Every summer when I was growing up, I would fly from my home in Canada to visit mygrandparents, who lived in Mumbai, India.
在我的成長過程中，每年夏天，我會從我在加拿大的家，搭飛機去看我的祖父母，他們住在印度孟買。
Now, Canadian summers are pretty mild at best
現在加拿大的夏天很暖和，
about 22 degrees Celsius or 72 degrees Fahrenheit is a typical summer's day, and not too hot.
最高大約22度攝氏或72華氏度，這是典型的夏日，不算太熱。
Mumbai, on the other hand, is a hot and humid place well into the 30s Celsius or 90sFahrenheit.
而孟買是個又熱又溼的地方，會超過30攝氏度或90華氏度。
As soon as I'd reach it, I'd ask, "How could anyone live, work or sleep in such weather?"
一抵達孟買，我就會問：「怎麼可能有人在這種天氣下生活、工作或睡覺？」
To make things worse, my grandparents didn't have an air conditioner.
更糟的是，我的祖父母沒有空調。
And while I tried my very, very best, I was never able to persuade them to get one. But this ischanging, and fast.
我已經盡了我最大的努力，但我始終無法說服他們裝一臺空調。但這狀況在改變，且改變得很快。
Cooling systems today collectively account for 17 percent of the electricity we use worldwide.
現今的冷卻系統所用的電量加總起來佔全世界用電量的17%。
This includes everything from the air conditioners I so desperately wanted during my summervacations,
包括從我暑假當中超想要的空調，
to the refrigeration systems that keep our food safe and cold for us in our supermarkets,
到超級市場中確保我們的食物安全且存放於低溫的冷藏系統，
to the industrial scale systems that keep our data centers operational.
到確保我們資料儲存中心能順利運作的工業規模冷卻系統。
Collectively, these systems account for eight percent of global greenhouse gas emissions.
這些系統所排放的溫室氣體加起來佔全球總排放的8%。
But what keeps me up at night is that our energy use for cooling might grow sixfold by the year2050,
但讓我睡不著覺的是我們用在冷卻上的能量，到2050年時可能會增為六倍，
primarily driven by increasing usage in Asian and African countries. I've seen this firsthand.
主要的原因是亞洲和非洲國家的用量增加。我親眼見過。
Nearly every apartment in and around my grandmother's place now has an air conditioner.
幾乎我祖母家附近的每一間公寓，現在都有空調了。
And that is, emphatically, a good thing for the health, well-being and productivity of peopleliving in warmer climates.
就溫暖氣候地區居民的健康、幸福以及生產力而言，那很明顯是件好事。
However, one of the most alarming things about climate change is that the warmer our planetgets,
然而關於氣候變遷最大的警訊之一，就是當地球變得更暖和，
the more we're going to need cooling systems -- systems that are themselves large emitters ofgreenhouse gas emissions.
我們就會更需要冷卻系統，這些系統本身就是溫室氣體排放的來源。
This then has the potential to cause a feedback loop,
這就有可能會形成一個惡性循環，
where cooling systems alone could become one of our biggest sources of greenhouse gaseslater this century.
光是冷卻系統就能在這個世紀後期變成最大的溫室氣體來源。
In the worst case, we might need more than 10 trillion kilowatt-hours of electricity every year, just for cooling, by the year 2100.
在最糟的情況下，到2100年時，僅僅為了冷卻，我們可能每年就會需要超過十兆千瓦小時的電力。
That's half our electricity supply today. Just for cooling.
那是現今我們電力總供應量的一半。僅僅為了冷卻。
But this also point us to an amazing opportunity.
但這也為我們點出了一個很棒的機會。
A 10 or 20 percent improvement in the efficiency of every cooling system could actually havean enormous impact on our greenhouse gas emissions,
如果每一種冷卻系統在效能上都能有10%到20%的改善，就會對溫室氣體的排放有非常大的影響，
both today and later this century. And it could help us avert that worst-case feedback loop.
