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Lesson 6 The Mpemba Effect
- The mystery of freezing -
1 This is a story of a Tanzanian student named Erasto B. Mpemba. He happened to make an
happen to do
incredible discovery by misusing a refrigerator. His experience sparked a scientific mystery that has
not been solved yet. The phenomenon Mpemba found is now known as the Mpemba effect. It is the
☆大切る。
very counterintuitive idea that, under certain circumstances, very hot or even boiling liquid can freeze
faster than cold liquid.
2 Mpemba made his accidental discovery in Tanzania in 1963, when he was only 13 years old and in
secondary school. A common activity among the boys of his age was making ice cream. They would
中学校
はやり
boil milk and mix it with sugar, and then put the combination in the freezer section of the refrigerator./
冷凍庫
The combination had to cool to room temperature first, because putting boiling mixtures in the
常温に戻す。
refrigerator could damage it. Limited space in the freezer, however, led to a race among students.)
lead to Ar
SのせいでAがおこる」とりあい
4 3 One day, Mpemba started boiling milk. Another boy, who wanted to make ice cream, ran to the
refrigerator when he saw Mpemba boiling up milk. He quickly mixed his milk with sugar and poured
it into the ice tray without boiling it. Mpemba knew that if he waited for the boiled milk to cool before
placing it in the refrigerator, he would lose the last ice tray. So, he decided to risk ruining the
場所取り
refrigerator by putting hot milk into it. The other boy and Mpemba went back an hour and a half later
A
and found that Mpemba's tray had frozen into ice cream while the other boy's was still only a thick liquid)
~だけれども
どろどろとした
4 He asked his physics teacher why it had happened like that. The answer he received was, "You
were confused; that cannot happen." When Mpemba reached high school, he decided to ask his teacher
12?
the same question again. However, the teacher's response was the same: "The answer I can give is that
you were confused."
5 Mpemba did not give up and decided to try the experiment in a biology lab. One afternoon, he filled
two beakers, one with boiling water and the second with tap water, and put them in the freezer of the
ふっそう
水道水
lab's refrigerator. After an hour, he found there was more ice in the one that had had boiling water.
カンカン][カブニン

ページ4:

20°
80°~気体
Solid liquid
gas
固
☆
☆
6 One day, a college professor named Denis Osborne came to lecture on physics, giving Mpemba an
物理
opportunity to talk to an expert on the subject. He repeated his question, but this time he got a quite
different reaction. The professor first smiled and asked, “Is it true? Have you done it?" After
Mpemba answered “Yes,” the professor said, “I do not know, but I promise to try this experiment when
I am back at my college."
7 Professor Osborne kept his word and carried out the experiment himself. He found that for
約束を守る 実行す。 彼自身で実験した。
temperatures up to 20℃ the time was roughly proportional to the temperature above freezing, up to a
大ざっぱに
まで
maximum of 100 minutes at 20℃. For higher temperatures, however, the time dropped dramatically,
down to 40 minutes for water at 80°C.
40分で
80℃→額(40分)
20℃→永(100分)
~というんもいれば
8 Later experiments on the effect have not been clear. Some have seen similar results, while others
have observed no effect at all! It seems that the Mpemba effect depends on the specific experimental
特定の実験関係
circumstances. Because of this, some physicists have been skeptical about whether the effect truly
うたが
exists.
理由
9 The skepticism may be attributed to assuming that a liquid is characterized by only one scale: its
~のせいである「~と推定する」 液体の性質
尺度
However, there are other characteristics of liquid that could be changed due to its
temperature.
heating the amount of gas the presence of other solutes, the presence of convection currents, and
対流の存在
differences in the rate of temperature change between different parts in the container) It is important
容器
to realize that a liquid at various temperatures may be characterized by a number of different properties.
特性
10 Mpemba's discovery is a wonderful illustration of many important lessons in science: the significance
実例
教訓
重要性
of experiment over theory, the danger of clinging to preconceived notions, and the difficulty of making/
学 ことのこわさく「~にしがみつく」先入観
単純な物理の問題
judgments on seemingly simple physics problems/ It also shows the importance of perseverance in the
判断する難しさ、一見すると
忍耐力
face of unreasoned denial.
大切
・不合理な否定
おんど

ページ5:

