What is a dimension? How many dimensions are there? How many dimensions do humans exist within?
547162
Dimension are ways you can define things. \nThe ones that we can measure are width, length, height and times. For example a box 5*5*5 in width length and height was there at a specific time. \nThe other dimensions that exist are incomprehensible to us but Physicist still use them in calculations.
332409
Our universe has 4 dimensions: up/down, back/forth, left/right, and time. According to well established theoretical physics, it is likely that our universe has more than 4 dimensions and could have as many as 11 (according to String Theory). As to why we can't see them, the leading explanation is that, at the beginning of the universe, all dimensions were curled up, but that at the time of the "big bang", 3 of the spacial dimensions and time unfurled, creating the universe we know to day.  The other 7 dimensions currently remain curled up in space where we cannot see them.
1095974
this is sort of trival, dimensions can be thought of as derivatives, and you can take a formula and make any number of derivatives of the original derivatives and still end up with a line that bends, indicating no limit to the number of dimensions we can really conceive..   \nModern string theory is a bunch of hoo haa,   such a sub-atomic idea makes no sense, the reality we know could not have order if there were "strings".  "strings" have no way of organizing themselves into different sub-atomic particles, the universe would just be a bunch of "strings"
191182
I am not sure about life more than 4 dimensions. Why? Is this funny for you?
236155
What do you mean by dimensions? I don't understand the question you are asking.\n\nFor information you can visit here http://www.himalayanacademy.com/resources/books/hbh/hbh_ch-6.html\n\nIt is a good site about Hinduism as well as http://www.himalayanacademy.com
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).
322523
The fact that we can observe only four dimensions seems obvious, but that doesn't mean that there are not more.\n\nAs an example: the sea as seen from an airplane looks pretty flat and seems to have two dimensions only. But as the airplane looses height, the waves can be distinguished and we see that the see surface in reality is three-dimensional.\n\nThe same might be true for the universe: it could be that more dimensions are present, but we don't see them as they are tiny, too small to observe from our human scale.\n\nTheories that suppose the existences of more dimensions have been proposed.\n \nThey were invented because we are not so happy about the models we use now. For instance, there are four forces in nature. Three of them -electromagnetism, the strong nuclear force and the weak nuclear force- have been combined into one force that has three manifestations at our energy scale.\n \nTo model the fourth force -gravity- Einstein invented general relativity.\n\nThe problem is that both theories are incompatible. Calculations done with them in the region where they overlap, notably when we go back in time to the Big Bang, give different results.\n\nThat is ...embarrassing.\n\nSome of the newer theories, like superstring and M-theory, try to overcome these problems. The price to pay is the assumption of extra dimensions.
911710
This is a very difficult concept and you probably won't get a great answer for it.  First off, this is only speculation - there is not a shred of evidence that there are 11 physical dimensions.  We can only claim 3 (time is considered the 4th dimension, because you need all 4 to describe to fully describe an event - for example, if you throw a rock in the air, if you want to know everything about where it lands you have to know the longitude, latitude, altitude and time with regards to a reference point).\n\n11 physical dimensions spring from string theory, which postulates that everything including time and space and matter and force are made up of vibrating "strings", either open ended or looped like rubber bands.  These strings are inconceivably tiny - if an electron were the size of the solar system out to Jupiter's orbit, filling in the volume, the string would be about the size of a granny apple.  It's thought that physical dimension 4-11 curled in on themselves at the Big Bang, and are only relevant on the same scales as the strings themselves - the other 3 expanded to fill the universe that we know today.\n\nOne way to image it is to imagine the Earth as a perfect sphere, without mountains or valleys, no hills, no riverbanks, no sidewalks, just a perfect, absolutely perfect sphere.  Now imagine an ant walking on the sphere.  The Earth is so fricken huge compared to the ant that the ant will only think there are two dimensions, x and y (assume that the ant has no self-awareness, and didn't realize he himself is above the x-y plane).  In reality, the Earth is a sphere, with a z component, but the ant will never know that.  The same, in reverse, could be true for the other 7 dimensions - they are so small we can never comprehend them.\n\nUnfortunately, with today's physics, that also means we can never confirm or deny their existence.  Without empirical proof, string theory is just beautiful mathematics, without a shred of proof.
747739
Theories such as string theory predict that the space we live in has in fact 10 dimensions, but that the universe measured along these additional dimensions is subatomic in size. As a result, we perceive only the three spatial dimensions that have macroscopic size.
255954
I will take a shot at it.\n\nWe are all very familiar with 3 dimensional space, up down, left right, forward backward. To describe the location of an object in space we have to use those three dimensions. BUT. Nothing is actually fixed in space. Everything is moving. So in order to describe the location of an object in space you must also describe at what time that object was at that location or will be at that location. That is why time is called the 4th dimension. \n\nNow here is the really bizaar part. Some scientists think there are more than 4 dimensions. Some propose 10 dimensions and some 26 dimensions. It is called string theory and it is all over my head.