對於現今以及本世紀後期都是如此。並且它能協助我們避免發生最糟狀況的惡性循環。
I'm a scientist who thinks a lot about light and heat.
我是一位常常在思考光和熱的科學家。
In particular, how new materials allow us to alter the flow of these basic elements of nature inways we might have once thought impossible.
我特別著重研究新材料如何能協助我們改變大自然這些基本元素的流動方式，用我們以前認為不可能的方式來做到。
So, while I always understood the value of cooling during my summer vacations,
所以，我一直都清楚暑假降溫的重要性，
I actually wound up working on this problem because of an intellectual puzzle that I cameacross about six years ago.
由於六年前我遇到的智力難題，我實際上已經完成了解決這個問題的工作。
How were ancient peoples able to make ice in desert climates?
古人怎麼能在沙漠氣候下製冰？
This is a picture of an ice house, also called a Yakhchal, located in the southwest of Iran.
這張照片中的是一間冰室，也叫做「Yakhchal」，位於伊朗西南部。
There are ruins of dozens of such structures throughout Iran,
在伊朗各地，有數十個這類建築物的遺蹟，
with evidence of similar such buildings throughout the rest of the Middle East and all the wayto China.
有證據顯示，這類建築物還遍及了中東其它地區，一路延伸到中國。
The people who operated this ice house many centuries ago,
幾百年前使用這些冰室的人
would pour water in the pool you see on the left in the early evening hours, as the sun set. Andthen something amazing happened.
會把水倒入照片左側的池子中，時機是太陽下山，剛剛進入傍晚的時候。接著，神奇的事就會發生。
Even though the air temperature might be above freezing, say five degrees Celsius or 41 degrees Fahrenheit, the water would freeze.
雖然空氣中的溫度還在冰點以上，比如5攝氏度，或41華氏度，水卻會結冰。
The ice generated would then be collected in the early morning hours and stored for use in thebuilding you see on the right,
一大清早，產出的冰就會被收集起來，儲存放在右邊的建築物裡備用，
all the way through the summer months.
夏季的所有月份就是這樣度過。
You've actually likely seen something very similar at play
你們其實有可能見過類似的現象發生，
if you've ever noticed frost form on the ground on a clear night, even when the airtemperature is well above freezing.
如果你有注意過，在晴天晚上，即使空氣溫度在冰點以上，地面也會形成霜，就是類似的現象。
But wait. How did the water freeze if the air temperature is above freezing?
但稍等一下。如果空氣溫度沒有低於冰點，為什麼水會結冰？
Evaporation could have played an effect, but that's not enough to actually cause the water tobecome ice.
蒸發的效應就很重要了，但光是這點還不夠讓水變成冰。
Something else must have cooled it down.
還要有其他東西來將水冷卻。
Think about a pie cooling on a window sill.
想像一個派，在窗臺上冷卻。
For it to be able to cool down, its heat needs to flow somewhere cooler. Namely, the air thatsurrounds it.
若要讓它冷下來，就要讓熱流到比較冷的地方。也就是，流到它周圍的空氣中。
As implausible as it may sound, for that pool of water, its heat is actually flowing to the coldof space.
雖然這聽起來很不合情理，一池水的熱怎麼可能流到低溫的外太空中。
How is this possible? Well, that pool of water, like most natural materials, sends out its heat aslight.
這怎麼有可能發生？嗯，那池水和大部分的自然材料一樣，以光的方式將熱發送出去。
This is a concept known as thermal radiation.
這概念就是大家所知的「熱輻射」。
In fact, we're all sending out our heat as infrared light right now, to each other and oursurroundings.
事實上，我們現在都在用紅外線光的方式把我們的熱發送給彼此和周遭的環境。
We can actually visualize this with thermal cameras and the images they produce, like theones I'm showing you right now.
使用熱感攝影機就能將這現象視覺化，它們所產出的影像，就會類似各位現在看到的這一張。
So that pool of water is sending out its heat upward towards the atmosphere.
所以，這一池水把它的熱向上發送到大氣中。
The atmosphere and the molecules in it absorb some of that heat and send it back.
