令和 5 年度
Ａ Ｏ 入 試 問 題 集（医学部医学科）

公表期限：2026 年 3 月末
東北大学入試センター※ 以下の(1),(2)の場合を除き，複製，転載，転用することを禁じます。
(1)受験予定者が自主学習のために使用する場合(2)学校その他の教育機関(営利目的で設置されているものを除く。)の教職員が教育の一環として使用する場合゜volume—to fulfill ®�, scholars and practitioners will need to continue to I economic value of thework togetller to assess how ecosystem services are l止ely to change in an uncertain 1 oeean,eoastal areas, andthe
future, pW:.ticulaily iJ.1 the face of humanity's adaptati�n to our changing environment. 1 Great Lakes(Used with permission of American Association for the Advancement of
Science, from A Roadmap to Nature's Benefits" by HEATHER M. LESLIE,Vol 332, Issue 6035
pp. 1264-1265 DOI: 10.1126/science.1207662, Copyright © 2011;
permission conveyed through Copyright Clearance Center, Inc.
一部改変）

問1.

下線部①を日本語に訳しなさい。

問 2.

下線部②の理由を本文の内容に即して蕊匪ヱ述べなさい。

問3．

下線部®で始まるパラグラフでは何に対する例があげられているのか，説明しなさい。

問4.

下線部④はこれまでの生態系サ ー ビスという考えを取り入れた事業とどこが異なるのか。 本文に即して2点述べなさい。

r、問5. 下線部®はどのようなものと考えられるか本文に即して述べなさい。

-6-discoveries, ideas, and policies spin arotu1d in a flurry, now more tl1art ever we must I flurry :突風anchor ourselves in and cherish the wisdom of personal interactions. The place where it
all starts.

(Marcin Chwistek, JAMA. 2020 Jul 14;324(2):149-150. Copyright © 2020 American Medical
Association. All rights reserved. 一部改変）

問l．

＆
下線①の発言の理由として患者が述べたことを 日本語に訳して述べなさい。

問2.

下線®について， 筆者はtelemedicineにはどのような利点があると考えているか述べなさい。

問 3.

Telemedicineと対局をなす診察について筆者は複数の表現を使用している。その中から1つ送語ヱ抜き問 4.

下線＠）が指す内容を説明しなさい。

問5.

MrM (8ページ目の第3パラグラフに登場する）の診察において， 下線④にあたるのはどのようなこ出しなさい。

とか述べなさい。

―、

9-polygraph evidence is reliable".

A f onnative figure behmd the claim that tltere are皿iversal facial expressions ofemotion is the psychologist Paul Ekm皿In tl1e 1960s, he travelled tl1e highlands of Papua

NewG血ea to testhis controversial hypothesis that all hun1ans exhibit a small number of、universal' emotions that are血ate, cross-cultural and consistent. Early on, antlrropologist 1· hmate :生来のMargaret Mead disputed tltis idea,·. saymg that it discounted context, culture 皿d social

factors.

Bll:t the six. emotions Ekman described fit perfectly hito the model of tlte

emergmg field of computer vision. As I write m my 2021 book Atlas ofAI, his theory was
adopted because it fit what the tools could do. Six consistent emotions could beistand紅diz�d and automated at scale - as long ·as the more co�plex issues were ignored.

Ektnan sold his system to tlte US Tr皿sportation Security AdmiI1istration after the 11

September 2001 terrorist attacks, to assess which airlme passengers were showmg fear or

stress, and so might be terrorists. It was strongly criticized for lacking· credibility and forbemg racially biased. However, m皿y of today's tools� such as 4Little Trees, are based on

I credibility :信憑性

Ektnan's six-emotion categorization.(Ekm皿 maiI1tains that faces do convey universal

emotio皿，but says he's see� no evidence tltat automated technologies work.)

Yet companies continue to sell software that will affect people's opportunities

without clearly documented, independently audited evidence of effectiveness. · Job

applicants- are bemg judged unfairly because their facial expressions or vocal tones don't

match those of employees; students are bemg flagged at school because tlteir faces seem

angry. Researcl}.ers have also shown tl1at facial-recognition software iI1terprets Black faces
as having more negative emotions than white faces do.

