From a scientific point of view (aka, what has actually been proven):
Empathy exists. It exists in everyone except sociopaths/psychopaths/etc. It is the natural ability of a human to be able to connect to another persons feelings. We do this by hearing what they say, judging how they look, and so forth. It is possible for people, with enough experience, to start being able to get an idea of a persons intentions, at times, without actually being told what they are.
Taking this further is what is referred to as instinct or "gut feeling". This is what happens when your mind starts connecting the dots, without you realizing it. This is based on experience and previous encounters of a similar nature.
This is basically what Lynn Seiser described.
With that said, being able to feel a persons energy, without seeing/hearing them, is not possible. Or at least it has never been scientifically proved in the history of human kind. It has been claimed by many, but has yet to be proven. While there is some pseudo-theoretical basis for it (the human brain gives off energy, you could "read" this energy), I would be more than extremely sceptic of anyone claiming such power. But of course, if they are willing to demonstrate it to you, under controlled circumstances, you have a potential Nobel on your hands
