The most dangerous type of light that we can't see is generally considered to be ionizing radiation, which includes gamma rays and certain types of X-rays.
Ionizing radiation has high energy and can cause significant damage to living cells and DNA. It can lead to radiation sickness, genetic mutations, and an increased risk of developing cancer. However, it's important to note that the danger of ionizing radiation depends on the dose and duration of exposure.
While gamma rays and some X-rays are invisible to the human eye, their harmful effects make them potentially more dangerous than other forms of light. That said, it's crucial to take appropriate safety precautions and minimize exposure to ionizing radiation sources, such as medical X-ray equipment, radioactive materials, and nuclear reactions.