Board Thread:General Discussion/@comment-35615238-20190121141916/@comment-27088233-20190308110240

The incorporeal nature of Memoryhead could make it one of the biggest clues into the fate of Gaster, his followers, and perhaps the connection between Undertale's universe and Deltarune's.

Being scattered across time and space, and yet still existing, is possible in a sense; radio signals, cellular signals, photons, all sorts of frequencies and wavelengths can be manipulated to transfer, store, break down and reassemble data. Teleportation may have been a major interest of the royal scientists as a means to bypass the barrier without the need for human souls. Many tests would have to be conducted on living subjects, and many would fail.

While the other amalgamates seem to be the result of experimentation with Determination, Memoryhead's behavior is more like what you get when a radio tries picking up two competing signals at once. It's not melting from an overdose of determination, it's a botched re-materialization of several subjects of a teleportation experiment. All of its interactions are as if it has one foot in the physical world while the other is just static.

As Gaster and his assistants improved on their signal-recieving technology, some successes resulted: small achievements like the underworld cell service, bigger deals like San's ability to teleport at will, and huge things like the awareness of other worlds and timelines existing simultaneously and adjacent to their own, within arm's reach (something I believe they discovered right after entry 17). This led to the eventual discovery that infinite timelines where free will is allowed ultimately means a force as determined and powerful as Chara will destroy every timeline in the universe. It can't be avoided.

My guess is that the goal switched to making contact with another universe, one that could recieve a cross-universal signal (it's also possible that Entry 17 is about this instead.) The plan became to jump Gaster to another universe, shattering him across time and space, with the intention of reassembling him there, where he could attempt to save the Undertale universe and/or its inhabitants. Did he succeed? Did he just get stuck in room 269? Are there Two gasters working together in the Deltarune universe, a universe where characters tell the player they have no ability to make meaningful choices and therefore can't be destroyed by Chara? I have a few guesses.

TL;DR: Memoryhead is several monsters, converted into signals that did not re-align properly. Like Gaster, they were shattered across space and time, but the attempt to reassemble them went terribly wrong. The method of converting monsters into a data signal is not discussed in either game, but if it exists, it could be at the center of every major mystery in the series.