Stay tuned until the end of the video for more about that.

更多相關資訊，敬請關注視頻結尾。

What is time?

時間是什麼？

In this channel, we've talked a lot about time.

在這個頻道中，我們經常談到時間。

As black holes warp space around them, we've learned that time slows down.

當黑洞扭曲周圍的空間時，我們已經知道時間會變慢。

We've discovered the time influencing effects of gravity, and even how the James Webb Telescope can peer through time to the distant past by taking advantage of the fixed speed of light.

我們發現了引力對時間的影響，甚至發現了詹姆斯-韋伯望遠鏡如何利用固定光速，穿越時間窺探遙遠的過去。

All this makes sense so far, but what actually is time?

到目前為止，這一切都說得通，但時間究竟是什麼？

You can't taste it, touch it or feel it, yet time has an unstoppable influence on us, and is pushing us forward whether we like it or not.

你無法品嚐它、觸摸它或感受它，但時間對我們的影響卻是不可阻擋的，無論我們喜歡與否，它都在推動著我們前進。

Doesn't something that impacts everything we do deserve some additional understanding?

難道影響我們一切行為的東西不值得我們多一些瞭解嗎？

I'm Alex McColgan, and you're watching Astrum, and while this is an area that scientists have many theories about, I'd like to share with you today one model that might help you understand this mysterious concept that is ticking all around us.

我是亞歷克斯-麥考根（Alex McColgan），您正在收看的是 Astrum。雖然科學家們對這一領域有很多理論，但今天我想與您分享一個模型，它或許能幫助您理解這個在我們身邊滴答作響的神祕概念。

By the end of this video, we are going to have a possible explanation for why time slows down as velocity increases, and why shapes warp when undergoing velocities close to the speed of light.

在本視頻結束時，我們將對為什麼時間會隨著速度的增加而變慢，以及為什麼在速度接近光速時形狀會扭曲有一個可能的解釋。

This video is a collaboration with my brother, based on recognised scientific theory, where we have taken scientific concepts and combined them into something you may not have seen before.

這段視頻是我和我哥哥合作完成的，以公認的科學理論為基礎，我們將科學概念融合在一起，創造出你可能從未見過的東西。

But before we get to that, we have to begin with one foundational idea.

但在此之前，我們必須從一個基本概念開始。

Time is actually another dimension.

時間其實是另一個維度。

Now, before you double check that you haven't logged into some sci-fi channel by mistake, let's discuss what I mean by dimensions.

現在，在你仔細檢查自己是否誤登了某個科幻頻道之前，讓我們來討論一下我所說的維度是什麼意思。

While in popular culture, different dimensions are often described as parallel worlds that are very similar to ours, yet subtly different, in this context, when we talk of different dimensions, we are referring to the dimensions of space, as in 3-dimensional space, or 3D space, which may be far more familiar to you.

雖然在流行文化中，不同維度通常被描述為與我們的世界非常相似，但又有微妙區別的平行世界，但在這裡，當我們談論不同維度時，我們指的是空間的維度，如三維空間，或三維空間，這可能是你更熟悉的。

This is by no means trivial though. 3D space is all around you, it is the around you, and is very relevant to our topic.

但這絕不是小事。三維空間就在你的周圍，就在你的周圍，與我們的主題息息相關。

Let's begin by making sure we understand the 3Ds, and the relationships between them before we add the 4th D.

在添加第 4 個 D 之前，讓我們先來了解一下 3D 以及它們之間的關係。

Broadly speaking, 3D, or 3-dimensional space, simply refers to space that can be measured in three different perpendicular directions.

廣義上講，3D 或三維空間是指可以從三個不同的垂直方向測量的空間。

The perpendicular nature of these dimensions is important, but we'll get to that later. 3-dimensional space is usually described as having height, width and depth, and they all have 90 degree angles between them.

這些維度的垂直性質很重要，但我們稍後會講到。三維空間通常被描述為具有高度、寬度和深度，它們之間都有 90 度的夾角。

Simply put, objects like us that exist in 3D space can move left and right, up and down, and forwards and backwards.

