Once upon a time

我們生活在經濟與金融 的增長和繁榮中。

we lived in an economy of financial growth and prosperity.

這就是人們所說的“大穩健”時期，

This was called the Great Moderation,

這種誤導性的看法被大多數經濟學家，

the misguided belief by most economists,

政策制定者以及中央銀行所相信著。

policymakers and central banks

他們深信我們已經演進到一個新時代，

that we have transformed into a new world

一個永不停止增長和永葆繁榮的世界，

of never-ending growth and prosperity.

這個結論是由強健和穩定的GDP增長、

This was seen by robust and steady GDP growth,

受到良好控制的低通貨膨脹率、

by low and controlled inflation,

低失業率，

by low unemployment,

和受控制的低金融波動率而得出的。

and controlled and low financial volatility.

但是2007年和2008年的大衰退，

But the Great Recession in 2007 and 2008,

和大崩盤，打破了這個繁榮假象。

the great crash, broke this illusion.

金融行業損失了數千億美元，

A few hundred billion dollars of losses in the financial sector

整個世界的GDP

cascaded into five trillion dollars

流失了五兆美元，

of losses in world GDP

還有全球股市大概虧損了

and almost $30 trillion losses

30兆美元。

in the global stock market.

因此，人們對大衰退的理解

So the understanding of this Great Recession

是一場完全出乎常理的意外、

was that this was completely surprising,

是突然湧現的危機，

this came out of the blue,

就像是眾神的憤怒一般。

this was like the wrath of the gods.

沒有人有辦法為此負責。

There was no responsibility.

作為對這場危機的反饋，

So, as a reflection of this,

我們成立了金融危機觀測局。

we started the Financial Crisis Observatory.

我們當時要達到的目標

We had the goal to diagnose in real time

是能實時判斷出金融泡沫，

financial bubbles

和預先判斷出它們的臨界點。

and identify in advance their critical time.

具體來說，是什麼架構了 金融觀測台的地基與科學方法呢？

What is the underpinning, scientifically, of this financial observatory?

是我們開發的一個叫“龍王”的理論。

We developed a theory called "dragon-kings."

"龍王理論"代表著各個種類中的

Dragon-kings represent extreme events

極端事件。

which are of a class of their own.

他們是特殊的，也是異常值，

They are special. They are outliers.

他們衍生於某些特殊機制，

They are generated by specific mechanisms

因此是可以預測的

that may make them predictable,

還可能是可控制的。

perhaps controllable.

“龍王理論"考慮到了 金融價格的時間序列，

Consider the financial price time series,

和一支給定的股票，你的最佳股票

a given stock, your perfect stock,

或者一個全球指數

or a global index.

你能看到這些上下起伏的狀況。

You have these up-and-downs.

峰谷法則是一個金融市場 非常好的測量風險工具，

A very good measure of the risk of this financial market

從高峰至低谷呈現著

is the peaks-to-valleys that represent

一個最糟糕的劇情，

a worst case scenario

你在最高點買入，又在最低價賣出。

when you bought at the top and sold at the bottom.

你可以看到統計資料--不同規模的峰谷法則

You can look at the statistics, the frequency of the occurrence

的出現頻率，

of peak-to-valleys of different sizes,

這些都會在表格裡呈現。

which is represented in this graph.

現在有趣的是，99%的

Now, interestingly, 99 percent

不同振幅的峰谷法則

of the peak-to-valleys of different amplitudes

都可以由普通的冪次定律反映出來

can be represented by a universal power law

由這條紅線反映。

represented by this red line here.

更有趣的是，這還是離群值，這些屬於特例。

More interestingly, there are outliers, there are exceptions

在這條紅線之上

which are above this red line,

和那些基於其他99%峰谷法則校準的

occur 100 times more frequently, at least,

所預測會發生的推論相比

than the extrapolation would predict them to occur

發生的頻率

based on the calibration of the 99 percent remaining

至少超過100倍以上。

peak-to-valleys.

這可是個依聯性極強的準則，

They are due to trenchant dependancies

損失的後頭跟著一個損失，

such that a loss is followed by a loss

又接續著另一個損失。

which is followed by a loss which is followed by a loss.

大多標準風險管理工具都遺漏了

These kinds of dependencies

如此露骨的關聯性，

are largely missed by standard risk management tools,

當他們應該留意"龍王"的時候

which ignore them and see lizards

常常是忽略它而只看到一些蜥蜴。

when they should see dragon-kings.

