I was too positive, but yes in finance we can understand exactly why they show up in some models, and the solution is to choose models without them, adjust input-parameters such as numbers of time-steps etc to remove negative probabilities. In physics they invented all kind of crap fake interpretations about reality to save their fake probabilities:

*"negative probability was thus replaced with negative mass"* from a Brief History of String Theory!

*"providing a clear example of the negative (or “extended”) probabilities characteristic of quantum mechanics."*
*"This result provides a clear example of the negative probabilities appearing in quantum mechanics and confirms previous findings suggesting that any statistical interpretation of quantum mechanics cannot be based on a plain equivalence between quantum mechanical and classical stochastic processes." Quantum Mechanical versus Stochastic Processes in Path Integration*
*"The main result in the just mentioned paper was the surprising discovery that the renormalized....contains the ghost state -- which has a negative probability."*
*Negative quasi-probability as a resource for quantum computation*

*"Negativity is necessary for magic state distillation."*
why are several finance quants often referring to physics as being much more sound than quant finance?

We are in the magic-mystical age of quantum physics that at some point should be replaced with science and logic? Very advanced curve fitting, no matter how well predictions it gives is not deep science (and I bet it all breaks at the Planck scale)!

"

String theory and string cosmology
"

**At present there is only one known theory of gravity, string theory, that contains fields and matter that manages to give calculable non-negative quantum mechanical probabilities. "**
Assume we can trust the Swedes (??), what do you go for Chuh, evil-strings or fake-negative probabilities?

If one are in the middle of a dark age will one notice it before one are out of the darkness?