簡單地說，像我們這樣存在於三維空間中的物體可以左右、上下、前後移動。

We are comfortable with this kind of space.

我們對這樣的空間很滿意。

Using this as our basis, it becomes much easier to imagine what we mean by 2D space, and even 1D space.

以此為基礎，我們就更容易想象二維空間甚至一維空間的含義了。

To move from one space to another, all we need to do is remove or add an extra dimension of measurement or movement that must be a 90 degree angle from all previously existing angles.

要從一個空間移動到另一個空間，我們需要做的就是移除或增加一個額外的測量或移動維度，這個維度必須與之前存在的所有角度成 90 度角。

So, 2D objects move in a plane that's bounded by the x and y directions, or the x and z directions, or the y and z directions, but not all three at once. 1D objects can only move either along x, or y, or z.

是以，二維物體是在以 x 和 y 方向、或 x 和 z 方向、或 y 和 z 方向為邊界的平面內移動，但不能同時在三個方向上移動。一維物體只能沿 x、y 或 z 方向移動。

Imagine a person who lived in such a 1D world.

想象一下，一個人生活在這樣的一維世界中。

Their whole existence would be found either moving one way or the other.

他們的整個存在都會被發現，不是在朝一個方向移動，就是在朝另一個方向移動。

All of reality would exist either to the left or to the right of them, and would appear as a singular dot.

所有的現實都會存在於它們的左邊或右邊，並以一個單一的點的形式出現。

They could not move or see in any of the other directions, and probably could not even comprehend such directions as even existing.

他們無法移動或看到任何其他方向，甚至可能無法理解這些方向的存在。

Photons whizzing by them would only be visible if they entered the singular line that was a 1D person's whole area of existence.

只有當光子進入 1D 人的整個存在區域的單線時，從他們身邊呼嘯而過的光子才會被看到。

Now, adding extra directions of movement is what's needed to move things up from 1D to 2D to 3D.

現在，需要增加額外的運動方向，才能將事物從一維提升到二維再到三維。

So, in theory, we can predict what we need to do if we were to jump to 4D.

是以，從理論上講，我們可以預測如果要跳轉到 4D，我們需要做什麼。

However, here we hit a snag.

然而，我們在這裡遇到了一個障礙。

While it's easy to draw a line that's perfectly perpendicular to a single other line, or to draw another line on top of those lines that is perpendicular to the two previous lines, how would we draw a fourth line that's perpendicular to all three?

要畫一條與另一條直線完全垂直的直線，或者在這些直線上畫另一條與前兩條直線垂直的直線，都很容易，但我們如何才能畫出與三條直線都垂直的第四條直線呢？

Surely such a thing is impossible.

當然，這是不可能的。

Well, within 3D space, such a thing is impossible.

那麼，在三維空間內，這樣的事情是不可能發生的。

The best we can do is draw approximations.

我們能做的最好的事情就是得出近似值。

For instance, it's possible to draw an approximation of a 3D shape on 2D paper by doing something like this.

例如，可以在二維紙上畫出三維形狀的近似值，方法是這樣的。

These lines are all two-dimensional, but we look at this and our brain recognises that this is a picture of a 3D shape.

這些線條都是二維的，但我們看著它，大腦就會識別出這是一幅三維形狀的圖片。

So, in the same way, we could probably do something similar to what a 4D object might look like using just 3D lines.

是以，同樣地，我們也可以只用三維線條來製作類似於 4D 物體的效果。

Mathematicians have attempted to do this, although their results tend to be a little confusing.

數學家們曾嘗試這樣做，儘管他們的結果往往有點令人困惑。

Although this is mathematically sound as a basis for a 4D object, I personally don't find my understanding of 4D space deepened by looking at it, so I won't focus on it in this video.

雖然這在數學上是合理的四維物體的基礎，但我個人並不覺得通過觀察它能加深我對四維空間的理解，所以我不會在本視頻中重點討論它。

There is some evidence however that a fourth direction exists, and we are moving along it right now.

