人类进行星际旅行面临多重科学障碍，使得离开太阳系的前景极为黯淡。前往距地球最近的恒星系统阿尔法半人马座需要约19,000年，这意味着需要600至2700代人[1]。该恒星系统距离地球4.3光年，约合25万亿英里[1]。
长期太空生活对人体造成的伤害是另一个关键制约因素。宇航员在太空中骨质密度平均每月下降1至2%[1]，而在失重环境中出生的婴儿会出现心率减缓、平衡能力受损等主要生理缺陷[1]。国际空间站的宇航员因辐射病和癌症风险，停留时间仅限于6至9个月[1]。即使任务成功抵达比邻星B，该星球重力为地球的两倍，可能对人体造成严重影响[1]。
此外，地球气候变化对人类发展星际技术的时间构成压力。即使立即停止所有温室气体排放，大气中二氧化碳水平恢复到工业革命前的水平也需要65,000年[1]。这表明人类面临有限的时间窗口来克服技术和生物学障碍。
Interstellar travel presents insurmountable scientific obstacles that could prevent humanity from ever departing the solar system, according to analysis of the fundamental challenges involved in space exploration.[1] The nearest star system, Alpha Centauri, lies 4.3 light-years away—approximately 25 trillion miles—and reaching it with current technology would require roughly 19,000 years and span 600 to 2,700 generations of travelers.[1]
The biological barriers to long-duration spaceflight pose particularly severe constraints. Infants born in microgravity environments would experience significant developmental defects, including reduced heart rate and impaired balance.[1] Astronauts endure bone density loss averaging 1 to 2 percent monthly during space missions,[1] and current radiation exposure limits force extended stays in orbit to last only 6 to 9 months aboard the International Space Station to prevent disease and cancer risks.[1] Even reaching a destination like Proxima Centauri b would present additional hazards, as that planet's gravity may be twice that of Earth and could cause severe physiological damage to human inhabitants.[1]
Compounding these biological constraints is the matter of time. Earth's climate damage would require 65,000 years of recovery to restore atmospheric carbon dioxide levels to pre-industrial concentrations, assuming all emissions cease immediately.[1] This extended timeline means humanity faces insufficient time to develop the necessary interstellar technologies while addressing the environmental consequences already underway on its home planet.