Is the Universe Infinite or Finite?

The universe's finiteness or infinity is unknown, as current observations and Einstein's theories are compatible with both possibilities. While an infinite universe implies the existence of infinite copies of ourselves, the concept of the universe's expansion and its implications for an infinite space is also explored, including the Hilbert's Hotel analogy to explain infinite expansion.

Universe's Infinity/Finiteness

• 00:00:28 It is unknown whether the universe is infinite or finite, as current observations and Einstein's theories support both possibilities. The Big Bang suggests a finite observable universe, but beyond that, the universe may extend infinitely or loop back on itself. The universe could be a higher-dimensional structure like a cylinder or a donut, allowing light to travel in multiple ways, creating repeating patterns.

Curvature of Spacetime

• 00:01:01 Einstein's theory of general relativity describes spacetime as a curved entity, influencing the movement of objects through gravity. The curvature of spacetime is measured internally, and this concept is illustrated through the example of a flat sheet of paper versus a sphere, where triangles' interior angles differ. This intrinsic curvature is different from the extrinsic curvature that can be measured from the outside.

Universe Expansion in Infinite Space

• 00:08:01 If the universe is infinite, the Big Bang occurred everywhere at once, meaning the universe has always been infinite. The concept of expansion in an infinite space is explained through Hilbert's Hotel analogy, where infinitely many guests can still be accommodated despite full occupancy. Mathematically, this shows how infinity + 1 or infinity * 2 remains infinity.

Infinite Copies of Ourselves

• 00:09:24 An infinite universe implies the existence of infinitely many copies of every possible configuration of matter, including ourselves, with slight variations. This concept was first discussed by George Ellis and Graham Brundrit in 1979, and it is considered a simple and least controversial type of multiverse.