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Thread: Quick Question.

  1. #1 Quick Question. 
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    Hello all. First post here, and hope to come back often.

    My question is; If I had two barriers that are 1 cm apart, and in the space between the two barriers are vacuumed sealed, is it possible for temperature to transfer from one side to another? FYI, light is not present, one side is room temperature, and the other side is below freezing.

    Thank you, James.


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    Are you asking if energy can transfer through a vacuum? If it didn't, we'd be in trouble.


    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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    Light may not be present, but the plates will generate EM radiation and exchange it. This will evventually lead to the temperature being identical on both.
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    Flick Montana - I thought there would have to be something there in the vacuum to transfer the energy/heat, yes? If it's vacuumed sealed, whats transferring the energy/heat? We don't feel heat in space, right, it's vacuumed? But we do here on earth, which is not. Please, I'm not Science Savvy, so go easy on me, Lol.

    TheUnknowable - But it will transfer at a slower rate than if it was not vacuumed sealed, yes?

    Edit: Thank you two for the quick reply, much appreciated.
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  6. #5  
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    Well, space isn't hot because there isn't a medium to absorb that heat. However, radiation will travel freely through a vacuum and warm an object like Earth over time.
    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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    You will only have radiant heat, not conduction, so yes, it will cool slower.
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    Quote Originally Posted by James.Jr View Post
    Flick Montana - I thought there would have to be something there in the vacuum to transfer the energy/heat, yes? If it's vacuumed sealed, whats transferring the energy/heat? We don't feel heat in space, right, it's vacuumed? But we do here on earth, which is not. Please, I'm not Science Savvy, so go easy on me, Lol.

    TheUnknowable - But it will transfer at a slower rate than if it was not vacuumed sealed, yes?

    Edit: Thank you two for the quick reply, much appreciated.
    You feel the warmth of the sun's rays, yes? There's your answer. And the sun will still heat you up if you're in space.

    There are three mechanisms you need to consider: Convection, conduction and radiation. A vacuum necessarily precludes convection and conduction, but still leaves radiation. That's how the sun warms your face, despite 93 million miles of vacuum in between. That's also how the hot plate will cause the cool plate to heat up eventually. So, even though you declared that there was no light in the intervening space between the plates, there actually is. Remember: Just because you can't see it doesn't mean it isn't there.
    Last edited by tk421; July 29th, 2013 at 02:57 PM.
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    tk421 - I thought I felt the Suns Rays (heat) because it heats up the air molecules around me, which in return heats me, yes? I could be very wrong.

    ...So, there's NO way to stop radiation? Your saying even though there is NO light (that we can see), there still is?
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    Quote Originally Posted by James.Jr View Post
    tk421 - I thought I felt the Suns Rays (heat) because it heats up the air molecules around me, which in return heats me, yes? I could be very wrong.

    ...So, there's NO way to stop radiation? Your saying even though there is NO light (that we can see), there still is?
    Consider this: Why does a red hot object glow red?
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    IDK, maybe because the molecules are agitated?
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    Quote Originally Posted by James.Jr View Post
    tk421 - I thought I felt the Suns Rays (heat) because it heats up the air molecules around me, which in return heats me, yes? I could be very wrong.
    Partially. The sun's radiant energy does heat up the atmosphere, which leads to conductive and convective heat being transferred to you, but that doesn't account for all of it. If it did, standing it the shade wouldn't do any good, as the air temp, and most of the movement, is the same.
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    Quote Originally Posted by TheUnknowable View Post
    Quote Originally Posted by James.Jr View Post
    tk421 - I thought I felt the Suns Rays (heat) because it heats up the air molecules around me, which in return heats me, yes? I could be very wrong.
    Partially. The sun's radiant energy does heat up the atmosphere, which leads to conductive and convective heat being transferred to you, but that doesn't account for all of it. If it did, standing it the shade wouldn't do any good, as the air temp, and most of the movement, is the same.
    Very good point. Didn't see it like that.
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    Quote Originally Posted by James.Jr View Post
    tk421 - I thought I felt the Suns Rays (heat) because it heats up the air molecules around me, which in return heats me, yes? I could be very wrong.


    Well, think carefully about your supposition above: Even if it were the air that gets heated up, how does the sun heat the air? Again, there's a vacuum between the air and the sun, remember.

    That said, the air is quite unnecessary. Following up on KJW's post, suppose I were to bring a red-hot fireplace poker next to your face. Do you believe that you'd feel nothing if I were to pump out the air between it and you?

    Or how about a laser beam? Do you believe air is necessary for you to get burned by a laser beam? If yes, then how would the laser heat a medium that is essentially transparent to it?

    ...So, there's NO way to stop radiation? Your saying even though there is NO light (that we can see), there still is?


    Objects radiate power with a proportionality to the fourth power of their temperature (see Stefan-Boltzmann radiation law). All objects are, effectively, light bulbs. Some are dimmer than others, some radiate in wavelength bands your eyes can't see, but light bulbs they still are.
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    All make very good points, and are very intelligent. I feel ultra dumb, Lol. Also, ya'ls explanations are very easy to understand and comprehend. Thank you!
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    Quote Originally Posted by James.Jr View Post
    All make very good points, and are very intelligent. I feel ultra dumb, Lol. Also, ya'ls explanations are very easy to understand and comprehend. Thank you!
    Do not feel dumb! You are asking the right questions, and thinking about the answers. That's how we all learn. If this stuff were "intuitively obvious" they wouldn't have to write textbooks and make students study them. It's only "obvious" after the fact, meaning it ain't obvious.

    Keep asking questions; don't feel embarrassed at all. Hell, the number of "stupid questions" I've asked is approximately 2.7 times infinity.
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  17. #16  
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    Quote Originally Posted by James.Jr View Post
    IDK, maybe because the molecules are agitated?
    My point is that hot objects actually do emit light. For red hot objects, this is in the visible, but even at room temperature or below there is still thermal radiation emitted. The best way to reduce this is to have highly reflective surfaces.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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  18. #17  
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    On another forum a while back, someone asked whether the sun could reflect light. I considered the possibility that light might be reflected from the plasma, but someone (quite cleverly I thought) pointed out the sun's radiation has a near perfect black body spectrum, so no.
    There are no paradoxes in relativity, just people's misunderstandings of it.
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    Quote Originally Posted by James.Jr View Post
    All make very good points, and are very intelligent. I feel ultra dumb, Lol. Also, ya'ls explanations are very easy to understand and comprehend. Thank you!
    If you were dumb, you wouldn't be able to comprehend the words on the screen. Even worse, you might be one of the plethora of presumptuous cranks who show up here and deposit little turds of wisdom every once in a while.

    You had a question and you asked. So long as you understand the answers, you're far from dumb. You're doing what every other person has to do in order to learn. Don't ever stop.
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    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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