Tesla envisioned a world where electrical power could be transmitted wirelessly across vast distances. He conducted experiments in Colorado Springs and at Wardenclyffe to demonstrate this concept, but his efforts were ultimately unsuccessful in achieving practical, large-scale wireless power transmission.

Tesla spoke of developing a 'death ray,' or particle beam weapon, capable of destroying enemy aircraft and armies. He claimed to have made progress on this project but never produced a working prototype. The existence and feasibility of this weapon remain highly debated.

Tesla was certain airplanes could be greatly improved and contributed to theoretical improvements in his lifetime.

Tesla believed that the Earth resonated at a specific frequency and that it was possible to tap into this resonance to create a global energy grid. While the concept of Earth resonance is valid, Tesla's specific ideas about harnessing it for energy remain unproven.

In his later years, Tesla reportedly explored the possibility of anti-gravity technology. He never published any specific research on this topic, and the details of his ideas remain largely unknown.