Is it by now conclusively established that the universe is made mostly of exotic dark matter and dark energy? I need reassuring that there is no escape from this still startling conclusion. The following cautionary tale will explain why I have the temerity to ask such a question: In the late 19th century geologists had become convinced (correctly as it turned out) that the Earth is a great deal older (several Gyr) than the 6000 years that the Biblical calculator Bishop Ussher had estimated. Geologists had a great deal of evidence to support their conclusion. Then along came Bill Thomson (a prestigous physicist, aka Lord Kelvin) who proved, using impressive mathematics not understood by most geologists, that the Sun couldn't possibly be older than about 0.1 Gyr, and also that the Earth was not much older than that! Of course the discovery of radioactivity and fusion has long since resolved this conflict in favour of geology. Then in the early 20th century the prestigous mathematician/physicist Harold Jeffreys proved, again with impressive reasoning not familiar to the geological community, that the continental drift ideas of the geologists Wegener and Du Toit were nonsense. Of course the validation of plate tectonics by J.T. Wilson has since reversed this verdict in favour of the early proponents of continental drift. These examples show that even the most prestigous scientific folk are sometimes deceived by sly nature. The most prestigous scientific folk since WW II have been nuclear physicists, for very good reasons. And it is they who have explained to cosmologists, a different breed of scientists, how the observed elemental abundances of the lighter elements, placed in the context of their own area of expertise, nuclear physics, put an upper bound on the amount of baryonic matter in the universe. The fact that this bound is far below the critical density of stuff required to explain our flat universe has since made cosmologists jump through many hoops about exotic unobserved forms of dark matter/energy. Is it not possible that somehere in the setting of this upper bound sly nature has deceived those prestigous nuclear physicists? This is a cynical possibility suggested by an ignorant someone who is neither a mathematician, nuclear physicist, cosmologist or geologist. I don't suppose that nature would sink so low as to deceive folk clever enough to invent the bomb ... but I'd be grateful if contributers to this forum could reassure me that there is in fact plenty of independent evidence of nature's good character.