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

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Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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New post 23 Oct 2018, 15:29
1
Got 3/3 correct in 8 min including 3:45 min to read the passage!

Passage Map:


1) Background about quantum tunneling
2) History of QT
3) New evidence supporting it
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Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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New post 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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Most attempts by physicists to send particles faster than the speed of  [#permalink]

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New post Updated on: 12 Jan 2019, 07:02
The answer key in OG 2019 version is wrong: it states E as OA while the solutions confirm C

Originally posted by isabelle95 on 12 Jan 2019, 04:16.
Last edited by isabelle95 on 12 Jan 2019, 07:02, edited 1 time in total.
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Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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New post 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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New post 21 Feb 2019, 19:54
3/3

1 - 03:17, 2 - 01:01, 3-00:37

Total : 04:55
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Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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New post 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!
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Re: Most attempts by physicists to send particles faster than the speed of  [#permalink]

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New post 13 May 2019, 09:35
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 :-D :cry:
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Re: Most attempts by physicists to send particles faster than the speed of   [#permalink] 13 May 2019, 09:35

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