Consequently, recent conferences on the merits of active SETI have sought the advice of social scientists. Among their worries is whether to be up front about humanity’s seamy side: Should we tell the extraterrestrials about war and injustice?

Personally, I think this concern is overwrought. Any society that can pick up our radio messages will be at a level of development at least centuries beyond our own. They would be no more incensed by our bad behavior than historians who learned that Babylonians attacked one another with spears. It seems naïve to imagine that, by shielding aliens from the less flattering aspects of humanity, we would somehow lessen any incentive to do us harm. If there’s a danger, mincing words is unlikely to eliminate it.

A better approach is to note that the nearest intelligent extraterrestrials are likely to be at least dozens of light-years away. Even assuming that active SETI provokes a reply, it won’t be breezy conversation. Simple back-and-forth exchanges would take decades. This suggests that we should abandon the “greeting card” format of previous signaling schemes, and offer the aliens Big Data.

For example, we could transmit the contents of the Internet. Such a large corpus — with its text, pictures, videos and sounds — would allow clever extraterrestrials to decipher much about our society, and even formulate questions that could be answered with the material in hand. Sending the web on its way would take months if a radio transmitter were used. A powerful laser, conveying bits much like an optical fiber, could launch these data in a few days.

Sending messages — even big ones — is technically feasible. However, there’s still the highly controversial matter of whether to broadcast at all. Who decides? One could simply let the public weigh in, but doing so wouldn’t address the security issue. Even if a majority is comfortable with a transmission, how does that mitigate the possible danger?

The inability to gauge this peril prompts some critics to argue that, given the possibly existential threat posed by active SETI, we should choose the side of caution. We should simply forbid powerful transmissions to the skies. Indeed, a small consortium of academics in California has drafted a petition urging this.

It’s a wary approach. It’s also poor insurance. Any extraterrestrials with technology advanced enough to threaten us will surely have antennas larger than our own, instruments that can pick up the television and radio signals broadcast willy-nilly since World War II. We are already shouting into the jungle, albeit with less volume than a deliberate signal. But the dangerous creatures may have good hearing.