clock2.png (IMAGE) University of Wisconsin-Madison Caption One of the first steps in creating the optical atomic clocks used in this study is to cool strontium atoms to near absolute zero in a vacuum chamber, which makes them appear as a glowing blue ball floating in the chamber. Credit Provided by Shimon Kolkowitz Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.