Time is a dimensions? or is it really a scalar quantity?
827987
No, it's an independant variable (in the sense that it's not a linear combination of other variables such as length, mass, or charge) and, since it's linearly independant, it can be used as a dimension (or one of the spanning vectors) in a vector space.\n\n\nDoug
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.
1045387
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!
725282
Space and time aren't the same thing, they just form one continuum. Not that you're particularly interested in the actual answer mind.
301658
Yes of course...\nIts very interesting question from you... But I can give one best reference to you if you wish to know more about space/ dimension/time etc without any mathematical hectic equations...\n\n"A breif history of Time" by Stephen hawkings... excellent book on above concepts...
72098
Some new ideas in physics posit that there are more than the obvious 3 spatial and 1 temporal dimension. These theories are intended to explain all four fundamental forces in nature (electromagnetism, the strong nuclear force, weak nuclear force and gravity) by serving as a bridge between quantum mechanics and general relativity.\n\nIt turns out that one way that - perhaps - QM and GR can be connected is to postulate some extra dimensions, with an extra 7 spatial dimensions for a total of 11. If such extra dimensions exist they may be too small to interact with our standard 3D+time word.\n\nSo, in this case, a 6th dimension would be one of these smaller extra dimensions.\n\nIt should be noted, though, that thus far string theories are very theoretical, and there is no real physical evidence (yet), nor even a complete theory. Its still very much up in the air.\n\nA nice, simple guide to string theory basics can be found here:
910873
The fourth dimension is referred to as time because of 3d charting.\n\nSay you have a 3d chart of two airplanes traveling through the sky, and they both cross through the point x,y,z. That is a measure of depth, height and width on a coordinate map.\nNow, that would mean that the planes crash at that point. But they don't necessarily crash because there is another dimension involved, time. The way real world events are charted involves length width height and time when. That means its XYZ time. that makes time the 4th dimension.\n\nIf you are talking about another direction being the 4th dimension, then when we discover how to move in that direction, time will be the 5th dimension.\n\nALSO: Look at the animation by clicking on the helix at the right side of this website, it should help you.\n\nHope that helps.
912122
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.
215076
I fear i had even thought about the ∞ dimension once. Nearly anything could be described as rotations there. It has took a long time to get a foot on earth again.\n\nTime is not the real 4th dimension. Perhaps c*t. Look at this 'Minkowski space' thingy:\n\nhttp://en.wikipedia.org/wiki/Minkowski_space\n\nIf you measure across space AND time, there are negative distances. What shoud a negative distance mean in reality?\nIf you consider time as the 4th dimension, it is just a convenient way to write down long terms shortly or to visualize complex relations concisely. It isn't more than just mathematics.\n\n\n"As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality." \n\nAlbert Einstein (personally himself)
26586
Science currently views the nature of space-time has a 3-D surface which is difficult for us to comprehend since we are accustomed to 2-D surfaces only.  Like all surfaces they have no spatial boundary.  Imagine the surface of a balloon.  If you were confined to move on its surface and travel all over you would not find an edge.  Of course there is a "above and below" but in the context of the universe these are not spatial dimensions but temporal ones.
886
Classical physics theories describe three physical dimensions: from a particular point in space, the basic directions in which we can move are up/down, left/right, and forward/backward. Movement in any other direction can be expressed in terms of just these three.\n\nTime is often referred to as the "fourth dimension". It is, in essence, one way to measure physical change. It is perceived differently from the three spatial dimensions in that there is only one of it, and that movement seems to occur at a fixed rate and in one direction. The equations used by physics to model reality often do not treat time in the same way that humans perceive it.\n\nTheories 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.
241342
I agree with flandargo. The basic quantities mass, length and time and in elecricity the quantity charge cannot be difined.\nThese are all concepts understood by intution. We can define their units.\n\nSome may define that 'time is the interval between two events'.  But the question is what is interval.\n\nSimilarly mass is defined by some as quantity of matter.\nThe question is .'what is matter' \n\nHence Time cannot be defined.
89468
Ya Time is just a measure of change... If there is change then you can say that there is time... No-time isn't a "theory" it's an idea, a thought game.
1018923
Dimensions are not the same thing as a parellel universe.  It's one popular misconceptions carried on by mystics but created by turn-of-the-20th-century scientists when spirits were thought to exist in higher dimensions.\n\nDimensions are concepts of sides of objects and time, no more, no less.  We exist in what is visually a four dimensional universe, height, width, depth, and time.  We can't visualize objects in higher dimensional space because there is no evolutionary advantage to such a thing; tigers don't leap out at you from the fifth dimension.  String theory suggests there are 11 dimensions (or more); at the Big Bang all the dimensions existed at once then split apart.  Our 4-dimensional universe expanded in the however many other dimensions (the number depends on the theory) shrunk down to the Planck length (10^-35 meters).\n\nA parallel universe is usually what people and mystics mean when they say dimensions.  Even though a parallel universe is technically just another universe existing just out of reach of our own (possible even nanometers away).  This theory seems to be common to multiverse theory, string theory, m-theory, and a few others.\n\nOnward, if we shrink to smaller than an atom, down to the Planck length for example, we'd not lose our four-dimensionalism.  We'd just be really, really small.  We wouldn't be visible to the naked eye nor the most powerful of electron microscopes.  Nothing that exists today can probe down to that desperately small scale; there are plans to eventually do so, however.  We wouldn't slip into another world or into a 3-dimensional space (length, width, and time).\n\nThis isn't an insane question, nor is it stupid.  It's actually asking something very simple.  Remember Einstein asked himself a simple question when considering light.  "What would happen if you were to race alongside a beam of light?"  Einstein was a master of looking at things at their simplest level; from that question above came one of the most remarkable and elegant theories ever to exist: Relativity.
69551
Scientifically, time actually exists as a dimension, but a non-spatial one. Our perception of time may not be necessarily cover the whole concept of what time is. It could be possible that time is some type of "substance" even. But it exists as far as the universe and physics is concerned.\nSince our human experience only covers the present time as a "linear continuum", it's hard to understand time in terms of "existence". It's better to try to define first what "existence" means.\nFor example, for the Taoist, nothing actually exists.\nIn my opinion it's better to come up with a reasonable answer to the question then just put that baby to sleep, because you can throw away your time on a philosophical wild goose chase.\nYou can read "The Elegant Universe" and it'll be so mind-boggling that it might make you not worry about it too much.
302854
Are there only 3 easy dimensions to get around in or 4? The way we percive all that is around us seems to be that we can't seperate time from space except through artifical means. Non movement can be defined as 0 deagrees kelivin or absolute zero. If time is wrapped into space then if nothing is moving then no/time might pass.
719023
well i've been wondering for a long time about the nature of time. It seems that since time is the fourth dimension and we are living in 3 dimensions we may never actually understand the nature of time. Physicists say that time and space doesnt exist as such but a combined entity called spacetime exists. Philosophers may have better answers.