Notices
Results 1 to 11 of 11

Thread: 0 K, is it reachable??

  1. #1 0 K, is it reachable?? 
    New Member
    Join Date
    Feb 2006
    Posts
    1
    So I was thinking, temperature is the average kinetic energy of atoms/molecules and that absolute zero is the point where those atoms/molecules have no kinetic energy. But no kinetic energy = no mass, thus its believed that (by conservation of matter) that 0K cannot be obtained. So far this has been agreed with for isn't the coldest temp ever reached was like 170 nanokalvins by some guys in CU-Boulder. Now here's my point, if you were to stick a thermometer into a sealed glass jar and hook up a pump and create a vacuum, wouldn't you see the temperature inside the glass jar go down (because atoms/molecules wouldn't be in the jar thus there could be no avg KE when mass=0 in the jar). Thus if you could make a perfect vacuum (no light energy enter, no atoms inside from thermometer or the inside of the glass) you could reach 0K. Also, wouldn't this vacuum model agree with all the laws. Because no matter is destroyed, matter from the system is just placed in the surroundings (System-Mass + Surrondings+Mass = No Net Change) and that 0K = no kinetic energy because the vacuum (@ 0K) contains no particles thus no possible energy. Concluding that 0K is the point where mas cannot exist and can only be obtained by keeping molecules way from a space?


    Reply With Quote  
     

  2.  
     

  3. #2 Re: 0 K, is it reachable?? 
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,168
    Quote Originally Posted by b_bones@coloradocollege.e
    But no kinetic energy = no mass,
    I am not sure where you picked up this idea, but it is wrong. Kinetic energy and mass are very definitely not the same thing at all.
    The difficulty of attaining absolute zero is related more to two practical issues, I believe:
    How do you extract heat from the sample.
    How do you insulate the sample from stray thermal energy.


    Reply With Quote  
     

  4. #3  
    Forum Senior silkworm's Avatar
    Join Date
    Nov 2005
    Location
    Kansas
    Posts
    337
    0K is projected to be the bottom of the scale of temperature, which has no negative numbers. In order to take matter from it's initial temperature to 0K you must suck the energy out of it. Once you hit 1K and are approaching 0K the next step will not be 0K (which it wouldn't be anyway, I'm just using it to illustrate). Instead from 1K you'd go to 0.01K then 0.001K then 0.0001K and you'd have to keep going until past the point you had an infinite number of zeros and reach zero because it would mean there is absolutely no energy in the object. Due to the fact that the object that has mass must have energy (which is probably much too complicated to get into here but it has to do with matter itself and the nature of atoms and subatomic particles), you will never reach 0K on an object because that would mean you would have to convert its mass to energy and evacuate the energy in order to reach absolute zero in the space you were trying to (which would have to be beyond the bounds of EM/the universe), so you wouldn't be dropping the object to 0K, you'd just be evacuating space, which would take an infinitely long time.
    Reply With Quote  
     

  5. #4  
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,168
    Silkworm, you appear to be making the same error as b_bones: absolute zero is merely the point at which thermal energy is zero. It has nothing to say about the inherent energy of matter.
    Reply With Quote  
     

  6. #5  
    Forum Senior silkworm's Avatar
    Join Date
    Nov 2005
    Location
    Kansas
    Posts
    337
    How do you extract heat from the sample.
    How do you insulate the sample from stray thermal energy.
    I know what I'm saying sounds bizarre but the inability to reach absolute zero has nothing to do with engineering problems but because of the nature of matter itself. Actually, my favorite physics professors does superconductor research on supercritical helium at 0.00001K on a contraption he built out of spare parts and $500 back in the 1970s.

