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I think your mistaken there BM, partially, heat is caused by atoms colliding together or vibrating, pressure is the amount of force you place on something, greater pressure means more force on a smaller surface area. Surely I am reading your previous post wrong though, you must have already known that, it's the basis of astrophysics.
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Yeah, and the force placed on an object accomplished by moving atoms. In a volume of gas, such as we might find in an atmosphere, the molecules or atoms are moving about in random directions and bouncing off of each other and objects. All the gaseous molecules rebounding off of you are responsible for the atmospheric pressure you experience. They are what inflates a balloon, since the pressure inside the balloon is greater than the pressure outside, more molecules are bouncing off of the inside than the outside, so the outward force is the greater one until it is counteracting by the elastic force of the rubber. When more of the molecules are moving in one general direction than any other, you have wind, in which the pressure on one side of an object is greater than the other sides, which, if the force is greater than that of friction or gravity on that object, results in movement. Things blow around.
Heat, when the energy is in an object, does exist as excited atoms. They vibrate a lot. Collisions have no part in this, except for conduction. When one atom collides with another (or is simply next to it in an object), there is a transferring of energy. The hotter atom is now vibrating less, the cooler one is now vibrating more. This is how you get cold in the winter, or your beer warm in the summer (when in the shade). This transference always occurs, but eventually no net difference will result since all particles involved are at the same temperature. Heat is the end result of all forms of energy, and only useful to us when there is more of it in one place than another, since we can benefit from its transference from one place to another (all our energy comes from exploiting this). Once temperatures are the same, only the addition of more energy can change it. This is entropy. Eventually, everywhere will be the same temperature. This is the heat death of the universe.
In space, a vacuum, conduction is extremely limited. There are a few sprinklings of atoms, but for our purposes they can be ignored. Your atoms vibrate with body heat, but the only conduction is to other atoms of your body, or clothes. Some briefly to the vapour of your boiled saliva and tears. The only real means of transmitting energy in space is radiation. Excited atoms release some of their energy regularly as photons. Long wavelength, the infra-red portion of the electromagnetic spectrum. Invisible to humans. Radiation in the entire spectrum is how stars shine. Radiation in infra-red is the primary means of heat loss in space. Tin foil reflects a good deal of this, except perhaps very short wavelength, so the photons will be reflected back to your body.
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So you side with the argument that if you can see sunlight...you'll probably roast to death. Why don't you go hover a few kilometres above Pluto for five minutes and see how hot it is.
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If the sun emitted its photons parallel, ie a laser, you would, should you stray into the beam. But the sun's radiation, for lack of a better word,
radiates. It's intensity drops off in accordance with the inverse square law. At pluto it would be only slightly (perhaps immeasurably) warmer than in the shadow of the Earth in Earth orbit.
But in Earth orbit, without the atmosphere, its pretty bad, particularly to your eyes. Unfiltered UV.
