Our visual perception depends on the reception of energy reflecting or

Question

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Passage # 171 Date: 25-Jun-2020
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Our visual perception depends on the reception of energy reflecting or radiating from that which we wish to perceive. If our eyes could receive and measure infinitely delicate sense-data, we could perceive the world with infinite precision. The natural limits of our eyes have, of course, been extended by mechanical instruments; telescopes and microscopes, for example, expand our capabilities greatly.  There is, however, an ultimate limit beyond which no instrument can take us; this limit is imposed by our inability to receive sense-data smaller than those conveyed by an individual quantum of energy.  Since these quanta are believed to be indivisible packages of energy and so cannot be further refined, we reach a point beyond which further resolution of the world is not possible. It is like a drawing a child might make by sticking indivisible discs of color onto a canvas.

We might think that we could avoid this limitation by using quanta with extremely long wavelengths; such quanta would be sufficiently sensitive to convey extremely delicate sense-data. And these quanta would be useful, as long as we only wanted to measure energy, but a completely accurate perception of the world will depend also on the exact measurement of the lengths and positions of what we wish to perceive. For this, quanta of extremely long wavelengths are useless. To measure a length accurately to within a millionth of an inch, we must have a measure graduate in millionths of an inch; a yardstick graduated in inches is useless. Quanta with a wavelength of one inch would be,  in a sense , measures that are graduated in inches. Quanta of extremely long wavelength are useless in measuring anything except extremely large dimensions.

Despite these difficulties, quanta have important theoretical implications for physics. It used to be supposed that, in the observation of nature, the universe could be divided into two distinct parts, a perceiving subject and a perceived object. In physics, subject and object were supposed to be entirely distinct, so that a description of any part of the universe would be independent of the observer. The quantum theory, however, suggests otherwise, for every observation involves the passage of a complete quantum from the object to the subject, and it now appears that this passage constitutes an important coupling between observer and observed. We can no longer make a sharp division between the two in an effort to observe nature objectively. Such an attempt at objectivity would distort the crucial interrelationship of observer and observed as parts of a single whole. But, even for scientists, it is only in the world of atoms that this new development makes any appreciable difference in the explanation of observations.   1 
 1. The primary purpose of the passage is to 
 
(A) discuss a problem that hinders precise perception of the world 
(B) point out the inadequacies of accepted units of measurement 
(C) criticize attempts to distinguish between perceiving subjects and perceived objects 
(D) compare and contrast rival scientific hypotheses about how the world should be measured and observed 
(E) suggest the limited function of sensory observation

2 
 2. According to the passage, quanta with an extremely long wavelength cannot be used to give complete information about the physical world because they

(A) exist independently of sense-data 
(B) are graduated only in inches 
(C) have an insignificant amount of energy 
(D) cannot, with present-day instruments, be isolated from quanta of shorter wavelength 
(E) provide an insufficiently precise means of measuring length and position

3 
 3. Which of the following describes a situation most analogous to the situation discussed in lines  blue ?

(A) A mathematician can only solve problems the solution of which can be deduced from known axioms. 
(B) An animal can respond to no command that is more complicated syntactically than any it has previously received. 
(C) A viewer who has not learned, at least intuitively, the conventions of painting, cannot understand perspective in a drawing. 
(D ) A sensitized film will record no -detail on a scale that is smaller than the grain of the film. 
(E) A shadow cast on a screen by an opaque object will have a sharp edge only if the light source is small or very distant.

4 
 4. The author uses the analogy of the child's drawing (lines 17-J9) primarily in order to

(A) illustrate the ultimate limitation in the precision of sense-data conveyed by quanta 
(B) show the sense of helplessness scientists feel in the face of significant observational problems 
(C) anticipate the objections of those scientists who believe that no instrumental aid to observation is entirely reliable 
(D) exemplify the similarities between packages of energy and varieties of color 
(E) disparage those scientists who believe that measurement by means of quanta offers an accurate picture of the world

5 
 5. The author implies that making a sharp division between subject and object in physics is

(A) possible in a measurement of an object's length and position,but not in a measurement of its energy 
(B) still theoretically possible in the small-scale world of atoms and electrons 
(C) possible in the case of observations involving the passage of a complete quantum 
(D) no longer an entirely accurate way to describe the observation of the universe 
(E) a goal at which scientists still aim

6 
 6. The author's use of the phrase " in a sense " implies which of the following?

