Einstein's contribution post 1915

[jmatt]

Did Einstein contribute anything novel (or fundamental or of lasting importance or ... you know what I mean!) to physics after GR?

 

[Mentz114]

Did Einstein contribute anything novel (or fundamental or of lasting importance or ... you know what I mean!) to physics after GR?

yes, lots. In my opinion his paper of 1916, "On the Quantum Theory of Radiation" is ground breaking.

First published in the journal Mitteilungen der Physikalischen Gesellschaft Zurich (18) it was reprinted in 1917 in Phys. Zs. 18(1917).

In this paper Einstein invents the ideas of stimulated emission and spontanous emission, and shows that light quanta must exchange momentum when being absorbed or emitted. He makes the prescient remark that some future quantum theory would explain these, and he hoped remove the 'unpredictability' he introduced.

In 1933 Dirac did the first ( he also found the two modes of emission/absorption) - but could not remove the 'chance'. Einstein was the first to roll Gods dice.

 

[jmatt]

Thanks Mentz114 very interesting reply. The man was a true giant!

If you don't mind ... did anything useful come out of his work on a unified field theory? I understand he believed all physics could be described with geometry as he achieved with gravity. Did any that work contribute to physics?

 

[Mentz114]

Thanks Mentz114 very interesting reply. The man was a true giant!

If you don't mind ... did anything useful come out of his work on a unified field theory? I understand he believed all physics could be described with geometry as he achieved with gravity. Did any that work contribute to physics?

He had some desiderata that he did not achieve. He tinkered with tele-parallelism and other gravitational theories but abandoned them. I'm sure others will have something to say about this.

The problem is that SR and GR are very hard acts to follow.

 

[jmatt]

desiderata - one of the most haunting words in English.

 

[PeterDonis]

Did Einstein contribute anything novel (or fundamental or of lasting importance or ... you know what I mean!) to physics after GR?

The EPR paper, published in 1935, has certainly had lasting importance in quantum mechanics.

 

[jmatt]

Thanks all. It was the EPR paper that led to Bell's theorem as a response.

 

[Mentz114]

Bose-Einstein condensation, 1925. In the experiments ( first in 1996 ), the exchange of momentum between light-quanta and ions is used to slow down the ions to bring the temperature to a tad above 0K.

 

[NanakiXIII]

Einstein published what I think were the first detailed treatments of the post-Newtonian expansion of GR in 1938, 1940 and 1949. Perhaps not as ground-breaking as some of his quantum work, but those first results are the foundation of an extensive modern PN formalism used in gravitational wave research.

 

[bobc2]

Einstein and Unified Field Theory

History may eventually decide the impact of Einstein's work on unified field theory. My hunch is it will ultimately be decided that Oppenheimer, Bohr, Schroedinger, and others greatly betrayed the understanding of what physics is and what the pursuit of theoretical physicists is all about when they relagated Einstein to the ash heap of metaphysicists.