied to the settings used on an adjustable or movable base that actually articulates head and or feet to a level where you feel very little or no pressure. This can be a very confusing industry, so thanks for the question!