This Week's Edition Of "This May Take A Moment"

Really? The Sheldon black/white suit didn't give you a clue?

Doppler Shift, blue to red, compressed to expanded


Socket 1, Intel 80486
PREMO Member
Hope I'm gonna get at least one "like" here. I thought this was a really clever cartoon!

Yes, painful to be begging............

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Socket 1, Intel 80486
PREMO Member
I am not smart enough to get jokes like that :frown:
Don't sell yourself short! 👍

It's the same effect as when the train sounds differently to you coming as it does going.

We all know this effect; not everyone knows the name (or other applications).

--- End of line (MCP)


PREMO Member
Somebody explain it to me...

noun: red shift
  1. the displacement of spectral lines toward longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects. This is interpreted as a Doppler shift that is proportional to the velocity of recession and thus to distance.

In physics, redshift is a phenomenon where electromagnetic radiation (such as light) from an object undergoes an increase in wavelength. Whether or not the radiation is visible, "redshift" means an increase in wavelength, equivalent to a decrease in wave frequency and photon energy, in accordance with, respectively, the wave and quantum theories of light.
Neither the emitted nor perceived light is necessarily red; instead, the term refers to the human perception of longer wavelengths as red, which is at the section of the visible spectrum with the longest wavelengths. Examples of redshifting are a gamma ray perceived as an X-ray, or initially visible light perceived as radio waves. The opposite of a redshift is a blueshift, where wavelengths shorten and energy increases. However, redshift is a more common term and sometimes blueshift is referred to as negative redshift.
There are three main causes of red (and blue shifts) in astronomy and cosmology:
  1. Objects move apart (or closer together) in space. This is an example of the Doppler effect.
  2. Space itself expands, causing objects to become separated without changing their positions in space. This is known as cosmological redshift. All sufficiently distant light sources (generally more than a few million light years away) show redshift corresponding to the rate of increase in their distance from Earth, known as Hubble's Law.
  3. Gravitational redshift is a relativistic effect observed due to strong gravitational fields, which distort spacetime and exert a force on light and other particles.