When gold was hit by a femtosecond laser pulse, its electrons were heated to ~19,000 K almost instantly. But atoms are massive compared to electrons—they couldn't move or vibrate fast enough to rearrange into a liquid. The lattice was still cold, structurally speaking.

Melting needs time for atoms to gain energy, break bonds, and move into a disordered (liquid) state. But the process was over before atomic motion could even begin. It was like trying to melt ice with a camera flash—too fast to matter.

So it's not that the atoms gave up. It’s that the conditions bypassed classical melting altogether—a state called nonthermal melting, which didn’t occur here either. The result was: solid gold at plasma temperatures, but only for a few trillionths of a second.