Merry Christmas!

So, here is the promised quiz to conclude our seasonal program. It turned out to be not so easy to come up with questions that aren't immediately googleable, but still seemed answerable with an appropriate amount of effort.

1. The light deflection from the sun computed within Newtonian gravity differs from the result obtained in General Relativity by a factor ...
   
   (If your answer is smaller than one, take the inverse).



2. The ratio of these both scientist's name is the commonly used symbol for ....
   
   
   
   

   /

   
   
   [My husband complains this might be too tough, so here is a hint. The first guy is a Dutchman and you're supposed to know his name if you've made it through the physics undergrad courses. The second guy had something to do with geese. Don't bother checking the source code for the filenames.]
   



3. "I didn't attend the funeral, but I sent a nice letter saying I approved of it." ~ Mark Twain
   
   Is an example for .......
   
   Take the first four letters.



4. Two divided by zero. Always on my mind. I wouldn't normally do this kind of thing. It's a ...



5. Electromagnetism is the gauge theory of the group .... Drop the first letter.

Write down your answers in one line, add two spaces in the right places and translate into Greek.

The first correct answer wins a PI mug, see photo. And no, I didn't steal it in the kitchen, I actually bought it. (If you are not willing to provide a mailing address, or aren't interested anyhow, please do not post your answer in the comments). A Merry Christmas and nice holidays to all of you!

Update: The mug is gone, congratulations to Samuel! If you want to continue guessing, spoiler warning: the correct answer is in the comment section.