Quasars—celestial objects so far

Answer choices

1. A

   Speculating Cause4% picked this

   Instruments in use before 1963 were not sensitive enough to permit quasars

   This might be the reason we didn't see quasars until 1963. But maybe the instruments were sensitive enough and we just weren't pointing them in the right direction. Maybe we weren't looking at the right time of day/night.

   4%
2. B

   Too Strong: first reached One-Claim Support5% picked this

   Light from quasars first began reaching Earth

   We only know that they were first observed in 1963. It's possible that photons from quasars have been hitting Earth for millions or billions of years (not the same quasar, of course, since we learned their life spans are 100 million years tops). We should be very suspicious on Inference questions if we're picking an answer that sounds like it's being supported by one individual claim, i.e. "Quasars have been seen since 1963, thus choice (B)". The correct answer almost always involves pulling together multiple claims, so you should feel like you're doing more "legwork" to synthesize 2 or more ideas in order to support your answer.

   5%
3. C

   Too Strong14% picked this

   Anything that from Earth appears as bright as a quasar does must produce more light than would be

   Too Strong: anything that bright One-Claim Support We only know that "anything that bright and that far away" must burn at the rate of 90 billions suns. This answer is saying "anything that bright" burns that hot. The Moon definitely appears from Earth at least as bright as a quasar, so according to this answer, the Moon produces more light than 90 billion suns. We should be very suspicious on Inference questions if we're picking an answer that sounds like it's being supported by one individual claim, i.e. "2nd sentence says "anything that bright produces more than 90 billion suns, thus choice (C)". The correct answer almost always involves pulling together multiple claims, so you should feel like you're doing more "legwork" to synthesize 2 or more ideas in order to support your answer. Answers supported by one-claim are almost always skewing the meaning of what was originally said. Here, what was said was "anything that far away that appears the way quasars do would have to burn like crazy".

   14%
4. D

   Too Strong: nothing that far away16% picked this

   Nothing that is as far from Earth as quasars are can continue to exist for more than

   We only know that quasars can't exist for more than 100 million years, because they're burning at a rate that produces more light than 90 billion suns. Other objects that burn at much slower rates could definitely exist for more than 100 million years (for example, there are presumably stars and galaxies at least as far away as quasars and they exist for billions of years).

   16%
5. E

   Correct61% picked this

   No quasar that has ever been seen from Earth exists

   Why this is right

   The last two sentences combine to tell us that quasars can't exist for more than about 100 million years. Any quasar that's ever been seen from Earth was seen in the last 60 years (since 1963). Since it takes 500 million years for light from a quasar to reach us, what we've been seeing for the past 60 years is quasars, as they appeared 500 million years ago. But since they only exist for 100 million years, every quasar we've seen has been out of existence for the last 400 million years.

   Skill tested: Must be True · how this choice captures the argument's function is the move to repeat next time.

   61%