Since 1930, efforts have been made to get our best theory for gravity - general relativity (GR) - to work with our best theory for atoms - quantum field theory (QFT) in the forms quantum electrodynamics (QED) and quantum chromodynamics (QCD).  In this comparatively short blog, I will frame the struggle and let people provide their own speculations in the comments (mine will reside there too, so it will be easy to skip if you would like :-)

Consider three physicists: Feynman, Weinberg, and Hawking.

All are so far better in depth and breadth of their understanding of general relativity and quantum field theory than you are I (in particular) will ever be.  They devoted much effort toward this goal but have yet to resolve the gap.

Here are five possibilities for the chasm that remains despite diligent work on the subject:

1. GR and QFT are right.  A new bridge must be constructed between the two.
2. GR is wrong or incomplete and QFT is right.  A new theory for gravity is needed that shares a long list of properties with GR.
3. GR is correct and QFT is wrong or incomplete.  A new theory for atomic processes is needed that shares a considerably longer list of constraints put in place by QED and QCD.
4. GR and QFT are wrong or incomplete in the scientific sense of needing to be replaced by proposals that are only ever so slightly better in specific technical situations than GR or QFT.
5. Other than the above, because right or wrong does not feel like the right way to characterize the issues between GR and QFT.

Please feel free to cite the numbers in the comments.  Where would one place work on strings?  Loop quantum gravity?  Non-commutative geometry?

A two strike rule is in place for those who wish to claim they have figured out everything already.  I would prefer that if you are of that opinion of your work, you should sign up and start blogging at Science20.com.  That's what I did and now I don't have a theory on the table, which is better than selling t-shirts that are wrong.

Doug

Next Monday/Tuesday: 4-Parameter Analytic Animations, Solid Man