Quantum Theory, although of tremendous scientific value, has neverthel

Question

Quantum Theory, although of tremendous scientific value, has nevertheless prompted debate among physicists. The debate arose because quantum theory addresses the peculiar properties of minute objects such as photons and electrons. While one type of experiment shows that these objects behave like particles, with well-defined trajectories through space, another demonstrates that, on the contrary, they behave like waves, their peaks and troughs producing characteristic “interference” effects. However, scientists have failed to devise an experiment to demonstrate both behaviors simultaneously.

In the 1920s, two alternate interpretations of quantum theory attempted to resolve this apparently contradictory wave-particle duality. Physicists Niel Bohr argued that wave particle properties are not contradictory, but complementary. Contrary to our intuition that an object continues to exist in some determined form even though we cannot perceive it, he concluded that the physical reality of a quantum objects is actually undetermined before the object is observed via experiment.

Physicists Werner Heisenberg's “uncertainty principle”, by contrast, postulated that we cannot precisely determine two complementary properties, such as position and momentum, of a quantum object simultaneously: if we measure an object's position with absolute certainty, then there is an infinite uncertainty in its momentum, and vice versa. He concluded that although we are limited in our ability to measure objects at the atomic and subatomic levels, their position and momentum are nonetheless defined all along.   1 
1) Which of the following does the passage mention as providing evidence of the dual nature of quantum objects?

a) Scientists' inability to measure the position and momentum of quantum objects simultaneously.
b) Scientists' inability to measure the momentum of the quantum objects with certainty.
c) The similarities in the appearance of particles and waves.
d) The tendency of quantum objects to exhibit well-defined trajectories only at either extremely high or extremely low speeds.
e) The behavior of quantum objects as either particles or waves depending on the type of experiment that is performed.

2 
2) It can be inferred from the passage that if scientists were able to measure the position and momentum of quantum objects precisely and simultaneously, then the

a) theory that the dual properties of quantum objects are complementary would be proven.
b) basic postulate of the uncertainty principle would be refuted 
c) distinction between particle behavior would cease to exist 
d) debate about quantum theory among physicists would be unchanged.
e) trajectories of quantum objects through space would be more difficult to predict.

3 
3) All of the following are mentioned in the passage as possible characteristics of quantum objects except:

a) a minute size
b) momentum
c) position in space
d) sporadic movement 
e) wave like behavior

4 
4) Which of the following, if true, would most seriously undermine Bohr's conclusion about the physical reality of a quantum object?

a) The physical properties of particles and waves are inherently complementary.
b) Human intuition is not a factor in the interpretation of scientific data about quantum objects.
c) Results of experiments on quantum objects are sometime influenced by the expectations of the experiments.
d) The technology used in research on quantum objects has made tremendous advances since the 1920s.
e) Quantum objects posses distinct, continuously existing physical forms that do not depend on the experiments used to measure them

5 
5. Q. The passage suggests that the debate among physicists mentioned in the first sentence has arisen in part because

A. the rapid movement of quantum objects poses an insurmountable obstacle to precise measurement
B. scientists have been unable to devise a single experiment that reveals both particle and wave properties of quantum objects simultaneously
C. the controversial nature of quantum theory has made it difficult for scientists to agree on what evidence is acceptable
D. division among physicists has resulted in the design of experiments that produce unintelligible experimental results
E. research efforts have been undermined by irreconcilable contradictions between equally compelling interpretations of quantum theory

6 
6. Which of the following best describes the organization of the passage?

A. A thesis is introduced and then amended.
B. Arguments are presented, weighed, and then reconciled.
C. A problem is described and different interpretations intended to resolve the problem are presented.
D. Hypotheses are analyzed, their premises are refuted, and alternatives are suggested to replace the hypotheses.
E. A theory is advanced, opposing evidence is considered, and the theory is abandoned.

ID 00139

GMATNinja · Accepted Answer

Bohr's conclusion was "that the physical reality of a quantum object is actually determined before the object is observed via experiment." Even though this CONCLUSION is  contrary  to human intuition, Bohr's does NOT suggest that human intuition is not a  factor  in INTERPRETING scientific data. Human intuition might be used to  interpret  the data, and that analysis might yield CONCLUSIONS that are contrary to our intuition. Thus, choice (B) is not appropriate.

Bohr's conclusion is CONTRARY to the intuitive idea "that an object continues to exist in some determined form even though we cannot perceive it." Choice (E) says that the objects possess "distinct, continuously existing physical forms." Thus, choice (E) supports the intuitive idea. Since Bohr's conclusion OPPOSES the intuitive idea, choice (E) undermines Bohr's conclusion.

