# GeekDad: How Many Atoms of Hydrogen Are There in The Universe? Just The One. NASA, H. Ford (JHU), G. Illingworth (UCSC/LO), M.Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA

If I decided to build a model of the Universe in a computer and put Hydrogen atoms in it I would probably do it like this: I would create a Hydrogen “Method” which is a few lines of code (let’s say ten lines of code) that describes a Hydrogen atom.I might us a variable r for the radius of one atom as that’s the only dimension I need to describe a sphere (let’s imagine a Hydrogen atom is a tiny sphere).  I might describe x,y,z as co-ordinates for the position in space and then perhaps v as a vector for it’s direction of movement and m for mass.

If I then wanted to populate the virtual universe with one million atoms I would then have to replicate the ten lines of code a million times wouldn’t I? Well no, the whole idea of a software Method is that it is used only when needed by creating an “instance” of a Hydrogen atom, by simply calling on the Method and feeding in the quantities for the different variables, so there would be a single line of code for each atom, in effect one for each instance. The Hydrogen instances then behave according to the rules of the Method.

In the real Universe we often describe objects as being “identical” if they are somehow perceived as being the same, take two identical, newly minted coins for example. However, we know that they are not really identical, even new coins are different at dimensions larger than the atomic level. If you were to look at the coins through a basic microscope you would still see tiny scratches on the surface in different places and under an electron tunneling microscope you would see atoms in different locations. There appear to be no objects in the Universe that are truly identical at the scales we are used to dealing with, but at the atomic level, individual particles could be said to be identical. This begs the question, what if there is just one version or “Method” of each element, and when it is needed in the Universe, it is simply “called upon” and new “instances” created? All of these instances could have been called at the moment of creation, or if the Universe runs like a simulation, the instances are only created when needed or even more spooky, only when they are “perceived”.

An interesting thought: As the similarities between a simulated universe and the real Universe collide, a theory that the real Universe is a simulation becomes stronger.