Sometimes people who are autistic-spectrum have difficulty parsing the implicit meaning of speech, including intonation and body language. Songs are chock-full of conflicting expressions like "Yeah oh no no yeah" and "Oh whoah oh". This actually drives me nuts when I hear it—I think "make up your mind! Is it yes or no?"

Do autistic-spectrum individuals have trouble interpreting lyrics like these? How does it change their experience of music?

One of my professors, Arjendu Pattanayak, used to defer hairy questions in class with “That’s a beer question—meaning, buy me a beer at the pub, and we’ll talk about it.”

In that spirit, I will buy anyone who can explain this as many beers as it takes:

In general relativity, spacetime curvature is proportional to the stress-energy tensor T. T’s components are basically four-momentum density and flux, which are characterized as “momentum” and “energy”. Photons count. So do other particles with with four-momentum. Does anything else contribute? Electrostatics? The vector potential? The strong nuclear force? What is it that makes something contribute to T?