The Universe Is a Finite Book You Can Never Read to the End express
The Universe is a finite book. Its accelerated expansion, fueled by dark energy, binds distant pages, turning them into inaccessible chapters. Accelerating expansion draws a horizon, just like a black hole does: what lies beyond is lost. But the quantum nature of the text is even more treacherous: reading changes the letters. John von Neumann showed that an observer sees only the response, not the original.
No matter how elegant a model of the Universe is, it can't be fully tested. The total amount of information (its entropy) is large but finite, and only a tiny fraction is accessible. Leonard Susskind and Eugene Wigner uncovered fundamental blind spots for any observer. Here's a twist: the more detailed the attempt to describe curved spacetime, the more measurements distort the overall picture. There is no single plot you can follow to the very end.
Original abstract
as written by the authors arXiv:2605.13490
We argue that if de Sitter space is indeed represented by a finite dimensional quantum system, then semi-classical considerations, combined with the fundamental principles of quantum measurement theory, imply that any theoretical model of it is ambiguous. If our own universe asymptotes to such a de Sitter state, and if a model of it as a finite system can be embedded in a sequence of models that converges to a non-perturbative completion of a unique superstring model in asymptotically flat space, then one might be able to find a very precise mathematical model of our universe. However, even the most comprehensive experiments possible to local detectors in the universe cannot measure more than a tiny fraction of the total number of q-bits in the system.
If the Universe is a book with a finite number of pages, its total entropy (a measure of uncertainty) is like the maximum number of letters. That's why scientists speak of a 'digital' footprint of reality.
The metaphor of a book with unreachable chapters comes from Borges' story 'The Library of Babel'—where characters seek an absolute book, doomed to eternal incompleteness.