# Would a 4-dimensional being be able to see inside other people?

I have a tribe that is completely isolated from the outside world and there is a shaman that can see in 4 dimensions. He can identify disease before it manifests and is hailed as a god.

This 4th dimension would be purely spatial, he is not able to travel in time. He can only see in 4 dimensions.

What would the extent of this power be? I assume he can see inside people (using the 4th dimension), but is this correct? And are there other things he would be able to do that I'm not thinking about?

• What is the 4th dimension? What is the spatial relationship between two objects (say, me and the computer screen) along the axis of this fourth dimension? – kingledion Apr 20 '17 at 14:25
• @vrwim See Flatland also referenced in my answer below. Secespitus: Fortunately, this question is narrower. – WBT Apr 20 '17 at 14:38
• I find it odd that he cannot see through time but he is able to detect a disease "before it manifests". Being able to see through a 4th spatial dimension should not be enough to predict a disease. – Pharap Apr 20 '17 at 18:19
• Does visible light reflect off the internal organs of people? If not, the how could even a 4D being, see such internal organs? If it does, then you have to be able to explain how light got in there. Maybe it is not visible light a 4th dimension Shaman sees, but instead some higher frequencies like x-ray, or gamma-ray, etc that allow seeing inside an object. – gogators Apr 20 '17 at 19:39
• @chiliNUT There can be an arbitrary number of spatial dimensions (also, arbitrary number of temporal dimensions, but that's beside the point) and the question clearly asks about four spatial dimensions (i.e. 4+1 dimensional spacetime). Sure, (most?) humans can't imagine $n$-dimensional stuff for $n>3$, but that doesn't exclude the possibility of extra dimensions. – Danijel Apr 21 '17 at 7:25

Can you as a three-dimensional being see inside a two-dimensional circle? That depends on your position relative to it. When you are looking right at its edge, you can't. But if you are above or below the circle, you can.

So if a 4d being wants to look into a 3d object, it needs to move "upwards" or "downwards" in the 4th dimension in order to get a "vantage point". But that point will not be in the 3d space the 3d object can perceive. This of course assumes that the object the 4d being wants to look at is flat and open in the 4th dimension. If the 4d being wants to look into a sphere and that sphere is actually a hypersphere which is also round in the 4th dimension (something a 3d observer can not tell), it would not see much.

So if a 4d being is able to look into a human body, it would do so using a sensory organ which is shifted in the 4th dimension and can not be directly perceived by any observer limited to 3 dimensions. Also, it is only possible under the premise that the bodies of regular 3d humans do not extend into the 4th dimension. If the 4d being looks at another 4d being, it will see its surface in 4d (which might also be interesting), but it won't be able to see inside it.

• It also assumes he has some sort of "4D light" to probe us with, since our light is constrained to 3D. – BlueRaja - Danny Pflughoeft Apr 21 '17 at 2:38
• Do we know that light is constrained to 3D - or is that something we've concluded due to only being able to observe 3D light? the mystery unfolds... – Shadow Apr 21 '17 at 5:42
• @shadow Conservation of energy and the way light spreads leads us to conclude that light remain in our 3d hypersurface. – Taemyr Apr 21 '17 at 8:27
• @Baldrickk, only when not offset in the 4th. Consider that 3d being looking at a 2d, to be looking down on it from higher in the 3rd dimension it does not interact with the same plane in two dimensions so the 2d being is not aware of being observed. – Separatrix Apr 21 '17 at 9:26
• @kingledion four-dimensional space can be quite hard to grasp at first. – Philipp Apr 21 '17 at 13:37

If the 4th dimension is spatial, it really depends on how you want normal people to be 3 dimensional:

You could imagine that every visible thing is from a 4-dimensional POV flat and glued to the 3-dimensional surface of a 4-dimensional world. The surface being the visible world, the 4-dimensional world being the "real world" a shaman is able to see. A disease could be a 4-dimensional being itself, roaming the empty space above the visible surface that latches itself onto people and only manifests itself, when it is itself fully "flat" (flat meaning again 3 dimensional). In this case you would not be able to look inside a human (see their organs), but you could see a disease "coming".