We can no longer allow emotion-recognition technologies to go wrregulated..Itis time for legislative protection from w1proven uses of tltese tools in all domams education, health care, employment皿d crimmal justice. These safeguards will recentre

rigorous science and reject the mythology tltat iI1temal states are just ru.1other data set thatcan be scraped from our faces.

I mytlmlogy :神話

出典：Kate Crawford. Nature, 2021 （ 一 部改変）

(Used with permission of Nature, from "Time to regulate AI that interprets human emotionss"by Kate Crawford,Nature 592, 167 (2021), © 2021 Springer Nature ; permission conveyed
through Copyright Clearance Center, Inc. 一部改変）- 11 -

令和 5 年度（2023 年度）東北⼤学
AO ⼊試（総合選抜型）III 期

筆記試験問題令和 5 年 2 月 11 日
志望学部／学科

医

学

部

医

学

試 験 時 間科

9:30〜11:30（120 分）

ページ数

21 ページ

注 意 事 項1． 試験開始の合図があるまで，この「問題冊⼦」，「解答⽤紙」を開いてはいけません。
2. この「問題冊⼦」は 21 ページあります。ページの脱落，印刷不鮮明の箇所などがあった場合には申し出てください。ホチキスは外さないでください。
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「問題冊⼦」，「メモ⽤紙」
は持ち帰ってください。

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１

以下の英文を読んで質問に答えなさい。
We define “fake news” to be fabricated information that mimics news media

content in form but not in organizational process or intent. Fake-news outlets, in turn,fabricated：捏造された
mimic：真似る

lack the news media's editorial norms and processes for ensuring the accuracy andcredibility of information. Fake news overlaps with other information disorders, such as
misinformation (false or misleading information) and disinformation (false informationthat is purposely spread to deceive people).
Fake news has primarily drawn recent attention in a political context, but it also has
been documented in information promulgated about topics such as vaccination, nutrition,

promulgated：広めるand stock values. It is ① particularly pernicious in that it is parasitic on standard news

pernicious：有害な

outlets, simultaneously benefiting from and undermining their credibility.
Some—notably First Draft and Facebook—favor the term “false news” because ofFirst Draft：オンライン

the use of fake news as a political weapon. We have retained it because of its value as a

で誤情報や偽情報と戦う

scientific construct, and because its political salience draws attention to an important

プロジェクトの一つ

subject.

Facebook：オンラインソ② Journalistic norms of objectivity and balance arose as a backlash amongーシャルメディアの一つ

journalists against the widespread use of propaganda in World War I (particularly theirsalience：論点

own role in propagating it) and the rise of corporate public relations in the 1920s. Local

backlash：反動

and national oligopolies created by the dominant 20th century technologies ofoligopoly：売り手寡占

information distribution (print and broadcast) sustained these norms. The internet has
lowered the cost of entry to new competitors—many of which have rejected thosenorms—and undermined the business models of traditional news sources that had enjoyedundermine：侵害する

high levels of public trust and credibility. General trust in the mass media collapsed tohistoric lows in 2016, especially on the political right, with 51% of Democrats and 14%
of Republicans expressing “a fair amount” or “a great deal” of trust in mass media as anews source.
The United States has undergone a parallel geo- and sociopolitical evolution.
Geographic polarization of partisan preferences has dramatically increased over the past

partisan：党派心が強い

40 years, reducing opportunities for cross-cutting political interaction. Homogeneous人

social networks, in turn, reduce tolerance for alternative views, amplify attitudinalpolarization, boost the likelihood of accepting ideologically compatible news, andincrease closure to new information. Dislike of the “other side” (affective polarization)
has also risen. These trends have created a context in which ③ fake news can attract amass audience.
How common is fake news, and what is its impact on individuals? There are
surprisingly few scientific answers to these basic questions.
In evaluating the prevalence of fake news, we advocate focusing on the original
sources—the publishers—rather than individual stories, because we view the defining
element of fake news to be the intent and processes of the publisher. A focus on publishers-4-also allows us to avoid the morass of trying to evaluate the accuracy of every single news

morass：泥沼

story.
One study evaluating the dissemination of prominent fake news stories estimateddissemination：流布that the average American encountered between one and three stories from known
publishers of fake news during the month before the 2016 election. This likely is aconservative estimate because the study tracked only 156 fake news stories. ④ Anotherstudy reported that false information on Twitter is typically retweeted by ( A ) people,

