# Measuring Infinity – How Many Atoms Are There in the Universe ?

**It’s no secret that the universe is an extremely vast place. That which we can observe (aka. “the known Universe”) is estimated to span roughly 93 billion light years.** That’s a pretty impressive number, especially when you consider its only what we’ve observed so far. And given the sheer volume of that space, one would expect that the amount of matter contained within would be similarly impressive.

## Expressing the Number of Atoms Courtesy of Gauss

Believe it or not, regardless of how huge the figure must be, it’s possible to express the number using just four digits :

^{ 9 9 9}

Γ came courtesy of Carl Friedrich Gauss who wanted a ‘measurable infinity’, which is a little odd given that in mathematics infinity is a concept rather than a number, denoting something that is beyond any fixed bound and which can’t be resolved by counting or measurement, even in theory.

To write out that number in full would require 10^{369693100} digits, which, frankly, isn’t possible when you consider the estimated age of the universe is less than 10^{18} seconds.

## Infinity

The symbol for infinity, ∞, was introduced by the English mathematician John Wallis in 1655, although discussion of the concept of infinity can be traced back to the ancient Greeks.

## The Mass of the Known Universe

A related number is the estimated mass of the universe, which is calculated to be 10^{53} kg. This is the mass of atoms, ions, and molecules and excludes dark matter and dark energy.