Or you could say that every human is a 4-dimensional being; they just cannot see it, in the same way we cannot see time. We only ever see slices of time we call "now" - In the same way a human might be composed of a lot of slices, maybe all a bit different, but only one slice at a time is visible. A shaman now would be able to see all these slices at once. These slices might be bizarre and some might not be able to survive in the 3 dimensional world, so they are never visible. Every person could have a slice without skin, without flesh, etc. This way a shaman might be able to see the organs of people. An ill-meaning shaman might be able to slap such a slice into existence, that would give you a killing spell.

Another thought: Imagine you are a 2-dimensional being. To the left of you is a circle, to the right is a square. Both will appear to you as just lines assuming you distinguish edges. A 3-dimensional being is able see the difference, you are not. You could imagine that a lot of things in the visible world look the same, but are de facto dramatically different. A shaman might be able to distinguish plants that are poisonous and plants that have healing power that way even though they look exactly the same to anyone else.

Summarizing: The ability to see a fourth dimension is really not that interesting, if everything else is "flat" in three dimensions. You have to define how things look in the 4th dimension, and what it is that normal people cannot see.

• +1 For the point that just because we see in 3D doesn't mean we only exist in 3D. – Lio Elbammalf Apr 21 '17 at 9:35
• It is not so simple to say "just because we see in 3D does not necessarily mean we only exist in 3D". If we were to exist in a 4th spatial dimension (a true one with similar extent to the other 3, not a very flat one), then there would be lots and lots of "side effects" that were utterly impossible to ignore or to overlook. And if there is a very small 4th dimension which by all intents and purposes behaves just like it were not there, then a shaman will gain nothing by "using" it. Also, the comparison with "not seeing time" does not make sense - time is qualitatively different from space. – AnoE Apr 23 '17 at 9:17

The fourth dimensional directions you are referring to are called "Anra" and "Katra" as I recall it from long ago.

(Edit: Turns out my memory somehow added an 'r' to each word. The actual words are apparently "Ana" and "Kata".)

There was a line of thought that 'dimensionality' could exist as an potentially unending sequence of linear ever-increasing series of directions, so to speak. In modern thought, this concept has been largely discarded in favor of the more popular time-as-the-fourth-dimension idea. It can still be found in older science fiction in various places.

The basic idea is that one dimension is like a line. One can only move in two directions. From our observer's position, we shall call it left and right. Anything existing "in" said one-dimensional line would have to be either a point or a dash in nature.

Moving up to two dimensions, we have a plane - left, right, forwards and backwards. This effectively adds two directions (a single axis) to our options. Flatland has been referenced, and I recall another excellent story where a man wrote an AI program emulating a 2D world and what sort of life might exist, only to accidentally managing to communicate with a real inhabitant of a real 2D world - a very well thought out and interesting story it was.

Next up would be three dimensions, a cube or other three dimensional object. This adds yet one more axis to our options: left, right, forwards, backwards, up, and down.

Assigning a spatial direction to the fourth dimension relegates time to being a dimensionless phenomena, perhaps, but such is outside of the scope, so I will leave the matter of time alone. I recall the terms "Anra" and "Katra" being used to describe these directions, yielding left, right, forwards, backwards, up, down, anra, and katra. Enabling a "lower-dimensional" being to observe in such additional "higher-dimensional" directions would potentially have the following effects:

• Objects native to a three dimensional plane appear 'flat' to a sense of perception used to four dimensions, much how a three dimensional native would perceive a two dimensional world or object to be flat. However, a three dimensional native being would not be able to naturally or ordinarily perceive in the Anra or Katra direction, unless the being was also capable of motion, as for a 'flat' being to perceive in an extra higher dimension, they would have to position themselves further along the 4th axis (in either the Anra or Katra direction) in order to see along said axis. Think of this as z-axis order: if two three dimensional beings are at the same fourth dimensional level, they can't see inside of each other, but would only perceive each other normally. One of the beings not only has to be at a different level (z-order), but also has to be able to 'twist' their sensory organs to perceive along the fourth dimensional axis.

