[Editing Mindset] The Blue Lamp Theory

The “Blue Lamp Theory” was proposed by Walter Murch in In the Blink of an Eye. It applies not only to film editing, but can also be adapted to other kinds of editing.

At the beginning of the episode on “The Mindset for Connecting Music,” there was a mashup example. Now imagine we directly swap out the music, add a few shots before and after that have a similar mood, leave all the remaining shots untouched, and don’t adjust their order. Even though the music has changed, the finished piece feels almost the same as before, because there is an internal element of the piece that has never changed. That’s the Blue Lamp Theory we’re talking about today.

If we approach a blue room and see a very conspicuous blue light bulb inside, our first instinct is to assume that the room’s blueness comes from that bulb. But that’s not actually the case. When we unscrew the light bulb, we discover the room is still blue, and it even seems more naturally blue than before. It’s just that from the beginning, our attention was captured by that striking blue bulb.

This is the Blue Lamp Theory that Walter Murch proposes in In the Blink of an Eye. It sounds convoluted, a bit of a brain teaser, and it doesn’t seem to have much to do with editing. He then adds: “When you remove what you originally thought was the sole core of a particular creative idea, once you take it away, you discover the underlying idea is still there, and that it actually forms a more organic relationship with all the other elements.” That still sounds abstract. So what does the Blue Lamp Theory really mean? To be honest, I didn’t understand it the first time I read it either. Only after editing for many years did I gradually begin to notice some important implications of this theory.

In fact, the Blue Lamp Theory came from an idea Murch had while editing the film The Conversation. The film was cut down from five hours to under two hours. Murch eventually realized that by discarding certain things—cutting certain scenes, even some very important ones—he was actually able to reveal more information. So the Blue Lamp Theory refers to being able to remove elements that once seemed crucial from an already formed creation (or framework) without harming the whole, and sometimes even making the whole stand out more.

Here’s a direct example: this is a segment from one of my earlier independent films. This sequence mainly explains the female lead’s background. After the female lead gets married, her husband’s temperament changes drastically and he even becomes abusive, so she grows to hate him to the bone and starts to have the idea of killing him. If I were to re‑edit this sequence now, I would probably cut a few more shots—like removing two lines of dialogue from the male lead, and letting the female lead’s lines guide us instead. I might even cut this close‑up, because the male lead is portrayed as a quiet, taciturn character throughout the film. Cutting his lines here would actually highlight that character trait more strongly. Second, it would emphasize 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 intentional omission.

In creative work, not everything needs to be spelled out clearly. Appropriate blank spaces allow the audience to imagine and infer. Besides film, the Blue Lamp Theory applies to any kind of editing, which brings us to its most important point. Throughout Walter Murch’s lifelong philosophy of editing, he also proposed the famous “Rule of Six”: in editing, emotion has the highest priority. As long as the overall emotional tone of the piece is consistent, adding or removing individual shots will not greatly affect how the piece feels. We can think of the blue room as the film itself: if its emotional tone is unified and consistently “blue,” then no matter how many blue bulbs you install or remove, the overall emotional tone will not be affected.

Now let’s go back to the example from the beginning. When I edited that segment, I initially thought the most important part of the mashup was the music—it was like the light bulb in the Blue Lamp Theory. The music provided the basic foundation for the piece. But even if we directly swap out the music—that is, change what was once the core creative idea—the way it feels doesn’t actually change much, because its emotional core, “leaving and parting,” has remained the same all along. As long as you can find music that matches that theme, the result will not feel jarringly different.

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