[cynest]

It doesn't necessarily. It is an object that due to current models of quasar formation should not exist at that point in time. This means that there is something wrong with those or current estimations of the age of the universe. The latter is less likely.

[VladRussian]

yes, we are trying to estimate the behavior, mass, luminocity, etc... of the objects in the Universe that was several times smaller than it is now, ie. the space itself was much more "dense" (for lack of a better word) and the matter "warmer" - was the Universe behaving like it does today? We know that the fundamental forces behave differently ( at least quantitatively-wise ) when the matter is "hot". So our estimations may be several orders of magnitude wrong, and finds such as this help to adjust our theories and estimates.

[r00fus]

Are we sure that these large objects aren't being "lensed" into looking further than they are?

Isn't the third possibility that these quasars are illusory?

[hartror]

IIRC lensing won't produce the red shift observed.

[splat]

That's correct, lensing won't affect the observed redshift. It will, however, affect the observed luminosity of the quasar and make us perceive it to be more luminous than it really is. This would lead us to calculate a larger black hole mass. The lensing effect only goes as the square root of the magnification though, so you would need an extremely strongly lensed quasar to be able to explain the black hole mass. If that were the case, the lensing body would also be visible, which it is not.

[nitrogen]

If lensing (through one or more lenses) resulted in a significantly longer path for the light, would it not make sense for an object to seem older than it is (i.e. have greater redshift)?

[splat]

Lensing will make light travel through only a very slightly longer path. At most the difference will only be a few light-weeks. (This is seen in objects which have multiple images. Occasionally you will see one of the images flare up for some reason, and a few days later the other image will flare up.) It won't be anywhere near long enough for cosmological effects like redshift to be important. The main effect of gravitational lensing is just to increase the apparent luminosity of the lensed object.

[nitrogen]

Thanks for the clarification. I was imagining a situation that would require tens of degrees of deflection, with two or three lenses zig-zagging light across a cosmologically significant distance.