A doppelganger refers to the ghost of a person who is still living. It basically references a person’s physical double. Others think of a doppelganger as that of some type of an “evil twin” or a malevolent other.
The word doppelganger originates from the German word Doppelgaenger. This word literally means “double-goer.”
According to people, doppelgangers come in different types. The reason for this is that the term itself is now being used loosely and now refers to anyone kind of double. A doppelganger may appear either as a ghost or as a real physical person. The “evil twin” concept of the doppelganger refers to a double that the original person doesn’t know about but who sows mischief among friends and relatives by confusing them. A doppelganger can also refer to a person who is seen in two places at once, though this ability or phenomena is often called “bilocation.” Based on experiments conducted by scientists at the University Hospital in Geneva, Switzerland, electrical stimulation to the brain – the same one used for treating epilepsy – can produce a feeling of a doppelganger in the test subject.
According to myths and folklore, a doppelganger is unable to cast a shadow or reflection – just like a vampire. These apparitions are considered malevolent and a bad sign. It can even haunt the original person himself. Some are said to give bad advice to the original’s friends and relatives. There is also a belief that a person who sees his doppelganger is extremely bad luck and is meant to foretell the person’s death or serious illness.