然而，有證據表明，第四個方向是存在的，而且我們現在正在沿著這個方向前進。

That fourth direction, or dimension, is time.

第四個方向或維度就是時間。

Einstein predicted this connection when he linked space and time into one unified spacetime in his theories of relativity.

愛因斯坦在其相對論中將空間和時間連接成一個統一的時空時，就預言了這種聯繫。

According to him, time and space are two parts of the same thing.

他認為，時間和空間是同一事物的兩個部分。

To me, this connects with 4D space very nicely.

對我來說，這與 4D 空間有很好的聯繫。

Just as there is no real difference between the z and the x or y directions, so too would there not be any difference between time and space if time is just another direction, albeit one that we can't see.

就像 Z 和 X 或 Y 方向之間沒有真正的區別一樣，如果時間只是另一個方向，儘管是我們看不見的方向，那麼時間和空間之間也不會有任何區別。

And time is important.

時間很重要。

Without time, our 3D space wouldn't move.

沒有時間，我們的三維空間就不會移動。

It would perpetually be in one state, because it's time that allows us to move about in it.

它將永遠處於一種狀態，因為時間允許我們在其中活動。

But why can't we see it?

但為什麼我們看不到呢？

Why can't we look in the direction of time?

為什麼我們不能朝時間的方向看呢？

To explain this, let's look at the difference between the different dimensional spaces.

為了解釋這一點，讓我們來看看不同維度空間之間的區別。

We best notice this when we consider what 2D objects might look like if they were to move in 3D space.

當我們考慮二維物體在三維空間中移動時會是什麼樣子時，我們就會最清楚地意識到這一點。

This is where we start to delve into the model.

這就是我們開始深入研究模型的地方。

Let's begin by visualising a standard 3D space, but because we want to eventually see all of space and time in one model, let's cheat a little.

讓我們從一個標準的三維空間開始想象，但因為我們最終想在一個模型中看到所有的空間和時間，所以讓我們稍微作弊一下。

Let's compress all of 3D reality as we know it into a flat, two-dimensional place.

讓我們把已知的三維現實壓縮成一個平面的二維空間。

In this plane, let's make that our xy plane, which we will label space, which frees up the z dimension for time.

在這個平面上，我們把它設為 xy 平面，並將其標註為空間，這樣就騰出了 z 維度來表示時間。

In this model, all 3D people are now just 2D.

在這種模式下，所有 3D 人現在都只是 2D。

A 2D person could exist and live their lives in the place marked space at the bottom of our chart.

二維人可以在我們圖表底部標有空間的地方生存和生活。

However, by moving them up on the chart at a constant rate, they are also moving through time.

然而，通過在圖表上以恆定的速度向上移動，它們也在時間中移動。

Let's for ease and convenience say that the top of our diagram is the future, while the bottom is the past, so the higher up our 2D person goes in this diagram, the older they get.

為了簡單方便起見，我們可以說圖示的頂部是未來，而底部是過去，是以二維人在圖示中越往上，年齡就越大。

As we don't seem to have a whole lot of control over our ability to travel through time, let's imagine for a second that our 2D person travels upwards at a constant rate, as if there is some consistent force or wind at play pushing them upwards towards the future.

由於我們似乎無法控制自己穿越時空的能力，讓我們想象一下，我們的 2D 人以恆定的速度向上移動，就好像有一股持續的力量或風在推動他們向未來前進。

Sadly, we cannot slow down time for ourselves simply through willpower, no matter how much we might want to do so.

遺憾的是，我們無法僅憑意志力為自己放慢時間，無論我們多麼想這樣做。

However, it is misleading to say that we can't change it at all.

然而，如果說我們根本無法改變它，那是一種誤導。

The faster we travel in space, the slower we travel in time.

我們在太空中旅行的速度越快，在時間上旅行的速度就越慢。

This is one of the guiding principles of Einstein's relativity.

這是愛因斯坦相對論的指導原則之一。

This model can express this idea through the power of vectors.

該模型可以通過矢量的力量來表達這一想法。

As our 2D person tries to move to their left or to their right, their vector of travel changes.