L6
~への引き金となる, ~を引き起こす
[状況
000000000000
6
68 |Erasto B. Mpemba
6
68
freezing
6
70
|Tanzanian
固有名詞 エラスト・B・ムペンバ
名詞
形容詞
凍結、冷凍
タンザニア (人) の
6
70
Imisuse
動詞
~を誤用する
6
70
|refrigerator
名詞
冷蔵庫
6
70
spark
動詞
6
70
circumstance(s)
名詞
6
70
|boil
動詞
6
70 liquid
名詞
液体
6
70
lfreeze
「動詞
|凍る
6
70
laccidental
形容詞
偶然の, 予期しない
6
70 |Tanzania
固有名詞 タンザニア
6
70
cream
|~を沸かす. 沸騰する
講演をする 講義をする
副詞 |大まかに、だいたい
形容詞 比例した、釣り合った
名詞 |最高, 最大
形容詞 実験の, 実験に基づく
物理学者
~を(･･･) 起因すると考える
名詞
クリーム
6
70
freezer
名詞
冷凍室, 冷凍庫
6
70
Imixture
名詞
混合物
6
70
70
ltray
名詞
盆, 盛り皿
6 70 physics
6
71 biology
名詞
名詞
物理学
生物学
6
71
beaker
6
71
tap
名詞
名詞
|ビーカー
蛇口、桧
6
71
Denis Osborne
固有名詞
デニス・オズボーン
6
71
llecture
動詞
16
71
|reaction
名詞
|反応
6
71
|roughly
6
71
proportional
6
71
maximum
6
71
lexperimental
6
71
Iphysicist
名詞
6
71
skeptical ®
形容詞
懐疑的な、疑い深い
6
71
skepticism
名詞
懐疑的な態度 懐疑心
6
71
attribute
動詞
6
71
assume
動詞
6
6
71 characterize
動詞
~を特徴づける
6
71
characteristic
名詞
|特徴, 特性
6
71
solute
名詞
|溶質
6
71
convection
名詞 |対流
6
71
current
名詞
流れ, 水流
6
71
Crate
名詞
速さ, 割合
6
71
|container
名詞
容器,入れ物
6
71
|property
名詞
(物質の)特性, 属性
6
71 | illustration
名詞
例, 実例
6
71
significance
名詞
重要性、重大さ
6
71
cling
動詞
しがみつく。
6
71
preconceived
形容詞前から抱いていた
6
71 notion
名詞
観念、考え
6
71
ljudgment
名詞
判断
6 71 seemingly
副詞
見たところ、一見
6
71 perseverance
6
71 unreasoned
形容詞
不合理な, 理に基づかない
6
71 |denial
名詞
否定、否認
~と仮定する, 想定する
名詞 忍耐力
la Tanzanian man
below the temperature at which water turns to ice
lof or from Tanzania
to use something in a wrong incorrect, or inappropriate way or the
|wrong purpose
la large piece of electrical kitchen equipment used for keeping food
|and drink cool [=fridge]
to cause something to start or develop, especially suddenly
the conditions that affect a situation or event
to become very hot such that the liquid turns to steam [⇔freeze]
la substance that is not a solid or a gas, for example, water or milk
to turn to ice as a result of extreme cold
| happening without being planned
la country in East Africa between Kenya and Mozambique
the thick yellowish-white fatty liquid that rises to the top of milk,
used in coffee or to make cakes or ice cream
la large piece of electrical equipment in which you can store food for a
long time at a low enough temperature that it stays frozen
la combination of two or more different things or people
la flat piece of wood, metal, or plastic with raised edges, used for
|carrying things, especially food or drinks
the scientific study of objects, substances, and natural forces such as
light and heat
the scientific study of living things
la glass cup with straight or slanted sides and a lip, used in chemistry
| for holding or measuring liquids
la piece of equipment for controlling the flow of water from a pipe
la professor who experimented and confirmed Mpemba's finding
to give a talk or a series of talks to a group of people on a subject
(usually done by an expert on that subject)
| something that you feel or do in response to something that
| happened or was said
lapproximately but not exactly
lincreasing or decreasing at the same rate
the largest number or amount that is possible
used for, relating to, or resulting from experiments
la scientist who has special knowledge in physics
doubting or not believing [=scepticall
lan attitude or belief that claims or statements are not true or that
something will not happen
to say or believe that something is the result of a particular action or
|thing
to think that something is true, although you have little or no proof
lor knowledge
to describe the qualities of someone or something in a particular way
la quality or feature of someone or something that is typical of them
la minor component in a liquid in which a solid or gas is mixed
| the movement in a gas or liquid in which warm gas or liquid goes up
and cold gas or liquid goes down
la continuous movement of a liquid or electricity
the speed at which something happens
| something such as a box or bottle to store of hold things
la quality or characteristic that something has
|an example, event, or fact that shows that something else is true, or
shows what something looks like
the importance of an event, action, thought, or belief
to hold onto something tightly
(about an opinion) formed before you really have enough knowledge
for experience to make a conclusion
lan idea, belief, or opinion
lan opinion that you form about something after thinking about it
| carefully or having seen strong, convincing evidence
lin a way that appears to be true although it might not be
the quality of continuing to try to do something difficult
Inot based on facts or good logic
a statement saying that something is not true or accepted (cf. deny
vt.)

