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I'm thinking in terms of: We three dimensional humans can draw a square on a paper--that is the squares universe. It could grow bigger if we attached more papers and drew more squares. If it were possible for a 4 spatial Dimensional element/living object with cognitive abilities to have contact with our world, how could it directly affect our individual lives? What are the limits to what it could do?

My best guess would be uninterrupted freedom to arrive at every time period; since the theory of relativity teaches that only objects without mass can travel at the speed of light and above. Mass is the measurement of atoms an object contains, so since we can only measure 3D atoms, their mass would likely not apply here.

EDIT: By 4-D organism, I meant spatial dimensions, not our perceived four dimensions of x,y,z + time. This organism likely has organs and physical features modelling R4. Tesseracts are commonplace "boxes" in the universe this organism comes from, among other regular objects implementing that interface. Let's say it gains access to our world through its civilisation's version of 3D glasses or perhaps telekinesis, it can see or communicate with a few spiritually advanced people who can perform astral travel and other metaphysical exercises. Furthermore, if it were probable for it to have a shadow, would its resulting image be some sort of hologram of the observer?

EDIT2: Someone in the comments mentioned something about this organism having mass just like us. To elucidate on my earlier point, what we know as mass is the measurement of particles. Now, we measure these particles in terms of electrons, protons and neutrons. Let's say there are other particles which we "overlook" because of our limitations. In our universe, this organism's mass will be unable to be measured in grams (which leads to my earlier conclusion that it has no mass here, hence can move at lightning speed). I hope this makes it clearer.

Mmayboy
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    The book Flatland would be a nice read – Ovi Jan 22 '17 at 22:05
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    Ovi's recommendation is a good one. That being said, just having an organism in 4 dimensions isn't enough. You have to capture what its capabilities are. For example, we humans are quite often considered to be 4 dimensional beings: 3 spatial 1 temporal. It's called the perdurable view. Also, we often say "the 4th dimension is time" but that is not the only possible 4th dimension, its just one that is popularly called the 4th dimension. It would be reasonable for your creature to have 4 spatial dimensions (and probably 1 temporal dimension). – Cort Ammon Jan 22 '17 at 22:21
  • I have watched this video that summarized its plot. https://www.youtube.com/watch?v=C6kn6nXMWF0. I'm afraid it does not answer my question – Mmayboy Jan 22 '17 at 22:22
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    Well, in 4D space every 3D object looks like an open box so your being would be able to easily reach inside any closed space (including inside people) – Samwise Jan 22 '17 at 22:27
  • Time is usually considered the fourth dimension specifically because of Special and General Relativity linking space and time into a 4-dimensional system. I'd steer clear of that, because the rules for moving through it are well understood (if you have a physics degree with GR specialisation) and it gets tricky with mass and energy densities. – aphenine Jan 22 '17 at 22:47
  • Also, in terms of a 4th spatial dimension, you can always decompose any higher dimensional space into a 1D array of lower dimensional spaces. So you can imagine a 4D space as a 1D array of 3D spaces, which someone can move through. – aphenine Jan 22 '17 at 22:48
  • Why the downvote? It s an interesting question – Fred Jan 23 '17 at 01:35
  • I question the veracity of a 4D being being able to show up anywhere in time relative to the 3D spacial volume we inhabit, but it could certainly show up in any location without having to travel through all the intervening space (i.e. teleport). – Draco18s no longer trusts SE Jan 23 '17 at 02:36
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    Since there are no limitations of specifics given on what is so '4D' about this 4D creature, this question is 'too broad.' There are so many ways to imagine what 4D means, and then given a definition of 4D, so many ways to imagine what might happen. – kingledion Jan 23 '17 at 02:51
  • @kingledion Please see edit. – Mmayboy Jan 23 '17 at 11:11
  • I find the very concept of the 3D cross-section of a 4D object having no 3D mass suspect. Perhaps a reality check question on that first? That would give room to adjust this question, which is currently difficult to answer without saying that that's not how it works. – Brythan Jan 23 '17 at 12:49
  • @Brythan The question isn't about its cross-section. In my edit, I made mention of its shadow being visible in your terms of being cross-sectioned. I believe it should be able to exert a certain level of influence even if we couldn't comprehend it any more than as a phenomena. Except maybe people that can astral project into various other dimensions. – Mmayboy Jan 23 '17 at 14:58
  • Look at Charles Stross's Laundry Files for the interactions of higher dimensional beings with our world, he has some interesting thoughts. – Ash Jul 17 '17 at 11:33

