Dark matter is the unknown substance thought to make up some 27 percent of the universe. It can’t be observed but only theorized.
Scientists aren’t like “everyone else”: because of the prestige they enjoy, the impact of their being “uncritical of things that [they] want to believe” is tremendous. It can be quite corrosive, quite malign.
Douglas Hofstadter argued in much the same vein as Henry Markham, that the brain can be understand in rules-bound machine terms.
Cloning a human being is a terrifying prospect, from a moral perspective, and seems inevitable.
Further requirements could be listed, including some even more horrific than cloning.