Sending signals at optical wavelengths might be a viable alternative to radio wavelengths
A) only between civilizations around solar-type stars whose eyes have evolved to see such radiation
B) over relatively short distances where absorption by interstellar matter would not be a problem
C) as long as the light transmitted is a different color than the light given off by the parent star
D) over all distances as long as the intensity of the signal is strong enough
B
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The formation of a galactic central bulge is believed to ____
a. be a slow steady process lasting billions of years b. start after the formation of spiral arms c. be a violent process which adds mass to the central black hole d. begin when the central black hole has reached mature size e. continue throughout the galaxy's life body
Matter Waves: What is the de Broglie wavelength of a ball of mass 200 g moving at 30 m/s? (h = 6.626 × 10-34 J ? s)
A. 1.1 × 10-34 m B. 2.2 × 10-34 m C. 4.5 × 10-28 m D. 6.7 × 10-27 m
A solid object has a volume density ?0 at a temperature of 315 K. The coefficient of volume expansion for the material of which it is made is 7.00 × 10-5 K-1
What will be its density (in terms of ?0 at a temperature of 425 K, assuming that it does not melt and that its thermal properties do not change with temperature?
The Big Dipper is a(n)
a. cluster of galaxies. b. constellation. c. galaxy. d. asterism.