How can 3D space be curved?

You can curve Flatland in your three-dimensional reality by rolling the piece of paper into a tube, folding it into a paper airplane, or just crumpling it into a wad. Doing so would not be immediately apparent to Flatlanders, because light still travels in straight lines within their 2D space.

How do you curve the spacetime?

In general relativity, spacetime is not ‘flat’ but is curved by the presence of massive bodies. The curvature of spacetime influences the motion of massive bodies within it; in turn, as massive bodies move in spacetime, the curvature changes and the geometry of spacetime is in constant evolution.

What is 3 dimensional space-time?

Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called parameters) are required to determine the position of an element (i.e., point). This is the informal meaning of the term dimension.

What is the curvature of space-time?

Just the idea of four-dimensional space-time causes most of us to shudder… The answer in Quantum Field Theory is simple: Space is space and time is time, and there is no curvature.

What is the curvature of gravity?

As the theory is usually presented, it describes gravity as a curvature in four-dimensional space-time. Now this is a concept far beyond the reach of ordinary folks.. Just the idea of four-dimensional space-time causes most of us to shudder… The answer in Quantum Field Theory is simple: Space is space and time is time, and there is no curvature.

How do we see the curvature of the universe on a map?

The same way you see the curvature of the Earth on a flat map, through local scaling distortions of the map. Here is a map of a universe with positive curvature. The central galaxy is undistorted, but greater distortion is seen further from the centre. The “outermost” galaxy goes right round the map.

Why do straight lines not look straight in curved space?

The presence of mass, which we typically think of as gravity, distorts distance and time nearby. This, as we just learned, curves spacetime. And in a curved spacetime, straight lines don’t look straight. Now here’s the clincher.