Superfluidity facts for kids

The liquid helium is in the superfluid phase. As long as it remains superfluid, it creeps up the wall of the cup as a thin film. It comes down on the outside, forming a drop which will fall into the liquid below. Another drop will form—and so on—until the cup is empty.

Superfluidity is a really cool and unusual state of matter. It happens when a liquid starts to act in very strange ways. Imagine a liquid that can flow without any friction at all! That's what a superfluid can do.

What is Superfluidity?

A superfluid is a liquid that has zero viscosity. Viscosity is how easily a liquid can flow. For example, honey has high viscosity because it flows slowly. Water has low viscosity because it flows easily. A superfluid has no viscosity, meaning it flows perfectly without any resistance.

How Superfluids Behave

Superfluids can do some amazing things that regular liquids cannot:

• They can flow extremely easily. Because there is no friction, they can even creep up the sides of a container and flow out, even if the container isn't tipped over.
• If you spin a container with a superfluid inside, the liquid stays completely still. It doesn't form a whirlpool like water does when you drain a sink. However, if you spin the container very fast, whirlpools can form.

Where Are Superfluids Used?

Scientists have only been able to create superfluids at extremely cold temperatures. Despite this, superfluids are very useful in science today:

• In 1983, superfluid Helium was used in a special satellite. This helium was super cold, at about -271.4 degrees Celsius (-456.2 degrees Fahrenheit). It helped the satellite gather information about infrared waves in space.
• Superfluids can be used in special devices called gyroscopes. These gyroscopes can help machines detect tiny movements in gravity that regular tools might miss.
• One type of superfluid was used to slow down a beam of light. Normally, light travels incredibly fast, about 670,600,000 miles per hour (1,079,000,000 km/h). But in this superfluid, the light slowed down to only 38.03 mph (62.2 km/h)! That's super slow compared to its normal speed.

There is also another special state of matter called a supersolid. However, these are much more complicated to create and understand.

See also

In Spanish: Superfluidez para niños