Is quantum mechanics missing something? Three physicists on what is real
October 6, 2026 · 15 min read
Roger Penrose argues quantum mechanics is incomplete and that gravity may change it, Lisa Randall asks whether electrons exist when no one is looking, and Michelle Thaller describes entanglement and a connected universe. Their different answers show that the theory's predictions are settled while its meaning is not.
The rules, numbers and steps worth keeping in front of you.
- The predictions of quantum mechanics are not in dispute; the argument is about what they mean.
- Penrose: the theory is incomplete because the Schrödinger equation never produces single outcomes.
- Penrose: collapse of the wave function is added by hand and must be explained.
- Penrose: Schrödinger meant his cat as an absurdity, a sign that something is missing.
- Penrose: Einstein, Schrödinger and Dirac all thought the theory incomplete.
- Penrose: gravity should modify quantum mechanics, but he has no theory and no experiment yet.
- Randall: the wave function is real; an electron exists even without a definite position.
- Randall's analogy: a stock has no exact value until traded, yet it exists and can be estimated.
- Randall: exhaust existing frameworks before jumping to the most far-out idea.
- Thaller: entanglement is an experimental fact, confirmed since the mid-1990s.
- Thaller: two entangled particles are the same quantum system; distance does not matter.
- Thaller: gravity and quantum mechanics do not work well together.
- Penrose and Randall both reject the idea that an observer brings the world into being.
- Thaller's rule: be honest about what you do not know.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.