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Distance

physical science Maturity 11-13 Next article →

Distance is a way to measure how far apart things are.

Distance board in Vizag cropped
Distance board in Vizag cropped

It can be a number or a description of separation. We use it to talk about physical space between people or objects. It also helps us measure how different two ideas are. In math, these ideas are often part of a metric space. This is a way to organize measurements of difference.

Distance function animation
Distance function animation

Scientists and mathematicians use many different kinds of distance to understand our world.

One common way to measure is called Euclidean distance.

Distancedisplacement
Distancedisplacement

This is the length of a straight line between two points. It is the shortest path possible in a flat space. In geometry, you can find this using the Pythagorean theorem. For very small things, you might use a ruler. For long distances, you could use radar. To measure the huge distances in space, we use a cosmic distance ladder.

Sometimes the path is not a straight line. We cannot tunnel through the Earth to get somewhere else. Instead, we travel along the curved surface of the planet. The shortest path on a curved surface is called a geodesic.

Greatcircle Jetstream routes
Greatcircle Jetstream routes

Pilots often use these paths when flying airplanes. In a city with many streets, we use Manhattan distance.

Manhattan distance
Manhattan distance

This measures distance by counting the blocks you must walk. It follows the grid of the streets rather than a straight line.

Distance can also describe how much things change. In computer science, we use something called edit distance.

Distance between sets
Distance between sets

This measures how different two strings of text are. For example, the words "dog" and "dot" are very close. They only differ by one single letter. This idea helps spell checkers find the right words for you. It can also show how people are connected in social networks. You might hear about the "six degrees of separation" in a group.

Even math and social studies use these ideas. In statistics, distance shows the difference between two probability distributions. This can be measured using things like the Mahalanobis distance. In sociology, distance describes how people are separated by social class or race. In psychology, it can describe how an object feels removed from yourself. Distance is a tool that helps us map everything from tiny words to the entire universe.

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🖼️ Images & Media (6)
File:Distance board in Vizag cropped.jpg
Distance board in Vizag cropped.jpg
File:Greatcircle Jetstream routes.svg
Greatcircle Jetstream routes.svg
File:Manhattan distance.svg
Manhattan distance.svg
File:Distance function animation.gif
Distance function animation.gif
File:Distance between sets.svg
Distance between sets.svg
File:Distancedisplacement.svg
Distancedisplacement.svg
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