The glass avatars were a creation of the Testimony Foundation to preserve the memories of humans who were about to die. The Foundation took the original humans from their timeline just before the point of death and copied their memories into transparent human bodies that could take on the appearance of the person whose memories it contained. The original was then returned back to their own point of death to preserve their timelines. The glass avatars were then taken to New Earth in the year 5,000,000,012 so that humans could learn from the past.