celebrating what would have been Queen Elizabeth II 98th birthday through the years

Hell, even if you don't get stuck. Immortality is probably the worst fate that could befall a sentient being. Eventually, the Earth will change. That could be its own problems. But then, in a few billion years, there won't even be an Earth. And you will either have to have the ability to traverse space or be absorbed into a red giant star. Then, if you're unable to travel faster than light, you're stuck traveling the voids of space for who knows how long. Until the stars and galaxies around you flicker out to nothing. And then it's anyone guess. But my edible infused hypothesis is that at the end of time. When all the lights have gone out, and there is that sole immortal being. Its own sentience won't allow it to cope with absolute nothingness. And the final shattering of its psyche is the spark that kickstarts another Big Bang.