ページ6:

Lesson 6 The Mpemba Effect
1
This is a story of a Tanzanian student/
named Erasto B.Mpemba.//
He happened to make an incredible discovery/
by misusing a refrigerator.//
His experience sparked a scientific mystery/
that has not been solved yet. ||
The phenomenon Mpemba found /
is now known as the Mpemba effect. //
It is the very counterintuitive idea that,/
under certain circumstances,/
very hot or even boiling liquid /
can freeze faster than cold liquid. //
これはタンザニアの学生の話である
エラスト・B・ムペンバという名前の。
彼は信じられない発見を偶然に行った
冷蔵庫を誤使用することによって。
彼の経験は科学の謎の引き金となった
いまだ解決されていない。
ムペンバが発見した現象は
現在ではムペンバ効果として知られている。
それは~という非常に直観に反した考えである
ある一定の状況下で
とても熱い, あるいは沸騰してさえいる液体が
冷たい液体よりも速く凍ることがある。
12
Mpemba made his accidental discovery/
in Tanzania in 1963, /
when he was only 13 years old/
and in secondary school. //
A common activity/-
among the boys of his age /
was making ice cream.//
They would boil milk/
and mix it with sugar, /
and then put the combination/
in the freezer section of the refrigerator.//
The combination had to cool/
ムペンバは偶然の発見をした
1963年にタンザニアで
彼がわずか 13歳のときに
そして中学生のときに。
よく行われていた遊びは
彼の年ごろの少年たちの間で
アイスクリームを作ることだった。
彼らは牛乳を沸かしたものだった
そしてそれを砂糖と混ぜた
それからその混合液を置いた
冷蔵庫の冷凍室に。
この混合液は冷ましておかねばならなかった
まず常温まで。
to room temperature first,/
because putting boiling mixtures in
the
というのは、沸騰した混合液を冷蔵庫に入れると〜
refrigerator /
could damage it. //
Limited space in the freezer,/
however,/
led to a race among students. //
からである
冷蔵庫を傷つけかねなかった。
冷凍室のスペースは限られていたので
しかしながら
生徒の間で競争が起こった。

ページ7:

3
One day, /
Mpemba started boiling milk. //
Another boy,/
who wanted to make ice cream, /
ran to the refrigerator/
when he saw Mpemba boiling up milk.//
He quickly mixed his milk with sugar /
and poured it into the ice tray/
without boiling it. //
Mpemba knew/
that if he waited/
for the boiled milk to cool /
before placing it in the refrigerator, /
he would lose the last ice tray. //
So, /
he decided to risk ruining the refrigerator/
by putting hot milk into it. //
The other boy and Mpemba/
went back an hour and a half later /
and found /
that Mpemba's tray had frozen into ice cream /
while the other boy's/
was still only a thick liquid. //
ある日
ムペンバは牛乳を沸かし始めた。
別の少年が
彼はアイスクリームを作りたかったので
冷蔵庫へと走った
ムペンバが牛乳を沸かしているのを見ると。
彼はすぐに牛乳と砂糖を混ぜた
そしてそれを製氷皿へと注いだ
沸騰させずに。
ムペンバはわかっていた
待っていたら~ということを
沸騰した牛乳が冷めるのを
冷蔵庫へ入れる前に
最後の製氷皿を失うだろう。
そこで
彼は冷蔵庫を壊す危険を冒すことにした
熱い牛乳を冷蔵庫に入れることによって。
もう一方の少年とムペンバは
1時間半後に戻った
そして発見した
ムペンバの皿が凍ってアイスクリームになってい
ることを
もう一方の少年のものは〜なのに
まだただのどろりとした液体であった。
4
He asked his physics teacher/
why it had happened like that.//
彼は物理の教師にたずねた
なぜそのようなことが起こったのかと。
The answer he received was,/
"You were confused; /
that cannot happen."//
When Mpemba reached high school,/
he decided to ask his teacher/
the same question again.//
However, /
彼が受け取った答えは~だった
「お前は混乱していたんだ。
そんなことは起こりえない」。
ムペンバが高校生になったとき
彼は教師にたずねることにした
再び同じ質問を
しかしながら
NA

