Probability ions are a type of ions that exist in the world of Phineas and Ferb and Milo Murphy's Law, which tend to affect the likelihood of things happening in the surrounding area.


There appear to be two types of probability ions: negative and positive.

Negative probability ions tend to affect the likelihood of things going wrong. Anyone that inherited Murphy's Law, such as Milo Murphy, are surrounded by negative probability ions. The inheritance of these negative probability ions seem to have begun with Sheriff Murphy, the original Murphy's Law, although it is unknown how he acquired them. Orgaluth also has her own negative probability ions. Her DNA attract the negative probability ions, so they surround Orgaluth. The negative ions are powerful enough to create a Sphere of Calamity, a massive sphere made of negative probability ions.

In contrast, positive probability ions tend to affect the likelihood of things working out extremely well. Phineas Flynn and Ferb Fletcher are confirmed to have positive probability ions, and thus their affliction is dubbed the Phineas and Ferb Effect. Since Phineas and Ferb are stepbrothers instead of biological ones, it is unlikely that they inherited these ions from the same source, which is unknown.

The two different probability ions are unable to occupy the same space. If one form of the probability ions are surrounded by the other form, the lesser group of ions present will be pushed away to a different direction, like two magnetic fields of the same pole. With this in mind, the lesser ions can be redirected and aimed to a certain direction if manipulated correctly, and limit the effects to a certain object or area.



  • Milo's amount of negative probability ions appears to be extraordinary, sparking an interest in him from the Octalians.
  • A similar concept was brought up in the Phineas and Ferb episode "Just Our Luck": in that episode, Dr. Doofenshmirtz explains that he had discovered all objects have a positive or negative energy field, determining what kind of luck they would have.
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