This argument fails when it introduces a scientific conclusion based on authority. When it is said that the universe needs to have a beginning, the only reason given for that is that Stephen Hawking said so, and the concept of entropy. Both are scientific constructs. The argument, thus, does not solely rely on logic. Why is this a problem? Because 500 years ago, science dictated that the earth could not revolve around the sun, because that would result in wind blowing at several thousand miles an hour. Thus, the argument does not solely rely on logic, but also on falliable science.