I had heard about this, but not with this name.

Which reminds me that it was just a few months ago that the fifth-closest star (and third-closest star system) (known so far) was discovered! Must be something like 5 or 6 light-years away! Which means that this problem doesn't only apply to far-away objects.

>Hi Mike,
>
>My daughter actually covered this in science this year. I thought the Malmquist Bias had to do with observing objects at a distance. You only see the brightest objects within a group of objects and we are unable to see the dimmer ones. Supposedly since our technology hasn't improved enough yet to ensure we see all objects regardless of their luminosity it has to be accounted for in any analysis of data or else the results would be innacurate. I'm not sure it can accurately be accounted for though.
>
>
>>>>There would not be significant time dialation in galaxies that we'd consider neighbors, that is correct. But you have to remember that there are galaxies VERY far away that SEVERELY redshift and moving EXTREMELY fast. The supernova of these galaxies should demonstrate some of these effects. And indeed, based on current models (not observations) they have been able to calculate the time dialation involved. At first, the collected data seemed to support this, and it was widely used as definitive evidence that the universe was expanding. (Again, see http://www.astro.ucla.edu/~wright/tiredlit.htm and you'll notice non-inflationary models are dismissed based on this evidence.)
>>>>
>>>>But Jensen's paper appears to demonstrate that with newer and more accurate data that if it is interpreted correctly, this data simply defies what is predicted by the Big Bang.
>>>
>>>I very much doubt - but can't say for sure - that current measurements are accurate enough to notice a change in the Doppler Effect within a one-month period, due to the fact that the expansion rate of the Universe is either increasing or decreasing. A quick estimate indicates that this change would be much less than one part in a billion.
>>
>>Its actually alot simpler than that:
>>
>>
>>Has the time dilation of distant source light curves predicted by the Big Bang been observed?
>>
>>This time dilation is a consequence of the standard interpretation of the redshift: a supernova that takes 20 days to decay will appear to take 40 days to decay when observed at redshift z=1. The time dilation has been observed, with 5 different published measurements of this effect in supernova light curves. These papers are:
>>
>> * Leibundgut etal, 1996, ApJL, 466, L21-L24
>> * Goldhaber etal, in Thermonuclear Supernovae (NATO ASI), eds. R. Canal, P. Ruiz-LaPuente, and J. Isern.
>> * Riess etal, 1997, AJ, 114, 722.
>> * Perlmutter etal, 1998, Nature, 391, 51.
>> * Goldhaber etal, ApJ in press.
>>
>>These observations contradict tired light models of the redshift.
>>
>>http://www.astro.ucla.edu/~wright/cosmology_faq.html#TD
>>
>>Again, these papers purport to have observed the simple prediction (and the prediction is quite simple if you notice) but the interpretation of this data is now in question based on Jensen's claims that a "Malmquist Type II bias" exists in the data. I have no idea what a Malmquist Type II bias is.