Why a theory of everything may be centuries away, or impossible
September 29, 2026 · 19 min read
Don Lincoln thinks the needed energies are a quadrillion times beyond today's colliders, Sara Walker doubts reality has a ground or a theory of everything at all, and Adam Frank notes string theory has had decades of effort without a breakthrough. It tempers popular expectations that a final theory is just around the corner.
The rules, numbers and steps worth keeping in front of you.
- A theory of everything would join gravity to the other forces; none is close.
- Don Lincoln: unification energies are about a quadrillion times beyond current accelerators.
- Accelerator energy grows only about sevenfold every 20 years.
- Lincoln: earlier unifications took a century or two each.
- Predictions hold maybe ten or a hundred times beyond what is measured, not a quadrillion.
- Lincoln doubts string theory because its equations and solutions are approximate and untested.
- Lincoln still believes real rules exist and can eventually be found.
- Sara Walker: reality may have no ground and no final theory.
- Walker: fundamental particles mark the limits of our instruments.
- Walker: the frontier is life and intelligence, not higher energy.
- Adam Frank: decades of string theory effort have drifted away from data.
- Frank: do not assume progress always accelerates; unified forces would still omit agency.
- The pessimism is about a final theory, not near-term physics progress.
- Practical test: ask what a theory predicts at energies we can actually measure.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.