Stephen Hawking's first Facebook post and ice bucket challenge

Stephen Hawking is now on Facebook.

The author of "A Brief History of Time" wrote his first two Facebook posts Friday, which garnered over 22,000 likes, combined, within four hours.

In his first message on the social network, Hawking wrote:

Two hours later, he added a second post with a video of his children completing the ALS Ice Bucket Challenge on his behalf. "It wouldn't have been very safe for me to have done the ice bucket challenge, but that is why I have three beautiful children who could take the plunge for me," he wrote.

The page was set up by his team earlier this month. According to a note in the page description, Hawking will sign each message "-SH," to distinguish which posts he writes himself.