# Two part question.

1. Aug 29, 2010

### vidgmaetester

Part One
Why do physicists use grids with space if, we can go up, down, left, right, sideways, and so on?

Part Two
Why is time, used if "man" created it in physics?

2. Aug 29, 2010

### rock.freak667

Could you please elaborate on this, I am not too sure about what you mean.

Because we made a standard to measure time. Time would exist without mankind. That standard helps us measure other things, like rates and hence helps us predict outcomes.

3. Aug 29, 2010

### vidgmaetester

I mean in illustrations of a black hole it's a grid, why is that? (other then a visual enhancer so the user can see)

4. Aug 29, 2010

### Danger

I agree with the Freakish Rockster. Time is just Nature's way of keeping everything from happening at once. We humans have chosen to record its passing based upon increments found in Nature. A year is a solar cycle; a month is a lunar cycle (and another cycle that anyone with a girlfriend or wife would prefer to ignore); a day is a planetary cycle... hours, minutes, seconds all derive from those.

5. Aug 29, 2010

### Danger

Sorry, dude... you posted this while I was composing my previous entry. It is impossible for a human being to envision a black hole. The closest that we can get is a mathematical construction (model). We are four-dimensional beings, in that we have three dimensions of physical existence and one dimension of temporal placement. A black hole is also four-dimensional, but carries it to the point where the time component is interchangeable with the spatial ones.

6. Aug 29, 2010

### vidgmaetester

Can you explain how a black hole is four dimensions, and what is four dimensional?

7. Aug 29, 2010

### Danger

I'm no expert, but I'll give it a shot. Everything in our normal experience is 4D. It has length, width and height, which are the normal physical dimensions. It also has a prolonged existence, measured in units of time, the spot within which it resides constituting the 4th dimension. Of course, the latter is constantly changing. You can travel in any direction physically, but only forward temporally. A black hole sort of reverses that situation. You can physically travel only inward, but your temporal existence is variable. Relativistic time dilation due to the intense gravity starts playing hob with things. It's all rather over my head.