This is why Mel wasn't in Portal 2

“The Aperture Science Enrichment Center is proud to demonstrate the Aperture Science Temporal Reversion Device. You, [subject name here], are probably too young now to properly understand the function of this device, but we shall endeavor to explain it to you regardless. Originally a failed experiment in creating a portable space-time travel device, the Temporal Reversion Device creates a modified quantum singularity tunnel that reverses the subject’s body to an earlier stage of physical development. In layman’s terms: old thing goes in, young thing comes out. The Enrichment Center promises to always provide a safe and nurturing environment for all test subjects: in the all-too-likely event that you have been regressed to a point where you are unable to continue testing, [subject name here] will be taken to an Aperture Science Juvenile Care Facility until [subject name here] is old enough to resume testing. Thank you for helping us help you help us all.”

Source: http://www.furaffinity.net/view/5659257/

Bad things can happen if you go through things you know nothing about.