Twitter：ソーシャルネッ

and more ( B ), than true information, especially when the topic is ( C ). Facebook

トワーキングサービスのhas estimated that manipulations by malicious actors accounted for less than one-tenth of

一つ

1% of civic content shared on the platform, although it has not presented details of its

malicious：悪意のある

analysis.
We do know that, as with legitimate news, fake news stories have gone viral onsocial media. However, knowing how many individuals encountered or shared a piece of
fake news is not the same as knowing how many people read or were affected by it.
Evaluations of the medium-to-long–run impact on political behavior of exposure to fakenews (for example, whether and how to vote) are essentially nonexistent in the literature.
The impact might be small—evidence suggests that efforts by political campaigns to
persuade individuals may have limited effects. However, mediation of much fake news

mediation：仲裁

via social media might accentuate its effect because of the implicit endorsement that

accentuate：強調する

comes with sharing. Beyond electoral impacts, what we know about the effects of media

implicit endorsement：おmore generally suggests many potential pathways of influence, from increasing cynicism

墨付きand apathy to encouraging extremism. There exists little evaluation of the impacts of fakecynicism：冷笑

news in these regards.

apathy：無関心
extremism：極論主義(Reprinted with permission from AAAS, from The science of fake news, by David M. J. Lazer, Matthew A.
Baum, Yochai Benkler, Adam J. Berinsky, et al. © 2018 American Association for the Advancement of
Science; permission conveyed through Copyright Clearance Center, Inc. 一部改変)

問1.

Fake news が下線部① particularly pernicious である理由を本文に即して述べなさい。

問2.

下線部② Journalistic norms of objectivity and balance はどのように生まれ，20 世紀まで維持されてきたのか本文に即して述べなさい。

問3.

下線部③ fake news can attract a mass audience の理由を本文に即して述べなさい。

―――次ページに続く
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問4.

下線部④の“Another study”に該当する論文に記載されているグラフを以下に示す。グラフから推察して、空欄（A）,（B）,（C）に入る語を下記のア〜カから選び答えなさい。
ア．businessイ．lesserウ．more エ．politics オ．rapidly

カ．slowly

グラフの説明：上段のグラフは全ツイートのうち X 回以上のカスケード（連続的伝達）があったツイートの割合(%)をツイートの種類別に示している。下段のグラフはカスケード（連続的伝達）の量（Depth）とそれに要した平均時間(Mean Minutes)の関係をツイートの種類別に示している。

問5.

"fake news" に関する研究の課題について，最終パラグラフの内容を参考にして日本語 150 字～180 字程度で述べなさい。

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２

以下の英文を読んで質問に答えなさい。

Overcoming an evolutionary barrier
The scientists working to find and develop plastic-[ ① ] organisms must contend
with a basic reality: evolution. Microbes have had millions of years to learn how tomicrobe:微生物

biodegrade organic matter such as fruits and tree bark. They have had barely any time atbiodegrade：生物分解さall to learn to decompose plastics, which did not exist on Earth at any scale before roughly

れる

1950.