    We've had a few conversations on the subject. What I'm saying is valid. I must remind you too, I'm not talking about 0.000000000000000000000000000000000000000000000000 0000000001K.
    I'm talking about 0K.
    Reply With Quote  
     

  7. #6 Re: 0 K, is it reachable?? 
    Forum Professor
    Join Date
    May 2005
    Posts
    1,893
    Quote Originally Posted by b_bones@coloradocollege.e
    So I was thinking, temperature is the average kinetic energy of atoms/molecules and that absolute zero is the point where those atoms/molecules have no kinetic energy.
    This is a very common misconception about absolute zero. All motion does not necessarily stop at absolute zero; molecules still have a small amount of vibrational energy left, which is called the “zero point” energy. This energy is inherent to the matter, and can’t be transferred away.
    Thus if you could make a perfect vacuum (no light energy enter, no atoms inside from thermometer or the inside of the glass) you could reach 0K.
    If there is no matter in the jar than there is no temperature in the jar. "No temperature" is not the same as "a temperature of 0 kelvin".
    Reply With Quote  
     

  8. #7  
    VM
    VM is offline
    Forum Freshman
    Join Date
    Feb 2006
    Posts
    8
    Two points...

    1) At 0 K all motion does not stop. All motion CANNOT stop. If motion stopped completely, then you would know exaclty the momentum of the particles and therefore they could be anywere. It is the uncertainty priciple that dictates that there is motion at absolute zero.

    Really what absolute zero is, is this; At absolute zero, all the particles in the system are in their lowest availible quauntum state. Thus, at absolute zero, the molecules are still vibrating, since a vibrational quantum number of 1 is unalowed -- again, by the uncertainty principle (sort of).



    2) I do belive that absolute zero is unubtainable. Thought i could be wrong about this, I think i remember reading once that specific heats have a slight temperature dependence that causes the specific heat of a material to increase towards infinity as temperature goes to zero. An inverse relationship, if you will. Thus, in order to obtain 0 K you would need to remove an infinite amound of heat from the system!

    I am unsure as to the origins of this, but i think it (at least in part) has something to do with obtaining a perfectly ordererd system at 0 K (see above) and the decrease in entropy required for that.


    Anyways, that is my two coppers worth.
    Reply With Quote  
     

  9. #8  
    Forum Freshman
    Join Date
    Oct 2005
    Posts
    22
    well Say that all motion does stop. wouldn't we not notice becuase it wouldn't be able to move through time and dissapear and be frozen in time? we have gotten very very close I believe that the current lowest 20 Nano Kalvins which is very very close. We humans have gotten to 20nk in which I would love to know what method they used to get it that cold if anyone could tell me that would be cool. anyways what says there wasn't a 9.9x10^99999999999999999999999999999999999 m^2 that was absolute zero and lost in time it's self?
    Reply With Quote  
     

  10. #9  
    Forum Senior silkworm's Avatar
    Join Date
    Nov 2005
    Location
    Kansas
    Posts
    337
    Ian12
    we have gotten very very close I believe that the current lowest 20 Nano Kalvins which is very very close.
    20 nK is nowhere near 0K. 20 nk = 20x10^-9 Kelvin. Absolute zero is beyond 1.0 x 10^-(infinity) K. There's still a hell of a long way to go, and it's impossible to reach with anything that has mass.
    Reply With Quote  
     

  11. #10  
    Forum Senior
    Join Date
    Mar 2006
    Posts
    309
    0K is achieved when the pressure of a gas is lowered to zero and there is no heat. Since the pressure of a gas can never be completly reduced to 0, absolute zero cannot be achieved, and thus remains purly theoretical.
    I don't suffer from insanity, i enjoy every minute of it

    the road to succes is never paved or clearly marked
    Reply With Quote  
     

  12. #11  
    Forum Senior
    Join Date
    Mar 2006
    Posts
    309
    Quote Originally Posted by Ophiolite
    Silkworm, you appear to be making the same error as b_bones: absolute zero is merely the point at which thermal energy is zero. It has nothing to say about the inherent energy of matter.
    you also made a mistake. energy has everything to do with heat. you forget that heat is atoms moving faster and faster. and for speed, you need energy. see my topic about heat or my wesite.
    I don't suffer from insanity, i enjoy every minute of it

    the road to succes is never paved or clearly marked
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •