Ruby split by whitespace

This is the default behavior of String#split:

input = <<-TEXT
 aa bbb
cc    dd ee
TEXT

input.split

Result:

["aa", "bbb", "cc", "dd", "ee"]

This works in all versions of Ruby that I tested, including 1.8.7, 1.9.3, 2.0.0, and 2.1.2.