"龍王理論"的根本機制

The root mechanism of a dragon-king

是一項緩慢而走向不穩定的成熟過程

is a slow maturation towards instability,

它就是泡沫，

which is the bubble,

而泡沫的頂點往往被隨破滅的開始。

and the climax of the bubble is often the crash.

這跟用文火燒開水很相似

This is similar to the slow heating of water

在實驗中當試管中的水達到沸點時，

in this test tube reaching the boiling point,

裡頭的水將產生不穩定的狀態，

where the instability of the water occurs

轉變型態為蒸氣相。

and you have the phase transition to vapor.

而這個過程絕非是線性演變，

And this process, which is absolutely non-linear --

故無法透過標準化技術去預測，

cannot be predicted by standard techniques --

這是集體緊急行為的反射，

is the reflection of a collective emergent behavior

是根深蒂固的內在根性。

which is fundamentally endogenous.

所以，泡沫破滅的根源，危機的根源

So the cause of the crash, the cause of the crisis

須從系統內在的不穩定中發覺，

has to be found in an inner instability of the system,

且任何細微的擾動 都會讓這個不穩定現形。

and any tiny perturbation will make this instability occur.

現在你們當中某些人可能已經察覺，

Now, some of you may have come to the mind

這和黑天鵝效應並不相關，

that is this not related to the black swan concept

你經常聽到這個名詞嗎?

you have heard about frequently?

要記得，黑天鵝是稀有的鳥類，

Remember, black swan is this rare bird

那種你才看過一次，便會讓人突然粉碎

that you see once and suddenly shattered your belief

過往"天鵝都該是白色的"那種信念

that all swans should be white,

所以它也囊括著不可預測性、不可獲知性，

so it has captured the idea of unpredictability,

表示那些極端的事件

unknowability, that the extreme events

根本就無法得知。

are fundamentally unknowable.

幾乎沒有什麼能脫離

Nothing can be further

我提出的"龍王理論"範疇，

from the dragon-king concept I propose,

它恰好完全相異於大多數的極端事件，

which is exactly the opposite, that most extreme events

是可獲知且可預測的。

are actually knowable and predictable.

因此我們可以擁有權力並擔起責任

So we can be empowered and take responsibility

去對這些事件進行預測。

and make predictions about them.

現在就讓我的龍王來燒掉黑天鵝吧!

So let's have my dragon-king burn this black swan concept.

(笑聲)

(Laughter)

有很多先期的警報訊號

There are many early warning signals

可以透過這個理論預測。

that are predicted by this theory.

讓我為您舉例說明，

Let me just focus on one of them:

這個超級指數成長伴隨著正向的反饋，

the super-exponential growth with positive feedback.

這是什麼意思呢?

What does it mean?

假想你現在進行一項投資，

Imagine you have an investment

第一年你獲得了百分之五的報酬，

that returns the first year five percent,

第二年百分之十、第三年百分之二十，

the second year 10 percent, the third year 20 percent,

再下一年有百分之四十， 這不是很令人驚奇嗎?

the next year 40 percent. Is that not marvelous?

這就是超級指數成長。

This is a super-exponential growth.

一種標準指數成長，相對於其他增長

A standard exponential growth corresponds

比如說線性增長只維持在百分之十。

to a constant growth rate, let's say, of 10 percent

重點在於，在泡沫化期間重複演變了很多次

The point is that, many times during bubbles,

諸多正回饋在多次演變中產生，

there are positive feedbacks which can be of many times,

過程中到達先前的成長增強幅度

such that previous growths enhance,

再更往前推進，增長到下一個成長級距，

push forward, increase the next growth

直至超級指數成長的程度

through this kind of super-exponential growth,

它是非常強而銳利的，並不是維持穩定發展的，

which is very trenchant, not sustainable.

主要概念是來自於

And the key idea is that the mathematical solution

表現在這類有限時間奇異點模型的數學解法。

of this class of models exhibit finite-time singularities,

意思是在某個臨界時間上，

which means that there is a critical time

它的系統將崩解，改變其體系，

where the system will break, will change regime.

這可能是崩盤，也可能是平穩的，或其他可能

It may be a crash. It may be just a plateau, something else.

關鍵放在臨界時間上。

And the key idea is that the critical time,

在早期發展超級指數成長時，

the information about the critical time is contained

有關臨界時間的資訊是包含在內的。

in the early development of this super-exponential growth.

