If the FRLW scale factor is 1 now, was it smaller or larger at earlier times? Does it asymptotically approach zero or infinity as you look back closer to the big bang? Or what?
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1$\begingroup$ It was smaller in the past. By definition the Big Bang is the time at which it goes to zero. $\endgroup$– Sir CumferenceCommented Feb 13 at 4:17
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The universe is expanding, so $a$ is getting larger. In the past it was smaller. Extrapolating back to a classical, General Relativistic big bang, it goes to zero.
