What is the rule of inherent improbability or physical impossibility on which defendant relies?

The rule of inherent improbability or physical impossibility on which defendant relies has been stated thusly: " 'Although an appellate court will not uphold a judgment or verdict based upon evidence inherently improbable, testimony which merely discloses unusual circumstances does not come within that category. [Citation.] To warrant the rejection of the statements given by a witness who has been believed by a trial court, there must exist either a physical impossibility that they are true, or their falsity must be apparent without resorting to inferences or deductions. [Citations.] Conflicts and even testimony which is subject to justifiable suspicion do not justify the reversal of a judgment, for it is the exclusive province of the trial judge or jury to determine the credibility of a witness and the truth or falsity of the facts upon which a determination depends. [Citation.]' " (People v. Lyons (1956) 47 Cal.2d 311, 319-320.)