For example: a two dimensional native would not be able to see inside another two dimensional native, unless the first was positioned outside of their two dimensional plane. However, if they were able to "lean" out their plane slightly, and had the mental training to put together the panoramic series of two dimensional slices that is all that they would "see" into an understanding of what is inside the second being, then they would be able to comprehend the insides of someone or something else - and likely have a raging headache from the effort to boot. In much the same fashion, a three dimensional native would have to at least be able to move or lean their sensory organs (likely the head, if a human) slightly in either the Anra or Katra direction and then turn their head to align with the opposite direction in order to see inside a fellow being within the same three dimensional space as they are in.

• Perception also assumes some sort of visible coherent medium. Does the sun radiate in 3 or 4 spatial dimensions? Our current experience would say that it only radiates in 3, and that light does not normally penetrate the 4th spatial dimension, unless of course there was a light source which was itself natural to a fourth dimensional plane.

• Other senses are also likely to be affected. To a mind trained to accept fourth dimensional phenomena, it is possible that the other senses may be stimulated from time to time, which could get awkward. Smells from the fourth dimension anyone? Tastes? Hearing, touch, balance, spatial awareness, positional awareness, internal awareness, heat, cold, pain... so many possible receptors that could be affected.

• Let us also consider the effects of cross-dimensional interactions briefly. Since objects natural to a three dimensional space are flat to a four dimensional native, said native could in theory reach over and 'flip' something, or someone over, much like we could flip a piece of paper over. This could have some odd effects: ketchup might taste like some heavenly concoction while other foods taste horrible, someone may suddenly have their hair parted on the opposite side and be right handed instead of left handed, or a poor young woman may suddenly look most ugly and peculiar. (All story references dealing with multiple dimensions, for those who get them.)

Worse, consider this: could a 'flipped' person obtain nourishment from non-flipped foods? Or what if a 'flipped' person or object is now technically composed of anti-matter?

I hope these thoughts are helpful in brainstorming more ideas. For a more complete description of four dimensional spaces, objects, beings, and interactions, please see this excellent (and illustrated) source.

• Holy crap, nice answer. Thank you for this, I will definitely use this. It's also pretty nice that the names are "anra" and "katra", which in itself sounds a bit shaman-y and tribelike. – vrwim Apr 21 '17 at 9:00
• You might find some more inspiration in a short story from Arthur C. Clarke called "Technical Error". In the story, an accident causes a man to shift into the 4th spatial dimension with interesting consequences. en.wikipedia.org/wiki/Technical_Error – Stephen Ruhl Apr 21 '17 at 13:29
• @StephenRuhl I remember reading that one! Thanks for the reference. – nijineko Apr 21 '17 at 22:31
• While I like this answer due to wrapping up a more historic view of what SciFi authors came up with in the past, it suffers from the non-holistic view of spatial dimensions. In this viewpoint, the 3 are somehow "normal" and then you take a step through the 4th or something like that. It's all coming from taking a mind game (i.e., flatland) and then imagining us as 3D observer somehow freeing the flatlanders. Similar to the "aliens from the 4th dimension" - as if that was a place you could travel to/from. It just doesn't work that way. – AnoE Apr 23 '17 at 9:27
• @AnoE You sure you didn't mean "aliens from the 8th dimension"? ;D While it may not be a "place" one could travel to, it is certainly a "direction" one could travel along, towards, or away from. Be it time, or a literal spatial dimension, travel along it displaces you with regard to your proper frame... pun intended. – nijineko Apr 23 '17 at 19:41

If you want him to only see in 4 dimensions I've got an idea:

There is a misconception in some of the other answers that we can see in 3D. What we see is a 2D composite image of 3D Objects at a certain angle. Only our brain can then understand the 2D image based on our experience in 3D space.
If we could see 3D, the well known optical illusions would have no effect on us.