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It wouldn't really be able to do much at all.

Firstly, the 4D being would likely have mass just as regular beings do. Increasing the dimensionality of space is not known to eliminate the concept of mass. Secondly, if the 4D being is composed of particles approximately the size of the particles we know of, the probability of a particular 4D particle being precisely in our 3D plane of existence is very, very small (on the order of $10^{-33}$ for a reasonably sized 4D being trying to interact with out world). Because all forces we know of except gravity are confined to our 3D plane of existence according to string theory, a particle in the 4D being would have to be precisely in line with our 3D plane to interact with anything in it, a virtual impossibility. (Interestingly enough, this also makes the being invisible to us and us mostly invisible to the being.) Therefore, the only effective way for the being to alter our 3D plane would be through gravity, because it is thought to permeate all dimensions, not just our three.

However, gravity is extremely weak, so weak that it takes a mass the size of the planet Earth to hold us down, whereas a magnet, for example, can easily lift something tens or even hundreds of times its mass, countering the action of the entire Earth. This 4D being would then have to be advanced enough to manipulate something a sizable fraction of the mass of the Earth in order to produce a powerful enough effect. Theoretically, with a much smaller mass, the being could alter the orbit of an asteroid or comet slightly over many years so that it would collide with the Earth, but that's about all it would be able to do. It would be very unlikely, if not impossible, that it could affect our individual lives.

praosylen
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  • Sorry for the late reply. I was presuming these modalities are ignored and this organism--obviously having higher senses--could perceive us as grains or lesser beings, but only a few of us could feel its presence, in what ways could it behave in our realm? To which I believe you replied in the field of gravity. Hypothetically, is there a way it could exert this gravity on inanimate or animate objects in our realm? I'm curious as to whether we could feel additional gravitational force to that being exerted on us by the earth. Would this organism spawn more potency if it were a 5-D creature? – Mmayboy Jan 26 '17 at 10:59
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    Exerting a gravitational force on ordinary 3D beings would be difficult for a not-very-advanced 4D being, but with 4D advanced technology, the being could likely manage that through the manipulation of very small, very dense masses. We would definitely be able to feel any gravitational force powerful enough to influence ordinary earthly events, but I would imagine most would only assume that they were ill. The being, if it could learn a human language, could also use gravitational forces to communicate by (for instance) causing drops of water to fall into letter shapes, or other similar means. – praosylen Jan 26 '17 at 20:14
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    A clarification: placing these masses close to 3D objects would necessarily create a gravitational force pulling the objects closer to the point "below" the 4D mass. And a 5D creature may or may not have advantages over a 4D one -- I don't know whether the "density" of matter would increase with dimensionality or remain constant. In my opinion, though, a 5D being sounds more "exotic" and less clichéd than a 4D one. Final note: assuming the 4D being is indeed that advanced, it could do a lot more with gravity than I suggested in my answer (e.g. redirecting nuclear missiles, etc.). – praosylen Jan 26 '17 at 20:27
  • Your last comment should be appended to the answer as it answers the question more than everything else there. – Mmayboy Jan 27 '17 at 22:53
  • @AidanF.Pierce, I have an idea that sounds like it might have something to do with this topic. Could something exist in another dimension or reality but exert its effects in our reality? I'm trying to create a sphere of gravity without a physical mass. Could the physical object be "elsewhere" but it's gravity be felt "here"? – Len Feb 06 '18 at 05:19