The world of attosecond physics hides many mysteries, including fundamental ones. So far, we can only conjecture that the laws governing the behaviour of complex systems, such as macromolecules accommodating a large number of electrons, are the same as the ones dictating the working of simple systems such as the hydrogen or the helium atom. But we do not have certainty. Insight into the working of the dynamic behaviour of complex multi-electron systems is one of the several grand challenges attosecond technology is facing.

In information technology the ultrafast motion of electrons dictates the computing power of chips. Light forces offer the fastest way of controlling this motion. Only light and its electric field has the potential to control electric signals in future atomic-scale chips at petahertz frequencies.

Exploring new ways of forming and destroying chemical bonds and thereby creating new molecular structures by controlling electrons on molecular orbitals is yet another challenge. Insight into the motion of low-energy electrons in molecules means understanding the origin of diseases at the most fundamental level, knowledge that may lead to discovering the most efficacious ways of curing them. Controlling high-energy electrons with lasers in turn holds out, for the first time, the promise of creating compact ultrabrilliant X-ray sources for biological and medical imaging of unprecedented resolution.