Praveen,

It's a method  used by Harold Sherman. He writes about his experiment in Thoughts Through Space

Thoughts Through Space had its origin in a daring plan conceived by two courageous men. It began in Autumn 1937 when a group of Russian flyers on a trans-polar flight crashed on a shelf of ice on the Alaskan side of the Pole. To find and rescue them--if they were still alive--the Russian government commissioned Arctic explorer Sir Hubert Wilkins to organize and lead an aerial search in those desolate regions.

While in New York, prior to his departure, Sir Hubert met Harold Sherman, a student of mental powers who had long been intrigued by telepathy, the phenomenon of mind-to-mind communication. Seeing an unusual opportunity to put telepathy to a scientific test, Sherman and Wilkins decided to collaborate on a six-month experiment....(continued)

It is quite common when you practice astral projection. Not to worry much about it.

cause knowledge is power.

Retrohelderziendheid is a kind of clairvoyance which one has knowledge of something through paranormal means after it happened.
My sister told me about an apparent case of retrohelderziendheid. She was to the television watching a message about a woman (Susan Smith of Union, South Carolina, United States) who claimed that her two young children were kidnapped by a black man her carjackte in a small town in southern the United States of America. They claimed that the black man drove to a lake, from left her steps and then drove off with the children. My sister immediately felt that the children were dead and that they were in the lake. It was announced that the woman herself by car to the lake had driven her children-alive-had tied in the back seat, the car then drove into the lake and in from the shore the car along with her...(continued)

Clairvoyance is an alleged psychic ability to see things that you do with normal vision can not see. Clairvoyance is usually associated with knowledge or retroactive clairvoyance. Who is clairvoyant can see into the future, with or without the aid of a crystal ball, drugs, trance, or other artificial means.
People can predict the future. We do it constantly, but usually, or always, by supporting. On our experience, knowledge and environment Some predictions of so-called psychics come from. The same applies to predictions of people who are not psychic. There is no doubt that a large part of our expectation of the future is unconscious, but it is based on very natural and ordinary faculties, not mysterious or supernatural forces.

Hi Praveen, I was reading it a website and I though of posting it here....

Nice one Tyler :)

I was dreaming that day and had these seeings , Ok i will tell you the story, In that dream i was at the school and visit a underground passage  :o and i was like "ooh there is something like this in here" there i met a old man that toured me in the whole underground after that the old man show me a red ball like candy, i dont remember what did he say , but i remember this word that he said, he said that you will be vanished and you will be seperated from your own body if u dont want to eat this red candy, i refuse to eat and i've gotten into the court of the school and i saw my classmates there and they cannot see me and interact with me, and one of my classmate talked to me {i dont remember either what he say to me} after that i was vanishing im looking at my hands they all turned into a spirit and i was seeing nothing until...(continued)

Hi Celeste,
That's true :)
Some internal meters :)

It makes you wonder how many experiences like this people might have all the time with no knowledge of it afterwards...or without the knowledge that it had any significance.