當我們的 2D 人試圖向左或向右移動時，他們的移動矢量會發生變化。

While travelling at a fixed rate, like a sail on a ship catching a breeze, we can only go as fast as the wind takes us, so the vector coming out from their front must always remain the same.

當我們以固定的速度行進時，就像船上的風帆迎著微風一樣，我們的速度只能和風的速度一樣快，所以從他們前面出來的矢量必須始終保持不變。

To travel the fastest through time, our 2D person must orient his vector completely in the future direction, or upwards.

為了以最快的速度穿越時間，我們的二維人必須將矢量完全朝向未來方向，也就是向上。

However, if they are to travel any amount in either direction to their sides, they can only do so by pointing their vector away from their direction of travel.

但是，如果它們要向兩側的任何一個方向移動，它們只能將矢量指向其移動方向以外的地方。

They have motion in the x direction now, but they have done so by reducing their motion in the z direction.

它們現在在 x 方向上有運動，但它們是通過減少在 z 方向上的運動來實現這一點的。

They are moving through space, but at the cost of moving a little slower through time.

它們在空間中移動，但代價是在時間中移動得慢一些。

Taking this to its furthest extreme, our individual has completely flipped on their side and now only has motion in the direction of x, and none in the direction of z.

如果將這一點發揮到極致，我們的個體已經完全側翻，現在只有 x 方向的運動，而沒有 z 方向的運動。

They have velocity in space, but not time.

它們在空間中有速度，但沒有時間。

So I suppose this implies our vector is the speed of causality, or the speed of light.

是以，我想這意味著我們的矢量就是因果關係的速度，或者說是光速。

If this is the speed we're talking about, then moving at low speeds through space would not have any noticeable difference in our speed through time.

如果這就是我們所說的速度，那麼在太空中的低速移動就不會對我們在時間上的速度產生任何明顯的影響。

We'd have to go really fast before we started to notice anything.

在我們開始注意到任何東西之前，我們必須走得非常快。

The vector still mostly points upwards.

矢量大部分仍指向上方。

An interesting result of this model is that, from the 2D man's perspective, nothing has really changed.

這種模式的一個有趣結果是，從二維人的角度來看，一切都沒有真正改變。

He has his own view of what reality is.

他對現實有自己的看法。

For him, the vector coming out of his chest is still time.

對他來說，從胸中噴湧而出的矢量仍然是時間。

The dimensions of the plane he's lying flat on is his space.

他平躺在飛機上的尺寸就是他的空間。

To him, it's the rest of the universe that's gone a little weird, but he himself is perfectly normal.

對他來說，是宇宙的其他部分變得有點奇怪，但他自己卻非常正常。

However, once he re-orients himself, it is clear that the rest universe has moved on without him.

然而，當他重新調整好自己的方向後，很明顯，沒有他的宇宙已經繼續前進了。

This is clearer if we add a second 2D person.

如果再加上第二個 2D 人，情況就更清楚了。

Initially, both of our individuals do not move in space, all of their vector is pointing in the direction of time.

起初，我們的兩個個體都不在空間中移動，它們的所有矢量都指向時間方向。

Nothing that strange seems to happen so far.

到目前為止，似乎還沒有發生什麼奇怪的事情。

However, if our stick man on the right turns and vectors at near the speed of light for a bit, then re-orients himself, while the second 2D man on the left just stays where he is, it becomes clear that our 2D men have not moved at the same rate through time.

然而，如果我們右邊的棍子人以接近光速的速度轉動了一會兒，然後重新調整了方向，而左邊的第二個二維人只是停留在原地，那麼很明顯，我們的二維人在時間上的移動速度並不相同。

Assuming that our two stick men can somehow still see each other, let's imagine that they somehow project an image of themselves onto the other person's space plane, they immediately notice that there is a difference in age.

假設我們的兩個 "棍子人 "還能以某種方式看到對方，讓我們想象一下，他們以某種方式將自己的形象投射到對方的空間平面上，他們會立刻發現年齡上的差異。

The one who travelled at the speed of light did not advance so quickly through time as the other, who remained stationary and so is younger.

