A simulation created by DG EYE science on YouTube shows what would happen to a human body in space without a spacesuit. The video explains that the gases in the body would expand, causing lung tissues to rupture, and water on the eyes, skin, and mouth would evaporate. The water in the blood would start to boil, causing the body to swell. Eventually, the heart would slow down and stop, leading to death by asphyxiation. The absence of pressure in space would cause water within the body to boil, which is a serious problem since humans are two-thirds water.