PrepTest 159, Section 2, Question 20
Since 1929, cosmologists have known that the universe(446 more words not shown)
It can be inferred from(18 more words not shown)
- APhysicists can use(22 more words not shown)
- BFrom 1929 until(12 more words not shown)
- CParticle physicists originally(12 more words not shown)
- DThe best available(17 more words not shown)
- EEinstein proposed the(14 more words not shown)
Reading the passage
The final paragraph connects a proposed change in gravity over huge distances to consequences on smaller scales. If those consequences can be observed within our solar system, local observations can help evaluate whether the existing gravitational theory gets things right.
What we’re looking for
That gives us a supported inference without assuming the tests have already been performed or that Einstein has already been proved wrong.
Working the answers
- ACorrect
The author explicitly says the implications of the revised theory could be tested in our solar system. Those tests would bear on whether gravity behaves as Einstein's theory predicts. A local test can matter to the larger theory because the proposed revision has local consequences too.
- B
The opening says cosmologists have known since 1929 that the universe is expanding. Before the late-1990s surprise, they expected slower expansion, not a fixed size.
- C
We learn that physicists have known about virtual particles for decades. We aren't given their original reason for proposing them. Their later use in a dark-energy explanation doesn't establish their original purpose.
- D
The gravity revision is a proposed explanation, not a conclusion established by the best available evidence. The observations show acceleration; they don't by themselves decide between the two explanations.
- E
Einstein's stated purpose was to explain why the universe wasn't shrinking under gravity. The virtual-particle account is a later proposed explanation of dark energy, not the reason attributed to his 1917 proposal.
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