Most attempts by physicists to send particles faster than the speed of

Can someone explain how to discard Option-E?:

Q542. RC00301-02. The passage implies that if tunneling time reached no maximum in increasing with barrier thickness, then

(A) Tunneling speed would increase with barrier thickness
(B) Tunneling speed would decline with barrier thickness
(C) Tunneling speed would vary with barrier thickness
(D) Tunneling speed would not be expected to increase without limit
(E) Successful tunneling would occur even less frequently than it does

My reasoning for E:

Excerpt from the passage:

Quantum theory says that there is a distinct, albeit small, probability that such a particle will tunnel its way through a barrier; the probability declines exponentially as the thickness of the barrier increases.

The gist of the above line: the probability that a particle will tunnel declines exponentially as we increase the thickness of the barrier.

I understood how Option-D is the correct answer. However, I was unable to reject Option-E.
Any insights is welcomed to reject Option-E on solid grounds!

Regarding answer Choice B:

The passage states that tunneling time increases with barrier thickness up to a limit. As the thickness goes up, tunneling speed should increase at the time limit. Doesn't this imply that if there is no time limit, then the speed can decline or stay the same infinitely?[/quote]

Let me try to explain. Let's look back at the passage:

"their grounds were calculations that suggested that the time it takes a particle to tunnel through a barrier increases with the thickness of the barrier until tunneling time reaches a maximum; beyond that maximum, tunneling time stays the same regardless of barrier thickness. This would imply that once maximum tunneling time is reached, tunneling speed will increase without limit as barrier thickness
increases."

to sum it up:

Until reaching maximum time: the time increases if the thickness increases; the important part is, there's no speed mentioned
After reaching maximum time: Time remains constant and speed increases if the thickness increases - both without any limit

So clearly, we can infer D from that. B would take another step to infer, namely that the speed decreases while time and thickness increase. However, the passage itself does not support that. Yes, we all know that this would be the case, but we can only assume what is supported by the passage. Thus, from the the statement "once maximum tunneling time is reached, tunneling speed will increase without limit as barrier thickness increases." we can simply add a no and have our answer D, whereas what happens with the speed before reaching maximum time is never really mentioned.

I must admit, I also chose B, tho

Hi GMATNinja MartyTargetTestPrep jennpt
I am confused in choosing the best/exact word in answer choice. Could you share insights, please?
In correct choice D, the hypothetical word (would) has been used to legit the choice D. The passage says: once maximum tunneling time is reached, tunneling speed will increase without limit as barrier thickness increases.
We can infer/imply that once maximum tunneling time is NOT reached, tunneling speed will NOT increase without limit as barrier thickness increases.
My Question: WHY do we use "hypothetical would" where we get will NOT?

GMATNinja
Sir, could you explain the significance of the word could in choice C?
Thanks__

GMATNinja

Thanks for the above clarifications !! I got the question 1 incorrect & eventually figured out what you explained so well.

I'm really interested to know how your mind map/Notes would look like for this one ! I'm practicing reading the passage (with notes) within 3min, but I am not able to. Even though I am able to make up for it by answering the question quickly, I don't think this approach will help me during the test itself.

Glad to hear that the explanation helped!

Unfortunately, there's no tactic that you can use to read faster and answer questions faster, without taking the risk of misunderstanding the passage or making a careless mistake on the question. Reading skills and reading pace can literally take years to improve, and no test prep trick will change that. And when it comes to tactics to help keep track of what a passage is saying (like note-taking), the solution really varies from person to person. (Much more on that in this long-winded beginner's guide to RC.)

All that said, remember that your goal is to understand the purpose of the passage. The more effectively you can comprehend WHY the author is writing the passage -- and how the author structures the passage to fulfill that purpose -- the less time you'll spend backtracking, re-reading, and second-guessing what was written. Shortcutting the reading process can actually make you slower, because you might end up spending tons of time going back and forth between the passage and the answer choices.

While this particular passage seems like a single paragraph without explicit structure, there is a structural break halfway through:


Everything from here through the end of the passage serves the purpose of explaining how physicists have confirmed that tunneling particles sometimes travel faster than light. And everything before this point serves the purpose of defining what quantum tunneling is. So in a way, there are two paragraphs, with two distinct purposes, masquerading as one wall of text here.

I hope that helps!

I'm not entirely sure what you mean by "significance." Are you just looking for the meaning?

We can take the word at face value, so "they didn't suppose that tunneling particles could travel faster than light" means they (the earliest scientific investigators of quantum tunneling) did not suppose that it was possible for tunneling particles to travel faster than light.

I'm not sure if I answered your question, but I hope this helps a bit!

VeritasKarishma

please explain qustion 3

option c & D

Q543. RC00301-04. Which of the following statements about the earliest scientific investigators of quantum tunneling can be inferred from the passage?

(A) They found it difficult to increase barrier thickness continually.
(B) They anticipated the later results of Chiao and his colleagues.
(C) They did not suppose that tunneling particles could travel faster than light.
(D) They were unable to observe instances of successful tunneling.
(E) They made use of photons to study the phenomenon of tunneling.

