Aliens, the Risk of Medical Care & More: 5 Things We Learned This Week

What would happen if we did receive a signal from aliens? DALE O'DELL/ALAMY

From the danger of overprescribing antiobiotics to why we don't delete annoying Facebook friends, here are five things we learned in Tech & Science this week:

According to a new study, medical errors are currently the third leading cause of death in the U.S. Suhaib Salem/REUTERS
A new study suggests abstinence education isn't more effective at preventing HIV transmission than teaching the public about how to practice safe sex. Romeo Ranoco/REUTERS
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Facebook has won a legal fight in China over copyright of the two-word term “face book.” Flickr/ CC
In the U.S., more than a quarter of antibiotics prescribed to patients each year are inappropriate. Lucy Nicholson/REUTERS