Ruler and internet: what they have in common

1. Step 1. Ruler — has part — Measurement scale. Marked graduations.
2. Step 2. Measurement scale — is part of — Barometer. Millimetres of mercury.
3. Step 3. Barometer — uses — Vacuum. The Torricellian vacuum above the mercury.
4. Step 4. Vacuum — is used in — LIGO. 4 km vacuum tubes.
5. Step 5. LIGO — is made of — Silica (sand). The mirrors are fused silica.
6. Step 6. Silica (sand) — is material for — Internet. The backbones are silica optical fibre.

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