Einstein's relativity rules chemical bonds in heavy elements, new research shows
New experiments on bismuth-based molecules provide direct spectroscopic evidence that relativistic effects—electrons moving at significant fractions of the speed of light—change how chemical bonds work in very heavy elements. Commenters link the results to long-standing theoretical predictions from Dirac’s relativistic quantum mechanics and to familiar phenomena like the color of gold and the liquid nature of mercury. The thread also branches into how chemistry is taught, the limits of deriving complex chemical and biological behavior from first-principles physics, and the role of computational and quantum methods in modeling such systems.
Relativistic Effects in Chemistry
- Many commenters note that relativity in heavy-element chemistry (gold’s color, mercury’s liquidity, uranium/plutonium behavior) has been known for decades.
- The novelty is framed as direct spectroscopic evidence that textbook bonding models (e.g., for triple bonds in very heavy elements) break down.
- Some criticize the article’s wording that “increased nuclear mass” speeds electrons up, arguing it’s really the increased nuclear charge and Coulomb potential.
Sigma/Pi Bonds and Chemistry Education
- Sigma and pi bonds are said to appear in AP or early college chemistry, but often with heavy handwaving.
- Several people report chemistry courses dominated by rote memorization, trends with unexplained exceptions, and little connection to underlying physics.
- Others say higher-level or physical chemistry, and certain classic textbooks, finally make bonding and periodic trends feel logical.
Empiricism, Abstraction, and “Magic Coefficients”
- Strong theme: chemistry (and especially chemical engineering) leans on empirical models, fitted constants, and “magic coefficients” that hide intractable physics.
- Multiple layers of approximations appear at each abstraction level (physics → chemistry → biology), with many competing models for the same phenomenon.
- A key professional skill is choosing the right model and knowing where its validity breaks down.
Computational Chemistry and Limits
- Detailed discussion of quantum-chemical methods: CCSD(T) for small systems, DFT for larger ones, scaling issues (e.g., O(N³–N⁷)), and sensitivity of bond predictions to small energy errors.
- Commenters emphasize that fully ab initio simulations beyond tiny systems are computationally prohibitive, especially at realistic temperatures and in solution.
- Quantum computers are mentioned as a possible future aid, but current capability and even long-term practicality remain unclear.
Quantum Mechanics and Relativity Clarifications
- Relativistic quantum chemistry is linked to the Dirac equation, spin–orbit coupling, and long-established theory; the experiment is seen as another confirmation.
- Clarifications are offered on how electrons can have high “speeds” despite position uncertainty, and how probability distributions in relativistic orbitals shift energy levels and thus colors.
Other Side Threads
- Debates on whether physics has “exceptions” compared to chemistry/biology.
- Short exchange on non-classical logics, contradictions, and whether different logical axioms could apply at different scales.
- Minor side questions on Bohmian mechanics and on whether charged neutron stars could host orbiting electrons (answer: not in any simple, external-orbit sense).