This one seems fun:If you’re a fan of “Friends,” the wildly popular television series from the 1990s and 2000s, you are likely to remember the famous “pivot” scene from Season 5, when Ross Geller (David Schwimmer) asks Rachel Green (Jennifer Aniston) and Chandler Bing (Matthew Perry) to help him move a couch up the stairs to his new apartment.

In the scene, Ross keeps telling the others to “pivot,” until Chandler shouts repeatedly for him to “shut up.” It’s funnier than it sounds (see video below). The couch gets stuck on the stairs. They eventually get it up the stairs, but it is wrecked, cut in half. And, yes, he tries to return it to the store.

With moving-in season beginning as colleges start up for the 2018-2019 school year, the U.S. apartment-sharing website SpareRoom asked for help from Caroline Zunckel, an astrophysicist, mathematician and data scientist in academia and the commercial workplace. Her research in astrophysics, incidentally, involved using big data sets to look at models of the universe from its evolution until today, and she says her time in academia at Oxford University, Princeton University and the University of KwaZulu-Natal in South Africa allowed her to refine her skills in research, data analysis, scientific computing, statistics and writing.

All in all, then, she seems to have the skill set to tackle the Ross-couch dilemma. And that’s what she did, analyzing the “pivot” scene to create a mathematical solution to show that the couch could have made it upstairs intact.

Zunckel applied the Pythagorean theorem — which states that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides — to the estimated measurements of Ross’s couch in a vertical position and to the dimensions of the stairwell. 

This is the equation she came up with, called “The Friends Solution” (see infographic below):

Angle of vertical tilt (T) = 44.15064 – 11.94274 x WS (Width of the Stairwell) + 8.69119xWC (Width of the Couch) + 3.65961xLC (Length of the Couch)

Step 1: First Ross should have measured the width of the stairs (WS), and the width (WC) and length (LC) of the couch.

Step 2: Ross then should have used the equation to find out the minimum angle (T) that the couch would need to be tilted upward to move around the 90-degree corner of the stairwell.

Step 3: After carrying the couch to the corner, Ross, Rachel and Chandler reach a point where they can’t move any more. When this happens Ross, Rachel and Chandler should have rested the couch against the corner.

Step 4: Here, the friends should have tilted the couch vertically toward the ceiling until the angle between the stairs and the base of the couch was greater than or equal to T. At this point the vertical length of the couch would be smaller than the horizontal length and they should have been able to successfully pivot the couch round the corner without it getting stuck. 

Step 5: Once round the corner, Ross, Rachel and Chandler should have moved the couch back to its original orientation and then carried it up to the apartment.

This is the PIVOT scene:


This is the solution: