What are the dimensions of our universe in meters?

1 Answer

Volume of the observable universe is roughly
#4/3 pi ((8.7xx10^26)/2)=1.8xx10^28m^3#


The first thing to understand about the answer I'm about to write is: we don't know.

What we do know is we can look to the edges of the observable universe - this is the distance from Earth to the edge of what is observable because we can observe the light coming from there - and can add the expansion of the universe into that number.

You see, light travels fast but not infinitely fast. The best estimates of the age of the Universe sit at around 13.8 billion years, which means that light from the edge of the observable universe and being observed by us is 13.8 billion years old, and that makes the distance between Earth and the edge of the observable universe 13.8 billion light years.

But the Universe is also expanding and the expansion of the Universe over those 13.8 billion years and that has added a roughly 32 billion light years to this distance.

So we can roughly say that the distance from Earth to the edge of the observable universe is 46 billion light years.

One more thing to keep in mind - we've really just defined what we can see as the edge of the universe as the Earth at the centre of a circle or a sphere. So we can say that the distance from one edge to the other edge with Earth sitting in the centre of this diameter is roughly 92 billion light years.

How many metres are in a light year? #9.461 xx 10^15#

So we take #(92 xx 10^9)(9.461xx10^15)=8.7xx10^26m#

We can take this one step further and look at the volume of the sphere of the observable universe. The volume of a sphere is #4/3 pi r^3#, so the volume of the observable universe is:

#4/3 pi ((8.7xx10^26)/2)=1.8xx10^28m^3#