How Long Can Radio Signals Retain Information Across Vast Distances?

AI Thread Summary
Radio signals can transmit over vast distances with surprisingly low power, but their effectiveness diminishes due to factors like signal dispersion. While theoretically, a perfect laser beam could send a signal across the galaxy, real-world limitations such as beam divergence make long-distance transmission challenging. As the distance increases, the signal's power spreads out, requiring larger detectors to capture it effectively. This highlights the complexities involved in cosmic communication. Understanding these principles is crucial for advancements in interstellar signaling technology.
wolram
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it has always seemed incredible to me how little power it
takes to transmit radio signals over vast distances,i have
read about how these signals are self sustaining, i was
wondering how long a signal could retain its information,
could it go clear across the galaxy?
 
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Originally posted by wolram
it has always seemed incredible to me how little power it
takes to transmit radio signals over vast distances,i have
read about how these signals are self sustaining, i was
wondering how long a signal could retain its information,
could it go clear across the galaxy?
Well, if you could produce a laser beam with zero dispersion, you could, in fact, transmit a signal to Andromeda as easily as across your living room. However, real laser beams always have some divergence, and the power spreads out over a non-zero solid angle. As the receiver gets further and further away, the beam spreads more and more. The receiver in Andromeda won't get all the power of the signal unless he's using a HUGE detector!

So it is, in fact, very difficult to transmit signals across cosmic distances.

- Warren
 
thanks chroot,
i think your answer has more significance than some would think
its one for my personal think tank.
 
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I am attempting to use a Raman TruScan with a 785 nm laser to read a material for identification purposes. The material causes too much fluorescence and doesn’t not produce a good signal. However another lab is able to produce a good signal consistently using the same Raman model and sample material. What would be the reason for the different results between instruments?
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