大氣以及大氣中的分子會吸收其中一些熱，再發送回來。
That's actually the greenhouse effect that's responsible for climate change.
那其實就是造成氣候變遷的溫室效應。
But here's the critical thing to understand.
但在這裡要了解一個關鍵點。
Our atmosphere doesn't absorb all of that heat. If it did, we'd be on a much warmer planet.
我們的大氣並不會吸收所有的熱。如果會的話，地球就會更暖和許多。
At certain wavelengths, in particular between eight and 13 microns, our atmosphere haswhat's known as a transmission window.
在某些波長，特別是在8到13微米之間，我們的大氣有個所謂的傳送窗口。
This window allows some of the heat that goes up as infrared light to effectively escape, carrying away that pool's heat.
這扇窗會讓其中一些以紅外線方式向上發送的熱有效地發散傳送，將池水的熱給帶走。
And it can escape to a place that is much, much colder.
這些熱會發散到一個更冷的地方。
The cold of this upper atmosphere and all the way out to outer space,
大氣上層的低溫當中，以及一路到外太空中，
which can be as cold as minus 270 degrees Celsius, or minus 454 degrees Fahrenheit.
外太空的溫度可以低到零下270攝氏度，或零下454華氏度。
So that pool of water is able to send out more heat to the sky than the sky sends back to it.
所以那池水發送到天空中的熱就多於天空發送回來的熱。
And because of that, the pool will cool down below its surroundings' temperature.
基於這個理由，那池水會冷卻到比環境更低的溫度。
This is an effect known as night-sky cooling or radiative cooling.
這就是我們常說的夜空冷卻，或稱輻射冷卻。
And it's always been understood by climate scientists and meteorologists as a very importantnatural phenomenon.
氣候科學家和氣象學家一直都知道這是個非常重要的自然現象。
When I came across all of this, it was towards the end of my PhD at Stanford.
當我接觸到這些信息時，我已經快要拿到斯坦福的博士學位了。
And I was amazed by its apparent simplicity as a cooling method, yet really puzzled.
這種冷卻方法表面是如此簡單，背後卻又是個複雜的謎，這讓我感到困惑。
Why aren't we making use of this? Now, scientists and engineers had investigated this idea inprevious decades.
我們為什麼不好好利用它？在過去數十年，科學家和工程師都在研究這個機制。
But there turned out to be at least one big problem. It was called night-sky cooling for areason. Why?
但結果發現，至少有一個大問題。它被稱為夜空冷卻是有原因的。為什麼？
Well, it's a little thing called the sun. So, for the surface that's doing the cooling, it needs to beable to face the sky.
因為有個小東西，叫做太陽。要進行冷卻的表面，必需要能夠面向天空。
And during the middle of the day, when we might want something cold the most, unfortunately, that means you're going to look up to the sun.
在日正當中時，我們最希望的就是能冷到最低點，很不幸的，在那時候你得要向上看向太陽。
And the sun heats most materials up enough to completely counteract this cooling effect.
而太陽會把大部分的物質加熱，熱到足以完全抵消掉這種冷卻效應。
My colleagues and I spend a lot of our time thinking about how we can structure materials atvery small length scales such
我的同事和我花了很多時間思考要如何建構出波長極短的材料，
that they can do new and useful things with light -- length scales smaller than the wavelengthof light itself.
讓它們能與光反應產生新的、有用的東西--波長要小於光本身的波長。
Using insights from this field, known as nanophotonics or metamaterials research,
使用這個領域的見解，也就是一般所知的奈米光子或超材料研究，
we realized that there might be a way to make this possible during the day for the first time.
我們第一次發現了可能有種辦法能夠在白天實現這一點，
To do this, I designed a multilayer optical material shown here in a microscope image.
我為此設計了一種多層的光學材料，在這張顯微鏡影像中可以看見。
It's more than 40 times thinner than a typical human hair. And it's able to do two thingssimultaneously.