decompose:分解する“Seaweed has been around for hundreds of millions of years, so there is a variety of
microbes and organisms that can break it down,” said Pierre-Yves Paslier, the co-founderof a British company, Notpla, that is using seaweed and other plants to make films andcoatings that could replace some types of plastic packaging. By contrast plastic is very
new, he said.
Still, recent discoveries of plastic-[ ① ] microorganisms show that evolution is

microorganism:微生物

already getting to work. A year after the 2016 discovery of Ideonella sakaiensis in Osaka,
scientists reported a fungus able to degrade plastic at a waste disposal site in Islamabad,

fungus：真菌（カビ）類

Pakistan. In 2017 a biology student at Reed College in Oregon analyzed samples from an
oil site near her home in Houston, Texas, and found they contained plastic-[ ① ] bacteria.
In March 2020, German scientists discovered strains of bacteria capable of degrading
polyurethane plastic after collecting soil from a brittle plastic waste site in Leipzig.
② In order to make any of these naturally-occurring bacteria useful, they must be

brittle:もろいnaturally-occurring：自然bioengineered to degrade plastic hundreds or thousands of times faster. Scientists have

発生のenjoyed some breakthroughs here, too. In 2018 scientists in the U.K. andbioengineer：生物工学に

U.S. modified bacteria so that they could begin breaking down plastic in a matter of days.

よってつくるIn October 2020 the process was improved further by combining the two different plastic[ ① ] enzymes that the bacteria produced into one “super enzyme.”

enzyme：酵素

The first large-scale commercial applications are still years away, but withinsight. Carbios, a French firm, could break ground in coming months on a demonstration
plant that will be able to enzymatically biodegrade PET plastic.
This could help companies such as PepsiCo and Nestle, with whom Carbios ispartnering, achieve longstanding goals of incorporating large amounts of recycledmaterial back into their products. They’ve so far failed to succeed because there has neverbeen a way to sufficiently break down plastic back into more fundamental materials.
(Because of this, most plastic that is recycled is only ever used to make lower-quality
items, such as carpets, and likely won't ever be recycled again.)“Without ③ new technologies, it’s impossible for them to meet their goals. It’s just
impossible,” said Martin Stephan, deputy CEO of Carbios.
Besides plastic-[ ① ] bacteria, some scientists have speculated that it may bepossible to use nanomaterials to decompose plastic into water and carbon dioxide. One

nanomaterial：ナノマテ

2019 study in the journal Matter demonstrated the use of “magnetic spring-like carbon

リアル

-8-

nanotubes” to biodegrade microplastics into carbon dioxide and water.
The challenges ahead④ Even if these new technologies are one day deployed at scale, they would still
face major limitations and could even be dangerous, experts caution.
Of the seven major commercial types of plastic, the plastic-[ ① ] enzyme at theheart of several of the recent breakthroughs has only been shown to digest one, PET.
Other plastics, such as HDPE, used to make harder materials such as shampoo bottles orpipes, could prove more difficult to biodegrade using bacteria.
Nor are the bacteria able to degrade the plastic all the way back into their coreelemental building blocks, including carbon and hydrogen. Instead, they typically breakelemental：元素のup the polymers out of which plastics are composed back into monomers, which are often

polymer：重合体

useful only to create more plastics. The Carbios facility, for example, is intended only tomonomer：単量体

convert PET plastic back into a feedstock for the creation of more plastics.

feedstock：供給材料

Even if one day it becomes possible to mass produce bacteria that can be sprayedonto piles of plastic waste, such an approach could be dangerous. Biodegrading thepolymers that comprise plastic risks releasing chemical additives that are normally stored

chemical additive：化学添

up safely inside the un-degraded plastic.

加物

Others point out that there are potential unknown side-effects of releasing
genetically engineered microorganisms into nature. “Since most likely geneticallyengineered microorganisms would be needed, they cannot be released uncontrolled into
the environment,” said Wolfgang Zimmerman, a scientist at the University of Leipzig
who studies biocatalysis.

biocatalysis：生体触媒

Similar issues constrain the potential use of nanomaterials. Nicole Grobert, ananomaterials scientist at Oxford University, said that the tiny scales involved in
nanotechnology mean that widespread use of new materials would “add to the problem
in ways that could result in yet greater challenges.”
The best way to beat the plastic waste crisis, experts say, is by switching to reusable
alternatives, such as Notpla's seaweed-derived materials, ensuring that non-recyclable
plastic waste ends up in a landfill rather than in the environment, and using biodegradable

landfill：ゴミ処理地

materials where possible.

