just to add something...
Don't think of dimensions as something you can only "see as an object". (this error is common because we can all "see" and imagine 1D, 2D and 3D objects). But a dimension is something you can identify, determine, ascertain or even experience if you like (seeing is only one of those things).
If you ask "What is 4D?" you also need to define your exact definition of "dimension". Otherwise, there is no way to exactly explain it. Most people (and thus indeed everybody in this thread) automatically assume you're talking about objects/spaces, but this isn't nessecairly the case.
For example, the experience in the form of feeling (things you feel on your skin etc.) is also a 4th dimension if you're talking about visual experiences. The most common and easiest example of this is the 3D movie experience where also real water, wind, etc is used to enhance the "movie experience". Another example is the "feeling" experience in virtual reality (think about industrial flight sims, robots which send back electric pulses so you feel the object the robot is touching, etc...)
Is time the 4th dimension? Again a question which can only be asked in the right context.
Because an object can, in theory, exist in the 4th dimension without any influence on time what-so-ever (as some examples in this thread showed); it can exist out of 4 dimensional planes; or also commonly used: it has planes in
tethraspace. Most papers about the 4th dimension, and what almost all the replies in this thread are about, are about
spatial dimensions. "Spatial" is the important part here... This (4th) dimension has nothing todo with time...
Time (the member
) was talking about "time" (the word
), this is NOT a strict
spatial dimension. So if you were only talking about spatial dimensions, then no, time is not the 4th dimension.
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