[Editing Mindset] The Blue Lamp Theory

The “Blue Lamp Theory” was proposed by Walter Murch in In the Blink of an Eye. It doesn’t just apply to film editing; it can be adapted to other forms of editing as well.

In the episode on “Mindsets for Music Transitions,” there was a mixed-edit example at the start. Now imagine we directly replace the music, add a few shots with similar mood at the beginning and end, and keep all the remaining shots exactly the same, without changing their order. Even though the music has changed, the finished piece doesn’t actually feel that different from before. That’s because there is an internal element in this piece that has never been altered, and this is what today’s Blue Lamp Theory is about.

If we approach a blue room and see a very conspicuous blue lightbulb inside, our first reaction is to assume that the room’s blueness comes from that bulb. But that’s not the case. When we unscrew the bulb, we find the room is still blue, and it even feels more naturally blue. It’s just that from the beginning, our attention was drawn to that eye‑catching blue bulb.

This is the Blue Lamp Theory that Walter Murch proposes in In the Blink of an Eye. It sounds convoluted and a bit of a brain teaser, and it doesn’t seem to have much to do with editing at first. He then adds: “When you remove what you once thought was the single core of a creative idea, once you take it away, you discover the creative idea is still there, and it actually has a more organic relationship with all the other elements.” Still sounds convoluted. So what exactly does the Blue Lamp Theory mean? When I first read it, I didn’t really get it either. After many years of editing, I gradually started to understand some of the important implications of this theory.

In fact, the Blue Lamp Theory grew out of an idea Murch formed while editing the film The Conversation. The film was cut down from five hours to under two hours in the end, but Murch eventually realized that by discarding certain things—cutting out some scenes, even some very important ones—he actually revealed more information. So the Blue Lamp Theory is about being able to remove elements that were originally very important within an already formed work (framework), without ultimately harming the whole, and even making the whole stand out more.

Here’s a direct example: this is a segment from one of my earlier independent films. The scene mainly explains the female lead’s background. After she gets married, her husband’s personality changes drastically, even becoming abusive, and she comes to hate him so much that she starts thinking about killing him. Now, if I were to re‑edit this scene today, I’d probably cut even more. I might cut two of the male lead’s lines and let the female lead’s dialogue guide us instead. I could even cut this close‑up shot, because the male lead’s personality in the film is inherently quiet and taciturn. Removing his lines here actually highlights that character trait better. Second, it emphasizes the weight of the female lead’s performance in this scene. This is one of the functions of the Blue Lamp Theory. Doing this also creates a sense of “negative space” or meaningful omission.

In creative work, not everything needs to be explained clearly and exhaustively. Leaving some things unsaid encourages the audience to imagine and infer. Beyond film, the Blue Lamp Theory applies to any kind of editing, and this is the most important point I want to make about it.

Throughout his life, Walter Murch also proposed the famous “Rule of Six” for editing: in editing, emotion has the highest priority. As long as the overall emotional tone of a piece is consistent, then no matter how you add or cut individual shots, the overall viewing experience won’t be affected too much. We can think of that blue room as a film: if its emotional tone is unified and consistently “blue,” then no matter how many blue lightbulbs you add or remove, the overall emotional feel won’t change.

So let’s return to the example mentioned at the beginning. When I first edited that sequence, I believed the most important thing in that mixed montage was the music. It was like the bulb in the Blue Lamp Theory: the music laid the basic foundation for the piece. But even if we later directly replace the music—essentially swapping out what was once the core creative idea—the viewing experience doesn’t change that much, because its emotional core, “departure and separation,” has always remained the same. So as long as you can find music that matches the theme, the result won’t feel jarringly different.

Many of the more abstract “mindsets” in editing are hidden within ideas that seem unrelated to editing—just like Walter Murch’s Blue Lamp Theory.