Topic 1: Basic Nuclear Physics – Step 18

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English Idioms

What does “double-edged sword” mean?

In Chapter 4, radioactivity is described as a “double-edged sword.”

This expression comes from Arabic and is a metaphor meaning something has or can have both positive and negative parts or consequences. Taken from the idea that two sides of the same sword blade are sharp.

Examples:

“Freedom of expression … can be a double-edged sword.”

Linda Connors

“A shaft of sunlight is a double-edged sword. The sun powers life on earth, but its ultraviolet radiation capable of bending DNA, RNA, and protein molecules into harmful shapes-poses a threat to life.”

 Jay Withgott, “Feeling the burn,” Natural History, Vol. 110, No. 6; p. 38, 2001 (Jul/Aug)

Think Ahead: How is radioactivity a “double-edged sword”?