There is nothing that we experience that does not take place in some duration of time.

我們所經歷的一切，無一不是在一段時間內發生的。

So if you can understand time, you're on your way to understanding reality.

是以，如果你能理解時間，你就能理解現實。

Hello.

你好

Hello.

你好

What's your name?

你叫什麼名字？

Kayla.

凱拉

How old are you, Kayla?

你多大了 Kayla?

I am nine years old.

我今年九歲。

So if you're nine years old, what does that mean about the earth?

那麼，如果你只有九歲，這對地球意味著什麼？

How many times has it gone around the sun?

它繞太陽轉了多少圈？

Nine times.

九次

Nine times.

九次

So there's a relationship between motion through space, the earth is going through space, and the passage of time.

是以，地球在太空中的運動與時間的流逝之間存在著某種關係。

They're kind of connected in some way.

它們之間有某種聯繫。

Have you heard of Albert Einstein?

你聽說過阿爾伯特-愛因斯坦嗎？

Yes.

是的。

What do you know about him?

你對他了解多少？

He has crazy hair.

他有一頭瘋狂的頭髮。

He does have crazy hair, and I think I may be heading in that direction, actually.

他的頭髮確實很瘋狂，我想我可能也會朝這個方向發展。

He showed us an approach to travel to the future.

他向我們展示了一種前往未來的方法。

You want me to tell you how you do it?

你想讓我告訴你怎麼做嗎？

You build a spaceship, you go out into space really quickly, you turn around and you come back to planet earth, and he showed us that when you're on that ship, your clock will tick off time more slowly.

他告訴我們，當你在飛船上時，你的時鐘會更慢地計時。

You will age more slowly.

你會衰老得更慢。

So that journey may only take you, say, a year, six months out and six months back, but you know what?

是以，這段旅程可能只花你一年的時間，六個月出去，六個月回來，但你知道嗎？

When you step out of the ship, it'll be 100 years into the future, or 1,000 years, a million years into the future.

當你走出這艘飛船時，將是未來的 100 年、1000 年或 100 萬年。

Would you do that if you could?

如果可以，你會這樣做嗎？

I would probably be dead by then.

那時我可能已經死了。

No, you'd be alive.

不，你還活著

That's the amazing thing.

這就是神奇之處。

I'd be dead.

我會死的

Everybody else would be dead who stayed on earth, but your body would only age one year, and yet it would be 1,000 years into the future.

留在地球上的其他人都死了，但你的身體只衰老了一年，而這已經是未來的 1000 年了。

That same guy with the crazy hair, Albert Einstein, showed that there's actually a limit to how fast things can go, and you know what the limit is?

那個留著一頭瘋發的傢伙，阿爾伯特-愛因斯坦，證明了事物的發展速度其實是有極限的，你知道這個極限是什麼嗎？

The limit is the speed of light, because light travels 671 million miles per hour.

極限是光速，因為光的時速為 6.71 億英里。

That is fast enough to go around the entire earth seven times in one second.

這個速度足以在一秒鐘內繞地球七圈。

So if we could build a spaceship that would go as fast as light, we'd be able to do what Einstein noted.

是以，如果我們能建造一艘像光一樣快的宇宙飛船，我們就能做到愛因斯坦所說的那樣。

If I was to ask you what is time, what would you say?

如果我問你時間是什麼，你會怎麼回答？

Time is kind of strange, because it's almost a man-made idea.

時間有點奇怪，因為它幾乎是一個人造的概念。

There is the tangible of how the earth revolves around the sun, or how we orbit around ourselves.

地球是如何圍繞太陽旋轉的，我們又是如何圍繞自己運行的，這些都是有形的。

It's almost in a way, does it exist if the way that we measure it is man-made?

從某種意義上說，如果我們測量它的方式是人為的，那麼它是否存在？

Before there was any life on planet earth, I think we all agree the universe existed, did things change before there was life on earth?

在地球上出現生命之前，我想我們都同意宇宙是存在的，那麼在地球上出現生命之前，情況是否發生了變化？

Yes.

是的。

And how would you talk about that change without invoking this concept of time?

如果不引用時間概念，你如何談論這種變化？

It's difficult to talk about something without adding time into it.

如果不把時間加進去，就很難談論一件事。

Even if it is a human-made concept, that the universe evolved, developed, changed through time, ultimately giving rise to galaxies, stars, planets, and on this particular planet, life.

即使這是一個人為的概念，即宇宙在時間的長河中進化、發展、變化，最終產生了星系、恆星、行星，以及這個特殊星球上的生命。

That conception of time gives a feel that it's universal, that it's out there, it's the same for everybody, it's independent of our actions or activities.

這種時間概念給人的感覺是，時間是普遍的，它就在那裡，對每個人都是一樣的，它與我們的行為或活動無關。

Do you know that Albert Einstein shattered that view of time?

你知道阿爾伯特-愛因斯坦打破了這種時間觀嗎？

He found that if you and I, say, have identical wristwatches, I'm sitting still and I'm watching you move, I will find that your clock is ticking off time more slowly than my clock.

他發現，如果你和我，比如說，有相同的手錶，我靜靜地坐著，看著你移動，我會發現你的時鐘比我的時鐘走得慢。

Back with Einstein, we wondered, does time change with speed?

在愛因斯坦時代，我們就想知道，時間會隨著速度的變化而變化嗎？

And that's another change with that before we didn't think possible.

這也是我們之前認為不可能實現的另一個變化。

Not only did we find that time changes with speed in special relativity, but we also found that time changes with gravity.

在狹義相對論中，我們不僅發現時間隨速度變化，還發現時間隨重力變化。

Einstein showed that the rate at which a clock ticks slows down based upon the stronger gravitational field or gravitational potential, actually, that it is experiencing.

