Through an in-depth study of the communication links between dolphins, scientists have discovered that the concept of entropy in Zipf's law and information theory can serve the analysis of extraterrestrial signals. After receiving any suspicious signals outside the ground, you should first use Zip Huf's law to analyze whether there is a certain straight line feature of the slope. If there is a certain feature, it proves that it is not meaningless noise. Then entropy analysis is performed, so that you can know the complexity of the communication without deciphering the signal. A suspicious signal, not only has a linear feature with a slope of -1 in the Zipf coordinate system, but also has a high-order entropy value, then this signal is most likely to be the long-term extraterrestrial civilization we are looking for. The most appropriate summary of this text is:. ['Research finds communication between dolphins is very similar to alien signals.', "How to use Zipf's law and entropy to analyze alien signals.", 'How to determine whether the suspected extraterrestrial signal is from an alien civilization.', 'How to judge the wisdom of alien civilization through extraterrestrial signals.']