Textbook: The Physics of Interstellar Travel

A comprehensive guide to the physics of getting an uncrewed spacecraft to nearby stars, suitable for both students and researchers.

What is the physics behind getting a spacecraft to the nearest stars? What science can it do when it gets there? How can it send back data over enormous distances? Drawing on established physics, Coryn Bailer-Jones explores the various challenges of getting an uncrewed spacecraft to a nearby star within a human lifetime. In addition to propulsion methods such as nuclear rockets and laser sails, this book examines critical issues such as navigation, communication, and the interstellar medium. Starting from fundamental concepts, readers will learn how a broad spectrum of physics – ranging from relativity to optics, and thermodynamics to astronomy – can be applied to address this demanding problem. Assuming some familiarity with basic physics, this volume is a comprehensive and self-contained introduction to interstellar travel, and an indispensable guide for studying the literature on deep space exploration.

This book will be published by Cambridge University Press in May 2026. It will be available both as open access as an eBook (ISBN: 9781009700429) and to purchase in printed form (ISBN: 9781009689328). Click here for the table of contents.

Here is some additional material related to the book, which I will update from time to time.

Summary videos

You can watch a brief summary video of each chapter on my youtube channel.

Supplementary data

If you want to reproduce any of my results, you might want to know the values of physical and astronomical constants I used. They are given in this R file. Some of these values may differ slightly from other sources. For example, my value of the Earth surface gravity of 9.80103 m/s^2 is slightly lower than the ISO 80000 value of 9.80665 m/s^2, because I derive it from the Earth's mass and equatorial radius. Such small differences should be of no practical consequence in the book.

Errata

None yet found, but will be listed here when they are. If you think you've found a mistake, send me an email.

Teaching

For many years I have taught an undergraduate lecture course on this topic at Heidelberg University (see here). I will next teach this as a Masters level seminar course in summer semester 2026.

Related work

I cover the space elevator in my intersellar travel lecture and seminar, but I didn't include it in the book. The slides of my lecture are available here.

Related publications

I have published a couple of papers on the topic of interstellar travel. The first concerns the use of the sundiver concept to accelerate a solar sail to a large escape velocity. The second looks at using a stellar catalogue to enable us to navigate autonomously within interstellar space using relatively simple measurements.

Exoplanet updates (last updated April 2026)

Table 2.1 in the book lists all known stars and brown dwarfs within 12.1 ly of the Sun, as well as their known exoplanet companions, as of 7 July 2025. As I note in the book, the field of exoplanets is evolving rapidly, so this list of exoplanet was expected to evolve. And so it did. In early August 2025, just a few days after I had submitted the manuscript to the publisher, there was a tentative announcement of the detection of a giant planet in the habitable zone around Alpha Centauri A. This was obtained using the coronagraph on the MIRI instrument on JWST as reported by Beichman et al. (2025) and Sanghi et al. (2025) (see also this summary). The authors refer to it as a `candidate', because the detection is tentative, having been observed in only one of three epochs. But they suggest it may correspond to a detection made by the VLT in 2019, as reported by Wagner et al. (2021), although those authors were cautious and warned that their detection might well be an intrumental artefact. While potentially exciting, these results are preliminary and need to be confirmed (or not) with additional data.

I list Proxima Cen d as having one confirmed planet, 'b', and two candidates, 'c' and 'd'. The paper by Suárez Mascareño et al. (2026) confirms 'd' as a real planet and also reconfirms 'b', although they find no evidence for 'c'. Interestingly, this paper was published online on the same day that I submitted the manuscript to the publisher, so I just missed updating my table.

The planet in the GJ 65 AB system was discovered astrometrically by observing the perturbation of the mutual orbit of the two stars, A and B, by VLTI/GRAVITY . This does not allow us to identify which of the two stars the planet is orbiting. The authors of the discovery paper don't give this candidate a name, so I simply refer to it as 'a' in Table 2.1 Exoplanet labelling usually begins with 'b' ('a' is implicitly the host). If and when it is confirmed, and the host identified, it would be called Ab or Bb, or potentially some other lower case letter if other planetary companions are found first.

Extra exercises

Some additional exercises can be found here.

Extra references

An appendix in the book list the sources I used and gives some pointers for further reading. Below is a selection of publications that are not listed in the book, but which I think add significantly new or useful information.