Why do so many people think that time is the fourth dimension?
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You've asked a very good question. When physicists refer to time as the fourth dimension, they don't mean that time is another spatial dimension like the 3 spatial dimension of up/down, right/left, and forwards/backwards.\n\nHowever, it turns out that time and space are intricately linked that Einstein coined the term "spacetime" in his Theory of Special and General Relativity. Also, time is not simply a measure of passage of events, because time and space are NOT absolute in the sense that time is flowing at the same rate everywhere to everyone, or that distance can be mesaured identically the same everywhere to everyone. Einstein discovered that depending on how fast you're moving, time, distance, mass, energy are all affected. This is because the speed of light is invariant no matter where you are and how fast you're moving, and nothing can travel faster than light.\n\nIn addition, Einstein discovered that spacetime forms a 4-dimensional surface that can be warped by the presence of matter and energy. This warping of spacetime fabric is what gravity is. So when you throw an apple up in the air and it falls back down to Earth, you are witnessing the apple following the shortest path possible along the warped spacetime 4-d manifold caused by the presence of the mass of the Earth.
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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.
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The idea that time is another dimension is not currently in favor, so if you were to take a contemporary view, time isnt a dimension at all.  Thus, a 2 dimensional object moving through time would be just that- a changable 2D object.  Time is a degree of freedom for motion, physical and chemical reactions, etc, but not (again, currently thought) to be a dimension equivalent to the three we exist in (or the 13 or so that are sub-microscopic).
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The 4th dimension is time and the 5th dimension is quantum probability, where every possibility occurs in an infinite number of "parallel universes."
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Some Philosophers say that thought exists simultaneosly on different dimensional layers, like existences can also exist simultaneously. \nIt could explain time travel, warps where people sometimes slip through, being able to foresee, dream or imagine things.\nThey also say that we cannot think up anything that has not already been thought up.\nWe also only use a minute portion of our brain...less than 5%..one day we will learn how to use the rest and then be able to tap into all the thoughts that are surrounding us.\nI feel that thoughts are drawn from another dimension that is around us and part of us all the time, and we simply send it back.\nWe are part of a huge cosmos that we know so little about.
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The universe that we live in has only three spatial dimensions. We are limited to length, width, and height, and we can only travel along three perpendicular paths. This page attempts to explain the properties of a hypothetical universe with a spatial fourth dimension. While people generally call time the 4th dimension in the universe we live in, time will be the 5th dimension in my hypothetical universe. \n\nMany fascinating possibilities exist when a spatial fourth dimension is present. Several types of wheels are possible, very complex machines can be built, and many more shapes are possible. Objects can pass by each other more easily, but they are harder to break into multiple pieces. Energy reduces much faster with distance than in the 3rd dimension, so both light and sound are weaker. Much more things can be compacted into a small space, but its much easier to get lost. In this page, I will explore these and many other interesting properties of the fourth dimension.
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it is a conception of Space, made not only of 3 dimension, but 4. The fourth is Time. The relativity equations are made in this 4 dimension Space-time "Space".\nThe idea was not from Einstein, but he was the one who hd spread it.
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yes time is the 4th dimension and it is not constant time slows when speed increases eg if you could fly at or near the speed of light time would slow down for the pilots relative to people staying on earth
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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
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Kemmy's answer is actually a very good answer.  It seems simple, but it's quite insightful.  Time is referred to as a 4th dimension (along with the three spatial dimensions) because you when you represent physical situations using geometric coordinates (x,y,z,t), you can treat time 't' in the same way as you treat the spatial coordinates x,y and z.  In fact, many physical laws such as special relativity are significantly simplified if you treat time in the same way as the spatial dimensions.\n\nHowever time is obviously very different in some ways:\n\n1. Units are different (seconds instead of meters, feet, cm)\n2. You can only move in one direction along the time axis, whereas you can move backwards and forwards along the spatial dimensions.\n3. Entropy (disorder) increases only increases with time, but seems to have no relationship with space.
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I believe yes.. It makes sense, You see all of these dimensions are just directions. If you say that the four dimensions are represented by X,Y,Z,T these are merely directions of dimensions then all of those are travellable (meaning you can travel in those directions). You can go to left & Right (X), You can go Forward & Backward (Y), you can go Up or Down (Z). The questions now is how do you travel through time. According to Albert Einstein if there is anything that can go faster than the speed of light then it will be possible to travel through time. It is actually true becuase our mind can go faster that speed of light that whay our mind can travel through time, sometimes we remember things in our past that the way our mind travels.
