Why is infinity an unacceptable answer? (see details...)

Question

When trying to combine general relativity and quantum mechanics you often get nonsensical answers such as a prediction that the quantum mechanical probability for some process is not 20 percent but infinity. What does a probability greater than one mean, let alone one that is infinity?

The above is a paraphrase from a book I'm reading...can you help me understand what it means and why infinity is not a acceptable answer?

Thanks!

Answer 1

its uncertainty...

Answer 2

You cannot have a probability greater than one. I suggest that you redo your calculations because you probably made a mistake somewhere

Answer 3

You might be reading up about the Klein-Gordon equation, which is the relativistic version of the Schrodinger Wave Equation.  That's one of its difficulties, the total probability doesn't add up to 1. This is the reason why Schrodinger rejected this equation when he first studied it.  Dirac resolved this difficulty by coming with with a first order variation of the KG equation (Dirac Equation), which offers more well behaved solutions---even though it implied the existence of negative energy states and antimatter.  What does it mean for something to have a probability greater than 1?  Let's say that a bag contains colored marbles, and you ask what is the probability of pulling out, say, a blue one?  If the probability is 1, that means anytime you pull out a marble, it's blue.  If it's greater than 1, then that means anytime you pull out A marble, you actually end up having MORE than one blue marble!  As nonsensical that seems, this reinterpreted version of the KG equation has become the successful basis of quantum field theory, where we deal with spontaneous pair production of virtual particles.

The concept of infinity is almost always a nuisance in theoretical physics.  Early work in computing the expected probabilities in quantum field theory was hampered by infinite results, so that an arbitrary work-around was devised to make these useless infinities go away, and actually produce good results that agree with experimental obsevations.  In mathematics, the concept of infinity is powerful and a necessary part in many branches, but in theoretical physics, it's employed only because it needs the same kind of math to carry out its work.  But I know of no example in physical theory that depends on the existence of mathematical infinity.  In other words, there's little or no distinction between the findings of Theoretical Physics A that employs mathematical infinity, and Theoretical Phyisics B that uses the same only as an approximation.  

Answer 4

because infinity practically means nothing the answer will never stop going