Which animal can communicate over the greatest distance?

Humans like the other dude said, but via radio waves.

We began to produce them in the late 1800s, but the ionosphere keeps most lower frequency waves from escaping into space. But by the time the 1920s rolled around we were putting out a lot of higher frequency waves too, and these can pass through the ionosphere. Think broadcast radio, HAM, CB radios... all HF (high frequency) waves. And then you've got VHF (very) and UHF (ultra). TV, phones, GPS. So a conservative estimate would be 100 light years. (For comparison the closest star is 4~ light years away, while Andromeda is 2.5 million light years.)

But even if you only count intentional communication, the '74 Aricebo broadcast is still 44 light years. 258,700,000,000,000 miles. Not as far as our earliest radio waves could potentially be but still pretty impressive.

Suck it, Voyager.

/r/askscience Thread