愛因斯坦的研究表明，時鐘滴答作響的速度會隨著它所經歷的引力場或引力勢能的增強而減慢。

I think you mentioned interstellar before.

我想你之前提到過星際。

Do you remember the scene in interstellar?

你還記得《星際穿越》中的那一幕嗎？

They're going to a planet that's near a black hole.

他們要去一個靠近黑洞的星球。

They go down to the planet and they spend just a couple hours there.

他們下到星球上，在那裡只待了幾個小時。

But when they go back to the ship, it's 23 years later on the ship because time is elapsing slowly near the strong gravitational field, comparatively quickly far away.

但當他們回到飛船上時，飛船上的時間已經過了 23 年，因為在強引力場附近時間流逝得很慢，而在遠處則相對較快。

And that's not science fiction.

這可不是科幻小說。

That's actually how time behaves.

事實上，時間就是這樣運行的。

I've always heard people say, oh, general relativity, you know, it might not seem applicable, but, you know, GPS due to satellites, we could synchronize those clocks by accounting for relativity.

我總聽人們說，廣義相對論似乎並不適用，但是，你知道，由於衛星的GPS，我們可以通過計算相對論使這些時鐘同步。

But that's even a really, really good point.

但這也是一個非常非常好的觀點。

The GPS would become completely inaccurate in a very short period of time if the satellites weren't taking account of, or the software wasn't taking account of the fact that time elapses differently for the clocks on the satellite compared to the clocks down here on Earth.

如果衛星沒有考慮到，或者軟件沒有考慮到，衛星上的時鐘與地球上的時鐘相比，時間的流逝是不同的，那麼全球定位系統就會在很短的時間內變得完全不準確。

So we walk around with general relativity in our pockets, even though most of us perhaps don't really know that.

是以，我們口袋裡裝著廣義相對論，儘管我們大多數人可能並不真正瞭解這一點。

I've heard a few different theories that people posit.

我聽說過人們提出的幾種不同理論。

Like maybe it is back to the future and you really change your own universe.

也許這就是回到未來，你真的改變了自己的宇宙。

I've also heard people say that you could have multiple universes spawn from this event or something along these lines.

我還聽人說過，這個事件可能會產生多個宇宙，或者類似的說法。

That's, if you're going to be able to change the past, that's the one that resonates most with me.

這就是，如果你能改變過去，這是我最有共鳴的一句話。

I think the same.

我也這麼認為。

Yeah.

是啊

So you go into the past and maybe you can prevent your parents from meeting, but you're preventing them from meeting in a parallel reality, which means that you will never be in that reality, but the origin of your birth is still completely understood.

所以，你進入過去，也許可以阻止你的父母相見，但你阻止的是他們在平行現實中相見，這意味著你永遠不會在那個現實中，但你出生的起源還是完全可以理解的。

It was in the universe from which you originated.

它就在你起源的宇宙中。

And when you think about past and future on a cosmological scale, there was a long period when there were no human beings in the universe.

從宇宙的尺度來思考過去和未來，在很長一段時間裡，宇宙中是沒有人類的。

The fact of the matter is there will be these two long stretches with our presence being sort of a flicker in between.

事實上，在這兩段漫長的時間裡，我們的存在就像是中間的一閃而過。

Does that thought inform anything about how you live?

這種想法對你的生活方式有什麼啟發嗎？

I rage against thinking like that because it might be a brief flicker on a single moat of dust floating in a cosmic eternity, but it's everything.

我反對這樣的想法，因為它可能只是漂浮在宇宙永恆中的一粒塵埃上的短暫閃爍，但它就是一切。

There's nothing else that I'll ever experience.

這是我從未有過的體驗。

And so in a way, there's nothing else to me.

是以，在某種程度上，對我來說沒有別的。

There's an eternity, but I'm never going to see it.

有一個永恆，但我永遠不會看到它。

I'm never going to feel it.

我永遠也感受不到。

It can be debilitating to imagine an eternal future of sort of nothing where none of what we do sort of persists.

想象一個什麼都沒有的永恆未來，在那裡我們所做的一切都不會繼續存在，這可能會讓人崩潰。

On the other hand, if you flip your perspective around and say, how remarkable is it that we have this brief moment that allows us to think and feel and love and explore and illuminate?

另一方面，如果你把視角轉過來，說，我們擁有這個短暫的時刻，讓我們能夠思考、感受、愛、探索和照亮，這是多麼了不起的事情？

Wow.

哇

How wonderful is that?

這該有多好啊？

Yeah.

是啊

One of the things that relativity also sheds a light on is what exists.

相對論還揭示了存在的事物。

That if someone's moving relative to me, what they consider now might be in my past.

如果有人搬到了我的親戚家，他們現在所考慮的可能是我的過去。

What they consider now might be in my future, which would suggest that all of time exists.

他們所認為的現在可能是我的未來，這意味著所有的時間都存在。

Does that hold water?

這站得住腳嗎？

Actually, it resonates with me for various reasons.

事實上，由於種種原因，我對它產生了共鳴。

So this idea that you have a continuum and time should not be made to disappear as soon as it's gone is very practical.

是以，這種 "你有一個連續體，時間不應該一去不復返 "的想法是非常實用的。

It's also what is behind the idea of histories in quantum mechanics.

這也是量子力學中 "歷史 "這一概念背後的原因。

I mean, the only thing that really makes you not fear what will happen or your own mortality is that every instant is eternal.

我的意思是，唯一能真正讓你不再害怕將要發生的事情或自己的死亡的，就是每一瞬間都是永恆的。

Absolutely.

當然。

It will always be there.

它將永遠存在。

Yeah.

是啊

Yeah.

是啊