Grey goo is a useful construct for considering low-probability, high-impact outcomes from emerging technologies. Thus, it is a useful tool in the ethics of technology . Daniel A. Vallero  applied it as a worst-case scenario thought experiment for technologists contemplating possible risks from advancing a technology. This requires that a decision tree or event tree include even extremely low probability events if such events may have an extremely negative and irreversible consequence, . application of the precautionary principle . Dianne Irving  admonishes that "any error in science will have a rippling effect....". Vallero adapted this reference to chaos theory to emerging technologies, wherein slight permutations of initial conditions can lead to unforeseen and profoundly negative downstream effects, for which the technologist and the new technology's proponents must be held accountable.