What does a world need?
Begin with air
A four-year-old can stop here. Air. Water. Warmth. Light. Touch a name. The rest of the field waits.
Words Eve reads
What does a body need? A body must keep receiving air, water, heat, pressure, food, energy, shielding, a way to handle waste, gravity, and shelter. Energy sits in the middle on purpose. When energy stops, heat, air, and water stop after it. Earth does this without asking. Another world does not.
First look
Air
A body needs the right mix of gases, over and over.
Words Eve reads
Air. A body needs the right mix of gases, over and over. Look closer. Humans need oxygen in, carbon dioxide out. The mix, the pressure, and the movement of air all matter.
Look closer. Humans need oxygen in, carbon dioxide out. The mix, the pressure, and the movement of air all matter.
Keep looking
Mars air is mostly carbon dioxide and far too thin to breathe. Making oxygen from it has been demonstrated in a small experiment. A whole town of air is a different problem.
When this stops, it also touches Food.
Energy sits in the middle on purpose. When energy stops, heat, air, and water stop after it. Earth does this without asking. Another world does not.