Blinovitch Limitation Effect

The Blinovitch Limitation Effect was the effect or non-effect of crossing timelines.The effect was named after Aaron Blinovitch who, in 1928, formulated the Blinovitch theory in the reading room of the British Museum. (PROSE: The Ghosts of N-Space)

Theory A
The Limitation Effect limited how much a person could change his or her timeline; in fact, any changes which caused a deviation created a time loop. (TV: Day of the Daleks)

Theory B
The effect when crossing one's own timeline and interacting with a past self (or future self depending on perspective) was energy released by the shorting out of the time differential between the two iterations. The energy caused memories to be transferred from the past self to the future self. It also caused the person to suffer amnesia until he completed the interaction from the other side. (TV: Mawdryn Undead) This aspect of the effect, however, did not appear to come into effect when different incarnations of a single Time Lord, such as the Doctor, interacted with each other, (TV: The Three Doctors, The Five Doctors, et al.) or when different versions of the same incarnation interacted. (COMIC: The Collector, TV: The Big Bang)

The energy released from contact between two versions of a person was usually enough to overload any surrounding technology. Just by being in the same room, the two versions created a Blinovitch Limitation field, a crackling blue energy resembling lightning. (PROSE: Touched by an Angel)

The Blinovitch Limitation Effect could sometimes be suppressed, permitting two versions of a being to touch with no ill effects. (TV: A Christmas Carol) One method of dampening the effect was through the use of a sonic screwdriver. (PROSE: Touched by an Angel) When the TARDIS was reconfigured into a multi-dimensional city, the ship itself contained the energies that would have been released by the Blinovitch Limitation Effect. (PROSE: Cat's Cradle: Time's Crucible)

Time Lords - but not sonic screwdrivers - appear to be immune to the effect. Multiple incarnations of the Doctor physically contact each other in TV: The Three Doctors, The Five Doctors, The Two Doctors, and Time Crash, without incident.

Amy Pond was repeatedly shown to be apparently immune to the effect. Her adult and childhood selves touched in TV: The Big Bang and implicitly do so off-screen when her adult self gives her childhood self an ice cream immediately after the events of TV: Good Night. Two incarnations of either adult Amy or of her identical Ganger, approximately one minute older/younger than the other, touch each other flirtingly in TV: Time. If they are Amy rather than her Ganger, then they each presumably contain an incarnation of the blastocyst later known as Melody Pond / River Song.

Theory C
The Limitation Effect stopped a time traveller from messing around with his or her own personal timeline. The limitation effect was possibly a precursor to a paradox. (TV: Day of the Daleks)