Hans Christian Orsted: Who He Was, and Why You Owe Him

Ker Than
for National Geographic News
August 14, 2009
Hans Christian Ørsted: He's not as famous as Darwin or Newton, but if you've ever used a modern gadget, chances are you have this 19th-century Danish physicist to thank—and what better time than on his 232nd birthday?

Today marks Hans Christian Ørsted's birthday—a fact made plain to puzzled millions by Google's artistic homage to Ørsted on the search engine's home page.

So who was Ørsted, and what did he do to deserve the Internet's ultimate accolade?

Born in 1777 in Rudkøbing, Denmark, Ørsted established in 1820 that an electrical current coursing through a wire creates a magnetic field that can deflect a compass needle.

Ørsted's seemingly simple observation was nevertheless likely the first to link electricity and magnetism, explained physicist Paul Cadden-Zimansky of the U.S. National High Magnetic Field Laboratory in Florida.

As separate forces, electricity and magnetism had been familiar for thousands of years. The ancient Greeks, for example, used magnetic rocks called lodestones and noticed that amber (Greek word: elektra), when crackling with static electricity, could attract wheat chaff.

But no one had ever before scientifically documented the connection between electricity and magnetism, Cadden-Zimansky said.

Ørsted's observation helped set the stage for the discovery of electromagnetic induction, whereby a changing magnetic field is used to produce an electric current and vice versa.

Hans Christian Ørsted: 21st-Century Man

Today Ørsted's fingerprints are on everything from medical scanners to your car's engine to theoretical invisibility devices.

"An MRI machine requires a high magnetic field to work, and you create that by sending current through a wire," Cadden-Zimansky said.

Cadden-Zimansky compared Ørsted's contribution to science to that made by another European scientist who lived more than a century before.

"Isaac Newton showed that the same phenomenon"—gravity—"causes a ball thrown into the air to fall down and [also causes] the planets to orbit the sun," he said.

Like electricity and magnetism, the different expressions of gravity "look like two different phenomena, but the same rules can describe them both. Ørsted's discovery was analogous."

Hans Christian Ørsted: Google Idol

Google spokesperson Anne Espiritu said Ørsted's birthday was chosen to be honored because it reflects the company's personality and love of innovation.

"We felt his work with electric current and electromagnetism would not only make for a fun doodle," Espiritu said, "but we also wanted to celebrate the work of a scientist not too many people may have necessarily heard of but benefit from everyday."

© 1996-2008 National Geographic Society. All rights reserved.