Magazine article Natural History

Word Exchange

Magazine article Natural History

Word Exchange

Article excerpt

Waves

Marcia Bartusiak ["Einstein's Symphony," 4/16] suggested that the propagation of gravity waves and of electromagnetic waves are "far different." Doesn't the fact that they both propagate at the same velocity of light suggest they are the same?

Rane L. Curl

Ann Arbor, MI

MARCIA BARTUSIAK REPLIES: Electromagnetic waves and gravitational waves do indeed share one property: they both travel at the same speed. But that similarity alone does not make them equivalent. They are far different in other ways. For example, the gravitational wave, as it proceeds, alternately compresses and stretches space-time along the way. Electromagnetic waves exhibit no such effect. They do not alter the fabric of space-time as they travel through it. If they did, the gravitational wave detectors would be continually registering signals, given how much electromagnetic radiation daily bathes the Earth.

Not Blight-less

Bernd Heinrich ["The Spreading Chestnut Tree," 4/16] states that none of Maine's native American chestnut trees have blight at the sixty-seven locations identified by The Maine Chapter of The American Chestnut Foundation (TACF). Actually, Asian chestnut blight is present in over half of these locations. Every year we see blight appear where it had previously been absent, and every year we see trees of all sizes die from blight infections. Being at the very edge of the native range, many chestnuts in Maine have grown bigger than in other states because of their relative isolation from blight. …

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