What part of the radio spectrum is thought most likely to be successful for communication with other civilizations? Why?
What will be an ideal response?
Because signals with wavelengths longer than 30 cm would get lost in the background noise of our Milky Way Galaxy, and wavelengths shorter than about 1 cm are mostly absorbed in Earth's atmosphere, the most likely wavelengths for communication with other civilizations is between these two wavelengths. Within this broad radio window lie the 21-cm spectral line of neutral hydrogen and the 18-cm line of OH. The interval between those lines has low background interference and is named the water hole. Any civilizations sophisticated enough to do radio astronomy would know of these lines and might appreciate their significance.
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An example of a nonpolar signaling molecule is ____
a. epinephrine b. insulin c. testosterone d. growth factors e. neurotransmitters
A(n) ________ increases the rate of a reaction without being permanently altered by the reaction.
A. catalyst B. catalyzer C. enzyme D. rate increaser
Seeds are reproductively superior to spores because:a
seeds contain a multicellular young plant. b. only seeds can survive for an extended period of time. c. seeds are used as a food source for humans. d. seeds are protected by a multicellular seed coat. e. seeds contain a young plant and also are protected by a seed coat.
Each cell contains two chromosomes with genes for the same traits; these chromosomes are called ________
Fill in the blank(s) with correct word