Cold Cryptography: Scientists Can Now Encode Secret Messages in Ice

Like it’s straight out of a James Bond film, scientists have unveiled a new way to store secret messages by embedding them in the bubbles trapped inside ice. Inspired by the natural air bubbles found in ancient glaciers, this cool innovation could offer a low-energy, durable, and covert way to store information in the world’s coldest places, from Antarctica to the Arctic.

Published earlier this week in Cell Reports Physical Science, the study details how the team led by Mengjie Song at the Beijing Institute of Technology managed to encode short messages in ice, using the physics of bubble formation. Their approach relies on manipulating the size, shape, and arrangement of air bubbles that naturally form as water freezes. A process that, in glaciers, has preserved samples of ancient air for thousands of years.

When water freezes, it pushes dissolved gases out, forming tiny pockets of air, commonly known as bubbles, inside the ice. These bubbles can be egg-shaped or needle-shaped, depending on how quickly the water freezes. The researchers realized that by carefully controlling the freezing process, they could create specific patterns of bubbles, each corresponding to a part of a coded message.

Frozen Bubble Text

The team used a special setup: a thin layer of water was sandwiched between two transparent plastic sheets and placed on a cold plate. By rapidly lowering the temperature, they could make the water freeze faster, resulting in layers of egg-shaped bubbles. Slower freezing produced needle-shaped bubbles, and by alternating the freezing speed, they created distinct layers; some with bubbles, some without. Each layer’s characteristics—whether it had bubbles and what shape they were—became the building blocks of a message.

“Since bubble position and shape are determined by the freezing rate, it is possible to manually control the freezing rate to manipulate the shape and distribution of bubbles in ice,” Song explained in a press statement.

For example, a layer full of bubbles could represent a “1” in binary code, while a clear layer without bubbles could stand for a “0.” By stringing together several layers, the team could encode numbers, letters, or even words. They also experimented with Morse code, assigning different bubble patterns to dots and dashes.

The Simple Art of Reading Bubbles

Decoding the message is surprisingly simple. The ice slice is photographed and the image is converted to grayscale. Because air bubbles scatter light, bubbly regions appear white, while clear ice looks dark. A computer program analyzes the photo, detects the bubble patterns, and translates them back into binary or Morse code, revealing the hidden message.

In their experiments, the researchers successfully encoded and retrieved English letters and Arabic numerals, demonstrating the feasibility of their approach. While the amount of information that can be stored in a single ice cube is currently limited, the technique could be scaled up by using larger or multiple ice slices.

While storing information in ice might seem like a novelty, it does have real advantages in extremely cold environments. Traditional data storage methods—like paper or electronics—struggle in places like the polar regions. Paper can degrade, and electronics require power and are prone to failure in the cold. In contrast, ice is abundant, and messages stored as bubbles require no ink, batteries, or special equipment to preserve them. Moreover, the researchers note that understanding and controlling bubble formation in ice could help in fields ranging from climate science—where glacier bubbles hold clues to Earth’s past atmosphere—to materials engineering, where similar principles apply to metals and plastics.

Currently, frozen bubble messages are best suited for short, simple messages in places where cold is guaranteed. But as the technology develops, it could provide a new, energy-efficient way to store information. Cool, yeah?