They say there is no proof. “They” Include many scientists. Some laypersons, and even fewer scientists, are naïve enough to think it is part of the scientific method to investigate strange occurrences and phenomena even if the subject is UFOs.  We sometimes even expect that scientists will make no judgment until they do. But, it seems, most of them are determined to either avoid that subject altogether, or to react with ridicule,  and unseemly emotion. 
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