The main utility of the polygraph is indeed as an interrogation tool for eliciting admissions.

Polygraph procedure entails the polygraph examiner attempting to convince the examinee that any attempt at deception will be detected, and it is hoped that the examinee's belief in the polygraph's ability to detect deception will cause him/her to react more strongly when answering a question untruthfully.

However, a person who understands that the polygraph cannot detect lies may still react when answering questions during the polygraph, not out of fear over being caught in a lie, but from other causes such as fear of the consequences of not being believed, or even just unease at being asked accusatory questions.

Your conclusion that "the science does not add up" is correct. For further reading on the scientific status of polygraphy, and on polygraph procedure in general, see Chapters 1 and 3 of The Lie Behind the Lie Detector:

http://antipolygraph.org/lie-behind-the-lie-detector.pdf

My question is, if one is not nervous about answering a question falsely, can the polygraph pick up the lie?  From what I understand there are only two ways a polygraph works 1. To try and scare the examinee into disclosing info out of fear that the test can actually tell when a person lies.  2. To convince the examinee that the examiner already knows the real truth or can easily find out therefore causing the examinee to become anxious and trigger the flight or fight response; in turn spiking their heart rate raising their blood presser and doing what ever else the body does and causing a elevated or change on the machine. Am I right?   Or am totally off base?   If I am right then if the examinee knows that the polygraph can’t really pick out a lie from the truth and they know with out any doubt that the examiner does not know the truth and can never find out then to answer falsely should not cause and reaction in the body or brain at all.  And if this is true how can people say that this is a proven tool to catch lie?  The science does not add up.  But I could be way off..   Thoughts?