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第1段
1 .Listen to a conversation between a student and her engineering professor
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2 .In class today, when we were talking about working with metal heating up metal。
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3 .you mentioned something about a vacuum furnace.
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4 .So I guess that works by.
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5 .They\'re designed to operate at very high temperatures without losing heat.
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6 .The vacuum acts as an insulator to maintain the heat.
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7 .because heat requires matter to travel through.
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8 .But vacuums are empty of matter. Right?
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9 .Which reminded me that other furnaces lose heat.
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10 .so the calculations that I\'ve brought to show you.
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11 .they might need to be redone in my design project, I didn\'t account for heat loss.
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12 .Well, I\'ll look at what you\'ve done.
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13 .but it is something you\'ll need to account for.
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14 .unless your project includes a vacuum furnace.
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15 .It doesn\'t. I actually didn\'t know there were such things as vacuum furnaces.
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16 .though it makes sense. I guess that a vacuum would be good insulation.
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17 .Right, it’s like those vacuum sealed thermoses that keep your coffee hot.
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18 .You\'re familiar with them, right?
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19 .Sure. Without a medium like a solid liquid or gas.
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20 .heat can\'t travel if a container with a hot liquid is surrounded by a vacuum.
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21 .there\'s no medium for heat to travel through.
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22 .so the drink stays hot.
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23 .But it does get cold after a few hours though.
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24 .if heat can\'t move through empty space, why does that happen?
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25 .Well, in your thermos, the area around the top, the part that screws off that area, probably isn\'t vacuum sealed.
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26 .the coffee would get cold eventually, even if you never opened it.
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27 .Plus, vacuum technology isn\'t flawless.
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28 .It\'s almost impossible to create a perfect vacuum.
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29 .Almost impossible?
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30 .In the best lab setting you can get pretty close.
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31 .But speaking of that.
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32 .recent experiments have shown that there is a way for heat to transfer on a small scale, even inside a vacuum.
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33 .in completely empty space. How does that work?
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34 .It\'s a bit too complicated to get into right now.
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35 .but the idea of heat traveling through a vacuum.
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36 .a lot of engineers are puzzled.
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37 .It\'s not what we learned in school about heat transfer.
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38 .Yeah, I\'m taking physics right now.
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39 .but we haven\'t talked much about heat, yet.
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40 .we\'ve talked about how sound can\'t travel in a vacuum.
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41 .That\'s why you don\'t hear sound in outer space.
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42 .Does the discovery about heat have implications for sound travel as well?
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43 .Huh, very good question. Experiments seem to show that.
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44 .just like heat, sound might be able to travel on a very, very small scale in an empty space.
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45 .You know, I think I\'ll hold on to the work I was going to show you and start over.
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46 .I want to think about it some more.
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47 .I\'ve got some new ideas.
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