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  • almost eight years ago when this channel was fresh and before I had gray hairs in

    大概八年前這個頻道還很新的時候 在我的鬍子有白髮之前

  • my beard in fact before I had a beard I made a video showing that if you take a


  • grape and cut it almost completely in half and put it in the microwave you can

    如果你拿一顆葡萄,把它完整切半 然後把它放在微波爐裡

  • make some plasma


  • but the explanation we had in that video was lacking this was


  • me and my friend Dr. Stephen Bosi a fellow physicist so you should look

    這是我 和 我的朋友Stephen Bosi博士 一位物理學家

  • forward to that on another episode of veritasium to be honest nobody really


  • knew how this effect worked that is until now as of the publication of this


  • video three scientists have published an explanation in the Proceedings of the


  • National Academy of Sciences they studied this effect with high-speed


  • cameras thermal cameras electromagnetic modeling and they came up with an

    三位科學家在"美國國家科學院院刊"(PNAS) 發表文章解釋

  • explanation that I think is pretty satisfying and it extends way beyond


  • just microwave great plasma so naturally I called up these scientists yeah


  • actually saw your video before that your videos before joining the grape project


  • oh really that's why I was like already kind of


  • like interested before joining the project the scientists showed you don't


  • even need to use a grape you can get the same effect with hydrogel water beads

    事實上在那之前看過你的影片 加入葡萄項目之前看過影片

  • these are those tiny polymer beads which when you soak in water they increase in


  • volume like 100 times


  • to understand how microwaving a grape gives you plasma we first need to know a


  • few things like a typical household microwave uses a frequency of


  • electromagnetic radiation at about two point four five gigahertz that means


  • that the wavelength of microwaves inside the oven is about twelve centimeters


  • long. now if you've ever studied electromagnetic radiation you might have


  • the intuition that interesting things start to happen when the object or


  • obstacle is around the same size as the wavelength which a grape certainly is not

    像是一台典型的家用微波爐 使用的電磁輻射頻率

  • it's not twelve centimeters but the important quantity is how big is the

    大約是2.45 GHz

  • wavelength inside the object inside the grape twelve centimeters in air but the


  • like index of refraction of grape material must be close to like one point


  • three three or something right like at visible wavelengths it is a lot lower


  • but in the microwave regime the index of refraction is a almost 10 so you have a


  • much higher index of refraction so microwaves are traveling you know like


  • ten times slower through the grape than they are through yet air yes and that


  • means that the wavelength is a tenth its size through air so instead of twelve

    在物體內部、葡萄內部的波長 有多大

  • centimeters it's about 1.2 centimeters right about the size of a grape now if


  • you take a single grape and place it inside the microwave don't cut it in

    但,像葡萄之類的材料 折射率應該接近1.33

  • half what you find is that the microwaves actually become trapped


  • inside the grape and that's because of its high refractive index and its size


  • because turns out that when you have like a ball where approximately the


  • diameter is roughly the same as the wavelength of the microwaves in the material. It

    所以微波在葡萄裡行進 比在空氣中慢了十倍 "是的"

  • actually turns out that it can be trapped in there so that it interacts its kind...


  • it's kind of it bounces at the borders of the of the ball and it can't get out


  • is it like total internal reflection? yes pretty much wow that's interesting I


  • hadn't thought of it that way so the microwaves become trapped inside

    現在你拿單一顆葡萄放進微波爐 不要切半

  • the grape and they actually form these resonant modes you can think of them as


  • standing waves just ways in which the electromagnetic fields like to


  • oscillate inside a grape such that the maximum electromagnetic field is

    因為事實證明 你有一顆球

  • actually in the center of the grape when you put in the microwave you see that it


  • heats up not from the outside in like you would expect if it was just


  • absorbing the microwaves but rather from the inside out. if you add a second grape


  • to the microwave you see that the same thing happens the microwaves get trapped

    這像是全內反射嗎? "是,差不多"

  • in the second grape too- and the amplitude is highest in the very center of the


  • grape and so the heating occurs most of all of there. but if you move these two


  • grapes close together so they're closer than say a wavelength well then you can


