Comment on work of Umrigar and Anderson "Energy needed to propel a tiny spacecraft to Proxima Centauri, and, an unstated assumption in Einstein's 1905 paper" (arXiv:2502.04331v1)

TL;DR

This paper critiques recent work by Umrigar and Anderson, highlighting that physical limitations, not just technological challenges, could significantly impede the development of relativistic spacecraft for interstellar travel.

Contribution

It emphasizes the importance of considering physical constraints in the design of relativistic spacecraft, an aspect overlooked in prior proposals.

Findings

Physical limitations may hinder relativistic spacecraft development.

Technological obstacles are not the only challenges for interstellar travel.

Physical constraints could be more serious than previously acknowledged.

Abstract

In a recent paper by Umrigar and Anderson, the authors make an important statement: it is possible to misunderstand the behavior of physical objects (parts of a spacecraft) if that object has reached a velocity comparable to the speed of light. Achieving such a velocity for a spacecraft is critical for interstellar travel, since only traveling at such speeds makes travel to distant stars possible within a human lifetime. Last years, several ideas have been proposed to achieve relativistic velocities for a spacecraft. The authors of these ideas understand that this task is very difficult due to technological obstacles. However, when describing these projects, the authors omit mentioning possible obstacles of physical origin. The paper by Umrigar and Anderson is the first to consider physical limitations on construction of future spacecraft. In this Comment, it will be shown that, according to Umrigar and Anderson, not only technological obstacles will arise in the project of interstellar flights, but also the physical limitations of a spacecraft moving at relativistic velocities may become more serious problems for the implementation of such a project.