What does a four dimensional object really look like?
110094
Yes, definitely multiple postings... \n\nwell... a fourth dimension is time... so anything that changes over time is a fourth dimensional object. But that isn't what you are really asking.\n\nWe can only perceive four dimensions with our senses, so perceiving it is difficult. To us it would look as if it were a regular three-dimensional object, perhaps changing over time in some subtle way. Jack L. Chalker did a good job of describing such a structure in his "Quintarra Marathon" books. This is similar in idea to how you would describe a three-dimensional object such as a pencil to a person living in a two-dimensional world, at best they could only see a cross-section of the pencil, or if the world they were living on were curved they would see multiple cross-sections and not realize they were the same object (put a pencil through a folded piece of paper).\n\nIf you are looking for a way to visualize it to help with problem solving I recommend thinking about it in terms of computer arrays, or a group of three dimensional objects, each can be looked at seperately.\n\nGood luck with your conundrum :-)
1101802
Refering to the four dimensions, I assume you mean three spatial dimensions, and one of time.  This is correct.\n\nString Theory, which is a possible candidate for the Ultimate Theory of the Universe, demands that there actually be ten spatical dimensions!  Four spatial dimensions is impossible for our brains to comprehend and picture let alone ten.  \n\nYou might be wondering why we aren't aware of the extra seven dimensions if they do exist.  The reason: they are curled.  Let me explain what that means.\n\nImagine looking at a clothesline.  From afar, it looks like the clothesline only has two dimenions: you can either go left or right.  Now when you move closer, you are able to see the third dimension of the line, which would allow say an ant to crawl around (up and down) as well as left and right.  You couldn't see that dimension from afar because it is curled up and very small.\n\nThis is the same principle with the other seven dimensions.  They are curled up, and can only be seen if we were able to probe to a small enough distance.  This distance is actually a millionth of a billionth of a billionth of a billionth of a centimeter!  That is way too small for us to be able to see today, and probably for quite some time.\n\nThere are some tricks though for getting a feel for 4 dimensions.  You consider an example that relates 2-D to 3-D, and then apply that to relating 3-D to 4-D.\n\nFor example: imagine a table top is a 2-D Universe, and on that Universe lives a being shaped like a square.  If you were above this 2-D plane and were to talk to the square, he would hear you, but not see you.  If you decided to show him a sphere, would have to pass the sphere through his 2-D Universe.  The only problem is, he wouldn't see the 3-D sphere.  He would see at first a point, followed by a succession of circles that kept growing until you reached the mid-point of the sphere, which would be the biggest circle.  Then as you continued to move the sphere through the plane, he would see a succession of circles that got smaller until he saw a point, and then nothing.  The point is, he would only see cross sections of the sphere, which are circles.  \n\nNow apply that to our Universe.  If a being were in the fourth dimension and tried to pass a hypersphere (a 4-D sphere) through our Universe, we would only be able to see cross sections of that hypersphere.  What would we see?  We would see a succession of 3-D spheres that kept growing, reached the largest size, and then shrunk back down to nothing!  So, the cross section of a 4-D sphere is a 3-D sphere.\n\nHere is another really cool example.  Going back to the square being, let's say he had a safe.  His safe would have four walls, in which one of the walls would act as a door.  It would basically be a hollow square.  Since there are four walls, a 2-D being in that Universe would have no chance at getting any money out of the safe without opening the door.  However, you being in the third dimension above the 2-D plane, could simply reach in and grab the money coming from the top. It would be a complete magic trick to the square.\n\nSimilarily, a 4-D being could reach in our 3-D safe reaching in from the fourth dimension, and take our money without opening the door!\n\nHope that helps.
182923
Yes. But, it's just a personal assumption, although it is an assumption held by the majority of people.\nThe most well known 4 dimensions are best described as width, length, depth and time. The order you list them does not matter, and there could be more - but humans have difficulty relating to more than these 4 (apart from imagining what they are like). The easist way to explain what a dimension is, is to say that you need all 4 to describe where an object is located.... eg, as a real world example I could tell you that I am located in a building at a certain cross-street (=length+width), a certain floor (=height) and at a certain time. You need all 4 dimensional descriptions to find me.\nTime is definitely the hardest of the 4 to properly comprehend. It's hard to think of time as being similar to length or width or height. It is special for sure to us humans, but that is only because our brain operates as a function of time... which means we are fooled into the perception that time 'moves'. Time does not move, no more than 'length' moves. You mind changes with time, just like the slope of a hill changes with height, but there is nothing to suggest that there is a certain special moment called 'now' that is somehow different to 'the future' or 'the past'. Read any scientific article on the topic if you really want to find out more about this 'special' dimension (see source link for an excellent read).
