The one on the left is a nanolaser, carved by high-energy plasma and strong acid, and invisible to the naked eye.  The one on the right is a hoodoo, carved by wind and rain, and is approximately 20 million times larger. And about 60 million times older.

The reason they look similar is that they’re actually carved by similar phenomena - different layers of these pillars are made of materials that are eaten away at different rates.  In both these cases, the top layer’s made out of the hardest material, and is supported by a pedestal of ever-decreasing thickness.  The hoodoo’s pillar will eventually be eaten away, making the pillar topple.  We face the same danger when making our nanolasers, where we have to time the etch length carefully to prevent the laser from collapsing.

Both pictures were taken by my labmate Qing, who built the nanolaser on the left, and is now on her post-PhD vacation in Utah, where she’s apparently still seeing nanolasers everywhere she goes.

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