"Is it necessary for the government to present evidence that it is not humanly possible for someone not to recall an event?"

So asked the jury in the Libby case, seeking a clarification from the judge about the meaning of reasonable doubt. They've been deliberating since February 22. Can anyone pick apart that question and tell what it means?

The question suggests that the jurors might be stumped about whether than can convict even though a juror keeps saying something like: But, of course, it's possible to forget anything. This would be an argument against convicting based on the evidence that demonstrated the importance of what Libby contends he forgot.

This question might mean that they are arguing about how high the standard of reasonable doubt really is. But there is also concern about the kind of proof that is required. Is it enough to simply show that the thing allegedly forgotten was extremely memorable, so that the jurors have to make an inference that he is therefore lying? Someone may be demanding that there should be evidence about the mechanism of forgetting.

I would think that the correct answer about the quantity and quality of the evidence needed would tend to make a jury that would ask the question that way likely to convict. Do you agree?