以光速旅行的那個人並沒有像另一個人那樣在時間中快速前進，他一直保持靜止，所以更年輕。

But why do we find this model so compelling?

但為什麼我們會發現這種模式如此引人注目呢？

Well, it is because of what those projections would look like during changes in direction.

這是因為這些預測在方向變化時會是什麼樣子。

From the point of view of the first stick man, initially the projection of their friend seems fairly normal.

從第一個棍子人的角度來看，他們朋友的投影最初似乎相當正常。

However, as they start travelling very quickly in space, and their vector oriented in a direction away from time, a 2D shape reveals its inherent flatness.

然而，當它們開始在空間中快速移動，並且它們的矢量朝向遠離時間的方向時，二維形狀就會顯示出其固有的平面性。

And from a face-on perspective, it goes from this to this.

從正面看，從這裡到這裡。

The speedily travelling stick man appears to flatten, with an effect that's more pronounced the faster they go, and the flattening takes place in the direction of their travel.

快速行進的棍人看起來會變平，速度越快，效果越明顯，而且變平的方向與行進的方向一致。

The stick man who remained stationary might wonder at the strange change that is occurring to their friend, never comprehending that it represents a re-orientation of a 2D figure in 3D space.

靜止不動的棍子人可能會對他們朋友身上發生的奇怪變化感到奇怪，卻不明白這代表著二維圖形在三維空間中的重新定向。

Now what captures my imagination about this is that this same happens in real life.

現在，讓我浮想聯翩的是，這種情況同樣發生在現實生活中。

According to Einstein's theories of relativity, objects travelling at great speeds in 3D space would appear from an external observer to flatten in the direction of their travel.

根據愛因斯坦的相對論，在三維空間中高速運動的物體在外部觀察者看來會沿著運動方向變平。

This squishing effect happens exactly in line with this model, and is to do with time dilation.

這種擠壓效應的發生與這一模型完全一致，並且與時間膨脹有關。

However, from the person who's travelling's perspective, they do not flatten, but it is the rest of the universe that warps.

然而，從旅行者的角度來看，他們並沒有變平，而是宇宙的其他部分發生了扭曲。

I talk about this in greater depth in another video of mine where we can see the effects of spatial warping in a computer model.

我在另一段視頻中更深入地談到了這一點，在這段視頻中，我們可以看到計算機模型中的空間扭曲效果。

From their perspective, everything would stretch at the edges of their vision, while their destination would seem further away, which is again what this model would predict.

從他們的視角來看，一切都會在他們視野的邊緣延伸，而他們的目的地則會顯得更遠，這也是這個模型所預測的。

The only difference is that in this model, we're just exploring a 2D object stretching, so the stretch is only in one direction, while in real life it's 3D, which means it stretches in two directions instead.

唯一不同的是，在這個模型中，我們只是在探索一個二維物體的拉伸，是以拉伸只在一個方向上，而在現實生活中，它是三維的，這意味著它在兩個方向上拉伸。

But that is what you might expect as you turn away from our conventional three dimensions and start orienting yourself away from time.

但是，當你脫離傳統的三維空間，開始擺脫時間的束縛時，這就是你所期望的。

But if this is correct, so what?

但如果這是正確的，那又怎樣呢？

Why does it matter?

這有什麼關係？

If time is truly a direction, then it deepens our understanding of the universe.

如果時間真的是一個方向，那麼它將加深我們對宇宙的理解。

It also raises more questions.

這也提出了更多的問題。

What is the force that pushes us ever forward in time?

是什麼力量推動我們在時間的長河中不斷前行？

Why does it seem that we can never move against it?

為什麼我們似乎永遠無法與之抗衡？

Although in this model there is no reason why a vector could not point downwards, in real life that doesn't seem to ever happen.

雖然在這個模型中，矢量沒有理由不指向下方，但在現實生活中，這種情況似乎從未發生過。

This model also answers the question of, if time is a direction, what is our shape in time?