KarishmaB · Answer

You are ignoring the first part of this sentence:

Physicists Niel Bohr argued that wave particle properties are not contradictory, but complementary.  Contrary to our intuition that an object continues to exist in some determined form even though we cannot perceive it , he concluded that the physical reality of a quantum objects is actually determined before the object is observed via experiment.

What he concludes is contrary to "an object exists in some determined form". He says the physical reality is determined  before  being observed. It may not stay the same once we observe it.

e) Quantum objects posses distinct, continuously existing physical forms that do not depend on the experiments used to measure them
This is telling us that the object exists in some determined form. Bohr concluded against this. So this is against what Bohr says.

baanhgraduate · Answer

I chose B for Question 4 because the second paragraph mentions that "Contrary to our intuition that an object continues to ..." so that if human intuition is not a factor in the interpretation, Bohr's interpretation makes no sense.

What's wrong in my explanation?

About the answer E, I don't understand because the 2nd paragraph just says "... is observed via experiment", which does not mean the experiment affects the physical forms of the objects.

ADiCR7 · Answer

Could you please explain why the answer for the 4th question is E?
I chose B.

mbaapplicant2019 · Answer

Hi all,

I found another question for this passage. Could you please help me explain why correct option is B. Thanks.

Question: The passage suggests that the debate among physicists mentioned in the first sentence has arisen in part because:
A: the rapid movement of quantum objects poses an insurmountable obstacle to precise measurement
B: scientists have been unable to devise a single experiment that reveals both particle and wave properties of quantum objects simultaneously
C: the controversial nature of quantum theory has made it for scientists to agree on what evidence is acceptable
D: division among physicists has resulted in the design of experiments that produce unintelligible experimental results
E: research efforts have been undermined by irreconcilable contradictions between equally compelling interpretations of quantum theory

TaN1213 · Answer

From passage: 
While one type of experiment shows that these objects behave like particles,  with well-defined trajectories through space , another demonstrates that, on the contrary, they behave like waves, their peaks and troughs producing characteristic “interference” effects.  However,  scientists have failed to devise an experiment to demonstrate both behaviors simultaneously.

The entire passage revolves around the confusion in the behavior of p&e (protons and electrons : Quantum particles)-  "Does the Quantum particles exhibit charateristics of Wave or Particle" 
If the scientists were able to demonstrate that p&e behaves as both wave and particle , then there would not have been any confusion.
--B--

ashisplb · Answer

Hi . Can anyone please justify the first question . I selected A as answer .

GMATNinja · Answer

The passage does mention scientists' inability to measure the position and momentum of quantum objects simultaneously (choice A), but this does not represent  evidence of the  dual nature  of quantum objects . Such evidence is presented in the first paragraph: "one type of experiment shows that   objects behave like particles" and "another   demonstrates that, on the contrary,   behave like waves". This corresponds to choice (E). This evidence demonstrates that quantum objects can behave like 1) waves and 2) particles and thus demonstrates the  dual nature  of quantum objects.

I hope that helps!

mSKR · Answer

Physicists Werner Heisenberg's “uncertainty principle”, by contrast,

What is contrast refer to here?
 Does it refer to 
-uncertainty principle?
- Physicists Niel Bohr argued that wave particle properties ?
- human intuition 
- interpretations of quantum theory

Please suggest GMATNinjaTwo ,  SajjadAhmad ,  GMATNinja

kunalc20 · Answer

Why C is not an answer ,please explain

mSKR · Answer

C can not be an answer because in the paragraph, scientists don't question the validity of the evidence. The evidence is true due to experiment on 2 different properties.

your question could be why not the scientists just accept and reject other experiment results?
But there is no reason mentioned in the paragraph of rejecting one experiment results and accept other experiment results.

the debat is because how to confirm dual property by showing both results in single experiments. ( please note: in each experiment one property is shown so they have no ground to reject any one of them)

Example: you get 85 marks in science. you get 20 marks in maths.
controversy: are you a good student of a weak student
You can not just ignore one result to come to census. you need to consider both facts because both belongs to you and both are true.

Hope it is clear why the answer C can not be an answer.

GMATNinja · Answer

The contrast is between the "two alternate interpretations of quantum theory" mentioned at the start of the second paragraph. These interpretations are Niel Bohr's argument that "wave particle properties are not contradictory, but complementary" and Werner Heisenberg's “uncertainty principle”. If that last sentence makes you think of Walter White, you have excellent taste in TV programs.

