Why is it NOT possible to look all the way back to the Big Bang itself?
A) Photons are not produced until the stars begin to shine at a redshift of z $\approx$ 20.
B) From redshifts of z = 0 to 100,photons are gravitationally lensed by the dark matter in the universe.
C) At redshifts of z 1,000,most of the photons are blocked by large amounts of cold gas and dust.
D) For redshifts of z 1,000,photons are heavily altered because they easily react with individual protons and electrons in the universe.

Question

Why is it NOT possible to look all the way back to the Big Bang itself?
A) Photons are not produced until the stars begin to shine at a redshift of z $\approx$ 20.
B) From redshifts of z = 0 to 100,photons are gravitationally lensed by the dark matter in the universe.
C) At redshifts of z > 1,000,most of the photons are blocked by large amounts of cold gas and dust.
D) For redshifts of z > 1,000,photons are heavily altered because they easily react with individual protons and electrons in the universe.

Quizplus · Accepted Answer

Before the universe became transparent, it was a hot, dense plasma where photons were constantly interacting with protons and electrons, preventing them from traveling freely. This period ended with recombination, around z > 1,000, when the universe cooled enough for electrons to combine with protons to form neutral hydrogen, allowing photons to travel freely and form the Cosmic Microwave Background.

Why Is It NOT Possible to Look All the Way ≈\approx≈

Why Is It NOT Possible to Look All the Way $\approx$