PrepTest 112, Section 3, Question 26
Before 1986 physicists believed they could describe the(47 more words not shown)
Which one of the following,(13 more words not shown)
- AThe extremely sophisticated(13 more words not shown)
- BNo previously established(12 more words not shown)
- CSome scientists have(18 more words not shown)
- DThe experiments were(24 more words not shown)
- EThe fifth universal(19 more words not shown)
Reading the argument
Explaining one surprising result is a promising start. Does the explanation work with everything else we know?
The experiments found less gravitational attraction than the established theory predicted. A force pushing particles apart could help account for that difference: the repulsion would work against the attraction. That makes a fifth force worth considering. It doesn't establish that the force exists. A proposed explanation might fit these results while conflicting with other well-established findings.
What we’re looking for
For a strengthen question, I'd look for more experimental evidence. If other experiments also point toward the proposed force, we have a better reason to believe it is real. That's my initial prediction.
Working the answers
- A
This could help explain why the experiments weren't performed earlier. But the question isn't why physicists proposed the force when they did. It's whether the proposed force exists. Learning when the equipment became available doesn't tell us that the interpretation of its results is right.
- BCorrect
This helps in a more defensive way than I predicted. It says the proposed fifth force doesn't conflict with any previously established scientific results. We have one set of findings it could explain, and B removes the concern that accepting the explanation would put us at odds with other results we already have.
That's support, even though it isn't direct confirmation from another experiment. B doesn't prove the force exists or say the theory has no possible problems. It makes this particular objection less available: we can't reject the proposal on the ground that it contradicts previously established results.
- C
This offers a reason to question whether we need a distinct fifth force. If the observed effect is an aspect of gravity, it might be accounted for within one of the four forces already recognized. That challenges the proposed addition rather than supporting it.
- D
This makes the evidence harder to interpret. If factors affecting gravity couldn't be measured precisely, we have reason to worry about attributing the unexpected measurement to a new force. It doesn't mean every measurement is automatically worthless. But uncertainty about other influences undermines our confidence in this explanation.
- E
Other productive ideas don't establish that this idea is right. A period of exciting research can still produce a mistaken proposal. We need something about this force or the evidence for it, not the reputation of the period in which it was proposed.
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