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Science Forum

  1. 13 Jun '08 22:56
    I saw a science program that said the coldest spot in our solar system is on one of Neptune's moons, where it is about 3 degrees above absolute zero, "where molecules stop moving". I'm curious, is that what Temperature means--some kind of function of moving molecules? And why can't there be temps lower than absolute zero? We can go negative on the Fahrenheit and Centigrade scales--why not Kelvin's?
  2. 14 Jun '08 00:39
    Originally posted by PinkFloyd
    I saw a science program that said the coldest spot in our solar system is on one of Neptune's moons, where it is about 3 degrees above absolute zero, "where molecules stop moving". I'm curious, is that what Temperature means--some kind of function of moving molecules? And why can't there be temps lower than absolute zero? We can go negative on the Fahrenheit and Centigrade scales--why not Kelvin's?
    The answer to the last question is simple. Celcius is defined by 0 degrees being the temperature at which water freezes and 100 degrees being the temperature at which water boils. I believe this must be at a given pressure, but I don't know what that measurement is.

    Fahrenheit is similar in how it determines its degrees - except it's based on a solution.

    I'm pretty sure that Kelvin is defined by 0 degrees being that absolute zero temperature.

    I'm also pretty sure that temperature does have a lot to do with how fast molecules move, although this is getting to where I'm very rusty in my scientific knowledge.
  3. Subscriber AThousandYoung
    Do ya think?
    14 Jun '08 01:00 / 1 edit
    Originally posted by PinkFloyd
    I saw a science program that said the coldest spot in our solar system is on one of Neptune's moons, where it is about 3 degrees above absolute zero, "where molecules stop moving". I'm curious, is that what Temperature means--some kind of function of moving molecules? And why can't there be temps lower than absolute zero? We can go negative on the Fahrenheit and Centigrade scales--why not Kelvin's?
    Yes, temperature is a measure of the average kinetic energy of the particles that make up an object, atmosphere or whatever. At absolute zero there is no movement of particles. There's no such think as "negative movement" because temperature ignores direction of motion.

    Other temperature scales set their zero at a point where there's still kinetic energy in the particles, so less kinetic energy makes sense.
  4. 14 Jun '08 02:34
    Originally posted by AThousandYoung
    Yes, temperature is a measure of the average kinetic energy of the particles that make up an object, atmosphere or whatever. At absolute zero there is no movement of particles. There's no such think as "negative movement" because temperature ignores direction of motion.

    Other temperature scales set their zero at a point where there's still kinetic energy in the particles, so less kinetic energy makes sense.
    Thank you.
  5. 14 Jun '08 18:14 / 1 edit
    Originally posted by PsychoPawn
    Celcius is defined by 0 degrees being the temperature at which water freezes and 100 degrees being the temperature at which water boils.
    Technically (pedant alert) this is no longer true. Nowadays the Celsius scale is defined by absolute zero being -273.15 degrees, and the triple point of water being 0.01 degrees.



    (The triple point is the only temperature at which water can exist as solid, liquid and gas phases in thermodynamic equilibrium)
  6. Standard member sonhouse
    Fast and Curious
    15 Jun '08 13:47
    Originally posted by mtthw
    Technically (pedant alert) this is no longer true. Nowadays the Celsius scale is defined by absolute zero being -273.15 degrees, and the triple point of water being 0.01 degrees.



    (The triple point is the only temperature at which water can exist as solid, liquid and gas phases in thermodynamic equilibrium)
    And even if something could achieve absolute zero, there is still energy in the system due to quantum uncertainty so even absolute zero does not mean totally zero energy.
  7. Standard member sonhouse
    Fast and Curious
    15 Jun '08 13:55
    Originally posted by PinkFloyd
    I saw a science program that said the coldest spot in our solar system is on one of Neptune's moons, where it is about 3 degrees above absolute zero, "where molecules stop moving". I'm curious, is that what Temperature means--some kind of function of moving molecules? And why can't there be temps lower than absolute zero? We can go negative on the Fahrenheit and Centigrade scales--why not Kelvin's?
    I think one of the coldest spots in the solar system is Triton and Pluto, both at about -391 degrees F. I think thats about 30 degrees Kelvin, not 3 degrees. The Cosmic Background Radiation comes in at about 2.7 degrees Kelvin so it seems to me nothing in the universe (unaided by machinery) can get to 3 K. BTW, Triton has liquid nitrogen (!) Volcanoes!
  8. 15 Jun '08 14:06
    The coldest spot in the solar system, perhaps the coldest spot in universe is at cryolaboratories on Earth. Only milli-kelvins (mikro- ? nano- ?) from the absolute zero point.