122257
We live and experience four dimensions. three of space, forward and back, left to right and up and down. we also experience one dimension of time, forward time. the other 7 dimensions are coiled into tiny doughnut like shapes the best model do describe this is the callabai-yau model.\n\nI'm sure you were hoping for a bit more then "they are to tiny to experience" but that is how it is.
1155114
We live in a universe of observable/measurable quantities. For example, length, width, height, time, mass, etc.  If different quantities cannot be expressed in terms of the other quantities, they are "orthogonal" to each other - you can think of them as being separate dimensions. For example, on an X-Y graph, the x-dimension is independent of the y-dimension because you cannot express a "y" quantity as a combination of "x" quantities. \n\nSpace has 3 dimensions (length, width, height); time is a fourth dimension that cannot be expressed in terms of the other three.\n\nAn n-dimensional space is just a space that is characterized by "n" orthogonal quantities - quantities that cannot be expressed in terms of each other. To completely define the space/universe, you only need to specify "n" values - any more than that would be superfluous because the other values would be some combination of the other orthogonal quantities.\n\nExample: if we lived in a 4-dimensional space characterized by length, width, height, and time, all you need to do is specify those 4 quantities to uniquely determine any point in that space.  If we add another quantity (such as temperature) that cannot be expressed in terms of the other 4, we now have a 5-dimensional space that requires 5 quantities to be specified.
1134654
We observe four dimensions everyday, three spatial and time.\nTime is called a dimension because it makes mathematical sense to do so. \nBut...theories such as string theory predict that the space we live in has in fact many more dimensions (frequently 10, 11 or 26), but that the universe measured along these additional dimensions is subatomic in size. As a result, we perceive only the three spatial dimensions that have macroscopic size.\n\nThis is not so strange as it sounds, which I'll show with an example. Imagine you are in an airplane, flying over sea. Seen from a height, the sea looks flat, two-dimensional. But when the plane looses height we start to perceive the waves, that move in a third direction we could see before.\n\nThe universe could be the same. Four macroscopic dimensions and a few more, hidden ones. We can only perceive them for instance, by the small effects their existence might have on subatomic particles.\n\nSerious enough?\nThe reference is a general article on the mathematical notion of dimensions, that contains links.
1151026
According to classical physics 3: length, wideth and depth.\nModern physics add to that a fourth dimension - time.\nThose we now for certain exist. But there could be more (as much as 10 or 11 according to superstring theory).
588539
I am assuming this question comes from some thought on the 10-11 dimensions needed by string theory. In this occasion these dimensions are not noticable and have been added because they are needed to make the equations work. In three dimensions and time you only have four variables to work with. But now many physicists have noticed that if you increase our dimennsions to 7,8,9,10,11 it gives more mathematical flexibility and enables us to make equations that can unify gravity with the quantum world. Now for what is the seventh dimension, the first three dimensions are the normal spacial dimensions, up/down, right/left, forward/back. There is also a time dimension sometimes noted as the fourth. Then string theory says there should be another 7 dimensions. Where these would be and why we cant see them is still up for debate but current though is that they are extremely small crumpled up dimensions that we cant notice because there small size makes them have a minimal effect on forces and measurements. I would reccomend reading David Greene's books if you are still intersted in the ideas of string theory and such.
119428
As the previous responder said, Einstein only knew of the existence of 4 dimensions. String theory accounts for the addition of other dimensions, but 10 is not universally accepted as the number of dimensions there are. String theory proposes 26 dimensions, while M-theory, the latest superstring theory to come out, created by Ed Witen, uses 11, and several other superstring theories use 10.
106587
There are in fact quite a lot of secrets of the world, I'll list a few:\n1. The world might be stranger than anyone could imagine.\n2. There could be 11 dimension in the world, 3 dimensions of lenght, width, and height, one dimension of time, and 7 curled up dimensions to small to be seen.\n\nImagine if you're holding a long stick real far, it would look like a 1 dimensional object, but if you get closer, you notice that it has 3 dimensions.  That's what they think about the 7 curled up dimensions, they're billions of billions of times smaller than an atom!\n\n3. There are at least 7*10^22 stars in the universe, that's 7 with 22 stars.\n\n4. There might be several parallel universes, some other universes could be 1mm beside you!\n\n5. Scientists now think that gravity may not be so weak after all, but a lot of gravity escapes into higher dimensions. \n\nThis intrigues an amazing possibility.  Since humans cannot see, hear, feel, smell, or taste the other universes, they think that they can communicate with other worlds using gravity.  For example, gravity phones might be developed in the future.\n\n6. Everything in the universes(all matter, forces, etc.) might be made up of tiny strands of vabrating energy called strings.  Strings are nearly 10^-34m small, that's 0.0000000000000000000000000000000001 metres small!\n\nThere are lots of other secrets, but these come to my mind first.