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Comment by ImTalking | Hacker News Reader

As our instruments get better, are we going to find these clusters further and further out until we hit the supposed age of the universe @ 13.7B years? Then what? When do we start thinking that maybe the models are potentially wrong?

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When we have evidence to the contrary. Speculation about what we might find in the future doesn't change anything.

Exactly right. Its exciting because we get new data and if it contradicts theory, it forces us to reconsider what we think is the correct answer. And in that reconsideration our understanding grows.

It is unfortunate that we cannot image this object once a day for 5 years and then watch its changes over that time period in one 30 minute viewing. Telescope time is too valuable to "waste" but I wonder what it might show us.

> Telescope time is too valuable to "waste" but I wonder what it might show us.

It would be great if we could build more of them. I'm hoping that the cheaper access to space coupled with some clever hacks will let us throw a few more up there.

Let's say our telescopes get better and better. Are there any hard limits for how well we can resolve the light from such a galaxy?

I don't understand the actual science well enough myself to explain, but my understanding is that there are lots of limits to do with optics, the behaviour of light over such distances, the wavelike nature of light, etc.

See https://en.wikipedia.org/wiki/Diffraction-limited_system for example.

The Planck constant presumably, if we can get that far.

https://en.wikipedia.org/wiki/Planck_constant#Significance_o...

Practically, yes, telescopes are limited by the diffraction limit. This depends on ratio of the wavelength of the light being captured to the size of the optics. In theory one could make larger and larger perfect lenses/mirrors, but practically there is a limit somewhere. More information at https://en.wikipedia.org/wiki/Angular_resolution

I suppose at some point quantum effects will take over, but I'm guessing the manufacturing requirements for perfect optics will be the limited factor long before then.

For large-aperture ground-based telescopes operating in the visible spectrum, the seeing limit is the dominant effect. Atmospheric turbulence is a bigger factor than the precision of your optics, in other words. See https://en.m.wikipedia.org/wiki/Astronomical_seeing

(Space telescopes are diffraction-limited but have other constraints, like mass budget and cost, that keep them from being as large as ground based facilities.)

I would say that galaxy clusters forming after only 2.6B years is an indication that our models are already wrong.

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