While space looks empty, it is in fact filled with matter. In 1933, Sw

While space looks empty, it is in fact filled with matter. In 1933, Swiss astrophysicist Fritz Zwicky coined the term “dark matter” to identify the substance that makes up an estimated 85% of all matter in the universe. Ever since, however, the search for the particles that compose dark matter has been ongoing with hypotheses and projections filling the minds of determined physicists in search of a breakthrough.

Among the most promising hypotheses is one that includes neutralinos, a proposed particle akin to the Higgs Boson particle as a building block of the universe we know. Neutralinos, it is proposed, will annihilate each other when they collide, producing both a matter and an antimatter equivalent (an electron and a positron, respectively). In such a reaction, each particle would carry with it as much energy as one neutralino has mass (per Einstein’s theory of relativity), and this energy may well provide the means for which scientists can finally identify these sought-after particles.

The plausibility of this theory has galvanized support in the scientific community for extensive research. Aboard the International Space Station lies the Alpha Magnetic Spectrometer (AMS), which is using magnetized sensors to identify the charges that would come along with these proposed particles. As it measures charges across space, AMS focuses on the variance of the ratio of positrons to electrons, under the theory that the “positron fraction” should peak when these high-energy positrons are created from dark-matter annihilation. To date, AMS has recorded over 30 billion cosmic rays and research indicates that it has indeed viewed hundreds of thousands of charged particles consistent with the theory of positrons. But scientists remain stoic on the issue, noting that these charges are potentially also consistent with those released by pulsars, the aftermath of exploded stars. Accordingly, research continues to better delineate between the positron fraction expected from pulsars and that from neutralinos.

1. Which of the following best summarizes the primary purpose of the passage?

To compare the search for neutralinos with that for the Higgs Boson
To detail the current hypotheses regarding the origin of dark matter
To prove that positrons are created from dark matter annihilation
To present a hypothesis to explain a mysterious scientific phenomenon
To explain the results of a current scientific research study

2. Which of the following can be inferred from the passage?

The highest positron fractions that AMS records will be from dark matter particles.
Electrons and positrons carry approximately the same amount of energy.
AMS has been able to view hundreds of thousands of positrons.
The charges emitted by pulsars are indistinguishable from the charges emitted by positrons.
The neutralino hypothesis is currently accepted as the most plausible existing explanation for dark matter.

3. According to the passage, scientists theorize that dark matter is created when

The positron fraction reaches its peak value
Pulsars result as the remnants of stellar explosion
Positrons release the same amount of energy as a neutralino has mass
Neutralinos collide with one another
Highly charged electrons annihilate positrons