Here are some ideas that were initially rejected by mainstream science but are now accepted as truth:

The germ theory of disease. In the 1850s, Louis Pasteur proposed that diseases were caused by germs, but his theory was met with resistance from the medical community. It wasn’t until the late 1800s that the germ theory of disease was widely accepted.

The theory of evolution. Charles Darwin’s theory of evolution by natural selection was published in 1859, but it was met with controversy and opposition from religious groups and other scientists. It wasn’t until the early 1900s that the theory of evolution became widely accepted.

The Big Bang theory. The Big Bang theory was proposed in the 1920s by Georges Lemaître, but it was not widely accepted until the 1960s, when evidence from Edwin Hubble’s work on redshifts and the discovery of the cosmic microwave background radiation provided strong support for the theory.

There are a number of reasons why new ideas are sometimes initially rejected by mainstream science. One reason is that scientists are often reluctant to change their minds, even in the face of new evidence. Another reason is that new ideas can be challenging to understand, and scientists may not be willing to invest the time and effort to learn about them. Finally, new ideas can sometimes threaten the status quo, and scientists may be reluctant to support them for fear of losing their jobs or funding.

Despite these challenges, new ideas can eventually gain acceptance if they are supported by strong evidence. The ideas listed above are just a few examples of ideas that were initially rejected by mainstream science but are now accepted as truth.