Originally posted by AndersHermansson
If the light reaching us from a distant galaxy is said to has been traveling for 12 billion years, then it is said to be 12 billion light years away. Did someone forget to consider the fact that the galaxy has been moving away from us in the meantime? The distance must be at least the double.
Originally posted by Mentat
That's why they always say that we are only seeing things as they were 12 billion years ago.
The age of a distant galaxy can be determined by measuring its distance and using the redshift of its light. Redshift is a phenomenon where the wavelength of light is stretched as it travels through space, and it can be used to calculate the galaxy's velocity and distance. By knowing its distance, we can estimate the time it took for the light to reach us, giving us an idea of the galaxy's age.
The "double" refers to a phenomenon known as gravitational lensing. This occurs when the light from a distant galaxy is bent and distorted by the gravitational pull of a massive object, such as a galaxy cluster, in between us and the distant galaxy. This can create two or more images of the same galaxy, appearing as if it is "doubled". By studying these distorted images, we can gather more information about the distant galaxy, including its age.
Knowing the age of a distant galaxy can provide us with valuable information about the evolution of the universe. By studying the age and properties of different galaxies, we can better understand how galaxies formed and evolved over time. This can also give us insights into the formation of our own Milky Way galaxy and the conditions that led to the creation of our solar system.
While we can estimate the age of a distant galaxy using redshift and other techniques, it is important to note that these estimates may not be entirely accurate. There are many variables and uncertainties that can affect the accuracy of our calculations, such as the accuracy of our distance measurements and the effects of dark matter. However, with advanced technology and further research, we are constantly improving our methods for determining the age of distant galaxies.
Aside from gravitational lensing and redshift, the age of a distant galaxy can also be affected by its size, composition, and environment. Larger galaxies tend to have older stars, while smaller galaxies may have younger stars. The chemical composition of a galaxy can also affect the rate of star formation and the lifespan of its stars. Additionally, the environment of a galaxy, such as its proximity to other galaxies or the presence of galactic collisions, can also impact its age and evolution.