4 ms·

Can someone explain why the CMB map in the first image is so suggestively annotated? The original looks far more isotropic: http://bit.ly/1MBURTA http://bit.ly/

Can someone explain why the CMB map in the first image is so suggestively annotated? The original looks far more isotropic: http://bit.ly/1MBURTA http://bit.ly/1MBURTA

rubidium 11y ago
To demonstrate the strange fluctuations. They just used a different colormap than "the original" (which, by the way, is just one more popular colormap chosen to represent the data). Don't worry though, this isn't just an artifact of the colormap. There's been work done to show that the hot and cold spots are statistically anomalous, thus this Nature article.
- biswaroop 11y ago
  Hmm. The official source says "In this image the anomalous regions have been enhanced with red and blue shading to make them more clearly visible." (http://bit.ly/1MBXXHg http://bit.ly/1MBXXHg) That sounds a bit more than a different colormap :) Also, can't we explain the dipolar variation with some motion in some direction we haven't accounted for (in our local cluster for instance)? I imagine that quadrupole and octopole variations are harder to explain through motion.
  - contravariant 11y ago
    >Also, can't we explain the dipolar variation with some motion in some direction we haven't accounted for (in our local cluster for instance)? I imagine that quadrupole and octopole variations are harder to explain through motion. As far as I know that shouldn't be the case. There's no standard frame of reference with respect to which you can move, so for nearly all intents and purposes the earth might as well be standing still. There's also not really any way to 'move' with respect to the CMB; it's always the same time (i.e. distance) away. And at the time of it's creation particles were (presumably) moving in random directions at random speed, with no specific average (or if you want to be precise, with a Lorentz invariant speed distribution). Searching for 'CMB Lorentz violation' does turn up a few results, but most of those seem to be pure conjecture, I couldn't find any experimental evidence either way.
    - biswaroop 11y ago
      > There's no standard frame of reference with respect to which you can move But a Doppler shift from the Earth's motion would create a dipolar pattern in the CMB wavelengths. I mean there is an obvious dipole in the CMB due to the solar system's motion (http://ned.ipac.caltech.edu/level5/March05/Scott/Scott2.html http://ned.ipac.caltech.edu/level5/March05/Scott/Scott2.html). I just wondered if we're neglecting the motion of some local cluster.

Can someone explain why the CMB map in the first image is so suggestively annotated? The original looks far more isotropic: http://bit.ly/1MBURTA http://bit.ly/1MBURTA

rubidium 11y ago

To demonstrate the strange fluctuations. They just used a different colormap than "the original" (which, by the way, is just one more popular colormap chosen to represent the data). Don't worry though, this isn't just an artifact of the colormap. There's been work done to show that the hot and cold spots are statistically anomalous, thus this Nature article.

biswaroop 11y ago
Hmm. The official source says "In this image the anomalous regions have been enhanced with red and blue shading to make them more clearly visible." (http://bit.ly/1MBXXHg http://bit.ly/1MBXXHg) That sounds a bit more than a different colormap :) Also, can't we explain the dipolar variation with some motion in some direction we haven't accounted for (in our local cluster for instance)? I imagine that quadrupole and octopole variations are harder to explain through motion.
- contravariant 11y ago
  >Also, can't we explain the dipolar variation with some motion in some direction we haven't accounted for (in our local cluster for instance)? I imagine that quadrupole and octopole variations are harder to explain through motion. As far as I know that shouldn't be the case. There's no standard frame of reference with respect to which you can move, so for nearly all intents and purposes the earth might as well be standing still. There's also not really any way to 'move' with respect to the CMB; it's always the same time (i.e. distance) away. And at the time of it's creation particles were (presumably) moving in random directions at random speed, with no specific average (or if you want to be precise, with a Lorentz invariant speed distribution). Searching for 'CMB Lorentz violation' does turn up a few results, but most of those seem to be pure conjecture, I couldn't find any experimental evidence either way.
  - biswaroop 11y ago
    > There's no standard frame of reference with respect to which you can move But a Doppler shift from the Earth's motion would create a dipolar pattern in the CMB wavelengths. I mean there is an obvious dipole in the CMB due to the solar system's motion (http://ned.ipac.caltech.edu/level5/March05/Scott/Scott2.html http://ned.ipac.caltech.edu/level5/March05/Scott/Scott2.html). I just wondered if we're neglecting the motion of some local cluster.