它比一般人的頭髮的40分之一還要細。它能夠同時做兩件事。
First, it sends its heat out precisely where our atmosphere lets that heat out the best. Wetargeted the window to space.
首先，它能精準地把熱發送到大氣層，達到最佳的降溫效果。我們對準了通往太空的窗戶。
The second thing it does is it avoids getting heated up by the sun. It's a very good mirror tosunlight.
第二是它能避免被太陽加溫。它是面很好的太陽光反射鏡。
The first time I tested this was on a rooftop in Stanford that I'm showing you right here.
我第一次測試它時，是在斯坦福的屋頂上，各位在照片上可以看見。
I left the device out for a little while, and I walked up to it after a few minutes, and withinseconds, I knew it was working.
我把這個裝置留在那裡一陣子，幾分鐘之後，我走向它，在幾秒鐘之內，我就知道它有用。
How? I touched it, and it felt cold.
如何知道的？我摸了它，摸起來是冷的。
Just to emphasize how weird and counterintuitive this is:
再強調一下這個現象有多怪異且和直覺不符：
this material and others like it will get colder when we take them out of the shade, eventhough the sun is shining on it.
這種材料及其它相似的材料，如果離開陰影反而會變得更冷，即使是被陽光直射著。
I'm showing you data here from our very first experiment,
各位現在看到的是我們第一次實驗的資料，
where that material stayed more than five degrees Celsius, or nine degrees Fahrenheit, colderthan the air temperature,
當時那材料的溫度比空氣的溫度，要低5攝氏度或9華氏度，
even though the sun was shining directly on it.
即使太陽光直射在它上面。
The manufacturing method we used to actually make this material already exists at largevolume scales.
實際量產這種材料的方法已然存在。
So I was really excited, because not only do we make something cool,
我非常興奮，因為我們不只是發明出了很清涼的東西，
but we might actually have the opportunity to do something real and make it useful.
我們可能真的有機會做出很有用的東西來。
That brings me to the next big question.
那就帶出了下一個大問題。
How do you actually save energy with this idea?
要如何用這個點子來節省能源？
Well, we believe the most direct way to save energy with this technology
我們相信，若要用這項技術來節省能源，最直接的方式就是，
is as an efficiency boost for today's air-conditioning and refrigeration systems.
對現在的空調和冰箱系統進行效能的提升。
To do this, we've built fluid cooling panels, like the ones shown right here.
為此，我們打造了液態的冷卻板，就像畫面上的這種。
These panels have a similar shape to solar water heaters, except they do the opposite
它們的外型和太陽能熱水器很相似，差別在於功能相反，
they cool the water, passively, using our specialized material.
它們能用我們的特殊材料被動地讓水冷卻。
These panels can then be integrated with a component almost every cooling system has,
這些冷卻板可以和一個元件整合，幾乎所有冷卻系統都有這個元件：
called a condenser, to improve the system's underlying efficiency.
冷凝器，目的是要改善系統的根本效率。
Our start-up, SkyCool Systems, has recently completed a field trial in Davis, California, shownright here.
我們的初創公司叫SkyCool Systems，目前已經在加州戴維斯完成了實地測試，如照片所示。
In that demonstration, we showed that we could actually improve the efficiency of thatcooling system as much as 12 percent in the field.
在那次展示中，我們展現了我們在實際當中，真的能夠改善冷卻系統的效率達12%。
Over the next year or two, I'm super excited to see this go to its first commercial-scale pilotsin both the air conditioning and refrigeration space.
在接下來的一、兩年，我很興奮地期待能看到商業規模的測試開始進行，用於包括空調以及冰箱上。
In the future, we might be able to integrate these kinds of panels with higher efficiencybuilding cooling systems to reduce their energy usage by two-thirds.
在未來，我們也許可以把這些冷卻板整合到更高效能的建築冷卻系統中，將這些系統所需要使用的能源減少三分之二。
And eventually, we might actually be able to build a cooling system that requires no electricityinput at all.
