1. Apple falls on Newton’s head.
2. Newton discovers Law of Universal Gravitation.
1. Apple falls on Newton’s head.
2. Newton publishes the following paper:
On the Impact of a 0.12 kg Apple with the Head
Fig. 1. Experimental Setup
Abstract. We have carried out an experimental study to determine quantitatively the risks faced by people standing under an apple tree. The Collision Induced Pain (CIP) produced by a 0.12 kg apple on the head was measured.
Introduction. Since the early days of Creation, Man has been interested in apples . Its nutritive properties  as well as its potential toxicity have been thoroughly discussed . More recently, apples have found important technological applications . However, little attention has been given to the critical issue of the risks faced by the eventual fruit picker who approaches the branches of an apple tree.
Experimental procedure and results. An experiment was carried out to determine the effect of an apple falling on the head. The experimental setup is sketched in Fig. 1. The experimenter sat under an apple tree for five consecutive days and different intervals of time ∆t (Table 1). On the fifth day an apple fell on the experimenter’s head from a distance d=1.8±0.1 metres. The mass of the apple was found to be M=0.12±0.01 kg. Immediately after the collision the experimenter reported a mild discomfort that decreased exponentially with time as he rubbed his hand against the Apple Impact Area (AIA).
Table 1. Recorded events
On a scale of 0 to 10, the Collision Induced Pain (CIP) was rated as 2.3±0.1 (Fig. 2) and it decreased down to negligible values after a time τ=14.6±0.5 seconds. Some authors suggest that a more vigorous rubbing on the AIA would reduce substantially the Pain Relaxation Time (PRT) , although this theory has been highly disputed. No structural damage was observed in the experimenter’s skull.
Conclusion. A quantitative determination of the effect of an apple falling on the head was carried out for the first time. A 0.12 kg apple falling on the experimenter’s head from a distance of 1.8 metres was found to produce a CIP of 2.3±0.1 arbitrary units. A future development of this work includes the measurement of the CIP induced by apples of different mass and investigating the collision with pears. These studies will be carried out as soon as the author finds a PhD student as he is not very keen on repeating the experience himself.
FIG 2. Plot of the CIP as a function of apple mass (solid square, d=1.8 metres).
Acknowledgments. The author thanks the University of Cambridge (UK) for providing the apple tree.
 Adam et al., Eden J. Nat. Hist. 1, 1 (8000 BC).
 Granny Smith, “1000 recipes with apples”, Orchard Publishers, Appleville, 1964.
 S. White and Seven Coauthors, J. Appl. Witchcraft A: Poisons 7, 2345 (1532).
 Macintosh et al., J. Hort. Comput. 52, 2167 (1973).
 Mrs. Newton, private communication.
Ed. Note: This Zero Gravity was contributed by Ricardo Torres of Imperial College. Since it is, essentially, a work of fiction, we hope our readers will indulge the author and forgive certain anachronisms and historical inaccuracies (e.g., the metric system had not been invented in Newton’s time, and the apple tree was in Newton’s home town of Woolsthorpe, not Cambridge).