English I Qualifier: Undated, Set A (undated)

Read the passage and answer the given subquestions.
To study the origins of our universe is to struggle with profound chicken-or-egg questions. We know the Big Bang happened. Cosmologists can see its afterglow in the sky. But no one knows whether the laws of physics or even time itself existed before that moment. Nor can we say exactly what happened next. The order in which certain celestial objects formed during the very early universe is hotly contested.
For a long time after the Big Bang, not much of anything could form. All of space was permeated by a roiling plasma. It was too hot and chaotic for any structure to cohere. Hundreds of thousands of years passed before a tiny hydrogen atom could even hold itself together. Another 100 million years or so after that, great clouds of hydrogen condensed and stars flared into being. Most cosmologists believe that these stars were the first large, free-floating structures to illuminate our universe, and that black holes appeared later. But some have proposed that it went the other way around.
In the deep sky, beyond the most ancient fully formed galaxies, astronomers have now found a mysterious and colossal object that may be a primordial black hole. Earlier this month, a team of them posted an analysis of the object based on observations made by the James Webb Space Telescope. If their account holds up, the standard view of how the universe evolved will need serious revamping.
Long before black holes were ever glimpsed in reality, they were theoretical objects, products of the scientific imaginary. In 1783, the English natural philosopher John Michell proposed the existence of “dark stars,” objects of such concentrated mass that light cannot escape their gravity. Michell was reasoning from Newton’s laws. More than 100 years later, Karl Schwarzschild and Robert Oppenheimer brought his dark-star idea into alignment with Einstein’s theory of general relativity. They showed how an ultradense star could keep collapsing until space-time curved back on itself, sealing off its light in a black hole.
Source: The Black Hole That Could Rewrite Cosmology – The Atlantic

Based on the context in this passage, what is the meaning of the phrase “chicken-or-egg questions”?

Read the passage and answer the given subquestions.
To study the origins of our universe is to struggle with profound chicken-or-egg questions. We know the Big Bang happened. Cosmologists can see its afterglow in the sky. But no one knows whether the laws of physics or even time itself existed before that moment. Nor can we say exactly what happened next. The order in which certain celestial objects formed during the very early universe is hotly contested.
For a long time after the Big Bang, not much of anything could form. All of space was permeated by a roiling plasma. It was too hot and chaotic for any structure to cohere. Hundreds of thousands of years passed before a tiny hydrogen atom could even hold itself together. Another 100 million years or so after that, great clouds of hydrogen condensed and stars flared into being. Most cosmologists believe that these stars were the first large, free-floating structures to illuminate our universe, and that black holes appeared later. But some have proposed that it went the other way around.
In the deep sky, beyond the most ancient fully formed galaxies, astronomers have now found a mysterious and colossal object that may be a primordial black hole. Earlier this month, a team of them posted an analysis of the object based on observations made by the James Webb Space Telescope. If their account holds up, the standard view of how the universe evolved will need serious revamping.
Long before black holes were ever glimpsed in reality, they were theoretical objects, products of the scientific imaginary. In 1783, the English natural philosopher John Michell proposed the existence of “dark stars,” objects of such concentrated mass that light cannot escape their gravity. Michell was reasoning from Newton’s laws. More than 100 years later, Karl Schwarzschild and Robert Oppenheimer brought his dark-star idea into alignment with Einstein’s theory of general relativity. They showed how an ultradense star could keep collapsing until space-time curved back on itself, sealing off its light in a black hole.
Source: The Black Hole That Could Rewrite Cosmology – The Atlantic

What evidence do cosmologists have that the Big Bang occurred?

Read the passage and answer the given subquestions.
To study the origins of our universe is to struggle with profound chicken-or-egg questions. We know the Big Bang happened. Cosmologists can see its afterglow in the sky. But no one knows whether the laws of physics or even time itself existed before that moment. Nor can we say exactly what happened next. The order in which certain celestial objects formed during the very early universe is hotly contested.
For a long time after the Big Bang, not much of anything could form. All of space was permeated by a roiling plasma. It was too hot and chaotic for any structure to cohere. Hundreds of thousands of years passed before a tiny hydrogen atom could even hold itself together. Another 100 million years or so after that, great clouds of hydrogen condensed and stars flared into being. Most cosmologists believe that these stars were the first large, free-floating structures to illuminate our universe, and that black holes appeared later. But some have proposed that it went the other way around.
In the deep sky, beyond the most ancient fully formed galaxies, astronomers have now found a mysterious and colossal object that may be a primordial black hole. Earlier this month, a team of them posted an analysis of the object based on observations made by the James Webb Space Telescope. If their account holds up, the standard view of how the universe evolved will need serious revamping.
Long before black holes were ever glimpsed in reality, they were theoretical objects, products of the scientific imaginary. In 1783, the English natural philosopher John Michell proposed the existence of “dark stars,” objects of such concentrated mass that light cannot escape their gravity. Michell was reasoning from Newton’s laws. More than 100 years later, Karl Schwarzschild and Robert Oppenheimer brought his dark-star idea into alignment with Einstein’s theory of general relativity. They showed how an ultradense star could keep collapsing until space-time curved back on itself, sealing off its light in a black hole.
Source: The Black Hole That Could Rewrite Cosmology – The Atlantic

What aspect of the formation of the universe is not accepted by everyone?