So if your shaman can perceive 4D spatial space, he can visually see 3D images. Since we cannot do this its impossible to imagine how such an image would look.

Here's my idea:

With our 2 eyes we can set a focus point on what we're seeing. This focus point can be shifted in horizontal and vertical directions to sharpen the point of interest.

What if your shaman has a 3rd inner eye that can shift the focus point in depth?
With this it would be possible to look inside objects. Basically the equivalent of an x-ray vision.
Regarding diseases this could be used to identify for example cancers, tumors, broken bones etc. Viral/bacterial infections could be hard to detect. Depends on how well your shaman can focus on a blood cell.

• Welcome to WorldBuilding! Interesting answer. If you have a moment please take the tour and visit the help center to learn more about the site (and earn a badge). Looking forward to your contributions to the site. Have fun! – Secespitus Apr 21 '17 at 9:28
• Good point about being able to only see 2D. In fact you could argue that we cannot even see 2D; technically we only see individual points (the receptive cells in the eye) being stimulated by lines (light ray) passing through a plane(ish) (the eye) etc. etc. It's all fake. ;) – AnoE Apr 23 '17 at 9:22

It can range from more likely to cause a cancer that to detect it to X-ray/MRI equivalent.

To see something, you have to interact with it. We usually detect stuff by seeing, i.e. by detecting light reflected from an object. That means that light first has to interact with the surface of the object.

Now, if 4D beings are watching 3D beings using something like light (propagation of ordinary light is obviously confined to our 3D hyperplane), this will have to interact with entire volume of the object. Usually, we don't have stuff constantly interacting with our insides in that way, so it probably wouldn't be very healthy to do it constantly, just like it isn't very healthy to get too much X-ray scans.

Therefore, our shaman would have to be very careful to take quick peeks at his patients' insides, but this really depends on the nature of interaction of 4D "light" with 3D matter.

He could detect some diseases before they manifest, but this would be limited to (stages of) diseases which visibly change the patient's insides.

• Unless the equivalent of photons for Mr 4D were neutrinos, which are constantly streaming through use with weak interactions anyway - physics.aps.org/story/v10/st21 – Pete Kirkham Apr 21 '17 at 12:23

It depends what you define the fourth dimension to be, but most conventionally the fourth dimension would be time (and it's consistent for a person be able to see in a dimension even if they can't move there).

Alternatively, the shaman might be better able to sense invisible electromagnetic fields around people at a greater distance than most people can.

These fields change depending on disease, emotion (this is one way animals can sense fear), etc.; it is sometimes represented as an "aura." In this case, he might not be able to see inside people in an x-ray vision sense of the phrase "see inside" (though you could choose x-ray vision if you want), but he could see signals emanating from the body which reveal internal activities.

I think you'd also likely find inspiration in Flatland by Edwin A. Abbot. One of many online copies can be found here; it should be public domain by now.

• Your first paragraph isn't terribly helpful: This 4th dimension would be purely spatial, he is not able to travel in time. He can only see in 4 dimensions. – Draco18s no longer trusts SE Apr 20 '17 at 17:37
• Flatland is out of copyright, and available on Project Gutenberg: gutenberg.org/ebooks/97 "I come from Space, or, since you will not understand what Space means, from the Land of Three Dimensions whence I but lately looked down upon your Plane which you call Space forsooth. From that position of advantage I discerned all that you speak of as SOLID (by which you mean "enclosed on four sides"), your houses, your churches, your very chests and safes, yes even your insides and stomachs, all lying open and exposed to my view." – Dewi Morgan Apr 20 '17 at 20:48
• @Draco18s Hence the comment about being able to see without being able to travel there. He is not able to travel in time but he might be able to see other points in time. – WBT Apr 21 '17 at 0:14
• My point was that the asker said that the 4th dimension in this context is spacial. Your first paragraph stats of with "well, it depends on what you define the fourth dimension as..." No it doesn't. It is spacial. End of story. – Draco18s no longer trusts SE Apr 21 '17 at 1:47
• @Draco18s I think time would be seen that way by someone with this knowledge, and that would be consistent with Einstein's view of the universe. – WBT Apr 21 '17 at 11:55

I will be referring to the additional dimension as "4th" (in quotes), because who is there to say which one comes first? - Btw, a hint on titles that are questions, the answer is often "no".

