Molecular Vibration of Solids

  • #1
why are molecular vibrations never synchronized in a way that would make them macroscopically observable?
 

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  • #2
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Why would you expect them to synchronize?

MRI has a process to synchronize some fraction of nuclear spins - enough to pick up a signal with a conventional antenna.
 
  • #3
anorlunda
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why are molecular vibrations never synchronized in a way that would make them macroscopically observable?
Isn't this the same question as "Why don't all the waves in the ocean synchronize to make one big wave?"

As @mfb said, "Why would you expect them to synchronize?"
 
  • #4
sophiecentaur
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why are molecular vibrations never synchronized in a way that would make them macroscopically observable?
The earliest practical examples of Stimulated Emission was with Microwaves. The MASER came before the LASER and in both cases, waves are produced in synchronism. You do need 'special' conditions for this to happen and it would never happen by chance because of the way the energy levels are naturally populated. It would be interesting to know the lowest frequency of stimulated emission that has been achieved. Probably something to do with thermal activity upsetting the population?
I did a search and found this PF link which suggests there is no actual lower limit. It's not done because it's much easier to produce a non-quantum based process (a common or garden electronic oscillator) for producing coherent RF waves.
 
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  • #5
DrDu
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why are molecular vibrations never synchronized in a way that would make them macroscopically observable?
That's not true. E. g., sound waves in solids are synchronised vibrations of the molecules. The term to look for is "collective excitations".
 
  • #6
ZapperZ
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why are molecular vibrations never synchronized in a way that would make them macroscopically observable?
What makes you think that they are not "synchronized"?

There are "normal modes" of vibrations in solids. And DrDu has pointed out another example.

Your starting premise is faulty. Rather than asking us to explain your faulty starting premise, it is wise to FIRST establish if that premise is true or false.

Zz.
 
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  • #7
Why would you expect them to synchronize?
If we had two magnets swinging on pendulums, I would expect them to synchronize after a while(Right?).

What makes you think that they are not "synchronized"?

There are "normal modes" of vibrations in solids. And DrDu has pointed out another example.

Your starting premise is faulty. Rather than asking us to explain your faulty starting premise, it is wise to FIRST establish if that premise is true or false.
you are right. I was thinking about the vibrations that are due too temperature.
 
  • #8
and it would never happen by chance because of the way the energy levels are naturally populated.
How so?
 
  • #9
sophiecentaur
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How so?
It's a while since I learned about stimulated emission but is it not true to say that a population inversion (necessary for lasing) is not a common natural occurrence?
 
  • #10
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If we had two magnets swinging on pendulums, I would expect them to synchronize after a while(Right?).
Based on friction macroscopic objects have. There is no friction on the level of individual atoms because you can't heat their constituents.
 
  • #11
Based on friction macroscopic objects have. There is no friction on the level of individual atoms because you can't heat their constituents.
Assuming that there was no friction, wouldn't two magnets swinging freely parallel to each other eventually synchronize?
 
  • #13
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Search Youtube for "Metronome Synchronization" , keep in mind they share a "floating" platform...
 

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