The light would bounce along the core, reflecting from the boundary between core and cladding.

光束将沿着纤维核左右折射，在物体的核心与覆层之间反复折射，但不越过边界。

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According to classical theory, at the boundary of a black hole-the so-called event horizon-light can no longer escape.

在经典理论中，在黑洞的边界，即通常所称的事件穹界，光是不能逃逸的。

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The buildings are connected through light steel and transparent glass elements, highlighting the stone volumes and allowing the boundary between in and out to melt.

建筑通过轻型钢和透明玻璃构件来连接，突出石质体量，使内外之间的边界渐渐消失。

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Plans for all-postal primaries for candidates in 200 seats before 2015, which are being reconsidered in light of the stalled boundary review process.

BBC: UK Politics

When light travelling through the core deviates from its course and hits the cladding, the boundary between the two acts as a mirror, and the errant light is reflected back into the core.

ECONOMIST: New-age crystals

The eerie light probably came not from the substance itself, but from the boundary between it and the glass layer below.

ECONOMIST: Combinatorial chemistry