For many years, black holes were merely theoretical

Question

1. For many years, black holes were merely theoretical constructs, predicted by physics but thought to be beyond the capabilities of science to observe because they are so dense that nothing, not even light, can escape their immense gravitational pull. However, scientists recently announced that a black hole has been detected at the center of the galaxy.

Which of the following, if true, most helps to explain the situation above?

A. Even though theory predicted the existence of black holes, many scientists remained skeptical about their existence.
B. Telescope technology has advanced considerably since black holes were predicted and scientists can now see objects hundreds of
millions of light years away.
C. As matter is drawn in by the black hole’s immense gravitational pull, it is super heated and gives off a burst of visible energy.
D. Black holes are not as dense as the initial theory predicted them to be.
E. The black hole at the center of the galaxy is many times larger than the black holes predicted by theory.

I thought A fits the bill better than C. Does anyone feel I am wrong? If I am , kindly explain how C is more advantageous.

N.B I am not taking as a reason-explanation answer because of the way in which the question is posed. It merely asks to explain the situation above.

Regards
Rahul

AbhishekSChauhan1 · Answer

For me..A seems a Better choice...

amit2k9 · Answer

The argument has reasoning gap hence require a supporter answer choice giving the reasoning.

A in fact weakens the point as scientists are skeptical about the existence.

C clearly provides the reasoning how perhaps the scientist might have been able to observe the Black Hole because of the visible light.

C is definite.

vivesomnium · Answer

We need to find a reason for the fact that for many years scientists had not been able to be sure of existence of black holes in reality because they could not see them, but recently they are sure of a black hold being present in reality. In other words, we have to find why the scientists have suddenly become sure that black holes exist. Clearly the explanation should be something that acts as a proof of black hole existence, and something which has been observed now, and wasn’t observed earlier.
A. Even though theory predicted the existence of black holes, many scientists remained skeptical about their existence.:  How can this explain the situation. this is only restating what the question stem is stating - that black holes were predicted by theory, but couldn’t be observed by scientists. This cant explain for the fact that now scientists are sure of existence of a black hole. 
B. Telescope technology has advanced considerably since black holes were predicted and scientists can now see objects hundreds of
millions of light years away.  The reason the black holes couldn’t be observed for many years, as per the question stem, is that they were "so dense that nothing, not even light, can escape their immense gravitational pull." It is about the density of the black hole, not its distance from the observation point. So the fact that objects farther can be seen now and couldn’t be seen earlier, which is the only implication of this option, doesn’t help. for all we know there could have been a black hole right next to earth and it still could not be seen because of its density. A more advanced telescope couldn’t have helped the situation. 
C. As matter is drawn in by the black hole’s immense gravitational pull, it is super heated and gives off a burst of visible energy.  This seems a plausible reason that the black hole has been observed. Scientists couldn’t 'see' the black hole for years, but may be they found out now the property listed by option C, observed this burst of visible energy and could now be sure of the existence of black hole.  
D. Black holes are not as dense as the initial theory predicted them to be. How does this explain how for years they couldn’t be seen. They couldn’t be seen because they were dense, not because theory predicted them to be dense. If the option had stated that the black holes got less dense with years, then it could explain why they can be seen now but couldn’t be seen earlier. 
E. The black hole at the center of the galaxy is many times larger than the black holes predicted by theory.  Again, similar to B, nowhere does the question statement say that the black holes couldn’t be observed because they were too small. question only highlights their density to be a hindrance, size of the black hole cant it being seen or not seen.

AbhishekSChauhan1 · Answer

After reading ur explaination..I think it should be C as it is bridging the reasoning gap...TY

IanStewart · Answer

If you need to 'explain' a situation or paradox, you'll first want to identify just what that situation or paradox is. Here, we're told that scientists at first did not think black holes could be observed (because they don't emit light), but that now scientists have observed black holes. That's what we need to resolve: if black holes are supposed to be invisible, how have scientists been able to detect them?

A doesn't explain anything; the skepticism of some scientists doesn't help to explain how scientists have detected black holes.

B is tempting, but is not correct. It wasn't because of bad telescopes that scientists could not see black holes; it was because black holes emit no light.

