Board Thread:General Discussion/@comment-32194023-20170603220826/@comment-32194023-20170605200142

I get it. By the way, that also makes sense, since it would give Asgore a reason to not kill the children which fell down. And what Gaster follower n° 1 said... "[...] Asgore took so long to hire a new Royal Scientist."

I guess this makes the most plausible theory the following:

Right after Toriel left, Asgore orders Gaster to begin a research programme on an alternative way of breaking the barrier (without souls): Gaster comes up with wormholes by "trailing" black holes (a method to do this has been published).

To do so, he constructs the CORE and begins testing/experimented (combined programme ?).

However, right after he manages to make a black hole (which Entry Seventeen probably describes), he falls into it.

Asgore then reverts to the "easy" way, and hires Alphys only after children stop falling into the Underground.