What is the fourth dimension? Please explain simply.?

Question

What is the fourth dimension? Please explain simply.?

Answer 1

You could say that the "fourth dimension" is time, but that's not quite the full story.



Think of a bug on the ceiling in your room, at midnight. From your chair, that bug is 2 feet in front of you, 4 feet to the side, and 5 feet up. That's three dimensions.



But imagine that it's 11PM, and the bug won't appear until midnight. That bug is 2 feet in front, 4 feet to the side, 5 feet up, and 60 minutes away from you. That is an example of using four dimesions to identify the location of an event (the bug appearing on the ceiling).



We don't notice a fourth dimesion (unless we're geeks, which, well, I am) because we can jump up and down, walk back and forth, but time only goes one way, like a boat on a river that never ends or stops.



Hope this helps!

Answer 2

There is no fourth dimension, it is just an idea, if it really existed then these three dimensions would not. Many people say that time is the fourth dimension, but this is really silly as time is just another way of measurement, just like inches, or centimeters, or degrees. Time is not a dimension - from point A to point B it takes two hours at three miles per hour. How else could we measure the speed of light if not by time? Think about it, how could time possibly be a dimension? Time is only relative to humans as a way of measuring their measly lives, this whole universe exists outside of time, there was no beginning,　There will be no end. Just as there is no beginning or end to God.

Answer 3

see friend, let us be clear about what we call 'dimension'. in physics we often (almost always) talk of vectors. if the vector you are considering can be written uniquely in terms of some convienient set of vectors which are independent of each other, i.e any of them can not be written in terms of the rest, then the number of such independent vectors is called 'dimension'. For example, let

dispalcement vector A=3 i + 4 j +5 k, be a vector written in cartesian form, where (3,4,5) are its coordiantes, and i,j and k form the reference vectors. because your three reference vectors i,j and k are independent we say that A is defined in three dimensional 'world', the hence cartesian space is '3 D', or more adequately it is 3 D vector space. Now, for modeling the newton's laws this 3 D space was found to be adequate and so abundance of 3 D is found. now if i begin with writing some vector f in terms vectors a, b, c, d, e, f with all of them independent then i am constructing a six d vector space !!

i do not know what my f represents physically but still my space is there ! things like these form what is called linear algebra in mathematics/mathematical physics, and have independent existence. amusingly in quantum mechanics one often works in infinite dimensional vector space !! there the vector space needed to understand simple harmonic oscillator is also infinite dimensional..... !!!!!!!!. so there nothing very physical about dimensions.

now let me come to your answer. while studying maxwell equations in electrodynamics, lorentz discovered that the magnitude of usual position vector r changes under rotations of this vector, that is maxwell equations do not fit with the vector space of three d. so he fitted the problem by making a four d space with coordinates x, y, z, as usual and c*t as new addition, where c is speed of light and t is time. this was consistent with the maxwell eqns. and in this manner it forms more general representation for explaning any phenomena. now it is this vector space which is refered as 4 D space, and t as 4th d (simply forgetting about c because it is a constant any way). people often confuse t with role of x,y and z. remember, t is simply a parameter which specify the degree of disorder in your system, that is all, it can not be controlled at will and always changes whether what or not you want !?!

so in that sense there is nothing really "fourth" about it.



i hope that you understood, and if you are serious physics student/professional then please do not read popular science books, because they do not depicit the ground reality, instead go for good textbooks it may take more time/effort but then you will end up learning more !!

sorry for such along, and complicated answer, if you find it boring please ignore it.

Answer 4

If you have an equation that involves four variables, like

x + 3y + z - w= 0 you are working with a problem of dimension four, because the solutions are point as (1,1,1,5) or (0,0,1,1) and so on. Points with four coordinates are points of the four dimension. No mystery.

Answer 5

Time is the 4th dimension. Continuity or lack thereof. Pretty simple actually. Look at the earth. It has heighth, width, and depth. It also exists in time.....the 4th dimension, as it rotates.

Answer 6

Time.



First three dimensions put you onto a point in space, the fourth says when you're at that point.

Answer 7

If time is the fourth dimension, than infinity is the fifth.

Answer 8

Maybe think of it as a vector field in 3d. With a particular point in an inertial time frame having different clocks. But that's only special relativity.

Answer 9

Time has been considered the 4th dimension, due to its ability to allow us to measure why 'things' dont happen to us all at once.

Answer 10

It is often stated as time, the movement of the other three, but it may be spatial, as in a tesseract.

Answer 11

http://en.wikipedia.org/wiki/4th_dimension