When we talk about the observable Universe we encounter numbers beyond any human logic, we set off on an extraordinary journey
To try to understand these enormous numbers it is necessary to understand what is meant by an observable universe. Imagine a sphere centered on an observer: theobservable universe it is that region that it actually manages to identify. In general it is understood as the portion of the universe that can be investigated by man. Therefore this sphere is centered on our planet but it is important to point out that each position in space has its own Observable universe.
Billions of light years
The Universe is expanding (as proven by Hubble) and therefore the light sources, such as or rather the galaxies, are moving away from our observation point. If this were not the case, the radius of the observable universe would be equal to 13.8 billion light years approximately, that is, the distance traveled by light since the beginning of the Universe (since Big Bang). But since it is expanding, the distance to the horizon is much greater: electromagnetic radiation that started 13.8 billion years ago and now reaches an observer would be relative to a source that has moved away from the observer. The latest estimates hypothesize that the space could have expanded by about 4.7×1023 km or 46.5 billion light years. Therefore the diameter of the sphere would be exactly equal to 93 billion light years.
And it didn’t end there
The spherical volume would be approximately 5×1032 light years cubes capable of containing approximately 7×1022 stars, grouped in approximately 2×1012 galaxies that form groups and clusters and superclusters of galaxies (according to the latest estimates of the number of galaxies would be underestimated). The light year is a measurement of space, not time. It represents the distance traveled by light in a vacuum in one year at a speed of 300,000 km/s. It travels approximately 9,460,730,472,581 kilometers in a year.
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