Vacuum gap between glass walls and GPS (satellite navigation): what they have in common

1. Step 1. Vacuum gap between glass walls — is part of — Dewar flask. It does not conduct heat.
2. Step 2. Dewar flask — evolved into — Vacuum flask. A household Dewar flask.
3. Step 3. Vacuum flask — has part — Mirror. The silvering reflects heat radiation.
4. Step 4. Mirror — is part of — Interferometer. Mirrors.
5. Step 5. Interferometer — inspired — Theory of relativity. The Michelson–Morley experiment found no ether.
6. Step 6. Theory of relativity — is used in — GPS (satellite navigation). Corrections for the relativistic slowing of clocks.

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