Light?

I have a tribe that is completely isolated from the outside world and there is a shaman that can see in 4 dimensions.

This has the implication that there is some form of radiation that works outside of the traditional 3 dimensions. Something that this shaman is able to perceive.

Inverse-square law - we find examples of it in gravitation and elecromagnetism.

The fact that we measure that the intensity decreases following the inverse of the square of the distance and not to the inverse of the cube of the distance, suggest that the front of the propagation has two dimension (it is a sphere, in ideal conditions).

If we were measure a radiation that decreases by the inverse of the cube of the distance, we would hypothesize that the radiation is somehow escaping the traditional three dimensions.

Note: with the intensity of this radiation falling much faster than the ones we know... if this is what the shaman sees, everything will be very dark. I will assume the perception will be adapted to that.

Now, if this shaman sees in 4 dimensions, it must be by perceiving some radiation that has that property. Evidently this would something that nobody else perceives or knows how to measure, making it an exclusive trait of the shaman.

Time Travel?

This 4th dimension would be purely spatial, he is not able to travel in time. He can only see in 4 dimensions.

I will take this as you saying that the shaman does not control his position on the "4th" dimension. In addition, therefore there is no "4th" dimension travel.

Below is the part where I go technical on you... because, you know, technically correct is the best kind of correct.

The shaman does time travel, like everybody else, tight to the frame of reference of the environment on which the shaman lives... which I would expect marches forward in time...

Also know that we can make space dimension work like time dimensions. As you know, in our everyday lives, we all move inexorably in a single direction in time (to the future, and you cannot go back). Inside a black hole, space moves inexorably in a single direction (to the singularity, and you cannot go back). And you die.

All of that without considering tightly curved dimensions as those proposed in string theory.

I understand that you intend your "4th" dimension to be a flat spatial one. Yet, it is good to consider some alternatives.

Vantage point?

What would the extent of this power be? I assume he can see inside people (using the 4th dimension), but is this correct?

There is a problem with looking inside of people. Drawing parallelism with looking inside of the people of flatland, is that you need a vantage point.

You can see - for example - a drawing on the floor which is two dimensional♪, yet that is only possible because you are above the floor. If you were trying to look at the drawing on the floor from the same height of the floor (imagine you are in a hole such that the eyes are just at floor level) then you will not be able to see the drawing.

♪: If we go by fractal dimensions then the number of dimensions depend on the level of detail we take into account. For my purposes, the floor is flat, because I do not care about corrugations for this example. Ok? Ok.

Because of that, being able to see in more dimension does not always translate into looking inside of things of lower dimensions.

Perception?

Even working around the above, you have another problem... whatever radiation the shaman perceives is one that does not interact with other things. That is, if this radiation only passes through everything, then everything is transparent to it.

One simple tweak would be to say that this fourth dimensional radiation actually interacts with the world in other ways, and there you have your chi / ki / chakra / aura / cosmos / mana / ether that fuels magic. Not everybody needs to be able to perceive it, but everybody would interact with it, intentionally or not.

If you allow this fourth dimensional radiation to have weak low energy interactions with matter, then perceiving it allows to see everything as translucent, semi-transparent, like x-rays.

Why did you just give the shaman a broader perception of the electromagnetic spectrum? Too cliché? Ok.

Projections?

There one more problem left. The problem of perspective!

We perceive projections of our 3D environment. Flat 2D images (that we compose to get depth perception). However, when you perceive a 4D environment, how do you distinguish the two additional dimensions? I mean, the image has two dimensions, we figure out an additional one for our 3D environment, but the shaman has to work out another one besides that.

