Table of Contents

## How do we measure the radius of the universe?

By taking the ratio of the standard three dimensional volumes for the observable universe to the Hubble volume, and setting it equal to the ratio of the corresponding volumes derived using the equations for the surface volume of a 3-sphere, we can solve for the radius of the observable universe.

### How did we measure the universe?

Scientists measure the size of the universe in a myriad of different ways. They can measure the waves from the early universe, known as baryonic acoustic oscillations, that fill the cosmic microwave background. They can also use standard candles, such as type 1A supernovae, to measure distances.

#### How big is the universe and how is this measured?

Let’s start by saying the Universe is big. When we look in any direction, the furthest visible regions of the Universe are estimated to be around 46 billion light years away. That’s a diameter of 540 sextillion (or 54 followed by 22 zeros) miles.

**Can you measure the total distance of the universe?**

By measuring the redshift of light from a galaxy, you can tell how fast it’s moving away from us, and thus its approximate distance. At the very end of this scale is the Cosmic Microwave Background Radiation, the edge of the observable Universe, and the limit of how far we can see.

**Can you measure the total distance of the universe Why or why not?**

The average distance between galaxies is about one million light years. There are roughly 100 billion galaxies in the observable universe. Another, often-used unit of distance is the parsec. Because they are so large, cosmological distances cannot be measured directly, and can only be indirectly inferred.

## How can the diameter of the universe exceed its age?

When the universe first “popped” into existence approximately 13.75 billion years ago, spacetime itself began expanding at speeds faster than the speed of light. This period, called inflation, is integral in explaining much more than the universe’s size.

### What is the radius of the universe?

The radius of the observable universe is about 47 billion light years, much more than the age of the universe multiplied by the speed of light.

#### How far back in time can we see the universe?

This essentially means that the furthest back in time we can see is 13.7 billion years, because it has taken 13.7 billion years for light (moving at the speed of light) to reach us. Therefore, the “observable universe” has a radius of 13.7 billion light-years and a diameter of roughly 27.5 billion light-years.

**How big is the universe?**

By using the Hubble Constant, we can calculate where the origin of those photons are now, and the answer is staggering – 46 billion light-years away! That means the “known universe” is 92 billion light-years in diameter! Clearly, calculating distances of this magnitude can bend the brain beyond the realm of human comprehension.

**What is the size of the observable universe in meters?**

The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light-years or 4.40×1026 meters) in any direction. The observable universe is thus a sphere with a diameter of about 28.5 gigaparsecs (93 billion light-years or 8.8×1026 meters).