這個模型還回答了這樣一個問題：如果時間是一個方向，那麼我們在時間中的形狀是什麼？

Does part of us protrude into the past, or into the future?

我們的一部分是突出於過去，還是突出於未來？

According to this model, that does not happen.

根據這種模式，這種情況不會發生。

We are flat pancakes in the fourth dimension, pennies that look round when you look at us head on, but our thinness when we turn away from you.

我們是四維空間中扁平的薄餅，正面看時是圓圓的一分錢，轉過身去時卻又是薄薄的一分錢。

That's a strange thought, but it may just be true.

這種想法很奇怪，但可能是真的。

This might explain why we are unable to see through time, we just don't extend enough in that direction for it to be visible.

這或許可以解釋為什麼我們無法看穿時間，因為我們在那個方向的延伸不夠，所以無法看到時間。

Your form might be quite different than you first thought.

你的形式可能與你最初想象的大相徑庭。

Of course, this model is just a theory of ours, although we have tried to base it on scientific observations and conventional theory.

當然，這個模型只是我們的一種理論，儘管我們試圖將其建立在科學觀測和傳統理論的基礎上。

But what do you think?

你怎麼看？

Does this model help you make sense of time as a fourth dimension?

這個模型是否有助於你理解時間這個四維空間？

Please leave your ideas in the comments below on the nature of time, and what it might actually be instead.

請在下面的評論中留下你對時間本質的看法，以及它實際上可能是什麼。

I hope to explore more strange concepts like this in a new series called The Unseen World, where I want to explore the shape of reality around us.

我希望在一個名為 "看不見的世界 "的新系列中探索更多類似的奇特概念，探索我們周圍現實的形態。

While it's normally invisible to us, the shape and dimensions of the universe can explain why things are the way they are, and I'm excited to explore it with you, if you are interested in it.

雖然我們通常看不到宇宙的形狀和維度，但它可以解釋為什麼事情會是這樣，如果你對此感興趣，我很高興能和你一起探索。

Let me know!

請告訴我！

I'm very pleased to finally show you something that's been in the works for a while.

我很高興終於可以向你們展示一些醞釀已久的作品了。

I've been working together with Stuart McPherson and the Don Hanson Foundation to produce a book.

我一直在與斯圖爾特-麥克弗森和唐-漢森基金會合作出書。

It has already been sent to thousands of schools around the world to hopefully help school children develop a love for space, and now they are available to you too!

它已被送往世界各地成千上萬所學校，希望能幫助在校學生培養對太空的熱愛！

The focus of this 160 page book is the solar system, and contains thousands of facts about the different celestial bodies found there.

這本 160 頁的書的重點是太陽系，其中包含數千條關於太陽系中不同天體的資訊。

And what I actually love most about the book is the print quality combined with the images.

實際上，我最喜歡的是這本書的印刷品質和圖片。

Somehow these images just look so good when printed out compared to seeing them on a computer screen.

與在電腦屏幕上看到的影像相比，打印出來的影像不知為何看起來非常漂亮。

I spent hours finding the very best images to include, and I'm very proud of the finished product.

我花了幾個小時來尋找最好的圖片，我為成品感到非常自豪。

The initial sale is a limited edition of only 175 books, so it's really fast.

首批發售的是限量版，僅有 175 本，所以速度非常快。

And they will include a signed card from me and a serial showing your unique number.

它們將包括一張我簽名的卡片和一個顯示您的唯一編號的序列。

I really expect these to go fast, so don't delay and check my store link below!

我真的希望這些東西能很快賣出去，所以不要耽擱，請查看我下面的商店鏈接！

Thanks for watching!

感謝觀看！

I hope you learned something new today.

希望你今天能學到新東西。

If you did, consider subscribing for more.

如果您訂閱了，請考慮訂閱更多內容。

Liking and sharing also really help.

點贊和分享也很有幫助。

Another way to support is to become a patron or member.

另一種支持方式是成為贊助人或會員。

If you'd like to see your name added to this list, check the links below.

如果您想將自己的名字加入這份名單，請查看下面的鏈接。

All the best, and see you next time!

一切順利，下次再見！