into thin air

1. Also, into the blue. Completely disappeared, as in The report was here on my desk and now it's gone, vanished into thin air, or I don't know where they've gone—into the blue, for all I know. Both of these hyperbolic expressions, often preceded by vanish as in the first example, use the rarefied atmosphere far above the earth as a metaphor for an unknown location. Shakespeare wrote of ghosts that “melted . . . into thin air” (The Tempest, 4:1). An antonym for both is out of thin air, meaning “from an unknown place or source.” For example, She made up this excuse out of thin air, or The car appeared out of thin air. However, out of the blue is not precisely an antonym (see under out of a clear blue sky).

Example Sentences

Despite numerous public appeals including an appearance by Mike on Crimewatch, it seemed that Tony Parsons had vanished into thin air.

From BBC

Nine years ago, an Indian student vanished into thin air.

From BBC

"It's like he vanished into thin air."

From BBC

He recalled how his son, who trained five times a week, appeared "sluggish and wasn't himself" before he "started throwing punches into thin air".

From BBC

I read “Into Thin Air” in one night, my hands clasped so tight around the pages it actually warped the book.

From Los Angeles Times