Causality and Unitarity Are Not Violated in Space-Times with an Additional Compact Time-like Dimension

TL;DR

This paper investigates whether causality and unitarity can be preserved in space-times with compact extra time-like dimensions, challenging the assumption that higher-dimensional structures necessarily violate these principles.

Contribution

It demonstrates that causality and unitarity are not inherently violated in theories with compact extra time-like dimensions, contrary to common assumptions.

Findings

Causality and unitarity are preserved in certain higher-dimensional models.

Higher-dimensional laws can determine four-dimensional physical properties.

The paper provides a framework to avoid causality and unitarity violations in extra time-like dimensions.

Abstract

The hypothesis that the causal properties of space-time, as well as other properties of physical systems like unitarity, charge conservation, etc., might be decided by the higher dimensional structure (in particular, higher-dimensional physical laws), rather than by the four-dimensional one, is explored in order to evade the most awkward problems of higher-dimensional theories with compact extra time-like dimensions: violation of causality and of unitarity.