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Physics/serious doubt about blueshift.


We know blueshift happens when an object moves towards the observer with a great velocity.
So suppose a self illuminating white ball, or a white sun, moving towards earth at high velocity appears to be blue. How does this happen? Wait, let me explain
Because white light is composed of so many colours, therefore all frequencies are shrunken when it moves towards us, right? Thereore In VIBGYOR, violet increases its frequency to ULTRAVIOLET, indigo moves to violet, like all other lights increases its frequency to a wave just below it, finally red shrinks to orange and infrared to red. So finally again we got a complete visible light spectrum. Therefore all the light should be seen as white. But why does it shows blue light? Why does blueshift occur?
Please explain me

No, you misunderstand the concept of blueshift.  A "white" light source generally has a peak frequency.  There's no such thing as a white light source which has the frequencies spread evenly across the entire's actually not possible.  What we measure blueshift by is individual transitions of very known frequencies when there's no relative velocity.  When these frequencies are emitted, they shift one way or another in the spectral lines towards the blue or red end of the spectrum.  That's what redshift and blueshift mean.  


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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