Sealed bottle garden still thriving after 40 years without fresh air or water

What would've been really cool if he had weighed it with a very accurate scale. If I remember my chemistry correctly, it shouldn't have changed a bit, and would've been proof of it's isolation.

It looks like the bottle is sealed with cork, which is permeable to both air and moisture.

The retired electrical engineer has only watered the plant twice, the last time in 1972 when he oiled the plastic stopper so that it wedged so tightly it hasn't been out since.

Indeed - a reason wine bottles have a capsule in addition to a cork is to control diffusion.

The diffusion rate through the cork should be quite small, but might serve to help equilibrium. It's an inspiring thing to try... the plant of the long now.

I'm curious as to the evolution of the bacteria and other organisms inside the bottle.

I am a bit suspicious of the lack of algae on the inner wall of the bottle...

There might not be enough water. The walls don't look visibly damp.

Also, there might not have been any introduced from the start - if he used only dry rocks/soil, and planted from a seed.