Summary of “The Particle Problem in the General Theory of Relativity” by Einstein and Rosen

Key Points

  1. Objective:
    • Einstein and Rosen aimed to explore an atomistic theory of matter and electricity that excludes singularities in the field, using only the gravitational field variables from general relativity and the electromagnetic field variables from Maxwell’s theory.
  2. Modification of Equations:
    • They modified the gravitational equations to admit regular solutions for the static spherically symmetric case, leading to a representation of physical space by two identical sheets connected by a “bridge,” representing a particle.
  3. Elimination of Singularities:
    • By treating physical space as consisting of two congruent sheets connected by a bridge, they were able to obtain regular solutions free from singularities, even for elementary particles without mass.
  4. Interpretation of Particles:
    • In this model, an elementary particle (like a neutron or neutrino) is represented by a spatially finite bridge connecting two sheets of space. This approach provides a representation of particles using only field equations, without introducing new field quantities to describe matter density.
  5. No Negative Mass Particles:
    • The theory naturally explains why particles of negative mass cannot exist. Solutions corresponding to negative mass do not allow for the formation of a regular bridge.
  6. Multi-Particle Systems:
    • The model suggests that multi-particle systems could be represented by multiple bridges connecting the two sheets, though this aspect requires further investigation.
  7. Charge and Mass Independence:
    • The solutions showed that the electrical charge and mass are independent constants of integration. The most natural elementary charged particle in this theory is one without mass.
  8. Significance:
    • The theory aligns with the goal of achieving a unified field theory where particles and their motion are entirely described by the fields, without the need for additional postulates about particle motion.

Conclusion

Einstein and Rosen’s paper presents a novel approach to resolving the particle problem in the general theory of relativity by eliminating singularities and interpreting particles as bridges between two sheets of space. This method offers a potentially more coherent and unified field theory that integrates gravitational and electromagnetic phenomena without singularities .