(Reprinted from "The Race To Develop Plastic-Eating Bacteria" by EDITORS' PICK . From Forbes. © 2021
Forbes. All rights reserved. Used under license. 一部改変)

-9-

問 1.

[ ① ]に入るのに適切な言葉を以下から選びなさい。
ア）burningイ）eatingウ）producingエ）squashingオ）transporting

問 2.

プラスチックを分解する微生物が少ない理由を本文に即して述べなさい。

問 3.

下線部②の目的のために科学者たちは具体的にどのような工夫をしたか，本文に即して述べなさい。

問 4.

下線部③に相当する実際に発表された具体的な例としてどのようなものがあげられているか，本文に即して述べなさい。

問 5.

下線部④で述べられている大きな制約・危険性とはどのようなことか，本文に即して５点述べなさい。

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３

以下の英文を読んで質問に答えなさい。

CO2 but not as you know it
What might be the most demonized molecule on the planet? Perhaps hydrogendemonized：悪魔のよcyanide, the ingestion of which can cause coma and death? Or nicotine, an addictive

うな

component in cigarettes and the forerunner to bee-killing neonicotinoids? Another strong

coma：昏睡

contender is hydrogen peroxide, which can be easily combined with acetone to make theforerunner：先駆者

explosive triacetone triperoxide (dubbed ‘Mother of Satan’) that was used in severalhydrogen peroxide：過terrorist attacks in the past few years. But I argue that in recent history it is carbon dioxide,

酸化水素

CO2, that has been the most demonized. One of the first molecules to appear when Earthwas formed 4.5 billion years ago, CO2 has been key to the formation of the biosphere andbiosphere：生物圏

is paramount for the continuation of life on Earth. It is essential for plant growth throughthe process of photosynthesis, and without it we wouldn’t have the variety of fruit,

photosynthesis：光合成

vegetables and grains that we currently take for granted. Recently, it has been used tostimulate larger crop size in greenhouses.
Crucially, CO2 in our atmosphere has made life on Earth possible for humans; byabsorbing infrared radiation from the sun and re-radiating it to Earth, it has brought the

infrared radiation：赤外

planet’s surface temperature to a life-supporting 15 °C, as opposed to –18 °C otherwise. It

線放射

also dissolves in the ocean to form calcium carbonate (CaCO3), the building block formarine shells and skeletons, thus enabling marine life to flourish.
The dissolution of CO2 in potable water was used by sailors across the oceans after
Joseph Priestley suggested it as a cure for scurvy. Priestley didn’t profit from his idea, but

potable：飲用できる
scurvy：壊血病

J. J. Schweppe formed the Schweppes company in 1783, which still turns a profit to thisday. This drinks carbonation process is still applied, using CO2 from various sources —including captured directly from the atmosphere, by the Swiss company Climeworks.
Carbon dioxide also serves as a carbon source in industrial processes to make urea (afertilizer), salicylic acid (for aspirin) and as a green solvent in its supercritical form. With

fertilizer：肥料

all these life-giving and productive effects, how did CO2 gain such a bad reputation? The

green solvent：環境に優answer is of course global heating. Eunice Foote first noted the warming effect of CO2 in

しい溶媒1856 in her paper entitled “Circumstances affecting the heat of the sun’s rays”. Her
experiment involved her putting two cylindrical receivers containing thermometers indirect sunlight. One cylinder contained ‘common air’ and the other contained ‘carbonicacid gas’ (the archaic name for CO2). Eunice Foote noted that “the receiver containing thegas became itself much heated (…) and on being removed [from direct sunlight], it was
many times as long in cooling [compared with the receiver containing ‘common air’].” Shealso proposed that if, in history, there had been more CO2 in the atmosphere, it would haveresulted in a higher temperature on Earth. Five years later, but with no reference to Eunice
Foote’s work, John Tyndall published a paper observing that CO2 could absorb heat, andhe also made the link between increasing CO2 concentrations and a change in the climate.
Since the Industrial Revolution began in 1850 we have converted more and more
- 12 -

