In a nutshell: it's nothing new.
The baby boom that followed World War II created an entire new
generation almost overnight. While the world recovered from the
war, this generation grew up in a rapidly changing society:
technological developments, the cold war, population pressure and
the ever-increasing speed with which social changes took place.
It became much more difficult to 'fit in'. Society no longer offered
a secure haven to those who went along with it.
During the sixties, the majority of these post-war youngsters reached
adolescence, and started to look for a direction in life. The
hippie movement was born.
One of the most important aspects of hippie culture, along with the idealism/unrealism of Flower Power and the common use of drugs like marijuana and LSD, was the interest in the occult, and the desire to go "back to Nature". Having become dissatisfied with the Western points of view, many hippies turned to the east and embraced oriental religions, undertook pilgrimages to India, or tried to set up self-supporting communes to experiment with 'biodynamic' farming and such.
Many hippies eventually outgrew their ideals and the need for an alternative lifestyle. However, some of the ideals from that period have survived, and contributed to a gradual change in the public attitude. This change became more noticeable during the second half of the eighties. Concern for the environment has become generally accepted. Many people, especially the younger generation, are looking for something to replace 'conventional' religion. Large fairs devoted to various aspects of spirituality, including paranormal phenomena, are being held. Healers and channelers appear in TV documentaries. More and more literature on spiritual and paranormal subjects is published.
When the general public started to have a growing interest in the occult, many took this as one of the signs that a 'New Age' is dawning, that mankind is about to undergo (or is already undergoing) a 'quantum leap' in its development. (Some of these changes are attributed to entering the astrological 'Age of Aquarius'.) Most of this should take place during the period from, roughly, 1920 to somewhere during the next century (there seems to be disagreement about the end date). Afterwards, mankind will have a new, more complete awareness about itself and the universe, and new insights on things that were thought to be beyond the limits of human knowledge.
This is the basic idea behind the 'New Age' concept. It takes
many different forms, the most noticeable of which is the acceptance of
things like astrology, channeling. healing, spiritualism, mysticism,
numerology, UFO's, the theory of Atlantis, and much more. And some, it
can't be denied, take this to extremes.
Skeptics have said that New Age people will believe just about
anything. In some cases this may indeed be true, but that should
not be confused with the main goal of the New Age movement at
large. Most New Age people just intend to help bring about the
New Age. That is their primary goal. They may be willing to
discuss anything with an open-minded attitude, but that does
not mean that they will accept it all at face
value.
A sudden leap in the development of Man is of course quite possible. On the other hand, the world has always been changing, just as changes in society, public interest, knowledge and consciousness have been a continuous process. The only new factor in this process is the speed with which changes have been occurring. After all, the pace of these changes has picked up tremendously during the last few decades. Look at the developments in technology or the increase in population growth, for example.
Good question.
Aside from the spiritual aspects, if any, of a postulated New Age,
it is undeniably true that we are in the middle of a change. Our
society, our environment, and our way of living is changing with a
pace that rises almost asymptotically.
It is not unreasonable to assume that in the near future we will
arrive at a point where we'll have to revise our lifestyle, our
attitude, and our outlook on the universe.
For example:
None of this proves (or disproves) that there is a 'Higher Order' behind all this. But it's safe to assume that Mankind has arrived at another milepost in its development. (That has happened before, so this is also nothing new.) All available data points in that direction.