The gerund form is often used when describing other verbs in English, but since Norwegian doesn't really have any equivalent, it uses the infinitive form.
"You are reading outside to think" would translate "Du leser ute for å tenke" (You add the 'for' whenever you can say 'in order to' in the English sentence: "You are reading outside in order to think").
'uten' never translates to 'out/outside'. While it looks similar to 'ut/ute', they don't share the same meaning. 'uten' can only translate to 'without'.
yeah I realize that "uten=without" but "without to think" didn't make as much sense as accepting the fact that "uten" can mean "outside" to make the sentence meaningful :p I thought this was one of the many weird but beautiful details about Norwegian :) Again thanks for the help Fveldig!