ATT (attosecond) is a unit of time equal to 10-18 second, or one quintillionth of a second. It is the shortest possible interval of time that can be measured with current technology.
The attosecond is named after the Danish physicist Heinrich Atten, who was the first to measure such short intervals of time. Atten’s experiments in the early 1900s were able to measure times as short as a few hundred attoseconds.
Today, attosecond measurements are made with lasers and other light sources that can generate extremely brief pulses of light. These pulses are used to probe the behavior of electrons in atoms and molecules. By studying how electrons respond to very brief changes in their environment, scientists can learn about the fundamental nature of matter and how it behaves on ultrafast timescales.
In recent years, attosecond science has made great strides in understanding some of the most complex processes in physics, such as chemical reactions and energy transfer within molecules. In addition, attosecond techniques have been used to take “snapshots” of electrons moving around inside an atom—a feat that was once thought impossible. As our ability to generate ever shorter pulses of light improves, we will likely see even more amazing applications of this powerful tool in the future.