scientists have not physically traveled to other galaxies. The vast distances between galaxies make it currently impractical for human exploration.
However, scientists have gathered extensive observational evidence supporting the existence of other galaxies. They have used powerful telescopes and advanced imaging techniques to study the light emitted by these galaxies. By analyzing the properties of this light, such as its spectrum, intensity, and redshift, scientists can gain insights into the nature, composition, and distance of these distant galaxies.
One of the key pieces of evidence for the existence of other galaxies comes from Edwin Hubble's observations in the 1920s. Hubble discovered that there are numerous galaxies beyond our Milky Way and that they are receding from us, indicating that the universe is expanding. This discovery, known as Hubble's Law, provided strong evidence for the existence of other galaxies.
Since then, astronomers have made significant progress in studying galaxies through various observational techniques, including optical, radio, and infrared astronomy. They have mapped out the distribution of galaxies, studied their structures, and explored their diverse properties.
In addition to observational evidence, theoretical models of the universe, such as the Big Bang theory, also support the existence of other galaxies. These models provide explanations for the formation and evolution of galaxies over cosmic timescales.
While scientists haven't physically visited other galaxies, their understanding of the universe is based on a vast body of observational and theoretical knowledge, which continues to expand as new observations and discoveries are made.