(A) Quanta of extremely long wavelength are essentially graduated in inches. 
(B) Quanta of one-inch wavelength are not precisely analogous to yardsticks graduated in inches. 
(C) Quanta of extremely long wavelength, in at least one respect, resemble quanta of shorter wavelength. 
(0) Quanta of one-inch wavelength and quanta of extremely long wavelength do not differ only in their wavelengths. 
(E) Quanta of one-inch wavelength must be measured by different standards than quanta of extremely long wavelengths.

7 
 7. According to the passage, the quantum theory can be distinguished from previous theories of physics by its

(A) insistence on scrupulously precise mathematical formulations 
(B) understanding of the inherent interrelationship of perceiver and perceived 
(C) recognition of the need for sophisticated instruments of measurement 
(D) emphasis on small-scale rather than on large-scale phenomena 
(E) regard for philosophical issues as well as for strictly scientific ones

PoojanB · Answer

B& C are easy to eliminate. If we see D- there are no 2 hypothesis to be discussed. contrast is only present in last para stating between physics and quantum theory. E- limited function is one of the stated fact in first paragraph and cannot comprehend total RC which talks about quantum theory.
 Thus by POE we can select A as winner

Given in para 2- but a completely accurate perception of the world will depend also on the exact measurement of the lengths and positions of what we wish to perceive. For this, quanta of extremely long wavelengths are useless. 
 E is the answer.

Here is the para in blue-
 "There is, however, an ultimate limit beyond which no instrument can take us; this limit is imposed by our inability to receive sense-data smaller than those conveyed by an individual quantum of energy.' 
Now, the para means we can not sense any data which is smaller than quanta of energy.
A- known axioms- if new axioms are found-problem can be solved.
B-animal can be trained to respond to complex command.ability is not hindered by anything.
C-it talks about requirement to understand a perspective and not about limitations beyond which it is non-understandable.
 D- bingo- film can not record details smaller than the grain on film 
E-Yes true but how that hinders the capability of light source to cast shadow with sharp edges

Stated line along with the line written before it :" Since these quanta are believed to be indivisible packages of energy and so cannot be further refined, we reach a point beyond which further resolution of the world is not possible. It is like a drawing a child might make by sticking indivisible discs of color onto a canvas." 
The tone of line says we cannot perceive anything beyond the level of quanta-smallest denomination possible.
A- it does not show limitation of quanta. it is limitation of human being.
 B- makes sense. the whole RC talks about observations and how it is limited by quanta. 
C- Irrelevant IMO
D- Nope.it is the similarity between 2 situations and not 2 things
E- Irrelevant IMO

Directly stated in para 3
 We can no longer make a sharp division between the two in an effort to observe nature objectively. Such an attempt at objectivity would distort the crucial interrelationship of observer and observed as parts of a single whole. 
 D is the answer

In a sense- not exactly; B is a perfect match

Given in a paragrpah-3: "The quantum theory, however, suggests otherwise, for every observation involves the passage of a complete quantum from the object to the subject, and it now appears that this passage constitutes an important coupling between observer and observed." 
 B is the answer

carouselambra · Answer

SajjadAhmad ,

For Q5 :
5. The author implies that making a sharp division between subject and object in physics is

(A) possible in a measurement of an object's length and position,but not in a measurement of its energy
(B) still theoretically possible in the small-scale world of atoms and electrons
(C) possible in the case of observations involving the passage of a complete quantum
(D) no longer an entirely accurate way to describe the observation of the universe
(E) a goal at which scientists still aim

D is the right answer but please consider the line from passage -
"We can no longer make a sharp division between the two in an effort to observe nature objectively."

Are we assuming, nature= universe? I don't think it's a fair assumption. If yes, can we assume stuff like this during exam as well?

bM22 · Answer

Hi  shivangishar ,
 In addition to the lines you have mentioned above, consider the next lines also: "We can no longer make a sharp division between the two in an effort to observe nature objectively. Such an attempt at objectivity would distort the crucial interrelationship of observer and observed as parts of a single whole."
Option D is a direct paraphrase of the above lines.

