Einstein
Einstein
[Cueball and friend eating at a table.] Cueball: I'm currently conducting an experiment which may prove Einstein wrong! Friend: Ooh, exciting!
1947: [Einstein and Cueball walking.] Einstein: It's impossible to find a good sandwich in this town.

In this comic Randall is playing with the notion that since Einstein contributed so much to society, and many of his works have withstood testing, disproving Einstein must be a difficult task. This is proven false by taking a mundane declaration by Einstein and proving it false with a simple task.
Nobel laureate and Time Person of the Century Albert Einstein is often considered one of the smartest and most influential people in world history. His theories have revolutionized our understanding of the universe and inspired generations of scientists. In this comic, Cueball indicates to a friend that he is working on an experiment that may disprove Einstein. The implication is that Cueball is conducting a serious scientific experiment which may disprove one of Einstein's scientific theories. The second frame, however, implies that the Einsteinian "theory" Cueball's experiment may disprove is an offhand (and subjective) remark by Einstein about the availability of good sandwiches; this is not to mention the possible changing in quality of said sandwiches over time.
The experiment Cueball is "currently conducting" probably refers to the fact that he is currently eating a sandwich, and if that sandwich was indeed a good one, Einstein would be proved wrong. Part of the humor here is that Cueball's friend probably assumes that when Cueball says "currently," he means the experiment is part of Cueball's work, not what he is doing at that exact moment.
In 947: Investing , Randall comments on how people put too much credence in a joke Einstein made in passing, and in 799: Stephen Hawking we see Stephen Hawking in a similar predicament, every word he says taken as a major declaration.
The title text demonstrates the ability to "disprove" Einstein while not challenging his scientific work but rather one of his decisions in his capacity as a patent clerk at the Swiss Patent Office at the time he published his first major papers (previously alluded to in 1067: Pressures ). According to the Einstein FAQ on the Swiss Federal Institute of Intellectual Property's website, patent #39561 is one of several patents that "we can assume ... were personally examined by Einstein". A PDF of the patent, which was indeed a gravel sorter ( trommel ), can be found here in German.
[Cueball and friend eating at a table.] Cueball: I'm currently conducting an experiment which may prove Einstein wrong! Friend: Ooh, exciting!
1947: [Einstein and Cueball walking.] Einstein: It's impossible to find a good sandwich in this town.