Our two eyes resolve depth by providing two points of view (and a lot of brainwork: identify common features, triangulate, etc...). In a 3D environment a third eye may add some accuracy or expand the field of view... but if you can get a third eye slightly displaced into the "4th" dimension, then you have a solution for the vantage point and the resolution of the "4th" dimension.

The interesting part of a third eye displaced on the "4th" dimension is that it will not be visible to others (unless they also have fourth dimensional perception) and being displaced, it can be in the same 3D position as another body part.

Perhaps it does not look like an eye; it could be more like third ear. In fact, I do not expect regular eyes to function for fourth dimensional perception, but I digress.

The shaman needs to have some connecting tissue that extends on the "4th" dimension. That is, some way the extra eye(s) stay connected to his body and brain. This implies extra dimensional neurons. In fact, given that we need to brain capacity to process fourth dimensional perception, we could be talking of extra dimensional brain extension.

Magic?

And are there other things he would be able to do that I'm not thinking about? Not much, actually. This fourth dimensional radiation is less effective than electromagnetism. First, because it follows the inverse-cube law, and second because matter interaction with it is not very energetic.

Yet, for people sensitive to it, some things could be possible: 1) the shaman will be able to recognize others with this power, and 2) they may, to some extent, mess with each other. I guess this leads easily to telepathy, although I imagine it more like a sign language in four dimensions. Yet, if you and your opponent have body parts in extra dimensions, you may hit each other in extra dimensions.

While we are in the concept of four-dimensional battles, they are not one person sitting over here and the other over there, and some extra dimensional fireball flying from one to the other… they are more like boxing, with limbs, which nobody else can see.

Then why not weapons, or armor? If these battles are common, there might be battle gear for them. How to build such gear? I do not know. However the shaman got his powers, that is how.

As for your radiation source, I would propose to use the stars, just have it be an extra form of radiation. One that new to science. Which means that our calculation of the energy of stars is wrong. In addition, there you have a solution for dark matter (whatever is in the star that it turns into fourth dimensional radiation).

I want to expand on nijineko's idea of flipping. If we assume that atoms have fourth dimensional symmetry♪, then the rotation conserves chemical bonds, but not their handiness chirality. The flipped versions of chemicals are likely to be able to interact with the same or similar chemical receptors but with different effect. It could be as simple as changing taste or smell, or you could convert L-methamphetamine into D-methamphetamine and become a drug lord.

♪: Because otherwise, their rotation on the "4th" dimension means boom. Edit: Not necessarily. Depending on the 4D shape of atoms we can think about what would it mean for an atom to be rotated... yet, I'm assuming all the fundamental forces we know are constraint to 3D, and thus won't hold the atom, thus boom. Take your artistic license on this.

Flipping a living being is a different case. The problem is not the flip, as they stay internally consistent, but that their chemistry needs to work with the environment. Thankfully, oxygen, CO2 and water are symmetric. Glucose is chiral, yet as far as I know we have no problem consuming the two versions of glucose. However, proteins!

The RNA is able to select proteins with the correct chirality. Yet, what used to be the correct chirality for the organism, once flipped, it no longer is. The flipped organism will have to find sources of the flipped versions of the essential proteins to eat.

Sadly I am unware of studies that discriminate concentration of proteins by chirality in food (separating molecules by chirality is hard as it is). Because of that, I cannot tell you what they will need to eat - yet, I do not expect them to be rare, just let them follow their taste and gut.

What really worries me are microbes. Flipping a virus will create a new strand for which the population may not have defenses; the epidemic could be devastating for a small population.

Another way to think about a 4D space is to think of it as a 1D array of 3D spaces then think of what you can do by making an analogy of a 3D to a 2D space.

(The book Flatland talks of a 3D shape visiting a 2D world, so you have something to begin with there.)

Depending on how exactly you imagine the 3D world existing in the 4D one, your shaman should be able to do something like shift through 4D space until he finds a space that's empty if he wants to walk through a door that's locked, or enter into spaces that are closed.