  • start to get interactions between the electromagnetic fields in the one grape

    你可以把它們想成是駐波 就是電磁場偏好在葡萄內部震盪

  • and in the other and in fact if you get the grapes touching then the greatest


  • electromagnetic field actually occurs at that contact point between the two


  • grapes and so that is where you're gonna get the greatest oscillating

    你會看到加熱過程 不是你預期的從外而內的吸收微波

  • electromagnetic fields and that is where those grapes are going to get hottest


  • it's also interesting that you don't need to cut the grapes in half. two

    如果你放入第二顆葡萄到微波爐 你會看到一樣的事情發生

  • grapes placed side-by-side will make this effect work as long as they stay in


  • contact. but that's why in a lot of the videos you see there's a watch glass so


  • the reason the watch glass is there is to keep the grapes together now


  • with the very strong electromagnetic fields at the intersection of the two


  • grapes what you can get is some sparks some breakdown of air that is the

    所以它們靠得 比一個波長還短

  • electric fields are strong enough that they ionize the air creating those


  • Sparks and that is what leads to the plasma it creates these ions which can


  • then receive more energy from the microwaves. you can see it here pulsing


  • at 120 Hertz that's twice the 60 Hertz frequency of mains power which reflects


  • the fact that the amplitude of the microwaves is pulsing twice every cycle


  • and what is that plasma made of? well the scientists looked at the spectrum of the


  • plasma from a grape and they found that there's a strong potassium emission line


  • and also a sodium emission line so it seems like those ions must be pretty


  • common in the grape and when the plasma gets formed as those ions which are


  • sprayed up into the air and that is what we're seeing


  • who needs drugs?! now the size of the grapes is important which is something I


  • of course suspected because you don't see this happening with too many other


  • squishy fruits but you don't have to get them the exact right size and this is


  • because water absorbs microwaves so the scientists did some modeling of this and


  • if you had a material inside the grape that did not absorb microwaves then what

    你可以看到有個120Hz的脈衝,那是60 Hz主電源的兩倍

  • you would see is at certain particular sizes you get extreme amplification of


  • the electromagnetic fields it's basically one size that you'd have to


  • hit to get the amplification but made of an absorbent material like water this


  • broadens out the peaks so you get less amplification of the field but over a


  • broader range of sizes this is why a lot of grapes will work even if the sizes


  • vary. so in terms of like applications of this research what do you think I mean


  • obviously people like me are excited and because this is a fun trick but but

    且當電漿形成、這些離子被噴到空氣中 這就是我們所看到的

  • beyond that what do you think in terms of like applications of this? the main


  • limit in fabricating microchips right now and going smaller and smaller is the


  • lithography so how to make these very small features. this phenomenon shows

    當然有所懷疑 因為你在其他很多濕軟的水果看不到效果

  • that two spheres of the right size and refractive index can focus


  • electromagnetic energy down to a tiny spot in between them in this case down


  • to around a millimeter from radiation with a 12 centimeter wave length if


  • similar focusing could be achieved with light it would provide a significant

    如果你在葡萄裡面有一種材質 並不吸收微波

  • improvement over current lithography techniques. So if we could somehow harness

    你會看到在特定的尺寸 有著極大的電磁場放大效果

  • this to do this lithography to be able to maybe write things very small you


  • could actually use light to to make really small features you could do like


  • every two nanometers marks spot with about 2 nanometers resolution - it would help


  • help continue this like Moore's Law yes it would help continue Moore's Law like

    得到較少的放大效果 但是適用的尺寸範圍更廣了

  • putting much more small things in a single chip so I'm glad I was finally able to

    這就是為什麼很多葡萄都可以起作用 即使尺寸有變化

  • explain how this effect works did you enjoy it do you feel like you get it any

    所以,在這研究的 像是應用方面 你有什麼想法嗎?

  • questions put them in the comments below also I

    我意思是,顯然像我這樣的人很興奮 因為這是一個有趣的招數

  • really like this video that I made this is my previous video and so if you


  • haven't seen it go check it out I'll also put a link to the original


  • grape video which is maybe not that good cuz it was eight years ago but anyway

    而且要做得越來越小 就是微影製程

  • thanks for watching


almost eight years ago when this channel was fresh and before I had gray hairs in

大概八年前這個頻道還很新的時候 在我的鬍子有白髮之前


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