Note this:
... Though the extreme rapidity of quantum tunneling was noted as early as 1932, not until 1955 was it hypothesized—by Wigner and Eisenbud—that tunneling particles sometimes travel faster than light.

Though quantum tunnelling was noted in 1932, it was much later than faster than light travel concept was proposed.
So option (C) is correct.

Nowhere in the passage does it say that they were not able to observe instances initially.

Hello GmatNinja

Could you please explain in RC00301-02, why is the answer C, whereas the first line of the passage states that physicists attempted to send particles faster than speed of light. Why is D not the answer which is actually what happened.

Posted from my mobile device

The OA for question RC00301-02 (also listed as Question 2 and Q542) is (D), not (C).

I hope that clears it up!

OE
Q1. The author of the passage mentions calculations about tunneling time and barrier thickness in order to
A. suggest that tunneling time is unrelated to barrier thickness
B. explain the evidence by which Wigner and Eisenbud discovered the phenomenon of tunneling
C. describe data recently challenged by Raymond Chiao and colleagues
D. question why particles engaged in quantum tunneling rarely achieve extremely high speeds
E. explain the basis for Wigner and Eisenbud’s hypothesis
Evaluation
This question asks why the author discusses calculations about tunneling time and barrier thickness. According to the passage, these calculations provided the grounds for Wigner and Eisenbud’s hypothesis that tunneling particles may travel faster than light.
A. The passage states that tunneling time is related to barrier thickness, up to the point at which tunneling time reaches a maximum.
B. The passage indicates that the phenomenon of tunneling was noted at least as early as 1932. It provides no evidence that Wigner and Eisenbud discovered it.
C. The passage uses Chiao’s work to support the idea that tunneling particles may move faster than light, not challenge it.
D. The author describes calculations about tunneling time and barrier thickness in order to explain that particles engaged in quantum tunneling may in fact achieve extremely high speeds, not to explain the rarity of the phenomenon.
E. Correct. The calculations about tunneling time and barrier thickness supported Wigner and Eisenbud’s hypothesis that quantum tunneling could occur at speeds faster than that of light.
The correct answer is E.

Q2. The passage implies that if tunneling time reached no maximum in increasing with barrier thickness, then
A. tunneling speed would increase with barrier thickness
B. tunneling speed would decline with barrier thickness
C. tunneling speed would vary with barrier thickness
D. tunneling speed would not be expected to increase without limit
E. successful tunneling would occur even less frequently than it does
Inference
The passage states that because tunneling time reaches a maximum, then tunneling speed must increase as barrier thickness increases. But if tunneling time did not reach such a maximum, then speed need not increase without limit; the particle could have as low a speed in thicker barriers as in thinner ones and take longer to tunnel through a barrier.
A. If tunneling time could not reach a maximum, then speed might increase, decrease, or remain the same as barrier thickness increases.
B. If tunneling time could not reach a maximum, then speed might increase, decrease, or remain the same as barrier thickness increases.
C. Tunneling speed could vary with barrier thickness if tunneling time could not reach a maximum, but there is no basis in the passage on which to conclude that this is definitely so.
D. Correct. The tunneling particle could have as low a speed in thicker barriers as in thinner ones and simply take longer to make its way through a thicker barrier.
E. The passage states that the probability of successful tunneling declines as the thickness of the barrier increases. However, it does not address the issue of whether the differences in probability of successful tunneling are due to the greater time required to go through thicker barriers.
The correct answer is D.

Q3. Which of the following statements about the earliest scientific investigators of quantum tunneling can be inferred from the passage?
A. They found it difficult to increase barrier thickness continually.
B. They anticipated the later results of Chiao and his colleagues.
C. They did not suppose that tunneling particles could travel faster than light.
D. They were unable to observe instances of successful tunneling.
E. They made use of photons to study the phenomenon of tunneling.
Inference
This question asks about the earliest investigators of quantum tunneling. The passage notes that quantum tunneling’s extreme rapidity was observed in 1932; thus, the earliest investigators of this phenomenon knew of its existence at that time. Not until 1955 did Wigner and Eisenbud hypothesize that the particles traveled faster than light. Thus, it is logical to infer that the earliest investigators did not imagine such a speed.
A. There is nothing in the passage to suggest that the earliest investigators of quantum tunneling had difficulty manipulating barrier thickness.
B. The passage states that Chiao and his colleagues measured photons moving at 1.7 times the speed of light—but the passage does not provide evidence that the earliest investigators anticipated such speeds.
C. Correct. The passage suggests that prior to 1955, investigators of quantum tunneling had not hypothesized that the particles could travel faster than the speed of light.
D. The passage indicates that by 1932, investigators had noted the rapidity of quantum tunneling;
although this does not entail that they observed the phenomenon, it is consistent with their having been able to do so.
E. The passage indicates that Chiao’s work involves photons, but it does not indicate the type of particles used or observed by the earliest investigators of the phenomenon.
The correct answer is C.

Here's my breakdown of the passage -

Aim - send particle faster that Speedlight
How - QT
What is it - particles through soid barrier
Expectation - bounce back like ball
Reality - subatomic particles are achievers. theyre not balls!