C is good; it explains that there are visible effects of black holes that can be detected even if the black hole itself is invisible.

While D and E suggest that black holes are somehow different from what was initially predicted, neither answer explains why it is possible now to detect them.

retro · Answer

Thanks for highlighting my main concern. It was centered around what we needed to do: Explain a paradox or explain the situation existing (as the queestion asks).

Rgds
Rahul

mba4viplav · Answer

To solve the discrepancy, we shall consider the facts provided in the argument:

Fact 1:  Black Holes are beyond capabilities of science and it is impossible to observe them because of their immense gravitational power

Fact 2:  Scientists recently announced that a black hole has been detected at the center of the galaxy

The above facts contradict with each other. So, we need a statement which can hold both the facts are true.

Option (A) : It is not relevant to solve the discrepancy
Option (B) : Technology related to telescope has advanced since the discovery of Black Holes but this option doesn't say that the telescope can see black holes. So this option is ruled out
Option (C) : This option upholds both our facts. It says that even though the science we know doesn't have capability to observe Black Holes, the burst of visible energy produced by the matter helps the scientists to detect a black hole at the center of the galaxy
Option (D) : Even though this option looks like an answer, it is a direct contradiction to the fact provided in the argument (About capabilities of science)
Option (E) : This option doesn't provide any evidence to solve the discrepancy

So, the answer is (C).

gmatpapa · Answer

Can anyone explain why B is incorrect?

I cant seem to get answer choice C. If the black holes emitted visible energy when matter was drawn inside them, then scientists of earlier ages would also have spotted that *visible* energy.

retro · Answer

Going by your argument, a lot of things could have been done earlier. If somebody states that they are being done now rather than in the past, then a sn answer with that statement is not a good fit. That is as far as what I think you see the rationale for not picking C.

Now for the answer about why B is incorrect: (Again, this is my view). I will stay as close to the premises as possible, when I choose an answer. I'd choose answers that propose the least AMOUNT of new ideas in explaining the situation and hence C might be a better answer than B.

But that said, I still do not want to compromise on my answer to the question. The question merely "asks to explain the situation" and the situation is that scientists    were    not able to prove the existence of the black holes for a long time until the. After the experiment however, they ARE able to explain the existence.

Regards
Rahul

gmatpapa · Answer

Hmmm.. I agree that we need to bring in as little outside information as possible.

However, retro, there is no mention of any experiment, or anything that tells us why scientists of today are better off than those of yesterday. There is no mention of any experiment either. So, if we lack information of such sort, changes in technology could be one of the reasons right?

Consider option B:

This option choice states that there is better technology now that at the time scientists that black hole were predicted. Quote from stimulus:

The earlier scientists *thought* that at that time observing black holes were beyond the capabilities of science. But now that scientists have better telescopes, they are better equipped to see the black holes. I think B, does comes close.

retro · Answer

Interesting war of words (intended pun, words being used strictly in the sense of words written here).

In a way, B does come close. But B at the same time is an extreme in the sense that the telescope technology is overall being described and there is absolutely no reference to telescope technology specific to the observation of black-holes and hence does not explain this as better as C.

I'd reiterate that the 'SITUATION that existed in the past (as indicated by the tenses used int eh question" is what is to be explained by the answer. Not the fact that scientists made an advance now (by whatever means).

/Rahul

retro · Answer

More literally, 'scientists can see OBJECTS' several hundred light years away...

Several hundred light years away is totally tangential to this argument. Moreover, the argument does not distinguish between a black hole that is several hundred light years away or in the back yard of the solar system. Choice "B" in simpler words has too many implications and irrelevancies.

/Retro

IanStewart · Answer

I imagine this question is easier to make sense of for someone with a background in physics. The point here is that physicists initially thought black holes could not be detected because "not even light can escape" from them. That is, they're invisible. It doesn't matter how far away they are - there could be a black hole next door to your house and you wouldn't be able to see it if light can't escape from it - which is why B is not the right answer.

We're looking for an answer which explains why it might be possible to detect black holes. That is, black holes should have some visible effects, even if the black hole itself is still invisible. That makes C the right answer.

For many years, black holes were merely theoretical

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