# Professor Nagabhushana Prabhu has recently published a paper that potentially solves two major problems in Quantum Field Theory (QFT).

Author: | Nagabhushana Prabhu |
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Despite its many successes, QFT has two major shortcomings. First, several calculations within QFT give rise to infinities. Starting in the 1940s an elaborate—albeit mathematically questionable—framework called *renormalization* was developed to extract finite, physically useful results from the calculations by removing the infinities that arise in them. In 1985 Feynman, one of the architects of renormalization, wrote:

`*The shell *game* that we play … is technically called “renormalization.” But no matter how clever the word, it is what I would call a dippy process! … I suspect that renormalization is not mathematically legitimate.’ *

Dirac, one of the greatest physicists of the twentieth century, expressed similar reservations about renormalization in 1975 with the following words:

`*I must say I am very dissatisfied with the situation, because this so-called “good theory” does involve neglecting infinities which appear in its equations, neglecting them in an arbitrary way. This is just not sensible mathematics. Sensible mathematics involves neglecting a quantity when it is small—not neglecting it just because it is infinitely great and you do not want it!’*

Salam, recognized for his contribution to one of the crowning achievements of the twentieth century—the unification of two of the four known forces, encapsulates physicists’ despondence and `*the “misery” of the infinity problem’* in the following words he co-authored in 1972:

‘*Field-theoretic infinities … have persisted … for some thirty-five years. These long years of frustration have left in the subject a curious affection for the infinities; perhaps even a belief that they will never be circumvented.’*

The second major problem in QFT is that its prediction of the energy density of the so-called vacuum fluctuations exceeds the observational upper bound by a factor of several dozens of orders of magnitude. Professors Efstathiou, Hobson and Lasenby of the University of Cambridge call QFT’s prediction of the energy density of vacuum fluctuations `*probably the worst theoretical prediction in the history of physics!*’. This discrepancy between theory and observation is the infamous *cosmological constant problem, *which is one of the biggest unsolved problems in physics.

Drawing upon the seminal work of Gibbs in statistical mechanics (circa 1906), Prabhu’s paper presents a radically new method for doing QFT calculations. The new method, called *autoregularization*, potentially resolves both of the above problems, while preserving the successes of QFT. First, the calculations in autoregularization are free of the infinities that have plagued QFT since its inception, and thus autoregularization potentially solves the decades-old ‘*infinity problem’*. Secondly, the energy density of vacuum fluctuations of free fields predicted by autoregularization is smaller than the observed upper bound, potentially resolving the cosmological constant problem. In the paper, Prabhu goes on to present preliminary validation studies of autoregularization showing that its predictions are also in good agreement with the results from several other well-known experiments and over a vast range of energy scales.

Notwithstanding the initial successes, Prabhu hastens to add that autoregularization is a new theory and that it needs to be further vetted extensively—that is, its predictions must agree with results from a vaster set of experiments and also at higher orders of quantum corrections—if it is to reform the nearly-a-century-old, deeply entrenched QFT orthodoxy. Prabhu plans to contribute to the continued vetting of autoregularization*.*

Besides high-energy physics the work has potential applications in astrophysics, atomic, molecular and optical physics, including several emerging areas such as physics in the background of high-intensity lasers and around highly magnetic stars called magnetars. Prabhu hopes to demonstrate the possible potential applications of autoregularization in follow-up work.

**Writer: **Nagabhushana Prabhu

**Editor: **Allison Troutner

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