In Britain, like most of the developed world, stem-cell research is regarded as a great opportunity. America will be left behind if it doesn’t change policy.

Hawking contrasts the UK’s generally permissive, opportunity-focused stance on embryonic stem-cell research with the more restrictive U.S. policy climate of the early 2000s. The quote frames stem-cell science not only as a biomedical promise—potentially transformative for degenerative disease and injury—but also as a matter of national competitiveness. By warning that “America will be left behind,” he invokes the idea that scientific leadership depends on regulatory choices: limiting research can slow discovery, deter talent, and shift innovation to countries with clearer legal pathways and public support for ethically regulated work.