Hi, I am quite confused about followed question, I think scientist think the last scattering surface was dense plasma at the temperature of 3000K. If the today's universe much cooler and less dense then "the last scattering surface" how can anyone says entropy increased by time? Isn't universe now have more order than a plasma phase? Note: I am sorry If I couldn't make good sentences to explain my problem, it is almost 2 am and I just woken up and this question just bugs me a lot. I'll really appreciate if someone explains it.