Cosmologists, using new data, are now reconsidering their theories on the manner in which the universe began organizing itself after the Big Bang.

The uncertainty of science: Cosmologists, using new data, are now reconsidering their theories on the manner in which the universe began organizing itself after the Big Bang.

Scientists call it the epoch of reionization, the period in which a newborn universe went from darkness to light as the first stars, galaxies and black holes began forming and radiating energy.

In a paper published Thursday in Nature, researchers are challenging one long-held conception about how quickly the universe began warming during this transition period. Based on observations of X-ray emissions from binary star systems, as well as new mathematical models, cosmologists at Tel Aviv University and Harvard say that heating of the universe progressed much more slowly, and uniformly, than previously thought.