The newest fiberoptic cables that carry telephone calls cross-country are made of glass so transparent that a piece of 100 miles thick is clearer than a standard window pane.

• 最新全国电话的光纤电缆由玻璃制成。这种玻璃透明度极高，一片100英里厚的玻璃比一块标准的窗框玻璃还要清晰透明。