412 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1964 



bullet would be 'made' at the instant of firing by the powder, and 

 would share the energy of the powder charge with the ordinary bul- 

 let." His friends glance at one another in amusement, but he continues, 

 "Now if this new little bullet never travels down the barrel hut always 

 leaves the gun through the sides and hack of the hreech, then we could 

 keep our rules for the energy of a powder charge and explain the shape 

 of the pile of spent bullets in front of us." 



The idea is met with astonishment. How could any sane bulletmaker 

 seriously propose such a wild thought as this? Surely, this is just 

 a strained excuse for holding onto obsolete rules concerning the amount 

 of energy available in a given weight of powder. 



But another friend in the group speaks up. He says, "Let us assume 

 that this 'ghost bullet' idea is correct. Let us write an equation which 

 relates the distance the ordinary bullet travels with the direction of the 

 recoil of the gun and the amount of recoil, assuming that a ghost 

 bullet does travel off at some strange angle each time. We'll assume 

 that the powder makes the ghost bullet as it burns." 



When this is done, it is found that the same equation always describes 

 the situation correctly. It says how the recoiling gun and the ordinary 

 bullet are to act. They always do so. It correctly describes the shape 

 of a pile of spent bullets. It even suggests the rules for making new 

 powders that also behave strangely and predicts their spent-bullet 

 pile very well. 



And so the attitude of the assembly of bulletmakers changes. They 

 say, "This man's theory is correct in telling us about the pile of bullets 

 and the recoil of the gun. It preserves our old rules for these things." 



Thus it comes to pass that the Guild of Master Bulletmakers starts 

 making bullets once again as if they really believe in their recipes 

 for gunpowder. Every now and then a batch of strange powder is 

 made by accident. Then they recall the ghost bullet and say, "The 

 little bullet is being made here, too." Sometimes they have to say 

 that tiuo little ghost bullets are being made in order to explain a par- 

 ticularly strange batch of powder. 



When other friends ask them about the little bullet, they become 

 a bit evasive, pointing out how accurately they can describe the funny 

 recoils and the strung-out pile of spent bullets. "Of course, the little 

 ghost bullet exists !" they exclaim. Then, a bit wistfully, some might 

 be heard to say, "But it would be nice to find one someday." 



PAULFS SUGGESTION: A LITTLE GHOST PARTICLE AND THE FERMI-DIRAC 



THEORY 



Energy was being lost from beta decay that was not to be found in 

 the beta particle. This much was clear. There was widespread dis- 

 cussion of the problem, and some suggested that the laws of conserva- 

 tion of energy and momentum either failed when events occurred in the 



