This example is only 176 micrometers (about 0.007 inches) long, and is barely visible to the naked eye.

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Some of the fine layers on Mars may have formed by the slow accumulation of dust and ice, perhaps only 100 micrometers (0.004 inches) per year.

BBC: Mars south pole

If properly fitted and worn correctly, N95 respirators filter out at least 95 percent of particles as small as 0.3 micrometers, which is smaller than influenza viruses, the report notes.

CNN: Report on handling H1N1 cases: Use masks with airtight seals

Whereas analog measurement--in the form of slide rules, micrometers and electronic meters--increasingly hit a wall because of the limitation of human beings to capture the result, digital could just keep on getting more and more accurate.

FORBES: Computing Desire