Science Fiction novel. Time dilation/ aging backwards during space travel, being in a box. Read 1987-1990.

[Elaine]

I read this book on a summer vacation between 1987 and 1990. I don't know how long before that it was published. It was not a children's book. It's possible it was a collection of short stories and I'm remembering one of them.

It's told in the first person. The main character travels alone, maybe accidentally, out into space and then back. As he's traveling back, he gets younger and younger.

The story features a machine or box, which I'm sure was described as about the size of a washing machine (or maybe a dishwasher), that a person can live inside, in a state of suspended animation or at least unawareness of the passage of time. The inventor of the box is a character, and the narrator is maybe angry at or resentful of him.

The book ends with the narrator fixing himself some bottles as a young child so he'll have them when he becomes a baby, and preparing to shut himself into the box. It's implied he'll be an adult again by the time he returns to Earth.

The same person who lent us this book (not someone my family kept in touch with) also lent us some Stanislaw Lem books, but in the intervening decades I have read his major works and tried to find something of his that fits, but I don't think anything does.

This has been bothering me forever, so thanks in advance!

[SBC]

There is an Aging Backwards list but sadly I don't think your story is on it - it may be worth a check though! https://www.goodreads.com/list/show/1...