>>13732069>does the gas or fluid go into the chamber because a vacuum is created inside when you pull it or because of adhesion of the gas to the stopper?gas doesn't adhere to anything, it's literally particles flying around and bouncing off of everything inside the syringe
When you pull the syringe, you create less particles per volume, which means lower pressure inside. Air then comes in because of the pressure difference.
At another level, imagine a fuck-ton of balls bouncing around an arena. Divide the arena in half mentally, so the arena has a left side and right side (but no actual barrier other than the 4 walls). You can imagine the balls bouncing around will occupy the whole space pretty evenly; if you looked at the left vs right half of the arena, they'd have the same number of balls on average.
Now, take the left-most wall and immediately move it back like 50 feet. What happens? All of a sudden, the left-half of the area is super-empty compared to the number of balls, and all of the balls, just by randomly bouncing around, end up mostly in the left side of the area after a few seconds. That's what's happening when you pull the syringe back; the wall gets moved back, less air-per-area, and all of the air outside of the syringe rushes in by pure chance of bouncing around.
