# What would be the "scientific" explanation for having memories from a parallel universe?

This world is like ours but time travel is possible.

The character and others have made time travelling in their past to change things but did not think about the consequences, so they created multiple timelines without realizing it. The parallel universes are quite similar to my character's own universe. Some "minor" changes are for example that his wife is not his wife in another universe, but became an enemy, and some of his friends havent died, and so on.

One day the character starts to feel as if he had very different memories while still having his own. Sometimes these memories get quite real like he sees his wife as someone who always hated him and married his childhood enemy, sees the ones who died in person and remembers how they never died, but then realizes that they actually did. So he is torn apart between the two timelines. He also meets people who shouldn't have born in his universe. Nobody believes him until his other fellow time travellers start to see these too.

So can these timelines affect the "real" timeline this way? Can these parallel universes collide? At least in their minds? What would be a "scientific" explanation for it?

• If the parallel universe has a material effect in our universe then it is not a parallel universe but just a part of our regular universe. The basic idea about parallels is that they do not intersect. Jan 23, 2017 at 14:56
• Occam's Razor would suggest delusion or hallucinations Jan 23, 2017 at 14:56
• You need an plausibly sounding excuse, or real reason (or proof there isn't any)? Jan 23, 2017 at 16:49
• @AlexP Parallel lines not intersecting is an axiom of Euclidian geometry. Not so in Riemannian or other non-Euclidian geometries. Jan 24, 2017 at 1:17
• @a4android: Parallels never intersect, by definition. In Riemannian spherical geometry there are no parallel lines -- all great circles intersect. In hyperbolic geometry parallelism is not transitive: you can draw as many parallels to a line passing through a given point, but those parallels are not themselves parallel. Jan 26, 2017 at 23:37

The best scientists of our time are still only playing with ideas such as a multiverse. Only a handful of persons alive are able to try and comprehend the possible mechanics. Scientifically speaking there is no explanation, this is pseudo- or fringe-science.

Any answer will just do what you could probably do better: come up with something of your own.

You best bet would probably be

Quantum mechanics,

specifically quantum entanglement. There are even hypotheses that came up with something called the quantum mind, where human consciousness is related to quantum entanglement. Somewhere else I red that this could even explain things like telepathy, sadly I can't find the source right now.

• Quantum mechanics is where many theoretical physicists run to avoid saying "I don't know" or "it's magic". Jan 23, 2017 at 17:31
• If the particlee in the two brains are entangled, that won’t do anything to communicate between them. Jan 23, 2017 at 17:35
• Jan 23, 2017 at 20:38
• A theoretical physicist that talks about magic is not a scientist, and there's nothing wrong in admitting to not know something. What's really wrong is to presume to understand quantum mechanics when even the greatest minds still have trouble understanding it.
– r41n
Jan 24, 2017 at 8:07
• @TheNate Quantum mechanics is magic: you say the right incantations and it just works. I mean, when you realize that very small things are more aptly described as mathematical formulas instead of things, you realize just how weird reality is. Jan 24, 2017 at 15:56

If you introduce a 'history tries to fix itself' clause such that the two versions of the protagonist's brain are in perfect alignment then a partial transfer of brain cells between the two might result in the effect you're looking for. Hopefully other brain functions (like speech and motion) won't be affected as they won't be changed too much by the divergent universes, whereas memory can be messed about with (memories will be the only neuron/axon pairs that are significantly different).

However neuroscience is an immensely complicated subject, and it's just as likely that such a strange thing happening would just lead to them completely misremembering everything, as even slight imbalances in neurochemistry can lead to severely trippy effects. At the best you can expect to lose some of your own memories, at worst you'll end up remembering what colour your wife's perfume tastes like shortly before losing the ability to co-ordinate your own bowel movements and dying.

Or possibly just dying.

• Any explanation for the down vote or just a drive by? Jan 27, 2017 at 10:26

Assume there is "leakage" between parallel universes. The usual view of quantum mechanics is that if the many-worlds interpretation is correct that these worlds will not connect or interact. Your fictional world already allows for time-travel and the existence of parallel universes.

In which case, it's not unreasonable to assume that there is already a level of interaction between parallel universes. That in itself would explain there are distinct similarities between the parallel universes.

Possibly what is happening that matter and energy is being transferred between objects and people that have time-travelled. An exchange between two similar individuals could easily go unnoticed, but once their memories start being blended and shared this will become noticeable, at least, to the persons experiencing the phenomenon.

Consider this phenomenon will be happening to both versions of a person, and perhaps any others in other parallel universes. In one sense it is as if the parallel universe will have collided. Possibly it could be an exchange of information and, perhaps, matter. If this happens slowly enough, there could be unexpected doubling of persons and objects to create a new single universe blended out of two (or more) parallel universes.

For reference there is an early Bob Shaw novel, The Two-Timers (1968) that involves parallel worlds, time travel, doppelgangers, and murder. This has two parallel timelines interacting catastrophically. While your parallel universes do need to interact catastrophically, it might provide insights into one way of dealing with this situation.

Memories are due to the physical structure of the brain. In order to be remembering something else, the brain-cell connections must have changed to reflect that of the other timeline.

If you introduce this as a trope, it’s not at all scientifically realistic.

You need, perhaps, to purposfully introduce a communications mechanism that this version of the character has forgotten about, or the communication between parallel versions is a side-effect (they were nit expecting parallel versions!) of a mechanism installed for another purpose.