September 8, 2015

General Relativity at the Beach

A hammock turns out to be the perfect place to contemplate spacetime, especially if you happen to have some coconuts

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The theory of general relativity is what made Albert Einstein famous. To get the basics, we brought Einstein to the beach.

This is Scientific American’s 60 Second Science. I’m Clara Moskowitz. Got a minute?

It turns out that gravity isn’t quite what we thought it was.

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Instead of a force pulling two objects together, gravity, according to relativity, results from the shape of space and time. Einstein figured out that space and time are just different dimensions of one entity: spacetime. And it acts kind of like this hammock.

We live in a universe with three dimensions of space, and one of time.

In the absence of mass, spacetime is flat and objects traveling through it move in a straight line. But Einstein showed that when you add mass, including planets, people, and even coconuts, it warps the fabric of spacetime.

Spacetime bends around the mass and becomes curved. An object traveling through can no longer follow a straight line. Now it has to travel in a curve. This curving path brings it closer to the large mass, making it seem as if the objects are drawn together. This is the effect we know as gravity and it is the core of general relativity.

Thanks for the minute! For Scientific American’s 60 Second Science I’m Clara Moskowitz.

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