Core Law of Physics is Circular, Physicists Say

TL;DR

A new paper by Carlo Rovelli's group argues the second law of thermodynamics is a circular argument with no rigorous logical foundation.

Key Points

• 1.The Boltzmann Brain problem undermines the reality of the universe. Entropy fluctuations mean smaller clumps are statistically more likely than large ones, making it far more probable you are a disembodied brain imagining a universe than actually living in one.
• 2.The second law of thermodynamics is logically circular, the paper argues. Entropy increases because it was smaller in the past; we trust past records because entropy increases — the reasoning assumes what it needs to prove.
• 3.Even gravity and the Standard Model don't resolve the Boltzmann Brain problem. The authors conclude there is 'no fully rigorous argument that relies only on established physics' to rule out the Boltzmann Brain hypothesis.
• 4.The 1000CE hypothesis is logically equivalent to the Big Bang hypothesis. If entropy were minimal 1000 years ago instead of at the Big Bang, time would have run in reverse before that — and physics cannot formally rule this out, leaving the second law without unique justification.