{"id":273,"date":"2025-09-05T22:22:00","date_gmt":"2025-09-05T22:22:00","guid":{"rendered":"https:\/\/good-worldwide.go-vip.net\/upworthy\/2025\/09\/05\/carl-sagan-4d-ex1\/"},"modified":"2025-09-05T22:22:00","modified_gmt":"2025-09-05T22:22:00","slug":"carl-sagan-4d-ex1","status":"publish","type":"post","link":"https:\/\/goodinc.com\/qa-upworthy\/2025\/09\/05\/carl-sagan-4d-ex1\/","title":{"rendered":"45 years ago, Carl Sagan beautifully explained the fourth dimension with just an apple"},"content":{"rendered":"

The concept of the fourth dimension seems beyond human comprehension. As three-dimensional beings, we are unable to see beyond a physical object’s height, width and depth. What else could there be? Even if you understand the concept, it is almost impossible to picture it in your mind, which is bound by the limits and realities of the physical world around us.<\/p>

Enter Carl Sagan<\/a>, revered as one of the greatest science communicators of his time. Perhaps best known for his research into extraterrestrial life, he was one of the first<\/a> people to demonstrate that life could have existed on Mars. Sagan possessed a unique gift for demystifying complex scientific<\/a> concepts, making them accessible and thrilling for the general public. If you never had the pleasure of watching him on television, you could imagine him as something of a Scientific Mister Rogers<\/a>. Friendly, a wonderful storyteller, and always able to distill difficult lessons<\/a> into their simplest form.<\/p>

In 1980, on Episode 10 <\/a>of the groundbreaking PBS show \u201cCosmos,\u201d<\/a> Sagan embarked on a mission to explain the seemingly impossible fourth dimension.
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A great communicator and handsome, to boot. Giphy<\/a><\/figcaption><\/figure> <\/p>

Many of us have commonly heard of time being considered the fourth dimension. That’s not so hard to understand \u2014 in order to locate an object in the universe, you’d need to know three dimensions of its spatial location and also the time during which it exists.<\/p>

But there is also a more theoretical and harder to understand place, where all four dimensions are spatial. It is nearly impossible for any of us to comprehend… without the help of a gifted teacher.<\/p>

What\u2019s excellent about Sagan\u2019s explanation is that he uses simple and relatable objects: an apple and a Tesseract, or a hypercube.<\/p>

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Sagan explains that if an apple existed in a 2-dimensional space, anyone living in this Giphy<\/a><\/figcaption><\/figure> <\/p>

“In discussing the large scale structure of the cosmos, astronomers sometimes say that space is curved. Or that the universe is finite but unbound,” Sagan begins. “Whatever are they talking about?” <\/p>

Yeah, this guy gets it.<\/p>

Sagan then goes on to explain how a two-dimensional being living in a flat world would perceive a three-dimensional object like an apple.<\/p>

Watch his full explanation here. It’s hypnotic and entertaining and incredibly enlightening.<\/p>

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