[kawakiole]

We don't ever definitely know anything. That's why science and bayesian reasoning in general is so useful to begin with ;)

We can be more or less confident about how stuff works though. For instance, thermodynamics is something we are very confident of having gotten right, because there are plenty of ways to test if doesn't work, and those test fail all the time (so far, at least!).

So this article basically says: would it be easier to explain what we see if there were other dimensions? and the answer is it wouldn't, because we'd have to assume that things that we are very confident about (thermodynamics) are not correct, while simultaneously not providing any way to gain confidence in this new hypothesis (that there are new dimensions with different thermodynamic laws).

This might change some day: before spectrography was a thing, all the theories about star composition were non-falsiable either!!