If we have the technology to transmit messages, then why can't we "carry on a conversation" with an alien civilization?
What will be an ideal response?
Nature puts restrictions on travel through space, and it also restricts the possibility of communicating with distant civilizations by radio. One restriction is based on simple physics: Radio signals are electromagnetic waves and travel at the speed of light. Due to the distances between the stars, the speed of radio waves would severely limit humanity's ability to carry on normal conversations with distant civilizations. Decades could elapse between asking a question and getting an answer.
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a. 194 m c. 70.0 m b. 167 m d. 125 m
Velocity: When is the average velocity of an object equal to the instantaneous velocity?
A. only when the velocity is increasing at a constant rate B. only when the velocity is decreasing at a constant rate C. when the velocity is constant D. always E. never
Which of the following is true of ribonucleic acid (RNA)?
A) It carries the genetic code out of the nucleus. B) It remains safe in the nucleus of a cell. C) It is the building block of compounds such as proteins and carbohydrates. D) It is a long spiral molecule that stores the genetic code.
A 14-kg block rests on a level frictionless surface and is attached by a light string to a 5.0-kg hanging mass where the string passes over a massless frictionless pulley. If g = 9.8 m/s2, what is the tension in the connecting string?
a. 2.6 N b. 21 N c. 49 N d. 36 N e. 190 N