In that way, it'll be a lot like having access to alternate parallel dimensions, but where the dimensions have a mapping to each other, like in D&D's planes, or spirit-walking, but without leaving his body.

In terms of looking at things, the shaman can't see inside of things unless they have an uneven presence in the 4th dimension. The shape you want to look at is a Klein bottle. So, if different parts of the body had different projections in the 4th D, he'd be able to see them one by one by shifting, and interact with them (e.g. he could set a bone if bones were "bigger" in 4D than the soft tissue).

If you just have the world as one slice of 3D in that 4D array, then, no, there's no way he can see inside, unless light also moves in 4D, but that really makes my brain hurt trying to visualize that.

This Shaman should be able to 'think outside of the box', so to speak.

If he were in tune with a fourth spatial dimension, he may well be in tune with a fifth and sixth, and possibly a seventh...

It some respects, this shaman could detach himself from the scale of his existence, and view all straight paths as curves. His mind will be bent towards a vanishing point that always spirals out of view. He might encounter iterations of his own existence and might be at risk of being caught in an endless cycle of constantly occupying and vacating different versions of himself.

• ...but not an eighth. No sir, never an eighth. That'd be ludicrous! – xDaizu Apr 21 '17 at 7:24

I would assume that since his position in the 4th dimension is static (he cannot move along 4th dimension) then his perspective in said dimension would be anchored to the same position as everyone else. Given the curvature of time/space and his limited perspective - his view would be obfuscated to some degree by a natural "horizon" due to this curvature.

Also like viewing things in a three dimensional space - things could block said view. More immediate things in the view path would block the viewing of further things. Also from his perspective, very large things in the 4th dimension may only be partially seen. If you stand with your nose to the trunk of a tree, it would be impossible to see the leaves at the top. Also, to view a mountain you would have to stand far enough way to see its whole shape against the horizon, but if you were directly over it several miles, it would be difficult to judge its height.

I assume that we are dealing with the 4th dimension as an axis of time as it relates to our 3 dimensional universe.

Normal people - in terms of their understanding of past events and future events can only remember or predict events. Remembering is a biased mental interpretation of the changes in our 3 dimensional universe as perceived by our regular senses. Prediction is taking the information from those remembered events, our current observations, and making intelligent guesses about future events.

With this in mind it would be hard for anyone to understand being able to actively perceive not only how things are now, but also how they were and how they will be all simultaneously in context to their current position on that dimensional axis. In this way I imagine that your character would see people as both young and old, but would have difficulty seeing things clearly about future or past generations. During Winter he may have clear visions of Fall and Spring, but difficulty seeing Summer.

In this way he would be able to know if a woman was pregnant well before conception or he may perceive impending illness prior to symptoms or death. He might be able to see impending battles or previous crimes by simply being where they occured. As long as they do not disappear over that 4th dimensional horizon.

There will be a lot of things your character experiences that can be related to the reader and the rest would simply have to be summed up as being just what it is, an unrelated experience for those unable to perceive the 4th dimension as well.

Also, I dont think your character would see his own death. It would be impossible from his perspective. You cannot look back at yourself without a reflective surface and to see anything of his own future or past would require some sort of a 4th dimensional reflective surface.

Also keep in mind that constantly viewing the future would be maddening. Your ability to see things before they happened would put the future in a constant state of flux. Making active decisions to change the perceived future would lead to even larger distortion. It would be like throwing stones in a reflective pool, the larger the stone the more the image ripples and changes. Throw too many stones and the image is indecipherable.

• The 4th dimension was mentioned in a comment to be spacial. "I'm not an expert on this, but I saw a video on how the 3rd dimension exists for 2-dimensional creatures, they are just not able to see it. Also, I think about it in terms of those renderings of a tesseract, a 4-dimensional cube" – vrwim yesterday – user25818 Apr 21 '17 at 19:38

I don't think we can really see 2D objects or even see "inside them". If we look at the circle drawn at the paper, the only reason we can see it is that there are molecules of ink on that paper. And the molecules are 3D. So the answer to the question would be no, you'd not be able to see inside.