How can you breath without gravity?

Answer 1

Breathing is less about weight/mass/gravity, and more about pressure. You breathe in because your diaphragm contracts and pulls down, creating a lower pressure in your lungs. Air from outside the body rushes in to the lungs. (Things in nature try to reach balance or equalibrium, thus things in high pressure will want to balance out things in lower pressure.) Gravity has very little to do with air pressure.

Answer 2

no; you would float into space

Also...gravity is the force that causes all matter to aggregate (clump together).

Without it, galaxies would never have formed, stars would never have formed (fusion in stars produces the various elements beyond hydrogen and helium), planets would never have formed, and we would never have formed (not just because we would not have had an environment from which to evolve...but also because the elements necessary for life would never have been created...because the stars would never have formed to create such elements).

However, if you mean, "could we exist if gravity existed and then ceased to exist on Earth?"...then the first answer is correct -- No, you would float into space.

While this isn't a problem if you are in a self-contained vessel with enough food, water, heat, radiation shielding, and breathable atmosphere to help you survive, some studies have shown that the human body begins to lose bone density and undergo many other changes while in a zero-gravity environment...because we evolved to survive best with a gravity of 1 g. So, chances are that some detrimental effects would occur over time.

But, again, without gravity, the atmosphere around the planet would float away, leaving us without a viable shield against UV radiation (or a breathable environment)...plants and other lifeforms would die...the ecosystem would fail...and the planet would break apart and float out into space (not necessarily in that order).