我們前期將這個理論應用在實驗中，

We have applied this theory early on, that was our first success,

也是我們第一次成功地

to the diagnostic of the rupture of key elements

診斷出鐵火箭破裂的關鍵要素。

on the iron rocket.

我們採用聲發射器這種你可以聽見

Using acoustic emission, you know, this little noise

它發出小小噪音在對著你唱歌的東西。

that you hear a structure emit, sing to you

當它承受壓力，開始顯現損壞時

when they are stressed, and reveal the damage going on,

便產生集體的正回饋現象，

there's a collective phenomenon of positive feedback,

也就是越來越多的損壞會伴隨著更多損壞。

the more damage gives the more damage,

因此你可以在可能的範圍間

so you can actually predict,

去確切的預測

within, of course, a probability band,

它的破裂何時會產生。

when the rupture will occur.

所以現在可以成功地用在

So this is now so successful that it is used

確認飛機［能否］飛行的初期階段。

in the initial phase of [unclear] the flight.

也許更加出奇的是，相同的理論形式

Perhaps more surprisingly, the same type of theory

也能運用在生物學或是醫療上，

applies to biology and medicine,

像是在分娩、生產、癲癬發作時。

parturition, the act of giving birth, epileptic seizures.

從懷孕七個月，母體開始感到

From seven months of pregnancy, a mother

陣陣的子宮收縮前兆，

starts to feel episodic precursory contractions of the uterus

這類顯著朝向不穩定的、

that are the sign of these maturations

將要生下寶寶的成熟過程，

toward the instability, giving birth to the baby,

龍王理論的徵兆。

the dragon-king.

所以假如去測量這些前兆

So if you measure the precursor signal,

就可以預先判斷

you can actually identify pre- and post-maturity problems

事件發生前後的問題。

in advance.

癲癬發作也是有各種不同的形式，

Epileptic seizures also come in a large variety of size,

當大腦進入了超臨界狀態時，

and when the brain goes to a super-critical state,

採用龍王理論能有一定程度的預見，

you have dragon-kings which have a degree of predictability

進而協助病患去處理自身症狀。

and this can help the patient to deal with this illness.

我們已經在許多系統中應用這個理論，

We have applied this theory to many systems,

走山、冰川崩塌，

landslides, glacier collapse,

甚至是成功地預測熱門動態，

even to the dynamics of prediction of success:

像是賣座鉅片、YouTube短片、電影等等。

blockbusters, YouTube videos, movies, and so on.

但或許最重要的應用

But perhaps the most important application

是應用在金融面。

is for finance, and this theory

我相信這個理論闡明了 我們曾經歷過的金融危機，

illuminates, I believe, the deep reason

其深層的原因

for the financial crisis that we have gone through.

根自於三十年的泡沫歷史。

This is rooted in 30 years of history of bubbles,

自1980年起

starting in 1980, with the global bubble

全世界的泡沫在1987年破裂，

crashing in 1987,

接連在後的有其他諸多泡沫，

followed by many other bubbles.

當中最大的叫做2000年的"新經濟"網路泡沫

The biggest one was the "new economy" Internet bubble

在2000年破裂。

in 2000, crashing in 2000,

之後許多國家的房地產泡沫，

the real estate bubbles in many countries,

各處充斥著金融衍生產品泡沫，

financial derivative bubbles everywhere,

股市泡沫也是無所不在，

stock market bubbles also everywhere,

商品與各種泡沫，債務與信貸泡沫---

commodity and all bubbles, debt and credit bubbles --

泡沫，泡沫，泡沫

bubbles, bubbles, bubbles.

我們共有這全球性泡沫，

We had a global bubble.

這是全球市場被高估的程度，

This is a measure of global overvaluation

顯露出我所指的，

of all markets, expressing what I call

一台永久印鈔機的幻覺

an illusion of a perpetual money machine

突然在2007年崩盤了。

that suddenly broke in 2007.

問題在於我們總看到相同的策略，

The problem is that we see the same process,

特別是透過量化寬鬆，

in particular through quantitative easing,

各國政府老想著要永遠打開印鈔機 去解決金融危機

of a thinking of a perpetual money machine nowadays

打從2008年起，

to tackle the crisis since 2008 in the U.S., in Europe,

在美國、歐洲、日本都是。

in Japan.

