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Stretching Light

  1. Jan 1, 2015 #1
    Is it possible to create a doppler shift of EM radiation in a lab? or is it only feasible on universal scales?

    I was just thinking that high energy x-rays have a sub-atomic wavelength,could these be transformed to visible light to let us 'see' an atom?
     
  2. jcsd
  3. Jan 1, 2015 #2

    Dale

    Staff: Mentor

    Yes. That is how the police's speed detectors work and the weather radar also.
     
  4. Jan 2, 2015 #3
    They detect the frequency change created by the movement of the car the light is bouncing off but they don't induce a frequency change themselves.
    Also the scale of the change from x-ray to visible light is extreme to say the least, i assume it's not actually possible but thought i would throw it out there as the potential payoff would be amazing :-)
     
  5. Jan 2, 2015 #4

    Drakkith

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    Staff: Mentor

    We can create small doppler shifts, such as in Dalespam's examples of radar, but large doppler shifts like what you are suggesting are beyond our capability at the moment.
     
  6. Jan 2, 2015 #5
    Sorry Dalespan i was unaware we actually create the shift in the case of radar

    Thanks for your answer Drakkith, It is the answer i expected but i couldn't find much on the subject through google.
    so my next question is if we were able to create the necessary shift would my experiment be feasible?
     
  7. Jan 2, 2015 #6

    Dale

    Staff: Mentor

    We can already transform x rays to visible light in order to see the structure of matter. This is called xray crystallography. We just didn't use Doppler to do it. I don't see the benefit of using Doppler over existing approches.
     
  8. Jan 2, 2015 #7
    It's not something i have knowledge on but from what i ave read this is a different thing. This isn't converting x-rays to visible, it is sensing the diffraction pattern of the x-rays and then creating a visualisation of the perceived structure of the crystals.

    Whilst i wont argue that this is incredibly useful and sufficient for scientific purposes we are human and we love things that fit our set of sensory organs. For instance compare the difference in feeling you get when you look at a celestial object through a telescope compared to looking at a picture of the exact same thing...
    I'm not proposing this experiment as a way to further science as such but as one of those experiments that captures the public :-)
     
  9. Jan 2, 2015 #8

    Dale

    Staff: Mentor

    The public doesn't care a bit about the mechanism, only the end result.
     
  10. Jan 2, 2015 #9
    I disagree, the only scientific things i ever seem to hear the public discussing are nuclear power and GM crops, the end result of buying a tomato or switching on a light hasn't changed...
    The problem is that people don't often understand the mechanics and so are easily swayed by sensationalist media stories that pray on their fears, but the answer to this is not to dismiss them out of hand and become scientific caricatures driven by some kind of self imposed autistic utilitarianism. I think the answer is to battle the fear mongering with Carl Saganesque positive appeals to emotion and i think Sagan understood well that the public likes the really big and the really small. Look at this pale blue dot....and now look at this atom.

    But then again you could be completely right, it's a fairly subjective question that it's not possible to answer with any kind of certainty so for the sake of the question screw the public haha I want to see an atom damn it! So can someone tell me if it's possible? :-)
     
  11. Jan 2, 2015 #10

    Nugatory

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    No. A good exercise would be calculate how fast we'd need to moving relative to the imaging device to red-shift the frequency down to visible light.
     
  12. Jan 2, 2015 #11

    Dale

    Staff: Mentor

    That is not a counterexample. The public doesn't care about nuclear power as a mechanism or a technology. They care about the end result of having clean, safe, and cheap power. Similarly with GM crops. The public's interest in those has nothing whatsoever to do with the mechanism or technology itself, only the end result.

    Yes, this type of technology exists. There was a group in 2013 I believe that published a paper showing an image of the hydrogen molecule's wavefunction. Also, IBM made an atomic-size movie by moving atoms around and taking pictures.
     
    Last edited: Jan 2, 2015
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