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"The mathematician Hermann Minkowski, and ultimately Einstein as well, advocated thinking about time as another dimension of the universe - the fourth dimension - in some ways quite similar to the three spatial dimensions in which we find ourselves immersed. Although it sounds abstract, the notion of time as a dimension is actually concrete. When we want to meet someone, we tell them where 'in space' we will expect to see them - for instance, the 9th floor of the building on the corner of 53rd Street and 7th Avenue. There are three pieces of information here (9th floor, 53rd Street, 7th Avenue) reflecting a particular location in the three spatial dimensions of the universe. Equally important, however, is our specification of when we expect to meet them - for instance, at 3 P.M. This piece of information tells us where 'in time' our meeting will take place. Events are therefore specified by four pieces of information: three in space and one in time...In this sense, time is another dimension."
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I consider humans as being 4 dimensional and existing in a 4d world...unfortunately we cannot fully interact with the 4th dimension (I guess we are temporal retards)......but that aside......\n\nYour 2d and 3d examples are correct because they are both physical dimensions.\n\nHowever, a 4d observer would not be able to touch every molecule of a 3d world which he was observing........this is because the 4th dimension is temporal rather than physical....he would still have physical boundaries.\n\nHe would be able to interact with a 3d world in the same physical way as we would, but he could do it in the past or future....which we cannot unfortunately....we are stuck in our present...moving ever forward in the temporal plane.\n\nPhysically, he would also be able to interact with his 4d world in the same way as a 3d observer interacts with their 3d world (and it would simply appear normal to him).\nTemporally, he could interact with his 4d world in the same way as he could interact with a 3d world...he could travel in time, but would remain constrained by physical barriers.\n\n5d.....well.....what is your definition of the 5th dimension ?\n\nProbably somewhat different to mine !!!
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Okay I'm sure that there is more than a four dimensions out of this well known reality (real life).\n\nabout that string theory I have read a little from wikipedia and it says something, that maybe, the Universe was caused or founded pherhaps by a big Crunch.\n\nTo simplifies it for myself, I think that every Dimension is a continuing line. String is a very small thing that exist only in that dimension and not just one string but millions of it, but only that type or kind of string, for example a flashlight in a dark room you can see those particles of dust BUT refering the -strings- are actually those specific Lumens or Lux that are producing light and interacting in a very small subatomic scale, and refering -dimension- are that beam coming out from that flashlight all the way long to the wall.\n\nYou see only those lumens are interacting in the beam which is the well known Dimension, (we live in it) The Universe.\n\nBut there is fourth Dimensions apart that Can not even touch the beam of light wich represent the dimension or universe we are talking about, because the other Dimensions acording to this theory are beams (lines) but not of light for example another dimention could be as a water fall that comes out of spout (sink dishwasher). curiously that flow of wather is very similar to the beam of light.\n\nOkay I'm sure that this a very deep thing to think about it but friendly I advice you to not get more further because we are just humans and those are very Interesting themes or topics that we can not reach or complete understud \n\nI always have thought that the universe is spheric very similar like that crystal spheric snow ball present or souvenir they give you on birthdays maybe like a Marble.\n\nBut serious talking againg about Dimensions. you know, The Book talk about it, a dimension of living creatures and you know the other dimension of people that is not here anymore We can Not interact each other. \n\nLUX OR LUMENS (a Small Portion from Wiki)\nAchieving an illuminance of 500 lux might be possible in a home kitchen with a single fluorescent light fixture with an output of 12000 lumens. Lighting a larger area with the same number of lux requires a larger number of lumens.
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GOOD QUESTION: well done! There is not really any such thing as time, it is merely our way of describing a particular abstract concept. If it was a solid physical reality it surely couldn't be relative. Lets all go and read Einstein and try to figure it out!
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Yes, time is a relative and would be preceived differently if it could be perceived from all the various perspectives.  Time and space fold in upon each other and we see a result but not the only result.
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Time is called a dimension because in Einstein's theory of relativity it makes mathematical sense to do so. Events happen in spacetime, 3 spatial and 1 time dimension. But their orientation in space and time relative to each other, depends on the observer and the relative speeds of the events.\n\nIn Einstein's formulas these dimensions are mixed by transformations depending on the velocities. This works only if we add time as a dimension.    \n\nTo give the *position* of an event in four dimensional space-time you need to give a reference observer first, another event, relative to which you measure.  And the answer will depend on your speed and the speed of the observer. And that is just what relativity means: the resulting coordinates or not the same for everybody but depend on the relative speeds.