hydrocarbons into CO2 gas. This activity has increased the atmospheric concentration of
CO2 by almost 50%, (from 278 ppm to 417 ppm), and has led to a surface temperature riseof 1.2 °C since pre-industrial levels. This is destabilizing the planet, resulting in moredestabilize：不安定にす

frequent extreme weather events, famine, marine death, loss of habitat, rising sea levels,るand homes across the world being lost to the ocean, all leading to millions of climate
refugees. Industrial clusters around the UK are piloting the capture of CO2 from cement,
steel and other heavy-emitting processes. Year after year we are promised this as the① ‘silver bullet’ to fix the climate emergency by the UK government, but time is runningout and no appreciable scale has yet been reached.
It would thus be easy to conclude by commenting on the power of such a small
molecule to effect so much change across our planet. Actually, CO2 is innocent in all of
this. Rather than demonizing the molecule we should celebrate it and treat it with respect.
Carbon dioxide supports life on Earth. We humans are the reason our planet is becoming
uninhabitable. We need to take responsibility for increasing the concentration of CO2 in
our atmosphere — and urgently act to slow global emissions. I still have a modicum ofmodicum：わずか

hope that we can create a safer atmosphere, but there is no denying that we are in dire

dire：恐ろしいcircumstances. What will you do to take charge of your own emissions, at home and at
work?
（ア）

（イ）

（ウ）

Figure 1. Annual CO2 emissions
The distribution of emissions has changed significantly over time. The U.K. was – until
1888, when it was overtaken by the U.S.A. – the world’s largest emitter. The world’s largest
emitter today is China, followed by the U.S.A. and India. Emissions from these three
countries account for more than half of global emissions.

- 13 -

(Reproduced with permission from Springer Nature, from CO2 but not as you know it,by Jennifer A. Rudd, © 2022 Springer Nature Limited ; permission conveyed throughCopyright Clearance Center, Inc. 一部改変)
図出典：Our World in Data（一部改変）

問1.

本文中に述べられている CO2 の有用性を筆者があげている例の中から４点述べなさい（各々20 字以
上）
。

問2.

CO2 の bad reputation のきっかけになった実験の内容を 120 字以内で述べなさい。

問3.

CO2 ガスが急激に増加することになった歴史上の出来事と，それにより引き起こされた事象を 120 字以内で述べなさい。

問4.

下線部①はどのような意味で用いられていると考えられるか，本文中の説明から推察し日本語 20 字程度で述べなさい。

問5.

Figure 1 は”Our World in Data”から引用した、国別 CO2 排出量の推移を示している（縦軸： CO2 排出量、横軸：年代）。グラフ上のア，イ，ウに合致すると考えられる国・地域名を以下から選び答えなさい。
a. China (中国)
b. India (インド)
c. Japan (日本)
d. U.K.（イギリス）
e. U.S.A.（アメリカ合衆国）- 14 -

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以下は 2000 年に発表された英文である。この英文を読んで質問に答えなさい。

Imaging black holes
Black holes hold an almost mythical attraction for layperson and scientist alike. A mythical：神話のblack hole is an object so massive and compact that gravity prevents even light fromlayperson：俗人

escaping. The gravitational effect of a black hole on nearby objects provides compellinggravitational：重力のindirect evidence that they exist, but the ultimate proof has yet to come — a direct imageof the ‘black dot’.
Cash et al. present the first laboratory demonstration of an X-ray interferometer thatinterferometer：干渉計

will be useful to astronomers. Their approach will make it much easier to achieve theangular resolution of 0.1 to 1.0 microarcseconds required to obtain an X-ray image of black

angular：角度のholes in the centre of nearby galaxies. Astronomers divide up the sky into angular degrees,

microarcseconds：1×10-6

so that 90° is the distance from the horizon to a point directly overhead (there are 60

