A ring of gas emitting X-rays flickering 450 times per second has been observed in a stable orbit around a black hole. In light of certain widely accepted physical theories, that rate of flickering can best be explained if the ring of gas has a radius of 49 kilometers. But the gas ring could not maintain an orbit so close to a black hole unless the black hole was spinning.
Summary
Scientists have seen a ring of gas that maintains a stable orbit around a black hole. The gas ring emits X-rays that flicker 450 times per second. This flickering speed suggests that the gas ring has a radius of 49 kilometers, meaning that it is very close to the black hole. However, for the gas ring to maintain its orbit so close to the black hole, the black hole itself must be spinning.
Strongly Supported Conclusions
In some conditions, gas can orbit black holes at a close distance.
The black hole is spinning.
A
Black holes that have orbiting rings of gas with radii greater than 49 kilometers are usually stationary.
This is unsupported. We know only that black holes that have orbiting rings of gas with radii of 49 kilometers must be spinning. We do not know the conditions of black holes that have orbiting rings of gas with radii greater than 49 kilometers.
B
Only rings of gas that are in stable orbits around black holes emit flickering X-rays.
This is unsupported. The stimulus only tells us about this particular ring of gas. We do not have any information about the emissions of any other rings of gas.
C
The black hole that is within the ring of gas observed by the astronomers is spinning.
This is strongly supported. We know that the gas ring has been observed in a stable orbit very close to the black hole. Because the ring can only maintain such a close orbit if the black hole is spinning, we can conclude that the black hole is spinning.
D
X-rays emitted by rings of gas orbiting black holes cause those black holes to spin.
This is unsupported. The stimulus tells us that the black hole must be spinning based on the observed facts of the gas ring. However, it does not tell us what causes the black hole to spin.
E
A black hole is stationary only if it is orbited by a ring of gas with a radius of more than 49 kilometers.
This is unsupported. We know only that a black hole orbited by a gas ring with a radius of 49 kilometers must not be stationary. We do not know the conditions required for a black hole to be stationary.
Human beings can live happily only in a society where love and friendship are the primary motives for actions. Yet economic needs can be satisfied in the absence of this condition, as, for example, in a merchant society where only economic utility motivates action. It is obvious then that human beings _______.
Summary
People must live in a society primarily motivated by love and friendship in order to be happy. However, their economic needs can still be met outside of such a society. For example, humans’ economic needs can be met in a society that’s just motivated by economic utility.
Strongly Supported Conclusions
Human beings can have their economic needs met and still be unhappy.
Human beings cannot be happy in a society motivated primarily by economic utility.
A
can live happily only when economic utility is not a motivator in their society
This is unsupported. The stimulus says that love and friendship must be the primary motivators of a society in order for people to be happy. As far as we know, economic utility can still be one of the society’s motivators, it just must not be the primary motivator.
B
cannot achieve happiness unless their economic needs have already been satisfied
This is unsupported. The satisfaction of economic needs is not presented as necessary for happiness. Rather, a society motivated by love and friendship is necessary. Perhaps one could live in a society motivated by love, be economically unsatisfied, and still be happy.
C
cannot satisfy economic needs by means of interactions with family members and close friends
This is unsupported. The stimulus does not give us any information about whether a person can or cannot satisfy their economic needs through family and friends. We only know that economic needs can be satisfied in a society “where only economic utility motivates action.”
D
can satisfy their basic economic needs without obtaining happiness
This is strongly supported. Humans must live in a society primarily motivated by love and friendship in order to obtain happiness. Humans can satisfy their basic economic needs outside of such a society. Thus, humans can satisfy their economic needs without obtaining happiness.
E
cannot really be said to have satisfied their economic needs unless they are happy
This is anti-supported. The stimulus tells us that humans can satisfy their economic needs in a society primarily motivated by economic utility. In such a society, people are not happy. So a person does not need to be happy in order to be economically satisfied.