Space Time
1. A system of one temporal and three spatial coordinates by which any physical object or event can be located. called also space-time continuum.
2. The whole or a portion of physical reality determinable by a usually four-dimensional coordinate system.
Space
The unlimited or incalculably great three-dimensional realm or expanse in which all material objects are located and all events occur. The portion or extent of this in a given instance; extent or room in three dimensions: the space occupied by a body.
Time
1. The measured or measurable period during which an action, process, or condition exists or continues : duration.
2. A nonspatial continuum that is measured in terms of events which succeed one another from past through present to future.
How does Time work? It may need two dimensions to explain.
If you want to meet someone, you have to tell them both a place and a time. In a city like New York, that could be a cross street. The Broadway Plaza Hotel is on 29th and Broadway. You can also tell them to meet you on a floor, say, the 6th, at a time, 7 pm.
In general, to locate a place in space, you need three numbers, one for each dimension, right/left, back/forth, up/down. On Earth, a latitude, longitude, and an altitude fixes the location of a moving aircraft or orbiting spacecraft. To locate a place in space and time, you need a fourth coordinate, a when.
If you take all the points in space and all the whens and put them together, you get a four dimensional spacetime.
Einstein was the first to show that time behaves a lot like space. When you go faster, your time appears to move more slowly to those watching you accelerate. Your length also appears to get shorter in the direction you are moving. Time stretches. Space compresses.
Gravity bends space and time as well. You can, in fact, change the rate at which you move through time relative to other things just by changing how far you are from the Earth.
In the 1970s, they put a super accurate clock on an airplane and flew it around the world. It showed that more time had definitely passed…
