# Why would a five dimensional creature need memories?

We human lives in a four dimensional universe: three spatial dimensions and one dimension for time. We feel the flow of time as experiential due to the fact that our brain saves past experiences into memories, but in fact the past does not exist in any physical meaning.

In relativity you can say that someone's future had already happened in another's past... anyway let's get to the main point.

Imagine a creature who exists parallelly across every instances of time, so its entire life is predetermined. I wonder: what would it need of memory?

• What is memory for a creature which "exists parallelly across every instances of time"? And why would the life of such a creature be "predestin[at]ed", any more than the life of a regular creature? Either the past uniquely determines the future, or it doesn't. Dec 30 '20 at 9:25
• I've contemplated this for my book. I needed additional realities (alternate timelines/parallel universes) to make sense of it. With predestination, there is no change, motion or flexibility and the being is static. worldbuilding.stackexchange.com/questions/176601/… Dec 30 '20 at 11:48
• What is its fifth dimension? An additional (fourth) spatial dimension? Dec 30 '20 at 19:45
• It's impossible to answer this question without answering Alexander's question above: does your 5D creature have its own temporal dimension or not? Dec 31 '20 at 2:05
• To answer AlexP & others, I imagine the physical embodiment of such being is entangled to each and every instances of its entire life... I suspect only higher dimensional being can see all of these instances at once analogy to a director looking at a roll of films of herself except that one of the film negative can be overexposed without soiling the rest. That's settled I shall go back to see glue dry, my god the smell. Dec 31 '20 at 6:40

To know what is happening at the other end of its body,

This creature passes through time the same way a fence passes through a field. The fence has a start and an end and everything in between, but in reality the fence is there all at once. Similarly the creature already exists at all points in time at once.

Imagine you are lying down in a field, with your right hand being in the past and your left hand being in the future. There are some special ants that live according to field time. They are born at the right side of the field and due to some unexplained force move leftwards throughout their lives. They interpret field time as real time.

One day an ant bites your right hand and by instinct you close your left hand. This crushes the ants walking on your left hand. From the ants' point of view you are a high-dimensional creature that has remembered the bite in the past and used it to act in the future. From your point of view however it all happens at once. It's not a memory but just your sensory system.

The creature works the same way. What you might call memories it just calls its nervous system.

Of course none of this answers the question of how a full-dimensional creature would experience its lifetime if its consciousness does not pass through a timelike dimension. In the field example there is the higher dimensional real time and your consciousness passes through it linearly. You can act in the ant's past but not in your own past. How does a five-dimensional creature work if there is no sixth dimension for its consciousness to move along? It throws up loads of other questions. You also need rules for avoiding time paradoxes.*

*Assuming you're into that sort of thing. It's your world after all. Feel free to have as many paradoxes as you want. I promise I won't tell mum.

The concept of memory is a tad different for a creature who lives across every instance of time.

While for us memory is "remember what happened in $$\mathit{Life}(t-x)$$ while we live in $$\mathit{Life}(t)$$, for your creatures memory is simply "be aware of every value of $$\mathit{Life}(x)$$ in its entire dominion.

So, let's say John Doe was born in 1965 July 11th and died in September 2010 November 4th.

The time spread John Doe's "memory" would simply contemplate each and every moment of its existence in that time span, like we see a segment made out of all and every points belonging to it.

By the way I don't think that

a creature who exists parallelly across every instances of time

qualifies as 5 dimensional creature.

• It would almost be a 4D creature that is infinitely fat in the time dimension rather than the three spatial dimensions. Dec 30 '20 at 19:02

To understand things. If it turns its attention to John Doe's fourth birthday party, and has no memory, it has no memory of why it turned its attention on that date and time, and no understanding of its significance.

If you merely mean that it is conscious of its life and thoughts in a manner different from ordinary humans but does indeed know of what it was doing at them, it's not really not having memory.

Did you watch the 2019 version of Watchmen on HBO? It played quite well with this idea. Dr. Manhattan's consciousness exists simultaneously at all times his body ever inhabits, and the story plays pretty well with the paradoxes of backwards causation this can appear to cause to regular people who experience sequential time. He is able to transmit information from other character's futures into their pasts.

As for what "memory" means to him, memory is just a mental store of information. It happens to be that, because we experience sequential time, all of the information we store, from our perspective, was gathered in the past. Some creature that does not experience sequential time still has need of knowledge, even if, from its perspective, it acquires all of it at once. Wherever that knowledge is kept is "memory."

Lets assume this 5th dimension being named Jack is a human, or at least has the basic human biology externally. We humans can move freely in 3 space dimensions and forced to move unidirectional in time. A 5th dimensional being by that logic should be able to move freely in 4 dimensions and forced to move unidirectional in a 5th dimension, or simply be capable of perceiving a 5th dimension. With this established, there are two reasons to have memories:

1. what exactly is this 4th and 5th dimension. Time when seen as 2 dimensional, leads to a past-future dimension and a parallel multiverse dimension. So if 4th dimension(free movement) is past-future, then Jack is able to perceive his entire timeline simultaneously, but as he moves to another timeline, he can no longer perceive the other timelines, hence the need for memory. If past-future is the 5 the dimension(forced) for Jack, then that means Jack can perceive all possible "presents" simultaneously and move in between them, and needs memory to store these presents.An example of this would be tossing a coin and then being able to move between the two timelines of one with heads or one with tails.

2. If jack has human anatomy or anything of the kind seen in nature, he can only perceive a limited portion of space-time. Jack cannot know what is behind him or far away from him. So when Jack moves, his perception changes. But how would Jack know if his perception changed ? there in comes the need for memory.