Quote:
Originally Posted by August
What would it take to broadcast a signal that can be read on a distant planet? Power obviously. Lots and lots of power, but in what form?
Radio Frequency, Light, Microwave?
No matter what form one uses signal attenuation is gonna be a bear.
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Actually, it was purposely done once here on Earth that I know of from the giant Arecibo radio telescope in Puerto Rico. Although, arguably more as a PR stunt than anything else.
http://en.wikipedia.org/wiki/Arecibo_message
Quote:
The Arecibo message was broadcast into space a single time (not repeated) via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo radio telescope on 16 November 1974. It was aimed at the globular star cluster M13 some 25,000 light years away because M13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony.The message consisted of 1679 binary digits, approximately 210 bytes, transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 1000 kW. The "ones" and "zeros" were transmitted by frequency shifting at the rate of 10 bits per second. The total broadcast was less than three minutes.
The binary 'message' consists of:
1. The numbers one (1) through ten (10)
2. The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA)
3. The formulas for the sugars and bases in the nucleotides of DNA
4. The number of nucleotides in DNA, and a graphic of the double helix structure of DNA
5. A graphic figure of a human, the dimension (physical height) of an average man, and the human population of Earth
6. A graphic of the Solar System
7. A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish
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However, the chances, even if our galaxy is teeming with life, of someone listening, at the right frequency, at the right time, in the right direction is so mathematically remote as to be barely worth considering.