Extreme Ultraviolet Laser Challenges Einstein

No, not really. (Any headline that implies that Einstein might be wrong is invariably incorrect — these are things that have been tested for 100 years)

In the new study, the physicists shot xenon atoms with FLASH, an x-ray laser that uses intense photons in the extreme ultraviolet energy range, about forty times the energy of visible light. The xenon atoms lost a whopping 21 electrons at once, which indicates that it was hit by 50 photons simultaneously. Not only that, but the first electrons to pop off were from an inner region of the atom, like if you peeled an onion starting with the second layer.

Here’s the thing: there are situations where you look at E&M interactions classically. If you put a large electric field around a material, you can ionize it; even though E&M interactions are explained by virtual photons, this is a case where classical physics works out just fine, and a high-intensity laser has a large electric field. Another case is a FORT (far off-resonant dipole force trap), where the intensity profile of a focused laser gives an electric field gradient.

So ionizing 21 electrons is pretty cool, but one needs to be careful in how one phrases these “challenge to Einstein” headlines. You have models of light that are wave-like and particle-like, and you use the model that works. The lesson of the photoelectric effect is NOT that light always exhibits particle properties.