730887
I have a pair of those interesting deep-dish-shaped double-domed parabolic mirrors from Edmund Scientific, the top one sits upside-down on the bottom one, and the top one has a hole in it.  So when you put something inside it, and move away at an angle, an image of the object appears to be sitting above the top dish.  I ask people, "Hand me that little pink pig sitting on that dish".  They see it, reach for it, pick up nothing, reach for it again, and see their fingers apparently pass right through a solid object.\n\nWhat is the reality there?  My eyes tell me there's a little pink plastic pig sitting on the top of that dish.  Yet when I try to pick it up, my fingers pass right through it.  But then I distort the mirrors a little, and the pig blurs in an odd way that lets me see that he's actually a reflected image from inside the unit.  And if I understand optics sufficiently, I understand that it is possible, with certain arrangments of parabolic mirrors, to erect "real" images (versus the more common "virtual" images that we see in most mirrors and lens) of objects, and even design and build versions of my own, with the effects and capabilities fully determinable in advance.  That's reality.\n\nReality does exist.  Granted, we have a limited and distorted view of it due to the limitations of our senses, but it does exist.  For example, this desk in front of me seems like a solid object.  But in truth, my view of it is limited by the fact that my eyes are not able to resolve the electrons orbiting the nuclei that make up the desk, and that the vast majority of this desk is vacuum, therefore the fact that, when I touch this supposedly-solid desk, what's actually happening is that the electrostatic field generated by the electrons of the desk are exerting a force against the electrostatic field of the electrons orbiting the nuclei of the atoms making up my fingers.  There are no "solids" touching anything, just fields pushing against each other the way 2 magnets can push against each other.\n\nTo me it looks like reality begins immediately outside your eyes.  All is reality.  The only place it ends is inside your head, when you misinterpret what your limited senses tell you.
919171
To answer this question, you need to know the shape that these points make.  Are they on a line? or are they some two-dimensional shape?
830000
Imagine you put a yardstick on the floor facing exactly north and south. That would be the first dimension. Moreover, north and south anywhere in the room would also be the  first dimension. Now, put a second yardstick down on top of the first but facing east and west so they look like a big plus sign. That would be the second dimension. Notice, and this is very important, the two yardsticks are at right angles to each other - 90 degrees. All dimensions must be at right angles to each other. Now, put a third yardstick with the other two but remember, it must be at right angles to BOTH of them. There is only one way it can be oriented - in the center of the plus sign standing straight up and down. This is the third dimension. Take time either to try it or to actually build what I have just described using rulers or pencils and satisfy yourself that all three dimensions are actually 90 degrees to each other. Now go one step further. Can you add another yardstick (or pencil) which is at right angles to ALL THREE of the others? Before you exprience brain burnout I'll answer that for you. No - although you might like to try. You can't do it because we live in three dimensional space. However, many scientists feel that there is a fourth dimension although it can't be drawn or built - just imagined. Remember, it would have to be at right angles to each of the three spatial dimensions. Many scientists think the fourth dimension is time. No matter how we turn or in what direction we face, time is always like a yardstick facing behind us into the past and forward into the future. Remember, this is just a theory, an idea supported by many facts and observations but one which has not yet been proven. Are there more than four dimensions? Possibly. In math we can have as many dimensions as we want but math is strictly a mental exercise. The fact that math so nearly predicts what the actual universe is like is a tribute to the perfection of the universe.
934477
Why are you asking this again?  I just answered you.\n\nAgain:\nThere are "levels" to dimensioning.\n\nThe major dimensions are the overall height, width, depth of the whole object. \n\nThe next level down will sub-divide that major dimension to describe sub-components.\n\nAs example: Consider a house plan. \n* From one extreme side to the other extreme side is a MAJOR dimension (the overall width). \n* In between those extreme outer wall edges are interior walls that need to be located as well. So the next layer of dimensions (MINOR) still goes from one side to the other but pulls lots of dimensions from lots of walls. \n* Also, there are porches, corners for inset windows, etc Another MINOR level picks up those points.\n* And so on.\n\nIn your 3D drawing: \n* you only have 6 MAJOR dimensions to a cube shape anyway. Depending on how you rotate the drawing object, you see 3 of them and 3 will be hidden (back side).