Now coming to you question: Are we assuming, nature= universe?. We are not assuming anything that is not mentioned in the passage or that cannot be inferred from the passage. We need to consider these lines: "It used to be supposed that, in the observation of  nature , the  universe  could be divided into two distinct parts, a perceiving subject and a perceived object. In physics, subject and object were supposed to be entirely distinct, so that a description of any part of the universe would be independent of the observer. ", for better understanding of context.
The above mentioned lines clearly imply that for the observation of nature, some theories divide universe into 2 parts: subject and object, thus the co-relation of the same is present in the Option D.

For the next part of the your question: we should never make any assumptions or connection which are not mentioned in the passage. If you have read the passage carefully and still not able to find any connections between two things, never assume it explicitly.

Hope it helps.
Thanks.

RakshithTN · Answer

carcass  
Can you share the OE for this question?

mSKR · Answer

Hi  AndrewN  sir
 
Please check my explanation for Q-6 and Q1:

Quanta with a wavelength of 1 inch is measured in inches. But it will not be accurate as mentioned in first line that we can get readings only to one decimal place but not upto millionths of an inch. The same idea is mentioned in 3rd statement that these inches will also be useless if the wavelength is of large dimension.

E is wrong because our question is to identify the meaning of phrase " in a sense".
B fits in because our readings are not precise to measure wavelength of an inch to precise readings to more decimal places.

Q=1:

B: Wrong: a small topic in end of 2nd para: not a primary purpose
D: Wrong: only talked a little in 3rd passage; not a primary purpose.
E: Wrong: details have not been mentioned about functionalities

i was lost in A and C.
I chose C because in 3rd para: it is highlighted about subject and object and their relationships.
I rejected A because precise purpose was not talked in details but only in para 2, limitations have been talked about.
How shall i choose A  AndrewN   GMATNinja

AndrewN · Answer

Hello,  imSKR . My apology for getting to this so late, but two things happened to hinder an earlier response: 1) I lost power at my home for more than a day; and 2) by chance, I got a bunch of requests and a few PMs from other GMAT Club members, and I like to answer messages in the order in which I receive them. To get to your questions, in 6, notice that the line in which  in a sense  appears is discussing  quanta with a wavelength of one inch , and that the previous line also discusses such quanta. These types of questions often draw from the line prior to the one in question. Here, we see that a larger tool, a yardstick, that uses as its units a measurement, inches, that would encompass an entire set of smaller sub-lengths or units, would prove  useless  for making finer measurements. All that  in a sense  conveys in the next line is that, despite the quanta being described as those  with a wavelength of one inch , they are only being  compared to  the yardsticks mentioned earlier—their similar description does not make them  the same . Choice (E) can be enticing for those looking ahead in the passage, but by that time, the comparison has already been made. Choice (B) is harder to argue against.

In question 1, choice (C) is easy to eliminate by the first word:  criticize . The author uses no strong language in the passage to describe the views or actions of others. The passage is more neutral in tone, and  discuss  in (A) is much more fitting to that end. Neither can I find any issues with the rest of (A). The  problem  is the  limitation  (first line, paragraph two) of  our visual perception  (opening line), and all three paragraphs revolve around this central idea.

I hope that helps. You seem to be developing a keener eye for detail, per your analyses. Keep up the fine work.

- Andrew

himani007 · Answer

Given in para 2- but a completely accurate perception of the world will depend also on the exact measurement of the lengths and positions of what we wish to perceive. For this, quanta of extremely long wavelengths are useless. 
 E is the answer.

I don't quite understand why the answer to the second question is E and not B. When the passage clearly states that quanta with extremely long wavelengths are measured in one millionth i.e equivalent to inches.

himani007 · Answer

I dont understand how the second question's answer is not chouce B but E.

AndrewN · Answer

Hello,  himani007 . You have the right excerpt from the passage, but you did not stick closely enough to the question stem. Sentences two and three from the second paragraph map well onto the question stem and answer choice (E):

So, why can these quanta not  give complete information about the physical world ? Because  a completely accurate perception of the world will depend also on the exact measurement of the lengths and positions of what we wish to perceive . This is exactly what (E) says.

Answer choice (B) is inaccurate because it takes a comparison as a literal truth. The passage, again from paragraph two:

Note that the verb  would be  indicates a hypothetical condition, and  in a sense  reinforces the  sort of  nature of the information. Answer choice (B) is saying that  quanta with an extremely long wavelength are graduated only in inches , and the comparison made above has been lost in the process.

Perhaps the question makes more sense now. Good luck with your studies.

- Andrew

Our visual perception depends on the reception of energy reflecting or

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