    In the deepest space, between galaxies, there is only 3 Kelvin. Quite hot in comparison.
  9. Standard member ivan2908
    SelfProclaimedTitler
    15 Jun '08 16:07
    Originally posted by FabianFnas
    The coldest spot in the solar system, perhaps the coldest spot in universe is at cryolaboratories on Earth. Only milli-kelvins (mikro- ? nano- ?) from the absolute zero point.

    In the deepest space, between galaxies, there is only 3 Kelvin. Quite hot in comparison.
    Why do you know so much about that scientific stuff ?? Do you study physics ?
  10. Standard member shavixmir
    Guppy poo
    15 Jun '08 18:27
    Originally posted by FabianFnas
    The coldest spot in the solar system, perhaps the coldest spot in universe is at cryolaboratories on Earth. Only milli-kelvins (mikro- ? nano- ?) from the absolute zero point.

    In the deepest space, between galaxies, there is only 3 Kelvin. Quite hot in comparison.
    I thought Thatcher was the coldest point in the universe.
  11. Standard member sonhouse
    Fast and Curious
    15 Jun '08 19:59 / 1 edit
    Originally posted by FabianFnas
    The coldest spot in the solar system, perhaps the coldest spot in universe is at cryolaboratories on Earth. Only milli-kelvins (mikro- ? nano- ?) from the absolute zero point.

    In the deepest space, between galaxies, there is only 3 Kelvin. Quite hot in comparison.
    Nanokelvin, and working on picokelvin. The latest, a magnetic trap double laser cooler, called the Picokelvinator
  12. 15 Jun '08 20:52
    Originally posted by sonhouse
    Nanokelvin, and working on picokelvin. The latest, a magnetic trap double laser cooler, called the Picokelvinator
    Oh, that's cold... That means that it is 3 billion times (!) hotter in the space between galaxies. When hell freezes...
  13. Standard member flexmore
    Quack Quack Quack !
    16 Jun '08 13:06
    Originally posted by sonhouse
    And even if something could achieve absolute zero, there is still energy in the system due to quantum uncertainty so even absolute zero does not mean totally zero energy.
    Have you ever heard of the casimir effect?
    Theoretically it can produce negative mass/energy etc (lower than the random quantum fluctuations). We might need a few more years than we have got to find out much about that though!
  14. 16 Jun '08 15:07
    Originally posted by ivan2908
    Why do you know so much about that scientific stuff ?? Do you study physics ?
    Thank you for the compliment.

    I have a deep interest of natural science in general, astronomy in specifics. But I don't longer study it in organized form, but I read scientific magazines, search on internet, discuss, and attend lectures when/where I can.

    Science is simply fun!
  15. Standard member sonhouse
    Fast and Curious
    16 Jun '08 17:46
    Originally posted by flexmore
    Have you ever heard of the casimir effect?
    Theoretically it can produce negative mass/energy etc (lower than the random quantum fluctuations). We might need a few more years than we have got to find out much about that though!
    Yes, I have heard and read about the Casimir effect and we are actively studying it right now. It seems in nanomachines, like nanosized gears, the casimir effect has a detrimental action on the friction-like activity, called 'stiction'. The casimir effect was proven to be real only recently but now we can see it in nanomachines, it bolluxes up gears by attracting teeth together with an extra force that has to be overcome, in addition to the regular magnetic and electric field forces.