Can someone explain this? I understand it but I want to make sure my cat does too

The formula as it appears in the comic is truncated. The complete formula of the universe in this style (but arranged in decreasing order of abundance after carbon, which also happens to place hydrogen immediately after) would be C₁₀⁷⁷ H₁₀⁸⁰ He₁₀⁷⁹ O₁₀⁷⁸ Ne₁₀⁷⁶ N₁₀⁷⁶ Mg₁₀⁷⁵ Si₁₀⁷⁵ Ar₁₀⁷⁵ Fe₁₀⁷⁶ S₁₀⁷⁶ Ni₁₀⁷⁵ Ca₁₀⁷⁵ Al₁₀⁷⁵ B₁₀⁷¹ Be₁₀⁷¹ Na₁₀⁷⁵ As₁₀⁷² Br₁₀⁷² Li₁₀⁷² Cr₁₀⁷⁵ Ti₁₀⁷⁴ Mn₁₀⁷⁴ P₁₀⁷⁴ K₁₀⁷⁴ V₁₀⁷⁴ Cl₁₀⁷⁴ F₁₀⁷³ Sc₁₀⁷² Co₁₀⁷⁴ Cu₁₀⁷² Zn₁₀⁷³ Ga₁₀⁷² Ge₁₀⁷³ Se₁₀⁷² Kr₁₀⁷² Rb₁₀⁷² Sr₁₀⁷² Y₁₀⁷¹ Zr₁₀⁷² Nb₁₀⁷¹ Mo₁₀⁷¹ Tc₁₀⁰ Ru₁₀⁷¹ Rh₁₀⁷⁰ Pd₁₀⁷¹ Ag₁₀⁷⁰ Cd₁₀⁷¹ In₁₀⁷⁰ Sn₁₀⁷¹ Sb₁₀⁷⁰ Te₁₀⁷² I₁₀⁷¹ Xe₁₀⁷² Cs₁₀⁷⁰ Ba₁₀⁷² La₁₀⁷¹ Ce₁₀⁷² Pr₁₀⁷¹ Nd₁₀⁷² Pm₁₀⁰ Sm₁₀⁷¹ Eu₁₀⁷⁰ Gd₁₀⁷¹ Tb₁₀⁷⁰ Dy₁₀⁷¹ Ho₁₀⁷⁰ Er₁₀⁷¹ Tm₁₀⁷⁰ Yb₁₀⁷¹ Lu₁₀⁷⁰ Hf₁₀⁷⁰ Ta₁₀⁷⁰ W₁₀⁷⁰ Re₁₀⁷⁰ Os₁₀⁷¹ Ir₁₀⁷¹ Pt₁₀⁷¹ Au₁₀⁷⁰ Hg₁₀⁷¹ Tl₁₀⁷⁰ Pb₁₀⁷² Bi₁₀⁷⁰ Po₁₀⁰ At₁₀⁰ Rn₁₀⁰ Fr₁₀⁰ Ra₁₀⁰ Ac₁₀⁰ Th₁₀⁷⁰ Pa₁₀⁰ U₁₀⁷⁰ Np₁₀⁰ Pu₁₀⁰ Am₁₀⁰ Cm₁₀⁰ Bk₁₀⁰ Cf₁₀⁰ Es₁₀⁰ Fm₁₀⁰ Md₁₀⁰ No₁₀⁰ Lr₁₀⁰ Rf₁₀⁰ Db₁₀⁰ Sg₁₀⁰ Bh₁₀⁰ Hs₁₀⁰ Mt₁₀⁰ Ds₁₀⁰ Rg₁₀⁰ Cn₁₀⁰ Nh₁₀⁰ Fl₁₀⁰ Mc₁₀⁰ Lv₁₀⁰ Ts₁₀⁰ Og₁₀⁰ according to estimates of abundance.

From explainxkcd for those who want to see the whole formula.

Any astophysiologists here? Is this accurate?

The formula starts with CH, which means the universe is organic.

I’m not a physicist, but even if Astatine is being produced in minute quantities by decay, a half life of 8hrs should probably put it lower on the numbers than Americium.

Americium is produced anywhere you have lots of free neutrons. This may be rare on earth outside of nuclear power plants and bomb test sites, but not necessarily rare in the universe. Especially since it has a half life of 432years, so unlike astatine it can actually accumulate a bit and not just decay immediately.

Astatine basically doesn’t exist. The total amount in the entirety of earth’s crust at any given time is estimated to be less than a gram.

So I feel like the amounts should be flipped or at the very least closer in orders of magnitude.

There are exotic atoms in that chemical formula that aren't in the periodic table. Not even if you count the equivalent table of potential antimatter atoms.

Muonium is sure to exist in non-zero quantities at any one time, for example.

Gold and silver are nice

surprised there's so much gold.