秒角

arcminutes in a degree and 60 arcseconds in a minute). Apart from satisfying our curiosity
as to what the region surrounding a black hole looks like, this advance will allow us todirectly observe effects predicted by Einstein’s theory of general relativity under the mostextreme gravity fields known. It will also provide a formidable tool that will open new formidable：恐るべきvistas on a wide range of astronomical phenomena.

vistas：見通し

The X-ray band is the prime hunting ground for finding and studying black holes, as
shown by the first bona fide ‘black hole candidate’, Cygnus X-1, an X-ray source

bona fide：真実のdiscovered in the 1960s. Bright X-rays are the result of large amounts of gravitational

Cygnus：白鳥座

energy being released as the black hole attracts material from a nearby star or within its
host galaxy. This material forms a swirling, orbiting disk falling towards the black hole —swirling：渦を巻く

much like the flow of water down a drain (Fig. 1). Close to the ① ‘event horizon’, thetheoretical border of a black hole inside which nothing can escape, friction superheats thefriction：摩擦

material to many millions of kelvin, which is mostly radiated as X-rays. The black hole’s

kelvin：ケルビン(熱力strong gravity causes distortions of space-time that are imprinted on the emerging X-rays.

学的温度の単位)

Observations of supermassive black holes in the centre of nearby galaxies have alreadydistortions：歪み

revealed this signature in the spectral features of X-rays.

imprint：印する

Increasing the angular resolution of telescopes is one of astronomy’s main goals,

spectral：スペクトルの② but it is never easy. Even the most perfectly shaped telescope is ultimately limited by
the size of its aperture, also known as the diffraction limit. This is dictated by theaperture：レンズの口径

wavelength of the incoming light divided by the diameter of the telescope. The bigger thediffraction：回折

telescope, the better the angular resolution it can achieve. The Hubble Space Telescope has
a 2.4-metre diameter with an angular resolution of 0.1 arcsecond, which is close to thediffraction limit. Achieving microarcsecond resolution would require a 100,000-foldincrease in the Hubble telescope diameter to 240 kilometres.
Fortunately, there is a way of achieving such resolution without building impossibly
large telescopes. An interferometer combines the light from several small telescopes tocreate an image with a resolution as if it had come from a much larger telescope. The light- 16 -

interferometer：干渉計

waves from each telescope interfere with each other to create interference fringes (bands

fringe：回折による光of low and high intensity), which can be transformed back into real images inside aの縞computer. For interferometers at most wavelengths, the distance between the telescopes
replaces the diameter of the telescope in determining the diffraction limit. Radio
astronomers first used this technique to make huge gains in angular resolution withtelescope separations spanning continents and even out into space.

spanning：間隔

X-ray telescopes in general are difficult to build because X-rays reflect only at a very
shallow angle to the optical surface (1 degree or less), referred to as the grazing incidence.
To obtain a true focus, they must be reflected twice from precisely constructed hyperbolic

hyperbolic：双曲線のand parabolic surfaces. These surfaces are, in effect, nested cylinders that are expensive to parabolic：放物線(状)shape to the required precision. Complicating matters further, X-ray telescopes must beのplaced in space, because X-rays do not penetrate the Earth’s atmosphere. The recently
launched Chandra X-ray Observatory is the state of the art in X-ray imaging, whose optics

state of the art：最高水

alone cost several hundred million US dollars to build. Chandra achieves an impressive

準のresolution of about 0.5 arcseconds, yet it is still far from the diffraction limit. Building adiffraction-limited X-ray telescope, let alone an X-ray interferometer capable of imaging
the cauldron surrounding a black hole, has always seemed a distant dream.

