Physicists posit that at first our universe was infmitesimally small a

Physicists posit that at first our universe was infmitesimally small and infinitely hot and dense. It then underwent a period of extremely rapid, massive inflation (the Big Bang), and it has since continued to expand and coop.

According to physicists Sean Carroll and Jennifer Chen, the Big Bang was not a unique event; events like it happen periodically over an incredibly vast time scale. This is based on the suggestion of some physicists that the Big Bang was the beginning of our universe as we know it, but not the beginning of a larger Univers—or "multiverse"—that encompasses everything, including that which we can never see because it is beyond our "cosmic bubble."

Carroll and Chen were initially interested in why time flows in only one direction. In physics the flow of time is captured by the second law of thermodynamics, which implies that entropy—a measure of total disorder—naturally increases with time. Entropy increases because there are more ways for a system to be disordered than for it to be ordered. Therefore, if change occurs, it is more likely to be change toward greater disorder. For example, in a moderately orderly room, if one moves an object in the room randomly, there are many more places one can put it that will make the room less orderly than there are places that will make it more orderly. So if, over time, objects in the room are continually moved randomly, it is most likely that the room will get increasingly disordered.

While the Big Bang process and what followed obey the second law of thermodynamics, it is a mystery why there should have been a small, hot, and dense universe to begin with. Such a low entropy universe is an extremely unlikely configuration, not what scientists would expect from a randomly occurring initial condition. Carroll and Chen's innovation is to argue that the most common initial condition is actually likely to resemble cold, empty space--not an obviously favorable starting point for the onset of inflation.

Recent research has shown that even empty space has faint traces of energy that fluctuate on the subatomic scale. Physicists Jaume Garriga and Alexander Vilenkin have suggested that these fluctuations can generate their own big bangs in tiny areas widely separated in time and space. Carroll and Chen take our universe, and others, to be such fluctuations in a high entropy multiverse.

On this view, while the initial state that produced our universe would appear to be, taken by itself, a highly improbable one, in the vastness of the multiverse the creation of our universe is not that unlikely. Indeed it is likely not even a unique event.

1. Which one of the following most accurately states the main idea of the passage?

(A) Carroll and Chen theorize that our universe is the result of an energy fluctuation in a high entropy multiverse.
(B) According to Carroll and Chen, entropy increases because there are more ways for a system to be disordered than for it to be ordered.
(C) Carroll and Chen challenge the prevailing view of physicists that our universe underwent a period of extremely rapid, massive inflation.
(D) According to Carroll and Chen, a small, hot, and dense configuration is unlikely as a random initial condition for a universe.
(E) Carroll and Chen posit that our universe is one of many universes in an all-encompassing multiverse.


2. Which one of the following comes closest to capturing what the term "cosmic bubble" means in the last sentence of the second paragraph?

(A) all-encompassing larger universe
(B) universe contained in the multiverse
(C) inflation following a big bang
(D) theoretical preconceptions
(E) low entropy state


3. The author's stance toward Carroll and Chen's theory is most accurately characterized as that of

(A) an ardent adversary
(B) a dismissive critic
(C) a disinterested skeptic
(D) a sympathetic reporter
(E) a zealous proponent


4. The claim in the fourth paragraph that an initial condition is likely to resemble cold, empty space is most strongly supported by information in the

(A) first paragraph
(B) second paragraph
(C) third paragraph
(D) fifth paragraph
(E) sixth paragraph


5. The author's reference to a suggestion by Garriga and Vilenkin in the fifth paragraph primarily serves to

(A) question a presupposition of the Big Bang theory
(B) raise a potential objection-to Carroll and - Chen's theory
(C) illustrate an implication of Carroll and Chen's theory
(D) show how a puzzle raised by Carroll and Chen is resolved within Carroll and Chen's theory
(E) suggest an alternative explanation of the evidence upon which Carroll and Chen's theory is based


6. The primary purpose of the passage is to

(A) draw novel consequences from an established principle
(B) challenge a dominant point of view
(C) chronicle the history of a dispute
(D) adjudicate between two theories
(E) give the rationale for a theory


7. It can be inferred from the passage that the author presumes which one of the following to be true?

(A) The multiverse originated in a big bang.
(B) The initial state of our universe resembles cold, empty space.
(C) A hot and dense state is a state of low entropy.
(D) The multiverse is part of a larger system of multiverses.
(E) The second law of thermodynamics was formulated to answer a question about time.