---
title: "Physicists propose MAGIC model against time travel, but discover instability"
description: "Physicists from the University of New Hampshire have published a MAGIC model in Physical Review D based on metric-affine gravity, which excludes closed timelike curves under specific conditions. However, the model suffers from an unstable scalar regime and only operates in a limited space."
date: 2026-11-11T18:10:18.934Z
lang: en
url: https://xab.info/en/posts/physicists-magic-model-time-travel
tags: [time-travel, gravity, physics, spacetime, paradox, general-relativity]
author: "Alexander Buran"
publisher: "XAB.info"
---

# Physicists propose MAGIC model against time travel, but discover instability

![Holographic display with formulas and time paradox diagrams in a modern scientific laboratory.](https://xab.info/media/2026/11/11/fiziki-magic-model-puteshestviya-vo-vremya/fiziki-magic-model-puteshestviya-vo-vremya-1.webp)

## Key Points

- Mustafa Ismail and David Mattingly (University of New Hampshire) proposed the MAGIC model in metric-affine gravity, which excludes closed timelike curves
- The model is published in Physical Review D and implements Hawking's chronology protection conjecture at the level of internal gravitational dynamics
- Key issue: the scalar regime of gravitational waves in MAGIC does not decay but amplifies, making the model dynamically unstable
- Protection against time loops is limited to a specific region of space; additional assumptions are needed for cosmological scales

One of the most persistent paradoxes of theoretical physics — the so-called grandfather paradox — may receive a rigorous mathematical explanation. Physicists Mustafa Ismail and David Mattingly from the University of New Hampshire have published a paper in the journal Physical Review D, in which they propose an alternative model of gravity capable of making backward time travel fundamentally impossible. The study, which explains how to potentially resolve this, relies on metric-affine gravity theory and introduces a model called MAGIC (Metric-Affine Inflationary Cosmology with chronology protection). Under certain conditions, this model does not allow for the formation of closed timelike curves: time along any allowed trajectory moves only forward, which precludes returning to the past.

### From the Grandfather Paradox to Hawking's Hypothesis

The essence of the grandfather paradox is simple yet devastating to the naive concept of time travel: if a traveler kills their own grandfather before their father is born, they never appear in the world and, therefore, cannot make the trip. In 1992, Stephen Hawking formulated the chronology protection conjecture, according to which the laws of physics do not allow the emergence of closed timelike curves — trajectories that allow one to return to the past. However, Einstein's general relativity does not mathematically exclude the existence of such paths, and for more than three decades, physicists lacked a clear mechanism explaining exactly what prevents their formation. The MAGIC model claims to fill this gap, shifting the prohibition to the level of the structure of gravitational interaction itself.

### How the MAGIC model works

Unlike standard general relativity, where the spacetime metric and the affine connection (a mathematical object describing how vectors are carried between points) are rigidly linked, metric-affine gravity allows them to be described independently. Ismail and Mattingly used this freedom to build a model in which the geometry of spacetime and the "rules of parallel transport" evolve separately. As a result, in certain regimes, the model automatically imposes a ban on closed timelike curves: any worldline an observer might follow moves monotonically toward the future, and a "loop" closing the trajectory into the past becomes mathematically impermissible. Thus, chronology protection arises not as an external constraint, but as an intrinsic property of gravitational dynamics.

### The weak point: scalar regime and instability

Despite the elegance of the approach, the MAGIC model carries a serious internal problem. In metric-affine theory, besides standard tensor gravitational waves, an additional type of oscillation appears — the scalar regime. According to the authors' calculations, these oscillations do not decay under certain conditions but rather grow exponentially. This means the model becomes dynamically unstable: small perturbations in the scalar field grow over time, making it impossible to use MAGIC as a stable description of the real universe. Furthermore, the guarantee of protection against time loops in the current formulation applies only to a limited region of space. To extend the principle to the entire cosmos, researchers will have to introduce additional assumptions about global topology or boundary conditions, which significantly complicates the theory.

### A first step toward a holistic theory

The authors of the study honestly admit these limitations and do not claim that MAGIC is already the definitive theory of gravity. They position the work as a first step toward a more holistic model which, in the future, should explain why time travel to the past is impossible not by the "will" of some external law, but due to the internal structure of gravitational interaction. The publication in Physical Review D — a peer-reviewed journal among the most authoritative in physics — confirms that the approach is recognized by the scientific community as worthy of attention, even if its practical applicability remains in question. Further work, by the researchers' own assessment, will be aimed at suppressing the unstable scalar regime and expanding the scope of chronology protection to cosmological scales.

## Fact-Check & Sources

- [Физики ищут защиту от путешествий во времени: у новой модели нашли слабое место](https://www.rbc.ua/ukr/news/fiziki-shukayut-zahist-vid-podorozhey-chasi-1794411118.html) - Source: description of the MAGIC model, authors, Physical Review D journal, Hawking's 1992 hypothesis, scalar regime issue, and limited scope. All key facts in the article rely on this source.
- [ВШЭ присоединилась к поискам "новой физики" на китайской установке BESIII](https://tass.ru/nauka/28124869) - Source concerning HSE participation in the BESIII experiment. It has no relation to the MAGIC model or the grandfather paradox and is not used in the article.

## FAQ

### What is the grandfather paradox?

It is a logical contradiction arising from the assumption of backward time travel: if a traveler kills their grandfather before their father's birth, they are never born and cannot perform the travel. The paradox demonstrates that a naive concept of free time movement leads to logical contradictions.

### What is the MAGIC model and who proposed it?

MAGIC is a gravity model proposed by Mustafa Ismail and David Mattingly from the University of New Hampshire. It is based on metric-affine gravity theory, where spacetime metric and affine connection are described independently. Under certain conditions, the model forbids closed timelike curves, thereby implementing chronology protection.

### What is the main weakness of the MAGIC model?

The model features an additional scalar regime of gravitational oscillations which, according to the authors' calculations, does not decay but amplifies over time. This makes the model dynamically unstable and currently unable to reliably describe the universe as a whole. Additionally, the protection against time loops only works in a limited area of space.

### Why does general relativity not solve the time travel problem?

Einstein's equations mathematically allow for the existence of closed timelike curves in some solutions (e.g., in Gödel metrics or inside rotating black holes). However, the physical mechanism that should forbid such configurations is not formulated within standard GR. The MAGIC model attempts to provide such a mechanism at the level of an alternative gravitational theory.