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

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Manager
Joined: 01 Nov 2018
Posts: 80
GMAT 1: 690 Q48 V35
GPA: 3.88
Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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04 Jan 2019, 16:52
3/3 in 8:32 although I had to guess on question 2. I have a question to all gmat test takers and gmat moderators. For a question such as question 2, if you feel that you are no closer to getting the right answer after spending 1:30min and the clock is ticking, do you just pick an answer and move on? If I subtracted the time I spent on that question (2:40), I would have finished this passage in under 6 minutes and I felt confident that I got questions 1 and 3 correct. I feel on the actual test, spending that much time and hoping you made the right "educated guess" is risky and could impact you on the rest of the Verbal section. Thoughts?
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GMAT 1: 710 Q49 V36
Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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12 Jan 2019, 05:17
bpdulog wrote:
Shree9975 wrote:
Steinbeck

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. Several recent experiments have supported this hypothesis that tunneling particles sometimes reach superluminal speed. According to measurements performed by Raymond Chiao and colleagues, for example, photons can pass through an optical filter at 1.7 times the speed of light

Look at the bold part, we can infer from that.

Thanks,
SR

Thanks! This is helpful. Can someone explain why B is false?

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?

Tunneling speed = Barrier thickness/Tunneling time. We cannot comment whether the tunneling speed would decrease because we do not know how tunneling time is increasing with respect to increase in barrier thickness. We just know that these two variables ( thickness and time) will increase but we do not know how these two variables behave with respect to each other. if it takes less and less time to cover larger distance (do not get confused here..time will still increase with distance) , then speed will increase. If it it takes more and more time to cover larger distance, , then speed will decrease.
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Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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01 Apr 2019, 13:17
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!
Intern
Joined: 04 Apr 2019
Posts: 4
Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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13 May 2019, 09:35

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
VP
Joined: 23 Feb 2015
Posts: 1451
Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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03 Dec 2019, 03:12
Quote:
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. 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. 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. 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. 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. Several recent experiments have supported this hypothesis that tunneling particles sometimes reach superluminal speed. According to measurements performed by Raymond Chiao and colleagues, for example, photons can pass through an optical filter at 1.7 times the speed of light.

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 barrer thickness
(D) Tunneling speed would not be expected to increase without limit
(E) Successful tunneling would occur even less frequently than it does

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?
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VP
Joined: 23 Feb 2015
Posts: 1451
Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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03 Dec 2019, 12:10
GMATNinja wrote:
kunal1608 wrote:
Could experts please elaborate on the 3rd question explaining why exactly is option D incorrect .

The official explanation says "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."

Quote:
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.

Refer to the following lines:
Quote:
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.

What do we know about the earliest scientific investigators of quantum tunneling? We know that they noted the extreme rapidity of quantum tunneling. We also know that they did NOT hypothesize that tunneling particles sometimes travel faster than light.

GMATNinja
Sir, could you explain the significance of the word could in choice C?
Thanks__
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Re: Most attempts by physicists to send particles faster than the speed of   [#permalink] 03 Dec 2019, 12:10

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