Colliding photons were spotted making matter. But are the photons ‘real’?

In a demonstration of Einstein’s E=mc2, collisions of light yielded electrons and positrons

STAR experiment at Brookhaven National Laborator

The STAR experiment (shown) at Brookhaven National Laboratory detects particles produced when atomic nuclei collide within. Scientists have found evidence for smashups in which colliding particles of light create matter and antimatter.

BNL

Collide light with light, and poof, you get matter and antimatter.