In an interview from late 1990 which was published in the book, Matrix III by Valdamar Valerian, a man calling himself Duncan Cameron, who claims to be a former employee of The Montauk Project, describes a chair which was obtained from aliens that acts a mind amplifier. The alien technology was used to create a time vortex which allowed subjects to travel forward and backward in time. The subjects travelled as distant in the future as 10,000 AD, but apparently had difficulties with the timeline around 2012 AD.

From the interview:

Q. Can you change the present by sending someone to the past?

A. Yes. It’s a dreamlike reality. No one has picked up a tangible future beyond 2012 AD. There is a very abrupt wall there with nothing on the other side. Prophecies speak of earth changes around then. Curious, isn’t it?

Also of interest:

Q. Was the zero-time generator from alien sources?

That’s why they call it a zero time generator. Locking equipment to that is the only way you can get some of these higher function generators to work.

And:

Q. Why was it mentioned at one time that 2011 was the last year that they could see anything tangible?

A. Right. There seems to be some evidence of this.

Full text of the interview: AndersonInstitute.com

“What has been well hidden within the folds of your present four dimensional world will be clearly revealed by the additional Light available in the unfolding of the new, five dimensional world. In other words, there will no longer be places in manifestation where denial can hide. What has been hidden away since before linear time began will be revealed and clearly visible.”

Source: Godchannel.com

The original documentary that aired on History Channel detailing several sources of the doomsday date including the Mayan Calendar, the I-Ching, and the Webbot Project:

David Wilcock, a possible reincarnation of Edgar Cayce provides his views of the upcoming changes in 2012: