Are there methuselas that are known to be not glider-constructible?

[tcorlett]

I saw a tweet about the non glider-constructible still life. I was wondering if the same is true with some methuselas?
Or really, any oscillators or structures that are not "still" regardless of their longevity.

I just joined the forum out of curiosity - my knowledge of Game of Life structures is very basic. Forgive me if the question is ill posed or non-sensical.

[hotdogPi]

Yes. Most Gardens of Eden just look like random blobs; the ones that were stable were major discoveries.

[dvgrn]

Yes. Most Gardens of Eden just look like random blobs; the ones that were stable were major discoveries.

And while most random blobs aren't methuselahs, for any given definition of "methuselah" you can pretty much pick any Garden of Eden, write a program to randomly scatter more ON cells around its edges and see how long the resulting blob lasts, and you'll eventually find a methuselah (that is still a Garden of Eden, because you didn't change the original Garden of Eden part).

[dani]

...any oscillators or structures that are not "still" regardless of their longevity.

Of note is Unsynthesizable oscillator 1, which is a period 2 structure that cannot be synthesized. It didn't get as much coverage but is still pretty fascinating. It was found using a similar method to the discovery of the still life, soon after.

We don't know if any spaceships are unsynthesizable, but it's theorized that large, blobby spaceships like Sir Robin don't have a synthesis due to the chaoticness of their form, and how many gliders you'd have to pack together to keep it stable. I'm not sure if one could be explicitly proven along the lines of the still life and oscillator, but it doesn't seem too unlikely.