What technologies are close to the bottleneck and have not made major breakthroughs for a long time?

? Human beings have been engaged in scientific research since ancient times, and it has developed for thousands of years, especially since the First World War. However, the scientific and technological progress of all countries cannot be endless, because there will be bottlenecks for various reasons.

What I want to talk about today is the field of energy utilization. Because energy utilization accounts for more than 80% of the world, all kinds of cars, ships and planes, including electricity used in our lives, are all consumable energy, but how to improve energy utilization? Decades have passed since the Second World War, and there is still no breakthrough in this issue.

? In the use of ordinary energy, such as oil, which we commonly use, this energy is a consumable and will be used less. Oil has been used since the first car and the first plane were invented. For a long time, scientists all over the world have been studying ways to enhance the utilization rate of oil or new energy sources that can replace oil, but even so far, there is no alternative high-efficiency new energy sources. Jet planes consume several tons of fuel in two hours, and cars consume more than ten liters of oil when traveling 100 km. The problem of energy consumption has always been an insurmountable gap in the scientific community, which may be the bottleneck of the scientific community. In terms of energy utilization in the field of military aerospace.

? Nuclear energy is the main energy source in the field of military and aerospace. Since Einstein put forward the formula of mass-energy conversion in 1905, the utilization of nuclear energy has made great progress, but in the 50 years since World War II, it has basically stayed on nuclear fission, with no new progress. Today, nuclear submarines, aircraft carriers, nuclear power plants and other fields that use nuclear energy are basically nuclear fission energy. If you want to pursue higher energy efficiency, the purpose is to study nuclear fusion, but with the current technology, it will take at least 300 years, and more advanced energy such as dark matter energy will take at least thousands of years.