---
title: 'How Pressure Can Come From *Nothing*'
source: 'https://youtube.com/watch?v=zP5uhMpH4mE'
video_id: 'zP5uhMpH4mE'
date: 2026-08-27
duration_sec: 75
channel: 'Veritasium'
---

# How Pressure Can Come From *Nothing*

> Source: [How Pressure Can Come From *Nothing*](https://youtube.com/watch?v=zP5uhMpH4mE)

## Summary

This video explains the Casimir effect, a quantum phenomenon where two uncharged mirrors in a vacuum snap together due to pressure from empty space. It uses an analogy of ships in rough seas to illustrate how quantum waves create a pressure difference that crushes the plates together.

### Key Points

- **The Setup** [00:02] — Two uncharged mirrors are brought very close together in a vacuum. There is no air or magnetic force, and gravitational attraction is negligible.
- **The Ship Analogy** [00:16] — In rough seas, big waves crash against ships. When ships are close, the waves can't fit in the gap between them, so each ship experiences waves only from the outside, pushing them together.
- **Quantum Waves** [00:42] — Empty space is filled with quantum waves of all sizes. When plates are very close, the big waves are blocked from the gap, creating a pressure difference that crushes them together.
- **The Casimir Effect** [00:54] — This phenomenon is called the Casimir effect. At a gap of 10 nanometers, the pressure is one atmosphere, creating a crushing force of 103 kilograms on a plate of that size.

### Conclusion

The Casimir effect demonstrates that empty space is not truly empty but filled with quantum fluctuations that can exert measurable pressure. This force, though surprising, is a real and significant phenomenon at the nanoscale.

## Transcript

part of the universe and brought these two uncharged mirrors very closely happen. I mean, there's no air repelling magnetic forces. Okay, there is a tiny amount of gravitational attraction, but
it's so small that we can ignore it. But if you push them close enough, then suddenly they snap together. To understand why, let's look at these ships. In rough seas, big waves crash against them from
physically can't fit in the tiny gap between them. And if the left ship blocks waves from the left and the right ship blocks waves from the right, then from the left, and the right ship experiences waves only from the right,
which pushes them together. And it turns out that empty space is just like the ocean. It's filled with quantum waves with all kinds of sizes. And when the plates get really close, the big waves are blocked from the gap, creating a
massive pressure difference that crushes them together. It's called the Casimir effect, and it is strong. At a gap of just 10 nanometers, that pressure is one atmosphere. So, for a plate of this size, that creates a crushing force of
103 kilograms. That's a large adult human standing on a coaster created by human standing on a coaster created by nothing but empty space.