ページ8:

the teacher's response was the same:/
“The answer I can give /
その教師の反応も同じだった。
「私が君に与えられる答えは
君は混乱していたということだ」。
is that you were confused."//
5
Mpemba did not give up /
and decided to try the experiment /
in a biology lab.//
One afternoon, /
he filled two beakers,/
one with boiling water /
and the second with tap water, /
and put them in the freezer /
of the lab's refrigerator.//
After an hour, /
he found/
there was more ice in the one /
that had had boiling water.//
6
One day, /
a college professor named Denis Osborne/
came to lecture on physics,/
giving Mpemba an opportunity/
to talk to an expert on the subject. //
He repeated his question, /
but this time/
he got a quite different reaction.//
The professor first smiled/
and asked,/
“Is it true? /
Have you done it?" //
After Mpemba answered “Yes," /
the professor said, /
“I do not know, /
but I promise to try this experiment/
ムペンバはあきらめなかった
そして実験をしてみることにした
生物の実験室で。
ある日の午後
彼は2つのビーカーをいっぱいにした
1つ目は沸騰している水で
そして2つ目は水道水で
そしてそれらを冷凍室に入れた
実験室にあった冷蔵庫の。
1時間後
彼は発見した
より多くの氷がビーカーの中にあることを
沸騰している水が入っていた。
ある日
デニス・オズボーンという名前の大学教授が
物理について講演するためにやって来た
そしてムペンバは機会を得た
その問題の専門家と話をする。
彼は質問を繰り返した
しかし今度は
まったく異なる反応をされた。
教授はまずほほ笑んだ
そしてたずねた
「それは本当かね?
君はそれをやったことがあるのかね?」 と。
ムペンバが 「はい」と答えると
教授は言った。
「私にはわからない
しかし、この実験をやってみることを約束しよう
大学に戻ったら」 と。

ページ9:

when I am back at my college." //
7
Professor Osborne kept his word/
and carried out the experiment himself. //
He found /
that for temperatures up to 20°C,/
the time was roughly proportional/
to the temperature above freezing, /
up to a maximum of 100 minutes /
at 20°C. //
For higher temperatures,/
however, /
the time dropped dramatically,/
down to 40 minutes /
for water at 80°C. //
8
Later experiments on the effect/
have not been clear.//
Some have seen similar results,/
while others have observed no effect at all! //
It seems /
that the Mpemba effect depends /
on the specific experimental circumstances.//
Because of this, /
some physicists have been skeptical/
about whether the effect truly exists.//
19
The skepticism may be attributed to assuming/
that a liquid is characterized/
by only one scale:/
its temperature. //
However, /
there are other characteristics of liquid/
that could be changed/
オズボーン教授は約束を守った
そして自らその実験を行った。
彼は発見した
20℃以下の温度では〜ことを
(凍る) 時間は大まかに比例している
氷点より上の温度と
最高 100分かかる
20℃で。
それより高い温度では
しかしながら
時間が劇的に減ったのである
40分まで
80℃の水で。
その効果についてのその後の実験は
はっきりしていない。
よく似た結果を目にした人もいる
一方で, まったく効果を観測できなかった人もいる
のだ!
~のようである
ムペンバ効果は依存する
特定の実験環境に。
このため
物理学者の中には疑いを抱いている人もいる
その効果が本当に存在するのかについて。
そうした懐疑的態度は仮定しているせいかもしれ
ない
液体が特徴づけられていると
ただ1つの尺度によって
その温度。
しかしながら
液体の特徴はほかにもある

ページ10:

due to its heating: /
the amount of gas, /
the presence of other solutes,/
the presence of convection currents,/
変化しうる
加熱が原因で。
気体の量
ほかの溶質の存在
and differences in the rate of temperature change / 対流の存在
between different parts in the container.//
It is important to realize /
that a liquid at various temperatures/
may be characterized/
by a number of different properties.//
そして温度変化率の違い
容器のさまざまな部位における。
認めることが重要なのである
さまざまな温度の液体は~だと
10
Mpemba's discovery is a wonderful illustration /
of many important lessons in science: /
特徴づけられているかもしれない
いくらかの異なる特性によって。
the significance of experiment over theory, /
the danger of clinging to preconceived notions,/
ムペンバの発見はすばらしい実例である
and the difficulty of making judgments/
on seemingly simple physics problems.//
It also shows the importance of perseverance /
in the face of unreasoned denial. //
科学における多くの重要な教訓を示す。
理論よりも実験のほうが重要であること
先入観にしがみつくことの危険性
そして判断を下すことの難しさ
一見単純な物理学の問題に。
またそれは、忍耐力の重要性をも示している
不合理な否定に直面したときの。