QT definition and understandings
- distinct, very small P(can tunnel through)
- P(tunnelling) declines exponentially with thickness.

QT fame / rapidity / trend - 1932
QT hypothesis for experimentations- 1955

Let's discuss the experiment then -
- basis of calculations - time increases with thickness (obv, if the barrier keeps getting thicker, time to go through will keep increasing)
- Thickness inc = time inc.

BUT
at Timemax = it cant change any further = its reach its all time high = its constant now.
- so Barrier keeps increasing.
- Timemax constant.

What does that mean -
Speed x timemax = distance (thickness).
Speed x constant = distance
speed is directly proportional to distance (aka thickness)

(note if time is NOT max, then it is not constant, then it is going to change, so its a variable. which means speed will not increase with thickness - hint with Q2)

thickness keeps increasing, speed keeps increasing.

Final few sentences:
QT is spported - RC and photon study results.

I am so appreciative for the thorough discussion of this passage, but I still have a few lingering questions:
1. Is there a difference between "quantum tunneling" and "quantum theory" mentioned in the passage?
2. I do not understand this part of the passage: "If you throw a ball at a wall, you expect it to bounce back, not to pass straight through it. Yet subatomic particles perform the equivalent feat." What makes the feat "equivalent"? Subatomic particles are also not able to pass through it and bounce back? I am assuming that the author means subatomic particles can pass through the wall (based on "yet" and everything else mentioned in the passage).
3. For question 609 (which of the following statements about the earliest scientific....), I am caught up in Choice D. I chose D because of the first sentence in the passage "most attempts"--> this seems to simply that most physicists were unsuccessful. This question was very confusing to me because what does GMAC mean by "earliest"? There are the scientists that noted this as early as 1932.... then there are scientists in 1955 (Wigner and Eisenbud), and then later scientists (Raymond Chiao). Early relative to Wigner and Eisenbud or early relative to Chiao? Please note that I realize GMATNinja discussed why D is incorrect, but I am still lost based on my reasoning above.

Thank you for all of your time and help!

1. The passage defines quantum tunneling as "a remarkable phenomenon[...] in which particles travel through solid barriers that appear to be impenetrable." Quantum theory, on the other hand, seems to be the name for a broader framework that explains the probability of quantum tunneling.

The passage is primarily concerned with aspects of quantum tunneling, and doesn't really give us much separate info about quantum theory. When you're reading a passage, keep in mind the bigger picture of why the author is including the details -- if he/she is just mentioning quantum theory to better explain quantum tunneling, then you can focus on quantum tunneling as the more important element of the passage.

2. Yup, particles can tunnel through barriers. The author gives us the analogy of a ball bouncing off a wall to show how weird and surprising it is that particles can tunnel through something that seems impenetrable.

3. "Earliest" is different than "earlier" -- by saying "earliest," we know that question 3 is talking about the very first investigators of quantum tunneling. The earliest investigators mentioned in the passage are the ones working as early as 1932. So, we know without a doubt that the author is NOT talking about Wigner and Eisenbud, but about the scientists who came BEFORE Wigner and Eisenbud.

What do we know about these earliest investigators? That they noted the "extreme rapidity of quantum tunneling." If you note an aspect about a thing, then you must have observed that thing. So, we can't that these investigators didn't observe quantum tunneling -- the passage actually heavily implies that they DID observe quantum tunneling.

Nothing in the phrase "most attempts" implies that the attempts were unsuccessful -- I could say that "Most of my attempts to bake involve a lot of cursing." Does that mean I don't succeed in the end? Nope -- it could be that I DO successfully bake delicious goods.

I hope that helps!

GMATNinja

From the starting [first sentence]

Most attempts by physicists to send particles faster than the speed of light involve a remarkable phenomenon called quantum tunneling, in which particles travel through solid barriers that appear to be impenetrable. Though the extreme rapidity of quantum tunneling was noted as early as 1932.


Why did they not suppose that tunneling particles could travel faster than light?

1) send particles faster than the speed of light >> quantum tunneling
2) quantum tunneling was noted as early as 1932
Then, the earliest investigator did suppose that tunneling particles could travel faster than light.

Also, not until 1955 was it hypothesized—by Wigner and Eisenbud + Raymond Chiao and colleagues did prove and got the result supporting the hypothesis of Wignera and Eisenbud. I am not sure whether the earliest investigator were unable to observe instances of successful tunneling or not but we could imply there were no any results until 1955.

Could you help fix what and why I am wrong?

Question 3

There are two distinct things happening here:

1) Quantum tunneling: very fast movement through a barrier. The rapidity of quantum tunneling "was noted as early as 1932." So, we know that scientists observed quantum tunneling by 1932.

2) Sending particles faster than the speed of light: this is achieved through quantum tunneling, but not every instance of quantum tunneling went faster than the speed of light. This wasn't even hypothesized until 1955.

So, although pre-1955 researchers observed quantum tunneling, they did not hypothesize that particles could go faster than the speed of light.

(D) is out, and (C) is the correct answer to question 3.

I hope that helps!