1930s: Technology still has limited, though powerful, uses in warfare; a war must be won largely from the strength of armed forces, with technology playing a secondary role.

Today: The United States uses advanced technologies in its bombing campaigns against Iraq and Afghanistan, thus severely limiting the need for ground troops directly engaging in battle.

1930s: The world has still not been exposed to the threat of nuclear annihilation. Nuclear fission is viewed as impractical, and Einstein's theory of relativity is still a concept remote from everyday life

Today: With the help of Einstein's theories, many nations have nuclear capabilities and can cause the destruction of mankind. Atomic testing in certain desert and ocean regions has had a lasting and adverse affect on the environment, and the threat of nuclear war between states continues to exist.

1930s: Alexander Alekine, Mikhail Botvinnik, and José...