Back-in-Time and Faster-than-Light Travel in General Relativity

In this review of Back-in-Time and Faster-than-Light Travel in General Relativity, the bottom line is clear: this is a specialist, research-oriented book best suited to graduate students and researchers interested in causality, time machines and warp drives. Serguei Krasnikov compiles two decades of focused work and literature review to address the physical and geometrical aspects of causality violation and superluminal motion, making it valuable for readers seeking a rigorous, technical treatment rather than a popular overview.

Key Features

• Comprehensive coverage: The book compiles the authors results and reviews other important work, giving readers a broad yet detailed picture of the field.
• Focused questions: It directly addresses core puzzles such as whether quantum effects protect causality at Cauchy horizons, clarifying current lines of inquiry.
• Practical estimates: The text discusses how much exotic matter would be required for hypothetical constructs like time machines and warp drives, providing concrete order-of-magnitude reasoning.
• Conceptual clarity: Krasnikov examines distinctions such as a discovered time machine versus a created one, helping readers think clearly about theoretical implications.
• Interdisciplinary scope: The book links geometry and physics, treating topics like the speed of gravity and its operational definition in a way that bridges conceptual and mathematical work.

Who It's For

This volume is aimed primarily at advanced undergraduates, graduate students and researchers in general relativity, cosmology and theoretical physics who want a concentrated review of causality violation and superluminal solutions. It is most useful when read alongside technical papers and as a reference for research projects exploring time travel and warp-drive metrics.

Readers seeking a popular science treatment, an introductory textbook or an elementary explanation of relativity should look elsewhere, because the book assumes familiarity with the mathematical language and physical concepts of general relativity.

Pros & Cons

Pros

• Authoritative synthesis: brings together two decades of the author's research for coherent study of causality violations.
• Addresses concrete questions: offers detailed discussion on exotic matter requirements and quantum effects at horizons.
• Useful for research: serves as a focused reference for specialists working on time-travel and superluminal metrics.

Cons

• Not introductory: the technical level and specialized focus make it unsuitable for casual readers seeking nontechnical explanations.

Specifications

Title	Back-in-Time and Faster-than-Light Travel in General Relativity
Author	Serguei Krasnikov
Series	Fundamental Theories of Physics, 193
Subject	Causality violations, superluminal motion, general relativity
Coverage	Compilation of authors results plus review of other work
Focus topics	Time machines, warp drives, exotic matter, speed of gravity

Our Verdict

Back-in-Time and Faster-than-Light Travel in General Relativity is a concentrated, scholarly treatment that delivers strong value for researchers and advanced students interested in causality and superluminal solutions. Its focused synthesis of questions about exotic matter, Cauchy horizons and the speed of gravity makes it a practical research reference, though its technical level limits its appeal to specialists.

Frequently Asked Questions

Is this book suitable for beginners?
Not really; it assumes familiarity with general relativity and is aimed at advanced students and researchers.

Does the book quantify exotic matter needs?
Yes; it discusses estimates and order-of-magnitude reasoning about how much exotic matter hypothetical devices would require.

Does it cover quantum effects on causality?
Yes; the book addresses whether quantum divergence at Cauchy horizons can protect causality.