534038
That question is hard! Nobody has ever been there. Or maybe we all are always there. I don't know. But the different dimensions tell you a position and it is getting more exact with every dimension:\n1D: where x is\n2D: where x and y are\n3D: where x and y and z are\n4D: where x and y and z are and when they are there\n5D: I don't know, but you could think of something that would give a more exact description, such as (this is just an idea that went through my head, not anything from a scientist!):\n5D: where x and y and z are and when they are there and how they are there and then\nDo I make sense? Don't hate me if I don't!
789597
Mathematically n dimensions can be described but our experience is only 3 dimensions So the properties of fourth dimensonal shapes can be mathematically described and a fourth dimensional quantity that is in units^4 can also be calculated\n\nThis is an argument that the 4th dimension is time. That cannot be the case when one considers the properties in 3d are L, L, and L One would immediately envisage that the 4th, 5th .... nth dimensions would also all be L\n\nA tesseract, the 4 dimensional equivalent to the 2 dimensional square and 3 dimensional cube, is not a time related object at all. Its 3D projection can be build and the objects equivalent of a 2D shadow seen easily. In 4-space it occupies L^4 units^4. Wikepedia has some interesting information and projections of a tesseract
23789
technically, a klein bottle is only realizable in 4 dimensions, so you cannot make a complete physical representation of one in three-dimensional space.  \n\nit can, however be projectively mapped to three dimensions through a mathematical procedure called an immersion, just like a three dimensional object can be mapped to two dimensions when you take a photograph of it.  this three-dimensional projection is what you can see if you do a google image search for 'klein bottle', and physical models can be made.  it's a bit like a three-dimensional moebius strip.  however, these are not a true representation of the object.
406580
I'd say that your logic sounds good, but I don't know much about 4D.  All I know is that the theoretical "shadow" of a 4D object would be a 3D object (the shadow of a 2D think is 1D, and the shadow of a 3D thing is 2D, so the logic goes from there to 4D).\n\nOne thing is, if the video frames thing is true, you wouldn't be able to comprehend it all.  (I know this is random and not really related to what you are asking).  It is an interesting theory, though.
598308
As a 4D cube can be expressed mathmatically, an algorithm can be written that will display it on a 2 dimensional computer screen.  Displaying the figure is one thing, interpreting and understanding a 4D figure displayed on a 2D screen with a brain that can only comprehend 3 dimensions is something else entirely.
691753
maybe a hexagonal prism http://en.wikipedia.org/wiki/Hexagonal_prism http://en.wikipedia.org/wiki/Prism_%28geometry%29
1012182
A four-dimensional hypercube.   If you consider time as a fourth dimension, a tesseract would be a cube which has sides of, say 1 metre, suddenly appears, exists for the time equivalent of 1 metre, that's the time it takes light to travel 1 metre, which is 1/ 300 000 000  second,then vanishes.
1044107
None.  That is the point.  If they exist is not proved, and hypothetical tests to see if they exist are flawed.  \n\nOn your other question of visualizing multiple dimensions, I have a few hints.  Have you read Flatland yet?  Start there, its good, and not overly mathematical.  Multiple dimensions can mean different things to different scientists.  We use them all the time for their mathematical properties.  But mathematics is just a description, the real world is something observable.  In terms of observation, you would not be able to detect a separate dimension by any means pedantic.  We may be able to prove that physical space has more than three dimensions, but that does not mean that those other dimensions are physical space.  Just like time.  Some particle interactions appear to go backward in time briefly.  What if there is more than one time dimension?  \n\nSo the classic three dimensional physical picture of multiple dimensions will always be flawed by the observers expectation of the properties of the unseen dimension.  Which is why we describe those dimensions using 'imaginary' constructions.  Hope this helps a bit.
269761
Each 2D image shows some crosse section of the subject, let's say a brain.\n\nSay the brain is 20 centimetes deep. If you obtain one image for each centimeter of depth, print them out, cut out the brain shape, and then place them all so they are standing vertically next to one another and in order you will have a very good idea of what that brain looks like in 3D.\n\nThe more pictures you take the more accurate your model will be. With enough pictures you can easily guess at what fills the empty space between them and make a complete and accurate 3D model.
799446
electrons can't line up in a plane they wouldn't all fit... unless it was like a big 747... or one of those military airbus things... and by 3d do you mean 2 spacial dimentions + time or 3 spacial dimensions? cause we already live with 3 spacial dmension (4 including time)