These milestones including sitting up, rolling over, and crawling. Fortunately, by the time they were toddlers, these delays all seem to disappear no matter how your baby sleeps, so it's likely more appropriate to describe these kids as having a 'lag' in their development and not a true delay.
View full size image. In the early 1500s, when virtually everyone believed Earth was the center of the universe, Polish scientist Nicolaus Copernicus proposed that the planets instead revolved around the sun.iew full size image. In the early 1500s, when virtually everyone believed Earth was the center of the universe, Polish scientist Nicolaus Copernicus proposed that the planets instead revolved around the sun.
The Copernican Revolution. The 16th century finally saw what came to be a watershed in the development of Cosmology. In 1543 Nicolas Copernicus published his treatise De Revolutionibus Orbium Coelestium (The Revolution of Celestial Spheres) where a new view of the world is presented: the heliocentric model.