How can time be considered a 4th dimension?

Question

The 3 dimensions (x, y, z) allow for moving to any point within those coordinates. However, time has a restriction that it can only go forward. Unless someone determines that you can go to any point along the time dimension. How can time be considered a dimension?

Answer 1

Because time is orthogonal to the 3 dimensions x,y,z. That is, it is not dependent on, and exists separate from those 3. That it is named the 4th dimension is arbitrary - it could be the 5th, 6th, or whatever. But it is definitely its own separate dimension though.

Answer 2

The acid test for any question like this is, if we consider time a dimension, can we get useful results from it? Einstein certainly did.

But, there is nothing about a dimension that says you need to be able to move around in it. I suggest if you are interested read Greene's book, The Fabric of the Cosmos, which goes into great detail about time as a dimension.

Think of the whale in Adams' Life, the Universe, and Everything. It comes into being high in the air and falls to earth, where it splats. It moves forward in time and downward in space. By moving its flippers it can control its north-south-east-west dimension, but its time and altitude dimension move inexorably to the end. You wouldn't deny the altitude of the whale is a dimension just because he can't control it.

Answer 3

Just because you cannot revist the past does not mean that it did not happen in continuity with the present. It "exists" on a 4-D plot. Time is considered a 4th dimension because it *works* mathematically in general and special relativity.

It is extremely difficult and non-intuitive to think about this because our basic thought processes, biological functions, and biochemical reactions are *all* occuring inextricably in time, that, as you say appears to be moving forward only in a fixed way. Calculations that show this to be a very special case are mind-blowing, and not many can really get their heads around it (Einstein, Hawking, and their ilk).

Answer 4

Unfortunately, ideas in mathematics are often based on words that we use, but begin to diverge from them as the mathematical theory matures. For example, a "vector space" can be made up of functions, and often is. The idea of pointy arrows as vectors is not always applicable. Likewise, the dimension of a vector space is equal to the number of basis elements which are necessary to span the space. Here, the four vectors are the three standard position vectors, and another which is defined to be time.

Time was not discovered to be the fourth dimension. It was defined as such.

Answer 5

The obvious answer is that in order to specify any event completely you not only need its position in space but also *when* it happened, is happening, or will happen. Because we don't know how to travel in all directions of time yet does not mean that it is irrelevant to speak about the past or future.

The other answer is that Einstein proved that time and space are fundamentally intertwined into space-time, in his General Theory of Relativity. This became apparent once the speed of light was proved to be invariant no matter how it was measured - light speed could never change, so space and time had to change. Even the order of events can change depending on how you observe them!

Answer 6

After you've established a point within space, what else is there to define except for how long that point is present at that location?

The fact that time can only move forward is irrelevant. How many graphs have you seen with practical use that disregard negative space on a 2 dimensional plane completely? It is because we, as a race, have little to no understanding of negative space. In that same line, we have no understanding at all of negative time. Negative space exists only in our mind, as does negative (or reverse flow) time.

Think of these examples: When an object in our positive space reaches 0, it ceases to exist. When your gas tank on your car is 0, you have no more gasoline. When the amount of cookies in a package is 0, there are no more cookies. When your lifespan on this planet is done, you will no longer exist (except as a memory, but lets not get metaphysical here). There may come a time when an understanding of negative space exists out of necessity because of objects that may be found that survive in negative space, but for now we have enough trouble understanding everything in a positive-based world. Therefore time, regardless of its inability to be "negative," remains the 4th dimension in our understanding.

Answer 7

In the sense that time is a variable used to describe dynamic objects it is a variable. If you came with a set of 7 factors that determine how well the stock market will perform then you have created a 7 dimensional system.

Answer 8

Absolutely NOT true. There is no restriction in general relativity theory the prevents one going backward in time. The problem is you have to travel faster than the speed of light to do it. Some hypothetical particles appear to fit the bill for backwards time travel, but the idea is still controversial

Some debunking the argument is not about perspective or negative origins

Answer 9

If the God creature does exist on the 4th measurement... what's there to assert there are not different beings of equivalent and doubtless greater beneficial skill? could they automagically be qualified as Gods?... quite if that conflict deity does exist i could desire your top with regard to the 4th measurement considering that there could be greater creatures such because it... i could attraction to them for that God's destruction.