cauldron：大釜

Cash et al. take what at first seems to be a disadvantage — that X-rays reflect only atshallow angles — and turn it into an advantage. Instead of using expensive, precisely
figured optics to focus the X-rays, they instead use two sets of more easily made, flat
mirrors to steer incoming X-ray beams together to create interference fringes. A twodimensional image is created by combining many sets of these fringes taken at different
rotation angles. Because the X-rays are reflected at shallow angles, the permitted variationsin the positioning of the flat mirrors are about 100 times greater than for a traditional(normal incidence) mirror operating at the same wavelength. If you placed an X-ray
detector 500 kilometres behind the mirrors, the fringes would be amplified by the distance,and so could be measured with detectors that exist today.
There are still some technological hurdles, however. Even at very short X-ray
wavelengths, a telescope separation of 100–1,000 metres is needed to achieve the required
angular resolution. This would require a fleet of up to 33 spacecraft carrying optical mirrors,
flying in formation with a spatial precision of 20 nanometres, plus a detector spacecraft 500
kilometres behind the mirror. This is daunting by today’s standards, but probably no more

daunting：ひるませる

so than missions under consideration by the US and European space agencies (NASA and
ESA), such as the Darwin infrared space interferometer, which could search for Earth-size
planets outside our Solar System. A ‘pathfinder’ mission to build an X-ray interferometer

pathfinder：探検者

with a one-metre separation between the telescopes, so that the X-ray optics are all on one
spacecraft, is a reasonable first step. This is already under study at NASA, using Cash andcolleagues’ technique as the starting design. The Pathfinder would be a precursor to a muchlarger Microarcsecond X-ray Imaging Mission (MAXIM) required to image a black hole.
- 17 -

precursor：先駆者

But even as a first step, the Pathfinder would provide an impressive 1,000-foldimprovement over the Chandra X-ray Observatory, allowing astronomers to study thecoronae of other stars.

coronae：光環

Figure 1. Imaging a black hole requires an enormous improvement in telescope power —at least a million times better resolution than the Hubble Space Telescope, or the recently
launched Chandra X-ray Observatory. Top, a Hubble Telescope image of the M87 galaxy
core, where a black hole with a mass three billion times that of the Sun is likely to reside.
Bottom, a simulation of what the black hole might look like if you were looking down on
a disk of material swirling around the hole. The angular size that the black-hole event
horizon subtends on the sky is between 3 and 6 microarcseconds, depending on whether orsubtend：対する

not the black hole is maximally rotating.

maximally：最大限に- 18 -

(Republished with permission of Springer Nature, from Imaging black holes, by Nicholas White, Nature,
Copyright © 2000 Springer Nature ; permission conveyed through Copyright Clearance Center, Inc.
一部改変)

問1.

Black hole とはどのような天体か，本⽂に即して簡潔に述べなさい（50 字以内）。

問2.

① ‘event horizon’近傍ではどのようなことが起こるか，本⽂に即して簡潔に述べなさい（50 字以内）。

問3.

下線部②の理由を本⽂に即して述べなさい。

問4.

Cash らは⾼解像度の X-ray telescope の実現可能性を⾼めるアイデアを提供したが，それはどのようなもので，また，それに対しどのような技術的ハードルがあるのか本⽂に即して述べなさい。

問5.

この論⽂から 19 年後の 2019 年に，電波による M87 銀河の中⼼にある black hole の直接撮影が世界で初めて報告され，さらに 2022 年に下記（次ページ）にあるように，われわれの銀河の中⼼にある
Sagittarius A*と呼ばれる black hole が撮影された。
Black hole の直接撮影に成功した The Event Horizon
Telescope と呼ばれている⽅法について本⽂の内容と下記（次ページ）の解説を踏まえて述べなさい。

―――図とその解説が次ページにあります。

- 19 -

Left panel: The second-ever direct image of a black hole — Sagittarius A*, at the centre of the Milky Way.
Right panel: The Event Horizon Telescope combined signals from eight radio observatories across the world.
Together, the observatories have a resolving power equivalent to a telescope almost the size of Earth.
(From [Full Reference Citation] Re: A shot in the dark
CREDITS: (GRAPHIC) A. CUADRA/SCIENCE; (DATA) EVENT HORIZON TELESCOPE. Reprinted withpermission from AAAS. 一部改変）- 20 -

―――このページは⽩紙―――- 21 -