We are composed of molecules that interact to use or produce other molecules and energy. That’s what life is, physics and chemistry.
Each of these molecules is made up of atoms, but and since nothing is ever really destroyed…
The early universe expanded after the big bang for only 3 seconds before it cooled to a state where subatomic particles assembled into atoms. Hydrogen atoms formed first since they are the simplest type of atom.
So, hydrogen is big bang dust, everything else is star dust.
Now that we have established that every element in the periodic table aside from hydrogen is essentially stardust, we have to determine how much of our body is made up of this stardust. If we know how many hydrogen atoms are in our body, then we can say that the rest is stardust. Our body is composed of roughly 7×1027 atoms. That is a lot of atoms! Try writing that number out on a piece of paper: 7 with 27 zeros behind it. We say roughly because if you pluck a hair or pick your nose there might be slightly less. Now it turns out that of those billion billion billion atoms, 4.2x27 of them are hydrogen. Remember that hydrogen is bigbang dust and not stardust. This leaves 2.8x27 atoms of stardust. Thus the amount of stardust atoms in our body is 40%.
Since stardust atoms are the heavier elements, the percentage of star mass in our body is much more impressive. Most of the hydrogen in our body floats around in the form of water. The human body is about 60% water and hydrogen only accounts for 11% of that water mass. Even though water consists of two hydrogen atoms for every oxygen, hydrogen has much less mass. We can conclude that 93% of the mass in our body is stardust.
A conglomeration of stardust has mass that is acted on by gravity that can cause severe structural damage if the decrease in acceleration is virtually instantaneous. Repairing that damage requires the input of a large amount of energy, energy that is not always available in large enough quantities. In the end, from stardust we came, and to stardust we shall return.