if everything that is surrounding us and everything else (the sun, other stars, planets etc) is cold to the point of beeing at absolute zero, how can things be at such a higher temperature? how can, for example, a spaceship keep a confortable temperature in the inside if outside there is such a massive temperature drop?
sorry for the many questions, but they all are part of the same big one 😀
In: 10
The temperature of space is misleading. Yes, it is only ~3 Kelvin, but it is also incredibly little matter there. We are talking about as little as one atom per cubic meter for most of space. That’s an absurdly huge factor off from matter on a planet. Near a planet, the amount of matter is a bit higher by a meagre factor of less than 10 million.
Altogether, there is 10^^21 to 10^^24 as much matter per volume here on Earth than there is in space near us, and an even larger factor for deep space. Heat _capacity_ depends on how much there is, twice as much matter stores twice the cold/heat. his means **a single 1 meter cube of Earth stores as much thermal energy as a 10,000 kilometers sized cube of near-Earth space!**
So it needs quite a lot of that space to cool the planet, if we would give our warmth to it. In reality, this extreme lack of matter isolates the planet very well. Almost all heat we lose is actually due to thermal radiation. But that amount is matched by the much stronger thermal radiation from the sun, luckily restricted to small area of the day sky.
And even minor changes in radiation off from Earth or from the sun has devastating consequences. The effect of temperature is relative to the absolute numbers: if we are, say, at 300 Kelvin (~27° C) now, then a 1% increase of solar radiation, or a 1% decrease of our thermal loss, means a temperature change of ~3 K = 3° C. That is already significantly more than we are currently dealing with and quite a nightmare for life on Earth; humans included.
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