(uncountably infinite!)
yet its total length is exactly ZERO
Uncountably infinite, yet total length zero — Georg Cantor's dust
Start with the interval [0, 1]. Remove the open middle third (1/3, 2/3). From each remaining piece, remove its middle third. Repeat infinitely. What remains is the Cantor Set— "Cantor dust" scattered across the line, yet somehow containing infinitely many points.
After n iterations, total length is (2/3)ⁿ. As n → ∞, this approaches ZERO. The Cantor Set has no length—it's "invisible" to ordinary measurement. Yet it contains uncountably many points! This reveals the difference between counting and measuring.
Points in the Cantor Set can be written in base 3 using only digits 0 and 2 (never 1). This maps 1-to-1 with binary numbers in [0,1], proving the Cantor Set has the same cardinality as the real numbers! 2^ℵ₀ points in zero length.
Every point in the Cantor Set is a limit point (has other Cantor points arbitrarily close), making it "perfect." Yet it contains no intervals—it's totally disconnected. Around any point, you can always find gaps. A continuous dust!