Do Souls Exist?: A Gedankenexperiment Trishank Karthik (trishankkarthik@gmail.com) May 1 2006 (Revision: May 2, 2006) Abstract We calculate some physical properties of hypotheti- cal souls, hence presenting some methods for exper- imentally detecting them. Here there be no mon- sters. 1 Assumptions The great Carl Sagan once wrote[7][Chapter 10]: “Keeping an open mind is a virtue – but, as the space engineer James Oberg once said, not so open that your brains fall out.” With this in mind, we assume the existence of souls and observe whether the implications match the known laws of Reality. Souls, whatever they are, are commonly hypoth- esized to be the minimal representation of at least the brains of human beings. Let us simply assume that this representation is physical and: • A soul has a non-zero mass. • A soul is reincarnated over generations. 2 Calculations In Model 1, we consider the mass and density of an individual with an arbitrarily old soul. We say that the total mass of an individual is the sum of its body mass and its soul mass 1 . While the body mass, B, stays constant over each generation, the soul mass increments by a certain constant value, C, in order to store the information of a lifetime. It is easily shown that in any generation t, the total mass of an individual with a soul of age t will have a total mass of B + tC. Supposing that the average human body[5][Section 15.6.1] mass is 1 We construe the soul as a part of the body, so by ‘body’ we mean ‘body without soul’. Figure 1: Model 1 7.142857143 kg (70 N/9.8 ms 2 )[4][Chapter 9] and the average human body volume is 0.06 m 3 and the average soul mass is the average human brain[1] mass of 0.132653061 kg (1.3 N/9.8 ms 2 ), some pro- jections are shown in Figure 1. Given the con- stancy of an individual body volume and increasing mass in each generation, there might eventually be enough density to create a black hole under certain conditions[8]. It is conceivable that while souls reincarnate, the body and soul masses of an individual remain con- stant over the generations and so we do not ob- serve any trend of growth of population mass. In that case, a soul may store the information of, for example, one lifetime no matter how many reincar- nations it goes through (C/tC). Thus in Model 2, we calculate for that case the ratio of how much a soul actually ‘remembers’ compared to how much it could if it ‘remembered’ all of its lives. As seen in Figure 2, this limited 2 soul naturally remembers less as it reincarnates further. In Model 3, we keep track of the body and soul 2 A critic may argue that a soul may somehow contain infi- nite information in a finite volume of space. Ord[6][Chapter 4] notes that it is unclear whether this is physically possible. 1