Why are powerful infrared instruments like those on the James Webb Space Telescope essential for observing the very first galaxies?

Answer

Their light has been extremely redshifted, pushing the signature into the infrared

The very first galaxies formed when the universe was much younger and were intrinsically bright blue systems undergoing intense star formation. However, because these galaxies are so immensely distant, the light they emitted billions of years ago has traveled through a universe that has expanded significantly. This vast expansion has stretched the original blue and ultraviolet wavelengths so severely—an extreme redshift—that the resulting radiation is no longer visible light but has been pushed far into the longer-wavelength infrared portion of the spectrum. Infrared instruments are necessary because they are capable of detecting and analyzing these highly stretched signals, allowing astronomers to study the conditions of the early cosmos.

Why are powerful infrared instruments like those on the James Webb Space Telescope essential for observing the very first galaxies?

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