Sheldon, accompanied by Leonard, Howard, and Raj, leads an expedition to the North Pole, leaving in May of 2009. The boys work from a science station built on the ice. According to Sheldon, the research they're doing involves looking for evidence of slow moving magnetic monopoles, which, if detected, would confirm string theory. It's the possibility of becoming famous for this discovery which motivates the guys to actually venture out of their comfort zones and into the Arctic cold.
While they use a food freezer at the Cheesecake Factory to acclimatise themselves to the cold (a restaurant freezer is normally kept between 10 and 20 degrees below zero), the actual temperatures at the Pole in summer averages around 32 degrees F. The sun doesn't set at the Pole until sometime in September. Polar bears, which Sheldon suggests could be a danger, don't typically travel as far north as the Pole due to a lack of available prey.
The episode isn't clear about where the research is really being carried out. More than once, their destination is referred to as the "North Magnetic Pole". If they are actually working at the North Magnetic Pole, they're somewhere in the ocean off the coast of northern Canada and not really very near the actual North Pole. They'd better hope they're at the Magnetic North Pole. Scientists speculate that the North Pole itself might well be ice-free during the summer of 2009 ...