what are the theories or equations Albert Einstein try to put together into one unified field theory?

Question

Physics...doing research on Albert Einstein

Answer 1

Einstein was the one to formulate the cosmological constant.
Unfortunately he was diverted on the Basis of Hubble who indicated that Galaxies in the Universe were receding form the earth. Hence he negated and scraped the cosmological constant as a blunderous mistake.
He did not realized that the answer to a Unified theory really was inherent in the cosmological constant. So the whole secret of a Unified Theory lies in the cosmological constant and Dr Albert Einstein failed to realize it.
Its like looking for your glasses when you really had them on all the Time.

Answer 2

Unified field theory must incorporate all four known forces of nature in a relationship that shows (mathematically) how each separate and distinct force acts. At present, gravity remains the odd-man-out. Consider that Einstein's Relativity Theory and Quantum Theory are the two most robust theories ever invented by mankind, yet they appear to be incompatible in a serious way. Einstein spent many years trying to incorporate gravity and could not. Contemporary physics has only just begun to understand why, and what may have to change in our understanding of the universe.

Answer 3

To be clear, it was
1-Quantum (field) theory which describes the 3 of fundamental fields: electrodynamics (QED), weak (these two--QED and weak--are described by a unified framework of quantum field theory called electroweak theory), strong (described by QCD).
2-Einstein General relativity describing the 4th fundamental field: Gravity.

Gravity is the odd one because the other three describe the fields as fields of some particles (on space-time) acting on each other but gravity is described not by a field of particles on space-time, but by the dynamics of spacetime itself!

If you unify quantum field theories and gravity (quantize gravity), then some serious problems arise, for example the causal sructure of space-time (the difference between past and future and also causality), loses its meaning because you apply (uncertainty principle of) QFT to the (causal) structure of space-time itself.