What is space time, how can dimensions be fused, and how is time a dimension?
In: Physics
Dont mind people telling you the question is stupid.
If you have some basic understanding of geometry it doesn’t have to be very complicated. A dimension is really just a number that tells you where something is.
Do describe something in one dimension you need a number, an easy example are the natural numbers: 0,1,2,3,.. If you lived in the universe “natural-numbers”, you could perfectly describe every position with a single number.
Same way with 2 and 3 spatial (room) dimensions, pointing something out on a piece of paper needs 2 numbers (x,y in coordinate system) while pointing something out in a “grid” you need 3 numbers (up/down, back/forward, left/right).
The reason I said you need some basic understanding of geometry is because Pythagoras theorem (a^2 + b^2 = z^2) giving the relation of the length of the sides of a right-angled triangle, also works just as well in three spatial dimensions (a^2 + b^2 + c^2 = z^2).
The same is true for higher “theoretical dimensions” (4,5,etc). It’s maybe trivial to point out but our three spatial dimensions are also “fused” (I dont think this is a scientific term though…).
If you have grasped the things above, adding time as another dimensions is almost as simple as adding another X^2 term on the left side and suddenly, changes in the spatial dimensions are directly related to changes in the time-dimensions, they are no longer separate and you need to take into account how time is affected by moving around in space, hence Space-Time.
As a note generally the time-dimension has some special characters in most physics formulas to make it not work exactly like a spatial-dimensions (I think the term is negative instead of positive amongst other).
EDIT: If you are interested why space and time is “fused” you could google Einsteins Special Relativity or Space elevator thought experiment it will explain in a fairly logical way how all of this follows from the constant speed of light.
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