WATCH: This Is What The World's Lowest-Density Solid Sounds Like

What if you could hold a cloud in your hands?

It might seem like a fantasy, but aerogel—the world’s lightest solid—comes pretty close.

Despite being 99.8% air, this futuristic material is surprisingly strong, eerily transparent, and capable of withstanding extreme heat.

But here’s something you probably haven’t thought about: what does aerogel sound like?

If you had to guess, you might say nothing at all—after all, how could a substance that is mostly air make any noise?

But in a surprising twist, aerogel has an unexpected auditory identity.

When tapped or dropped, it clinks like ceramic or frosted glass.

Thanks to a video posted by YouTuber turlian, we now know that this ghostly solid has a sound just as strange as its appearance.

But sound is just the beginning of aerogel’s mysteries.

This material, first created in the 1930s, is now used in everything from space exploration to military armor, and even in everyday consumer products like cosmetics and wetsuits.

And the more scientists study it, the more bizarre and incredible its properties become.

What Exactly Is Aerogel?

Aerogel is often called frozen smoke because of its wispy, translucent appearance.

But unlike smoke, it’s completely solid—and one of the most remarkable materials ever made.

At its core, aerogel is a gel in which the liquid has been replaced by gas.

This process, called supercritical drying, removes the moisture while keeping the gel’s delicate structure intact.

The result?

A solid so light it barely exists, yet strong enough to support thousands of times its own weight.

Aerogels can be made from a variety of substances, including:

Silica (SiO₂) – The most common type, used in insulation and space exploration.
Alumina (Al₂O₃) – Used in military applications and high-temperature environments.
Carbon aerogel – Known for its conductivity, making it useful in batteries and supercapacitors.
Metal oxide aerogels – Often used for catalysis and chemical reactions.

What Does Aerogel Feel Like?

It’s hard to describe what aerogel feels like without actually holding it. According to experts at Aerogel.com, the experience is somewhere between:

A Styrofoam peanut
The green floral foam used for fake flowers
A Rice Krispie treat

Despite its ghostly appearance, aerogel is rigid and dry, and surprisingly fragile.

While some versions can withstand a gently applied load of up to 2,000 times their weight, it doesn’t take much force to shatter them.

In fact, crushing aerogel with your fingers requires about the same pressure as crushing a piece of Cap’n Crunch cereal.

The Unexpected Sound of Aerogel

If aerogel looks like a cloud and weighs next to nothing, shouldn’t it be silent?

That’s what most people assume—but they’d be wrong.

When aerogel is tapped, scraped, or dropped, it doesn’t sound like air or foam.

Instead, it makes a distinct ceramic-like “clink”, similar to frosted glass.

This is because, despite its low density, aerogel has a rigid, interconnected nanostructure that behaves more like glass than like a soft sponge.

This means that while aerogel might look delicate, it resonates like a solid—producing sharp, high-pitched sounds when struck.

From Space to Skincare

You might be wondering: If aerogel is so brittle, how is it useful?

Surprisingly, aerogel’s unique properties make it indispensable in high-tech industries.

1. NASA and Space Exploration

Aerogel is best known for its role in space missions. NASA has used it to:

Trap interstellar dust in the Stardust mission.
Insulate Mars rovers, keeping electronics warm in the planet’s freezing temperatures.
Protect spacecraft from extreme heat, thanks to its low thermal conductivity.

In fact, aerogel is such a good insulator that a blowtorch can’t melt one side of a piece while the other side stays cool enough to touch.

2. Military and Ballistics Protection

Researchers are exploring aerogel-based materials for bulletproof vests and armor. Because of its ultra-lightweight structure, it could provide protection without adding excessive weight—a game-changer for soldiers and law enforcement.

3. Everyday Products

Aerogel isn’t just for astronauts and the military. It’s found in surprising places, such as:

High-performance wetsuits – Providing insulation without bulk.
Cosmetics and skincare – Used in lightweight powders and oil-absorbing formulations.
Soundproofing materials – Thanks to its ability to absorb vibrations.

Is Aerogel Indestructible?

One of the biggest misconceptions about aerogel is that it’s completely unbreakable.

While it’s true that aerogel can withstand immense weight relative to its own mass, it is extremely fragile under direct pressure.

For example, while aerogel can support the weight of a brick resting on top of it, a firm poke with a finger can shatter it.

This paradox is due to its structure: aerogel distributes weight well across its surface, but pointed force easily breaks its tiny internal connections.

That being said, scientists are now working on reinforced aerogels that are more durable—potentially paving the way for aerogel-based building materials and even protective gear.

What’s Next?

Aerogel’s ultralight weight, extreme insulation, and high strength-to-weight ratio make it one of the most promising materials for future innovations.

Scientists are already exploring:

Flexible aerogels that don’t shatter upon impact.
Electrically conductive aerogels for futuristic electronics.
Aerogel clothing that keeps people warm without heavy insulation.

With advancements in nanotechnology, the possibilities for aerogel are just getting started.

The Material That Shouldn’t Exist, But Does

Aerogel defies expectations in almost every way.

It’s a solid that is mostly air, a fragile material that can hold immense weight, and an ultra-lightweight substance that sounds like ceramic when struck.

Whether it’s being used to capture stardust, protect astronauts, or insulate buildings, aerogel continues to be one of the most mind-bending materials on Earth.

And if you ever get the chance to hold it?

Just be careful—it may look like frozen smoke, but it can crumble in your hands as easily as a Rice Krispie treat.