You see on earth, humans have tremendous capabilities when it comes to activities like climbing mountains, running, soccer, and swimming through rivers and pools showing our physical strength but then when we are in the depth of the ocean and in space, the reverse is the case.
When we talk about the ocean, the case of the Titan implosion is a good example with the submersible being 2.5 miles at the bottom of the ocean, and the implosion was caused by immense pressure but when it comes to space, it is void of any pressure since it is a vacuum.
When talking about space, we refer to it as a vacuum because it is void of any atmosphere or having less atmosphere than the atmosphere measured on earth at sea level. On earth, the air around us consists of trillions of gas molecules like Nitrogen, Oxygen, carbon dioxide, and argon, and these molecules are pulled downwards towards the earth by gravity as it produces an atmospheric pressure on the object to make them come down.
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Compared to the pressure on land, water pressure is extremely high at the bottom of the ocean due to the height and weight of water molecules pushing down but when outside water, the water pressure is zero. once in space above earth atmosphere, there is absent of gasses meaning zero atmospheric pressure. In space, if a feather and balloon is drop, they will fall at equal speed.
As humans, we gases in our lungs, intestines, and stomach and the body itself is 60% water. We can find water in our mucus, saliva, and blood, and these compounds are held under pressure on earth but when a human find himself in space without putting on the required space suit, they begin to immediately suffocate as there are no air such as oxygen in space and the little one left in your lungs will be expended as alveoli begins to rupture and the lung tissue begin to get damaged.
The stomach and intestine will be stretched and possibly tear apart and it will cause forceful excretion of the stomach and intestine contents due to expanding gas. Within the next 5 to 10 seconds, the person will become unconscious as a result of oxygen deprivation. The mucus and saliva in the mouth and nose will be evaporated and the mouth will dry out. The water in the soft tissues and organs evaporate causing the skin and organs in the body to expand.
In space without a space suit the blood vessels will rupture from expansion as a result of oxygen, nitrogen, carbon dioxide in the blood. Within the 2 minutes the person would be dead because the brain will not be receiving oxygen and it will shutdown. Due to the evaporation of liquids in the body, the abdomen will be bloated. Space is cold with a temperature of -454 degree Fahrenheit, so the eyes, nose and mouth begin to freeze but due to the vacuum of space, the body will not immediately freeze but it will eventually crystalize and freeze causing rupture of the skin from internal pressure. Since there is no oxidation or bacteria in space, the body will float around for millions of years without decomposing.
Most of this knowledge are gotten from NASA experiments in the 1960s where they experimented on dogs in vacuum chamber. There have been cases where people were exposed to vacuum and it was seen that in about 10 seconds they were either unconscious or dead.
Reference
https://www.usatoday.com/story/graphics/2023
https://hypertextbook.com/facts/2000/DaWeiCai.shtml
https://scied.ucar.edu/learning-zone/air-quality/whats-in-the-air
https://hypertextbook.com/facts/2002/MimiZheng.shtml
https://earthhow.com/earth-atmosphere-composition/
https://www.washingtonpost.com/national
https://sitn.hms.harvard.edu/flash/2013/space-human-body/