Submitted by peep_da_toad t3_1124pge in askscience
Suppose I'm an astronaut and I go on a spacewalk with a syringe. I pull the plunger halfway out ("filling" the syringe with vacuum) and then I plug the syringe nozzle with my finger.
What happens if I try to pull/push the plunger further. Let's say that I'm surrounded by a complete vacuum. Will the plunger move? Will there be resistance? Or will it refuse to budge? There's nothing both outside and inside the syringe, so the plunger should move freely, right?