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The second law of thermodynamics states that;

The total entropy of an isolated system can only increase over time or it can remain constant in ideal cases where the system is in a steady state (equilibrium) or undergoing a reversible process. The increase in entropy accounts for the irreversibility of natural processes, and the asymmetry between future and past.

So if there was a universe made up of antimatter will the entropy of that universe increase or decrease?

Because according to my research;

The Feynman–Stueckelberg interpretation states that antimatter and antiparticles are regular particles traveling backward in time.

Will the entropy of a universe made up of antimatter increase or decrease? Or is there any possibility that there can be a universe made up of antimatter because the entropy always increases by time? And what will happen to such a universe assuming that the entropy decreases? (because antimatter travel backward in time)

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marked as duplicate by John Rennie quantum-mechanics Mar 12 '17 at 13:35

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  • $\begingroup$ antimatter goes backward in time is a quantum mechanical model . Entropy is thermodynamics and statistical mechanics. The statistical mechanics definition of entropy would treat antiparticles as particles and count the microstates for a given macrostate, so there would be no difference in the definition in the two (matter and antimatter) universes in the numbers coming out for entropy classically. Quantum mechanically remember that charge is arbitrary defined as + and - , and energies are energy differences ( think potential well) so a physisist in an antimatter universe would define $\endgroup$ – anna v Mar 12 '17 at 13:43
  • $\begingroup$ the same classical entropy concept and consider positive energy what to us is conventionally negative. $\endgroup$ – anna v Mar 12 '17 at 13:45