4.0. 146 meters
4.【Solution】The red dot is 0.618 meters from the left end of the strip, and 1 - 0.618 = 0.382 meters from the right end, so the yellow dot is also 0.382 meters from the left end.

The distance between the red dot and the yellow dot is: 1 - 0.382 × 2 = 0.236 (meters)

After cutting a segment of the strip, the remaining strip is 0.618 meters long. Fold it in half. Cut along the yellow dot, resulting in two segments that are 0.236 meters long and another segment that is: 0.618 - 0.236 × 2 = 0.146 (meters). After comparison, the shortest segment among the four segments is 0.146 meters.
4. A 1-meter long strip of paper, at 0.618 meters from one end there is a red dot. Fold the strip of paper in half, and mark a yellow dot where it aligns with the red dot, then unfold the strip and cut it at the red dot. Fold the segment with the yellow dot in half again, and cut it at the point where the yellow dot aligns, dividing the strip into three segments. What is the length of the shortest segment among the four segments in meters?