The Big Bang.

宇宙は突然始まり 無限ではない

The idea that the universe was suddenly born and is not infinite.

20世紀半ばまで 科学者は

Up to the middle of the 20th century, most scientists thought of the universe

宇宙は無限だと考えていた

as infinite and ageless.

相対性理論で

Until Einstein’s theory of relativity gave us a better understanding of gravity,

重力に関する理解が深まり

and Edwin Hubble discovered that galaxies are moving apart from one another

ハッブルは事前の予測通り

in a way that fits previous predictions.

銀河同士が離れていくのを発見した

In 1964, by accident, cosmic background radiation was discovered,

1964年には 宇宙背景放射が発見され

a relic of the early universe,

他にも様々な証拠が見つかると

which, together with other observational evidence, made the Big Bang

ビッグバン理論は確かな地位を得た

the accepted theory in science.

今 技術の進歩のおかげで

Since then, improved technology like the Hubble telescope

宇宙の構造の理解はより進んでいる

has given us a pretty good picture of the Big Bang and the structure of the cosmos.

ハッブル宇宙望遠鏡は

Recent observations even seem to suggest that the expansion of the universe

宇宙の神秘を教えてくれる

is accelerating.

では ビッグバンとは何か

But how did this Big Bang work?

一体何が起こったのか

How can something come from nothing?

それを見ていこう

Let’s explore what we know.

まず よくある誤解を解こう

We can ignore the beginning part for now.

ビッグバンは爆発ではない

First of all, the Big Bang was not an explosion.

空間が一度に 急激に伸びたのだ

It was all space stretching everywhere all at once.

とても小さかった宇宙が

The universe started very, very, very small

スイカ程度に大きくなった

and quickly expanded to the size of a football.

広がったのは宇宙ではなく

The universe didn’t expand into anything, space was just expanding into itself.

空間だということに注意

The universe cannot expand into anything because the universe has no borders;

宇宙に境界というものは存在せず

there is, by definition, no “outside” the universe.

定義的に 宇宙に外側はないからだ

The universe is all there is.

宇宙がすべて

In this hot, dense environment, energy manifested itself

さて 熱い所では

in particles that existed only for the tiniest glimpses of time.

エネルギーは一瞬だけ

From gluons, pairs of quarks were created, which destroyed one another,

粒子になることがある

perhaps after giving off more gluons.

グルーオンやクォークが

These found other short-lived quarks to interact with,

作られては一瞬で消えていく

forming new quark pairs and gluons again.

これらが様々に結合し

Matter and energy were not just theoretically equivalent,

様々な結合体が生まれた

it was so hot they were practically the same stuff.

物質とエネルギーは異なるものだが

Somewhere around this time, matter won over antimatter.

熱すぎると同じものになる

Today, we’re left with almost all matter and nearly no antimatter at all.

ここで物質が反物質に打ち勝ち

Somehow, one billion and one matter particles were formed

今存在する この物質世界が作られた

for every one billion particles of antimatter.

物質が反物質より

Instead of one massive ultimate force in the universe,

10億個につき１個多かったようだ

there were now several refined versions of it acting under different rules.

１つの巨大な力が分かれて

By now the universe has stretched to a billion kilometers in diameter,

異なる法則に従う４つの力となった

which leads to a decrease in temperature.

宇宙が直径10億キロまで伸びると

The cycle of quarks being born and converted back to energy

圧力が下がった

suddenly stops.

するとクォークはそのまま固定され

From now on, we work with what we have.

今の形へ向かった

Quarks begin forming new particles, hadrons, like protons and neutrons.

クォークは新しい粒子

There are many, many combinations of quarks that can form all sorts of hadrons,

陽子と中性子になった

but only very few are reasonably stable for any length of time.

組み合わせはたくさんあったが

Please take a moment to appreciate that by now, only one second has passed

安定して存在するものは少なかった

since the beginning of everything.

色々説明したが ここまで

The universe, which has grown to one hundred billion kilometers,

始まりから１秒しか経っていない

is now cold enough to allow most of the neutrons to decay into protons

宇宙が１兆キロになると

and form the first atom, hydrogen.

少し冷え 陽子と中性子がくっついて

Imagine the universe at this point as an extremely hot soup,

最初の原子 水素になった

ten billion degrees Celsius, filled with countless particles and energy.

まるでとても熱いスープだ

Over the next few minutes, things cooled and settled down very fast.

無数の粒子とエネルギーが

Atoms formed out of hadrons and electrons,

100億度で存在した

making for a stable and electrically neutral environment.

次の数分間 急激に温度が下がると

Some call this period the Dark Age, because there were no stars

原子核と電子が一緒になり

and the hydrogen gas didn’t allow visible light to move around.

安定で中性な環境を作った

But what’s the meaning of visible light, anyway, when there’s nothing alive yet

この時期を暗黒時代と言う

that could have eyes?

星がなく ガスも目に見えないからだ

When the hydrogen gas clumped together after millions of years and

見えないと言っても

gravity put it under great pressure, stars and galaxies began to form.

目では見えないだけだが

Their radiation dissolved the stable hydrogen gas into a plasma

ガスが集まって数百万年後

that still permeates the universe today and allows visible light to pass.

重力が力を持ち

Finally, there was light!

星や銀河が形作られた

Okay, but what about the part we didn’t talk about?

そして水素から発せられる放射線が

What happened right at the beginning?

今日の宇宙に浸透し

This part can be defined as the Big Bang.

可視光線となっている

We don’t know at all what happened here.

宇宙に光が満ちたのだ

At this point, our tools break down.

まだ話してないこともある

Natural laws stop making sense, time itself becomes wibbly-wobbly.

始まりの瞬間のことだ

To understand what happened here, we need a theory that unifies

ビッグバンとは定義したが

Einstein’s relativity and quantum mechanics, something countless

よくわかってはいない

scientists are working on right now.

ここでは人間の道具は壊れてしまう

But this leaves us with lots of unanswered questions.

時間が計算不能になるのだ

Were there universes before our own?

解明するには

Is this the first and only universe?

相対性理論と量子論の統一が必要で

What started the Big Bang, or did it just occur naturally,

今 無数の科学者が研究中だ

based on laws we don’t understand yet?

他にも疑問は残っている

We don’t know, and maybe we never will.

宇宙は以前も存在したのか

But what we do know is that the universe as we know it started here

今の宇宙だけか

and gave birth to particles, galaxies, stars, the Earth, and you.

なぜビッグバンが起きたのか

Since were ourselves are made of dead stars, we are not separate

未知の法則によって起きたのか

from the universe; we are part of it.

これはわかりそうにない

You could even say that we are the universe’s way of experiencing itself.

しかし 宇宙が今

So, let’s keep on experiencing it, until there are no more questions to ask.

ここにあることはわかる

Subtitles by the Amara.org community

そして粒子 銀河 星 地球