Despite his small stature, it is not recommended to touch Master Yoda: for all his modest size, he is a dangerous opponent even for the mighty Darth Vader. There is clearly much more hidden in him than might seem when looking at his childish figure.
Physicist and Wired columnist Rhett Allain drew attention to what is happening in one of the iconic scenes of the fifth episode ("The Empire Strikes Back"), in which Yoda teaches young Luke Skywalker how to control the Force. While the young Padawan does a one-arm stand, the Jedi Grandmaster balances on his extended leg (in the video at 0:58).
© Lucasfilm / 20th Century Fox
What's so special about this scene? The fact is that from the point of view of mechanics, it has everything you need in order to assess the weight of Master Yoda. "The Luke-Yoda system is completely balanced," explains Rhett Alain, "which means that its center of mass is exactly over the arm that Luke rests on."
There are only two assumptions to be made. Suppose that the planet Dagoba, on which the training takes place, has a mass approximately equal to the mass of the Earth (otherwise Luke would have had a hard time), and Luke himself has the size of an average person (height 175 cm, weight 68 kg). The typical distribution of a person's weight in individual parts of his body and limbs is known quite well, as are their standard sizes relative to the whole body: for example, the leg from the pelvis to the knee is 20% of the height and 15.5% of the weight. It remains to carry out the calculations.
The result is really fantastic: calculations show that Yoda weighs -43, 7 kg. Yes, the master (at least in this scene) has negative mass, otherwise Luke would not be able to balance in this position. It looks like he's using the Force.
“In fact,” says Rhett Alain, “if Luke had tried to balance in this position without Yoda creating an upward force, he would have failed. Its center of mass is displaced to the right of the supporting arm by as much as 12 cm, it would have turned over."
The main question arises: why does Yoda, teaching the Padawan to use the Force, use it himself, instead of forcing the student to turn to it?.. "Perhaps Yoda is just helping Luke to console himself and pull himself together after an unsuccessful fall in the cave", - suggests Alain. There is a very wise teacher!