It is more likely that I have misread the question completely — that it is actually about the smell of blue cheese, the color of dinosaur feathers, or some other thing — than that atomic theory is false.
Indeed, it is more likely that I have hallucinated Less Wrong than that atomic theory is false.
Because if atomic theory is false, then none of chemistry, electronics, etc. make any sense.
Therefore, so far as I am capable of caring, atomic theory is certain; I can go into solipsistic crisis on less evidence than I can seriously doubt it.
Might you be interested in offering your confidence levels on how likely it is that you /have/ 'misread the question completely', or 'hallucinated Less Wrong'?
How much confidence do you place in the scientific theory that ordinary matter is made of discrete units, or 'atoms', as opposed to being infinitely divisible?
More than 50%? 90%? 99%? 99.9%? 99.99%? 99.999%? More? If so, how much more? (If describing your answer in percentages is cumbersome, then feel free to use the logarithmic scale of decibans, where 10 decibans corresponds to 90% confidence, 20 to 99%, 30 to 99.9%, etc.)
This question freely acknowledges that there are aspects of physics which the atomic theory does not directly cover, such as conditions of extremely high energy. This question is primarily concerned with that portion of physics in which the atomic theory makes testable predictions.
This question also freely acknowledges that its current phrasing and presentation may not be the best possible to elicit answers from the LessWrong community, and will be happy to accept suggestions for improvement.
Edit: By 'atomic theory', this question refers to the century-plus-old theory. A reasonably accurate rewording is: "Do you believe 'H2O' is a meaningful description of water?".