I hope that helps!

GMATNinja · Answer

The passage tells us the disagreement has arisen because one set of experiments demonstrate that "photons and electrons... behave like particles" and another set of experiments demonstrates that "they behave like waves" but "scientists have failed to devise an experiment to demonstrate both behaviors simultaneously."

However, the passage does not tell us that there is any disagreement about what  evidence is acceptable . Without this disagreement, answer choice (C) cannot be the correct answer to this question.

I hope that helps!

Harsh2111s · Answer

VeritasKarishma   GMATNinja 
I have doubt regarding option E.
Look at these lines from the passage
" he concluded that the  physical reality of a quantum objects is actually determined before  the object is observed via experiment."
When physical reality is already determined before experiment then even though quantum objects posses distinct forms that doesn't depend on experiments, it will have no effect on physical reality.
Option E supports Bohr's conclusion.
Please explain what I missed.

Grihu · Answer

2) It can be inferred from the passage that if scientists were able to measure the position and momentum of quantum objects precisely and simultaneously, then the

a) theory that the dual properties of quantum objects are complementary would be proven.
b) basic postulate of the uncertainty principle would be refuted
c) distinction between particle behavior would cease to exist
d) debate about quantum theory among physicists would be unchanged.
e) trajectories of quantum objects through space would be more difficult to predict.

I chose E.
Please explain what is wrong with it.

Harsh9676 · Answer

Hi  Grihu

Choice E is incorrect because of the below text from the passage. It means that the trajectories can be predicted but different interpretations are made and we actually do not know how easy or difficult it is to make the prediction.

P1: While one type of experiment shows that these objects behave like particles,  with well-defined trajectories through space , another demonstrates that, on the contrary,  they behave like waves , their peaks and troughs producing characteristic “interference” effects.

Hope this helps.

Kudos if you like my explanation.

GraceSCKao · Answer

Hi,

I am not an expert but trying to share my thoughts, as I had the same question as you did and I figured it out.

The fact is that the key sentence in this passage "he concluded that the physical reality of a quantum objects is actually  determined  before the object is observed via experiment." is incorrect.

In the official prep software, the same passage says "he concluded that the physical reality of a quantum object is actually  undetermined  before the object is observed via experiment." (I checked the prep software because I was very confused— I answered this question correctly at the software but did it incorrectly here.)

Needless to say, the difference between determined and undetermined is significant. 
In the correct version, since Bohr contended that the physical reality of a quantum object is not determined before the object is seen in experiment, the option (E) directly attacks his contention.

In the wrong version, as you pointed out, the option (E) does not differ from Bohr's mistakenly cited contention.

Hope that the moderators could help fix the passage cited in the first page so that no more GMAT takers would be confused. 
Thanks!

Emmakim · Answer

Where can I find any hint from the passage of Q3?
I can't understand what "Possible Characteristic" means..

Please kindly help.

GMATNinja · Answer

Question 3 
 
In the passage, the author reveals some strange things about quantum objects. There is debate over whether they act as particles or waves, and why they sometimes appear to be one of those things and not the other.

So, not all of the characteristics of quantum objects are  fully  understood -- some of them are just "possible" characteristics that may not hold true all of the time.

Question 3 asks us which answer choice is  not  mentioned as a possible characteristic. Here are the options:
 
This is mentioned as a characteristic of quantum particles in the first paragraph, when the author says that "quantum theory addresses the peculiar properties of  minute  objects."

Because (A) is mentioned, we can eliminate it.

(B) is mentioned in the third paragraph: "...two complementary properties, such as position and  momentum , of a quantum object..."

Eliminate (B).

The same sentence mentions (C): "...two complementary properties, such as  position  and momentum, of a quantum object..."

(C) is out.

The passage definitely mentions the movement of quantum objects, but doesn't say that this movement is  sporadic .

(D) is not mentioned, so hang onto it.

In the first paragraph, we learn that quantum particles sometimes "behave like waves." While this isn't a set-in-stone characteristic that always holds true, it is a possible characteristic of quantum objects.

(E) is mentioned as a possible characteristic of quantum objects, so eliminate (E).

(D) is the correct answer to question 3.

I hope that helps!

Quantum Theory, although of tremendous scientific value, has neverthel

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Quantum Theory, although of tremendous scientific value, has neverthel

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

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