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Scientists Discover Way to Send Information into Black Holes Without Using Energy

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Scientists Create a Device That Hides and Reveals Images Using Just Air You Breathe

 Scientists at the University of California San Diego have developed a remarkable optical device that can reveal hidden images and change colors depending on the humidity in the surrounding air. This breakthrough, published in Light: Science & Applications, could transform the future of security systems, data storage, environmental sensing, and interactive displays.

What makes this innovation truly fascinating is its simplicity in concept but sophistication in design: a tiny chip that reacts to moisture in the air—so fast that even a breath can make it change.

🔍 A Device That Responds to Moisture Like a Living Surface

The newly developed device works like a visual “switch” controlled by humidity. Under dry or normal air conditions, one image appears clearly—for example, the UC San Diego Triton logo. But as humidity increases, that image fades and is replaced by a second hidden image, such as the UC San Diego library logo.

Even more interesting, this transformation is extremely fast. The switch happens in less than a second—around 300 milliseconds—and can be repeated many times without damaging the device. A simple breath on the surface is enough to trigger the change.

According to the researchers, this behavior opens the door to a completely new way of thinking about security and information display.

🧠 A “Environment-as-a-Key” Security Concept

One of the study’s key ideas is that the environment itself can act as a key to unlock hidden information.

Asad Nauman, the first author of the study and a postdoctoral researcher in electrical and computer engineering at University of California San Diego, explained the idea simply:

“You can imagine using this as a built-in security feature with the environment acting like a key that unlocks different pieces of information.”

He described possible real-world applications, such as credit cards with hidden codes that appear when someone breathes on them, or smart labels that reveal information only under certain environmental conditions.

This could make counterfeiting much harder, since the “key” is not a password or chip—but something as natural and uncontrollable as humidity.

🧱 How the Device Is Built: Two Layers Working Together

The device is extremely small—about the size of a postage stamp—but it contains advanced materials working together in a precise structure.

It has two main layers:

1. Bottom Layer: Rewritable Optical Storage

The bottom layer is made from a phase-change material called antimony trisulfide. This material acts like a reusable memory surface.

  • Images can be written using a laser

  • They can be erased and rewritten multiple times

  • It functions like a programmable optical storage medium

This makes the layer similar to a digital canvas that can be repeatedly reset and updated.

2. Top Layer: Humidity-Responsive Hydrogel

The top layer is made of a soft hydrogel called azido-grafted carboxymethyl cellulose.

This material has a special property: it reacts to moisture.

  • In dry air, it shrinks

  • In humid air, it swells

Researchers can permanently pattern an image into this layer using UV light. This layer is responsible for controlling how light interacts with the device depending on humidity.

🔬 The Power of Interdisciplinary Science

This breakthrough came from teamwork within the Nano Devices and Applied Optics (NDAO) lab at the University of California San Diego, led by Professor Abdoulaye Ndao.

The team combined two advanced research areas:

  • Phase-change photonic materials (for optical data storage)

  • Responsive hydrogels (for environmental sensitivity)

By merging these two fields, the researchers created a layered system that behaves in a completely new way—something neither material could achieve alone.

Professor Ndao explained that this layered structure could be useful for future computing systems:

“You could encode different pieces of information in different layers stacked on a single space and choose which one to access based on the humidity.”

🌈 Why the Device Changes Color

Beyond switching images, the device also changes color when humidity levels shift. This happens due to a very thin gap between the two layers.

Even though the gap is extremely small, it plays a critical role in how light behaves.

Here’s what happens:

  • The hydrogel layer expands when humidity increases

  • It shrinks when humidity decreases

  • This changes the distance between the two layers

  • Light reflects differently depending on that spacing

  • As a result, the visible color changes

This optical effect is similar to how soap bubbles or oil films show shifting rainbow colors—but here it is precisely engineered and controllable.

⚡ Fast, Reversible, and Scalable Technology

One of the most impressive features of this device is its speed and durability.

  • It responds in about 300 milliseconds

  • It can be cycled many times without losing performance

  • It works at low cost

  • It can be manufactured over large surface areas

This means it is not just a laboratory experiment—it has real potential for industrial-scale applications.

Because it is both fast and reversible, the device could be used in dynamic systems where information needs to change quickly and repeatedly.

🛡️ Possible Real-World Applications

Researchers believe this technology could lead to several important applications in the future:

1. Anti-counterfeiting Labels

Products, documents, or currencies could include humidity-responsive tags that reveal hidden patterns only under specific conditions.

2. Secure Data Storage

Multiple layers of information could be stacked in one space and accessed using environmental triggers like humidity.

3. Smart Environmental Sensors

Surfaces could visually change color based on humidity levels, acting as real-time indicators.

4. Interactive Displays

Displays could respond to human breath or environmental changes, creating new forms of interactive art or communication.

5. Smart Packaging

Food or medicine packaging could indicate storage conditions or spoilage risk based on humidity exposure.

🔮 Future Improvements and Possibilities

The research team is already exploring future versions of the device. One exciting direction is electrical control.

Instead of relying only on humidity, future designs could allow users to control image switching electronically. This would expand its use in computing, encryption, and adaptive display technologies.

Such developments could make devices that combine environmental sensing with digital control, opening the door to hybrid smart systems.

📘 Conclusion: A New Way to Hide and Reveal Information

This breakthrough from the University of California San Diego shows how combining smart materials can lead to entirely new ways of controlling light and information.

A simple idea—using humidity as a trigger—has led to a powerful technology where images appear, disappear, and transform in real time.

From secure identification systems to intelligent sensors and next-generation displays, this tiny optical chip may play a big role in shaping the future of smart materials and information security.

In a world where data security and environmental awareness are becoming increasingly important, this innovation shows that sometimes the most powerful “password” is not digital—but in the air we breathe.

Reference: Nauman, A., Gulinihali, G., Moncada, T. et al. Reversible optical data storage and encryption enabled by phase-change and hydrogel integration. Light Sci Appl 15, 238 (2026). https://doi.org/10.1038/s41377-026-02330-5

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