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Thread: Is the Universe Cold?

  1. #1
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    Another one of those questions........

    I know in our solar system we evolve around the sun which provides our heat and stuff, but beyond our solar system, is the temp cold? If so ... why? I would think of the Universe very quiet and with no wind, no temperature.

    If the answer is yes, its cold...... How and why is it cold? What elements produce the coldness?

  2. #2
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    It depends on how far u leave the Star (Sun or Bright Object) , if too far away, then its cold (abslute Zero), if too close, then its hot (10 - 30 million K). That means Dark Object is "COLD", Bright Object is HOT. Therefore we have 2 diferent types of Dark Matter in the universe. One is Hot Dark Matter, which is very Hot and Bright, and the other one is Cold Dark Matter, which is very Cold and Dark.... <_< (@_@ I dont even know what I am talking about) <_<

    What elements produce the coldness?
    Most likely its hydrogen, Oxygen, helium and baryon...

  3. #3
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    Originally posted by Forealfc@Dec 15 2003, 06:10 PM
    If the answer is yes, its cold...... How and why is it cold? What elements produce the coldness?
    Hrm. The difficulty, I think, is in thinking of cold as something, rather than as an absence of something. Cold is simply the state of not being warm; not a state of being in its own right.

    Also, it&#39;s important to recognize that bodies lose heat in two ways: conduction and radiance. Wind removes heat by conduction; the cold air striking the body is warmed by it (removing energy from the body). Heat has transferred from the body to the wind, in this case, by conduction. Conduction, obviously, requires two adjoining substances of dissimilar temperature.

    Radiance, however, is just a body which has heat energy losing it as photons. It&#39;s what causes people to show up on infrared scopes. The heat energy of the person is being radiated off as photons, which are detected by the camera.

    Of these two, only the latter occurs in space. Obviously, since there&#39;s no physical medium in which items exist in space (hence the name ) conduction doesn&#39;t occur. But radiance does. Look at it this way, if it helps: an IR camera can detect a warm body in a vacuum. Clearly, information/energy is flowing from the body to the camera. That energy has to come from somewhere, and that somewhere is the body&#39;s heat. Ultimately, of course, that means that it will run out of heat to broadcast.

  4. #4
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    Originally posted by Littlemews@Dec 15 2003, 08:20 PM
    then its cold (abslute Zero)
    I&#39;m afraid I have to disagree on this one. I don&#39;t believe that any point in the universe is actually at absolute zero (well, it&#39;s difficult to talk about the "temperature" of a volume which contains literally nothing, but if we consider the stray hydrogen atom, we can discuss it). The "background radiation" is ~4K (yes, I am aware that that&#39;s not actually a "temperature" in this sense, but it does mean there&#39;s background energy no matter which way we look, and energy means heat. In a way) in every direction observed from Earth (I don&#39;t have a link to reference that off the top of my head, can someone else confirm?). Pervasive energy means there isn&#39;t anything at absolute zero.

    Even if you had something in the deepest depths of intergalactic space, the very first photon to bang into it would impart energy and raise its temperature above absolute zero. Or look at it another way: any "pocket" of absolute zero would be at the steepest possible temperature gradient relative to the rest of the universe. Barring a perfect insulator, some energy has to leak through and raise its temperature.

  5. #5
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    I didn&#39;t realize I wasn&#39;t logged in until just now...those two anonymous replies are from me, so any mistakes, inaccuracies, or general stupidity can be directly attributed to me.

  6. #6
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    Universe is everything, so abslute Zero is exist in the universe, somewhere we dont know

  7. #7
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    Originally posted by Littlemews@Dec 15 2003, 08:49 PM
    Universe is everything, so abslute Zero is exist in the universe, somewhere we dont know
    *blink*

    I&#39;ve got a sneaking suspicion you&#39;re kidding, but I can&#39;t help but respond (I&#39;m very Pavlovian, in some ways).

    That doesn&#39;t necessarily follow...saying that "the universe consists of all existing things" is not the same as "all things must exist." If your statement is true, then it demands that all things definable exist somewhere in the universe...but I can define something such that "something is that which does not exist in the universe."

    That&#39;s a bit of a semantic game, I admit.

    The only way that rationale works is assuming an infinite universe, which would demand that all things having a non-zero percent chance of occurring must occur somewhere, sometime (and, actually, would have to occur an infinite number of times in an infinite number of places...any non-zero percent portion of infinity is, of course, infinite). But even then, the possibility exists that something has a zero percent chance of occurring, in which case it still wouldn&#39;t have to exist anywhere.

    Consider: if the logic holds that "the universe is everything, so [x] must exist in the universe," what happens when [x] is something which is in direct contravention of physical law?

  8. #8
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    The universe can&#39;t be absolute zero because you can see. All the stars impart photons, which have energy, which is what heat heat is, energy.

    Now 0 K is absolute zero. Temperatures of 0.00001 K have been achieved, maybe even a few newer experiments have reached colder temperatures. It is hard to measure the temperature of things when they are this cold, at 0 K nothing would be emmitted, so how would you measure the temperature? If you tried to bounce a photon off the matter it would impart energy, thus heating it up.

  9. #9
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    <_< Universe means planets, star, Nebula, galaxies...etc..
    Planets, such as Pluto, planet that far away from the Sun = Absolute Zero (-0 K) Even a ice object in the universe is absolute if the sun cant reach them....

  10. #10
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    Universe means planets, star, Nebula, galaxies...etc..
    Planets, such as Pluto, planet that far away from the Sun = Absolute Zero (-0 K) Even a ice object in the universe is absolute if the sun cant reach them....
    Light from the sun is not the only place where light comes from. Heat comes from a lot of places, I do not think absolute zero could be acieved naturally in the universe. But thats my view.

  11. #11
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    Originally posted by matthew@Dec 17 2003, 05:58 AM
    Light from the sun is not the only place where light comes from. Heat comes from a lot of places, I do not think absolute zero could be acieved naturally in the universe. But thats my view.
    I&#39;m pretty sure your view is accurate: if you were standing on pluto, you could see stars. That means that photons are hitting Pluto. Photons carry energy, and therefore Pluto can&#39;t be at zero energy (absolute zero).

    Basically, if the object can "see" stars, it can&#39;t be at absolute zero. And, since we can see any number of things through intergalactic space, even the area between galaxies isn&#39;t at absolute zero; photons are passing through it.

  12. #12
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    Control Group is obviously on the money. Littlemews, just because you can think it does not make it so. I can think up a nine-headed, four-bodied, 23-legged, blue dog with apples for teeth and etc etc ... but that doesnt mean one is out there. There may be a place where absolute zero exists or not (depending if you think that the obtaining of such is possible or not) but I doubt that it would be occuring naturally. If you are on a planet or asteroid and can see ... anything ... then there is energy there in the form of photons at least. If you&#39;re there and not dead then that&#39;s more energy. Just because you put something in a box and turn off the lights doesn&#39;t instantly make it cold.

  13. #13
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    Even a radio wave with an extrememly long wavelength would impart enough energy to keep it above absolute zero. Nutrinos sometimes hitatoms, giving of energy. Also an object would have gravity which is energy, so the mere fact of an object having mass gives it gravitational energy.

    Energy can be transfered into heat energy which makes the chance of having absolute zero natuarally very small.

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