Never say no in science

• Could not add any more value. Just listing the face book conversation
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• Krishna Kumar
  

  
  

  
  

  sir, one small help...... laser cutting is used in industries right? i want to know its mechanism,and finally,i want to know if a beam of light, even if it isa laser, can it be used for cooling?

  
  

  it may sound a bit idiotic, but is it possible to cool an object by passing a beam of light over it?
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  4/28, 9:20pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  light is nothing but a packet of energy in the form of electro magnetic radiation

  
  

  this energy is absorbed by the electrons

  
  

  so i do not see a way of cooling something by adding energy

  
  

  and heating or cooling is about motion of molecules or atoms as a whole
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  4/28, 9:21pm
  

  Krishna Kumar
  

  
  

  
  

  you mean vibrations?

  
  

  of molecules?
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  4/28, 9:22pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  in case of solids you can say vibration. in case of solids and liquids they move from one place to another

  
  

  sorry da. in case of liquids and gases
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  4/28, 9:23pm
  

  Krishna Kumar
  

  
  

  
  

  mmm get it...so hw is the heating happening in case of laser cutting?
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  4/28, 9:25pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  laser has so much energy beyond the melting temperature of the material. so they get vapourised

  
  

  just check if lasers work on ceramics
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  4/28, 9:26pm
  

  Krishna Kumar
  

  
  

  
  

  i doubt it sir..

  
  

  so, does the beam carry the heat?
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  4/28, 9:28pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  as we stated earlier, heat is the total kinetic energy of the molecules in solid, liquid or gas.

  
  

  but light can travel through vaccum.

  
  

  no medium

  
  

  hence it wont be proper to say that laser carries heat

  
  

  it is more appropriate to say it carries energy
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  4/28, 9:30pm
  

  Krishna Kumar
  

  
  

  
  

  then, how does it cut the metals sir?
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  4/28, 9:31pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  the energy when it is reaches the solid it is transferred to the atoms and molecules. they are set in motion and hence we call it heat

  
  

  ok got your question.
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  4/28, 9:32pm
  

  Krishna Kumar
  

  
  

  
  

  ryt.................. i got it......

  
  

  so only te transfer ofenergy take s place,.
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  4/28, 9:33pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  absolutely
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  4/28, 9:33pm
  

  Krishna Kumar
  

  
  

  
  

  mmmmm
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  4/28, 9:34pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  the packets of energy are absorbed electrons. they jump to the next energy level and comes back to its original level.

  
  

  it releases the energy and the process goes on
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  4/28, 9:34pm
  

  Krishna Kumar
  

  
  

  
  

  and hence they release energy while the transition occurs........
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  4/28, 9:35pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  yep
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  4/28, 9:35pm
  

  Krishna Kumar
  

  
  

  
  

  ok.. so it cant be reversed as i asked...
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  4/28, 9:36pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  it is very difficult to say a no in science
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  4/28, 9:37pm
  

  Krishna Kumar
  

  
  

  
  
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  4/28, 9:37pm
  

  Balathandapani K Ramasamy
  

  
  

  
  

  we have a think a little more and see. there might be some loop hole
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  4/28, 9:38pm
  

  Krishna Kumar
  

  
  

  
  

  well, i hav bin thinkin abt dis for de past week and i ended up in dopler cooling and some other stuff in wikipedia , which obiouslyi din understand..

  
  

  it was full of equations..

with this conversation, krishnakumar sent me a link 

http://en.wikipedia.org/wiki/Doppler_cooling

Lesson learnt. Never say no in science