The Change is the event that alters the course of history and plunges late twentieth century civilization back into the middle ages. It originated from an electrical storm that surrounded Nantucket Island. At 6:15 p.m. Pacific Standard Time on March 17, 1998, every living being with a spinal cord felt a flash of pain, technology failed and the Emberverse Series began. The effects were that metals become non-conductive, causing electricity to become virtually unusable. Gunpowder and other explosives no longer function as expected, although combustibles still burn; and water boils but, regardless of the amount of heat applied in a closed system, will not convert to high pressure steam. The effect seems to be localized to near Earth orbit since the Sun continues to fuse hydrogen.
The causes of the Change are subject to much speculation among the characters of the Emberverse universe, with a large range of theories relating to it. Popular amongst the Christian, Wiccan and other religious communities is the idea that the Change was a divine act by God, the Æsir, or the Lord and Lady, whether for punishment or to protect humanity from themselves. Another theory is that the effect was caused by an alien intelligence in an effort to minimize the ability of a competing civilization to wage war in their universe, or some other unknown purpose. These aliens apparently have the ability to affect matter and energy at the quantum level. This theory was referred by Ken Larsson, who referred to the alien intelligence as "Alien Space Bats". A smaller, less popular theory holds that the Change was a completely natural occurrence. There is no evidence that the Change is reversible.
As revealed in The Sword of the Lady, the Change was actually caused by a collective omnipotent and omniscient universal consciousness, made up of the collective memories and experiences of Humanity. The Change was, in its words, the result of an argument with itself regarding the best course for Humanity regarding its destructive use of technology, and the Change being seen as the least damaging compromise. It states that the Change may be reversed, as soon as mankind has grown mature enough spiritually and emotionally to use pre-Change technology responsibly.
The Change event also exchanges Nantucket Island of 1998 with its counterpart thousands of years in the past, resulting in Paleo-Amerinds living on Nantucket when the Quest Fellowship arrive on the island. This is the initiating event for the related Nantucket series that preceded the Emberverse series.