Global warming, meet cosmic warming. According to a new study, the universe is 10 times warmer today than it was 10 billion years ago. Back then, the average temperature of deep space was around 200,000° Celsius (360,000° Fahrenheit). Now it's roughly 2 million degrees C, which sounds pretty hot, but it wouldn't feel like it if you took off your space suit. (Pro tip: Don't disrobe in space. It's a bad idea.) People experience heat "by the transfer of thermal energy when we touch something," explains Martine Lokken, an astrophysicist at the University of Toronto. But in deep space, molecules tend to be very far apart. So it wouldn't feel hot, she says. It would feel like, well, nothing at all.
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