Advances in scientific understanding often do not
build directly or smoothly in response to the data that
are amassed, and in retrospect, after a major revision
of theory, it may seem strange that a crucial hypothesis
(5) was long overlooked. A case in point is the discovery
of a means by which the nuclei of atoms can be split.
Between 1934, when a group of Italian physicists
including Enrico Fermi first bombarded uranium with
neutrons, and 1939, when exiled Austrian physicist
(10) Lise Meitner provided the crucial theoretical
connection, scientists compiled increasing evidence
that nuclear fission had been achieved, without,
however, recognizing what they were witnessing.
Summary: Scientific hypothesis generally gets overlooked during scientific discovery. examples are provided. such is the case with splitting of atoms during uranium bambardment with neutrons.
Earlier, even before the neutron and proton
(15) composition of atomic nuclei had been experimentally
demonstrated, some theoretical physicists had
produced calculations indicating that in principle it
should be possible to break atoms apart. But the
neutron-bombardment experiments were not aimed at
(20) achieving such a result, and researchers were not
even receptive to the possibility that it might happen in
that context. A common view was that a neutron's
breaking apart a uranium nucleus would be analogous
to a pebble, thrown through a window, causing a house
(25) to collapse.
Summary: Theoretically, it was proved to break atoms apart but Neutron bombardment experiment was viewed as a pebble casuing a house window collapse.
In Berlin, Meitner pursued research related to that
of the Italians, discovering a puzzling group of
radioactive substances produced by neutron
bombardment of uranium. Fermi and others achieved
(30) numerous similar results. These products remained
unidentified partly because precise chemical analyses
were hampered by the minute quantities of the
substances produced and the dangers of working with
highly radioactive materials, but more significantly
(35) because of the expectation that they would all be
elements close to uranium in nuclear composition.
In 1938 Meitner escaped from Nazi Germany and
undertook related research in Sweden, but her research
partner Otto Hahn kept her informed of his continuing
(40) experimentation. Late in that year he wrote to her
of a surprising result: one of the substances resulting
from the neutron bombardment of uranium had been
conclusively identified as barium, an element whose
structure would have made it impossible to produce
(45) through any mechanism he envisaged as being
involved in the experiments. Hahn even remarked
that, despite the clear chemical evidence of what had
occurred, it went "against all previous experiences of
nuclear physics," but he also noted that together the
(50) number of protons and neutrons in the nuclei of
barium and technetium, the accompanying product
of the experiment, added up to the number of such
particles that compose a uranium nucleus.
Summary: Many substances resulting from bombardment were ignored because of the belief that they will be similar in structure to that of uranium etc. Meitner partner otto hahn informed her of barium discovery etc.
It was Meitner who finally recognized the
(55) significance of the data in relation to underlying
theoretical considerations: the researchers had actually
been splitting uranium atoms. Coining the term
"nuclear fission," she quickly submitted her
conclusion for publication in a paper co-authored with
(60) physicist Otto Frisch. When scientists in Europe and
North America rushed to corroborate the findings,
it became clear that the relevant evidence had been
present for some time, lacking mainly the right
conceptual link.
Summary: Meitner finally first recognized and published the findings and coined the term nuclear fission. Other scientists then corroborate their findings which was present already but lacking conceptual links.
1. The author's primary aim in the passage is to
Passgae talks about how scientific discovery take its form, sometimes even present for long time before getting recognised.
(A) criticize a traditional view of scientific progress and advocate a replacement
(B) illustrate the often erratic way in which a scientific community achieves progress
Correct
(C) judge the relative importance of theory and experimentation in science
(D) take issue with the idea that scientists make slow, steady progress
(E) display the way in which intellectual arrogance sometimes hinders scientific progress
2. The most likely reason that the theoretical physicists in line 16 would have been pleased about Meitner's insight regarding the neutron bombardment experiments is that her insight
Lise Meitner provided the crucial theoretical connection for neutron bombardment while theoretical physicists had produced calculations indicating that in principle it should be possible to break atoms apart.
(A) was dependent upon the calculations that they had produced
(B) paved the way for work in theoretical physics to become more acceptable abroad
(C) proved that the nuclei of atoms were generally unstable
(D) confirmed their earlier work indicating that atoms could be split
(E) came after years of analyzing the data from experiments conducted between 1934 and 1938
3. Which one of the following is most nearly equivalent to what the author means by "the relevant evidence" (line 62)?
(A) the results of experiments in neutron bombardment of uranium conducted by the physics community between 1934 and 1939
A case in point is the discovery of a means by which the nuclei of atoms can be split. Between 1934, when a group of Italian physicists including Enrico Fermi first bombarded uranium with neutrons, and 1939, when exiled Austrian physicist, Lise Meitner provided the crucial theoretical connection, scientists compiled increasing evidence that nuclear fission had been achieved, without, however, recognizing what they were witnessing.
(B) the results of related experiments in neutron bombardment of uranium conducted by Meitner in 1938
(C) the clear chemical evidence that Hahn had found of barium's being produced by neutron bombardment of uranium
(D) the fact that the sum of the number of protons and neutrons in the nuclei of barium and technetium was the same as the number of these particles in a uranium nucleus
(E) the fact that radioactive products of neutron bombardment of uranium went unidentified for so long
The products were identified but the conceptual link was missing.
4. Given the information in the passage, which one of the following, if true, would have been most likely to reduce the amount of time it took for physicists to realize that atoms were being split?
(A) The physicists conducting the experiments in neutron bombardment of uranium were all using the same research techniques.
(B) The physicists conducting the experiments in neutron bombardment of uranium did not have particular expectations regarding the likely nuclear composition of the by-products.
These products remained unidentified partly because precise chemical analyses were hampered by the minute quantities of the substances produced and the dangers of working with highly radioactive materials, but more significantly because of the expectation that they would all be elements close to uranium in nuclear composition.
(C) The physicists conducting the experiments in neutron bombardment of uranium had not been aware of the calculations indicating that in principle it was possible to split atoms.
(D) More physicists concentrated on obtaining experimental results from the neutron bombardment of uranium.
(E) Physicists conducted experiments in the neutron bombardment of some substance other than uranium.
5. According to the passage, which one of the following was true of the physics community during the 1930s?
(A) It neglected earlier theoretical developments.
(B) It reevaluated calculations indicating that atoms could be split.
(C) It never identified the by-products of neutron bombardment of uranium.
(D) It showed that uranium atoms were the easiest to split.
(E) It recognized the dangers of working with radioactive substances.
the dangers of working with highly radioactive materials