這有著非常重要的意義

This has very important implications

來幫助我們理解量化寬鬆

to understand the failure of quantitative easing

以及緊縮政策為何會失敗。

as well as austerity measures

除非我們直擊核心，

as long as we don't attack the core,

解決這種永久印刷機的結構性原因。

the structural cause of this perpetual money machine thinking.

這些都是龐大的主張，

Now, these are big claims.

為何你需要相信我呢?

Why would you believe me?

嗯，也許是因為在過去的15年裡

Well, perhaps because, in the last 15 years

我們從象牙塔裡走了出來

we have come out of our ivory tower,

並開始發表了"事前"

and started to publish ex ante --

我強調這個詞"事前"，意思指的是"預先"

and I stress the term ex ante, it means "in advance" —

在確認泡沫存在以及金融過剩，

before the crash confirmed

在崩盤以前。

the existence of the bubble or the financial excesses.

這些是近期歷史中，

These are a few of the major bubbles

我們已經歷的一些大型泡沫。

that we have lived through in recent history.

這些泡沫都有其有趣故事。

Again, many interesting stories for each of them.

再一次地，讓我告訴各位其中一兩件

Let me tell you just one or two stories

怎麼處理大規模泡沫的故事。

that deal with massive bubbles.

我們都知道中國奇蹟。

We all know the Chinese miracle.

這是股市的大規模泡沫展示，

This is the expression of the stock market

僅在短短數年間，指數跳漲了三倍，

of a massive bubble, a factor of three,

300%

300 percent in just a few years.

在2007年的九月，

In September 2007,

我受邀到一個總體對沖基金管理人會議

I was invited as a keynote speaker of a macro hedge fund

去做專題演講。

management conference,

我在會議上做了預測，

and I showed to the conference a prediction

在2007年底前

that by the end of 2007, this bubble

這顆泡沫就會發生質變。

would change regime.

可能是場崩盤，鐵定動盪。

There might be a crash. Certainly not sustainable.

你們相信這群絕頂聰明、積極、

Now, how do you believe the very smart,

又見廣多聞的總體對沖基金經理人們

very motivated, very informed macro hedge fund managers

對這個預測有何反應嗎?

reacted to this prediction?

你們知道嗎，他們直到現在

You know, they had made billions

已經丟下數十億在這棵泡沫上衝浪。

just surfing this bubble until now.

他們對我說: "Didier"

They told me, "Didier,

"是啦，這個市場確實是可能被高估"

yeah, the market might be overvalued,

"但你可能忘了"

but you forget something.

"2008年八月的北京奧運就要來了"

There is the Beijing Olympic Games coming

"顯然地"

in August 2008, and it's very clear that

"中國政府正在控制經濟"

the Chinese government is controlling the economy

"採取一切手段"

and doing what it takes

"也避免任何波動並控制股票市場"

to also avoid any wave and control the stock market."

在我發表完的三週之後

Three weeks after my presentation,

市值就蒸發了百分之二十，

the markets lost 20 percent

在經歷劇烈的波動後，

and went through a phase of volatility,

到了當年年底，

upheaval, and a total market loss of

總市值已經損失了百分之七十。

70 percent until the end of the year.

我們怎麼會犯下這種集體錯誤?

So how can we be so collectively wrong

怎麼會在發展成 即將轉變、系統已成熟的時候

by misreading or ignoring the science

誤解或是忽略了這樣的科學證據。

of the fact that when an instability has developed,

任何一丁點擾動

and the system is ripe, any perturbation

都會讓其無法控制

makes it essentially impossible to control?

中國市場崩垮了，而後再次復甦

The Chinese market collapsed, but it rebounded.

2009年的時候，我們也辨識出新泡沫。

In 2009, we also identified that this new bubble,

一顆規模略小、不穩定的泡沫。

a smaller one, was unsustainable,

我們就再次"預先地"公開預測

so we published again a prediction, in advance,

到2009年八月前，市場會開始修正

stating that by August 2009, the market will correct,

不會繼續維持現在的軌跡。

will not continue on this track.

批評家讀到這篇預測說

Our critics, reading the prediction,

"不，絕不可能"

said, "No, it's not possible.

"中國政府還在這兒呢!"

The Chinese government is there.

"他們已經學過教訓、中央會控制一切"

They have learned their lesson. They will control.

"他們想從這波成長裡撈些好處"

They want to benefit from the growth."

也許這群批評家 根本沒從之前事件得到教訓。

Perhaps <