Summary
Highlights
A higher 'Z' value (redshift) indicates that light has traveled longer through space, meaning the galaxy is farther away. For objects at extragalactic distances, redshift is largely synonymous with distance.
The video starts by introducing the farthest galaxy ever seen by humans, whose light has traveled for nearly 13.5 billion years to reach us. This distance is determined by a concept called redshift, denoted by 'Z'.
Cosmological redshift occurs because the expanding universe stretches light waves, making them longer and more red. The longer light travels, the more it is stretched, allowing scientists to determine how long the light has been traveling, when it was emitted, and how far away the galaxy is.
Redshift is measured by collecting light from a galaxy, splitting it into its constituent colors, and identifying missing colors called spectral lines. These spectral lines are unique fingerprints for each chemical element, allowing scientists to know what elements are present and how much their light has been shifted to the red end of the spectrum compared to laboratory measurements.
The galaxy with the highest measured redshift, JADES-GS-z14-0, was discovered by the James Webb Space Telescope with a redshift of 14.3. Using this redshift and cosmic parameters, calculations based on Einstein's general relativity show this galaxy is nearly 34 billion light-years away.