4 ms·
What's meant by "the wavelengths are equal"? (And have we measured comparable wavelengths in other galaxies?)
by rkagerer 2y ago
What's meant by "the wavelengths are equal"? (And have we measured comparable wavelengths in other galaxies?)
- fnordpiglet 2y agoPresumably they mean propagating EM radiation we observe from earth appears to behave the same on earth as we observe from distant galaxies since the event that created them happened at a time much different than ours and a distant region of space.
- saalweachter 2y agoI mean, technically the EM radiation we observe from distant galaxies does look different than the EM radiation we observe locally: it's red-shifted. I'm sure someone has proposed this is due to physical constants changing over time, rather than the expansion of space-time, and I'm sure someone else has explained why this is wrong.
- itishappy 2y agoThe wavelengths of physical processes are equal. If fundamental constants changed, we'd expect, say, the Lyman series to change too.
- analog31 2y agoYes, we've measured comparable wavelengths. It's one way we can measure the red shift. Not just (red shifted) absolute wavelengths, but the relative spacing between them are quite sensitive to physical constants. These spectra can also be used for identifying the elemental composition of stars.
- cryptonector 2y ago> What's meant by "the wavelengths are equal"? Absorption lines of the elements in the stars whose starlight we observe. THey are the same after correction for redshift.