最終，我們可能可以打造一個完全不需要電力輸入的冷卻系統。
As a first step towards that, my colleagues at Stanford and I have shown that
要做到這點，第一步，我和斯坦福的同事已經讓大家看到，
you could actually maintain something more than 42 degrees Celsius below the airtemperature with better engineering. Thank you.
確實可以將物體維持在比空氣溫度低42攝氏度的狀態，用更好的工程方式就能做到。謝謝。
So just imagine that -- something that is below freezing on a hot summer's day.
想像一下，在炎熱的夏日，有低於冰點的東西。
So, while I'm very excited about all we can do for cooling, and I think there's a lot yet to bedone,
所以，雖然我對於我們能為冷卻做出的貢獻感到很興奮，但我認為還有很多還沒完成的，
as a scientist, I'm also drawn to a more profound opportunity that I believe this workhighlights.
身為科學家，我也被這項發明所突出的無限機會給深深吸引著。
We can use the cold darkness of space to improve the efficiency of every energy-relatedprocess here on earth.
我們可以利用太空的寒冷黑暗來改善地球上每一項與能源有關過程的效能。
One such process I'd like to highlight are solar cells.
我想要特別提出來的其中一種過程，就是太陽能板。
They heat up under the sun and become less efficient the hotter they are.
在太陽下，它們會被加溫，當它們本身越熱，就越沒沒效率。
In 2015, we showed that with deliberate kinds of microstructures on top of a solar cell,
2015年，我們展示出在太陽能板上方刻意加上微結構，
we could take better advantage of this cooling effect to maintain a solar cell passively at alower temperature.
就能夠更善加利用這種冷卻效應，來被動地將太陽能板保持在較低的溫度。
This allows the cell to operate more efficiently. We're probing these kinds of opportunitiesfurther.
這樣太陽能板就能更有效地運作。我們還在進一步研究這些機會。
We're asking whether we can use the cold of space to help us with water conservation.
我們在問的問題是，我們是否能用太空的低溫來協助我們做水資源保存。
Or perhaps with off-grid scenarios. Perhaps we could even directly generate power with thiscold.
或許協助我們不再使用電網。我們甚至可以直接用這低溫來發電。
There's a large temperature difference between us here on earth and the cold of space.
我們地球這裡的溫度和太空的低溫有很大的落差。
That difference, at least conceptually, could be used to drive something called a heat engine togenerate electricity.
那種落差，至少在概念上，可以被用來驅動所謂的熱引擎來產生電力。
Could we then make a nighttime power-generation device that generates useful amounts ofelectricity when solar cells don't work?
那麼我們是否能夠做出一種夜晚的發電裝置，能夠產生夠用的電力，在太陽能板不能運作時代勞呢？
Could we generate light from darkness?
我們能否用黑暗來產生光？
Central to this ability is being able to manage the thermal radiation that's all around us.
這項能力的關鍵，在於要能夠管理我們周遭的熱輻射。
We're constantly bathed in infrared light;
我們經常處在紅外線光之中；
if we could bend it to our will, we could profoundly change the flows of heat and energy thatpermeate around us every single day.
如果我們願意改變這一切，我們就能深深地改變每天在我們周圍比比皆是的熱與能量之流動。
This ability, coupled with the cold darkness of space, points us to a future where we, as acivilization,
這種能力，再加上太空的寒冷黑暗，就能為我們的文明指點未來的方向，
might be able to more intelligently manage our thermal energy footprint at the very largestscales.
讓我們能在非常大的規模下，更智慧地管理我們的熱能足跡。
As we confront climate change, I believe having this ability in our toolkit will prove to beessential.
我們正在面臨氣候變遷，我相信把這種能力放入我們的工具箱是非常重要的。
So, the next time you're walking around outside, yes, do marvel at how the sun is essential tolife on earth itself,
所以，下次當你在外面四處走動時，是的，當我們對太陽在地球生命的重要性感到驚豔時，
but don't forget that the rest of the sky has something to offer us as well. Thank you.
也別忘了天空中的其它部分，也能為我們提供某些資源。謝謝。
點擊了解，擦亮工程商金字招牌
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