Stargazing Does Our Picture of the Universe Become Less Accurate the Farther We Look?

[Victor Lee]

I'm not sure if this has already been discussed, but does our picture of the universe become less and less accurate the farther we look? By farther I mean light years away, when we concentrate our telescopes to a certain area light years away, could we be looking at a star that we aren't seeing but is there or vice versa?

 

[phinds]

I'm not sure if this has already been discussed, but does our picture of the universe become less and less accurate the farther we look? By farther I mean light years away, when we concentrate our telescopes to a certain area light years away, could we be looking at a star that we aren't seeing but is there or vice versa?

It becomes less specific and less precise but it does not become less accurate unless the Cosmological Principle is wrong, and how likely is that?

 

[|Glitch|]

I'm not sure if this has already been discussed, but does our picture of the universe become less and less accurate the farther we look? By farther I mean light years away, when we concentrate our telescopes to a certain area light years away, could we be looking at a star that we aren't seeing but is there or vice versa?

It depends on the scale you are talking about. If, for example, you are referring to the location of a single star, then the answer is yes. The closer the star is to us, the more accurately we can determine its distance. At a distance of about one million parsecs (3,261,560 light years) we can no longer identify individual stars (unless they are going supernova). Therefore, the further an object is away from us, the less accurate we can be about its distance.

At distances beyond one million parsecs we no longer focus on individual stars, but rather look at individual galaxies and approximate their distance by either using Type Ia supernova or red shift. The former being more accurate than the latter.

 

[Torbert]

I'm not sure if this has already been discussed, but does our picture of the universe become less and less accurate the farther we look? By farther I mean light years away, when we concentrate our telescopes to a certain area light years away, could we be looking at a star that we aren't seeing but is there or vice versa?

Some of the galaxies we see at ten billion years distance may no longer exist in our current universe, but we have no way of knowing for sure due to time and distance.
On a smaller scale. Betelgeuse is fairly close but may have exploded long long ago. We will not know until the light gets here, which it eventually will do.
The picture is accurate to the time, it is just not our time.

 

[Teichii492]

does our picture of the universe become less and less accurate the farther we look?

Yes.
Since we can only view parts of the universe that are light-years away using various forms of detection equipment. The resolution of our picture is limited by the sensitivity of that equipment. However, we do assume that the laws of physics that apply here, apply in those far-away places, in the same way.

If you are referring to the accuracy of our theories when applied to distant locations, then as far as we can tell from observations, our assumption is correct, the theories that seem to apply in our local area, appear to also apply in distant locations. The issue being that the farther away we look, the more those objects are 'red-shifted' out of view and require ever more sensitive equipment to detect.

There is a notion in cosmology called 'The Cosmological Principle'. Which has so far held up to observational evidence. We observe that the universe is statistically uniform at scales on the order of a few hundred million light-years. Statistically uniform, meaning that the distribution of matter seems to be the same in every direction when you view the universe on a large scale.

In fact, the structure we observe in the Cosmic Microwave Background Radiation, CMBR (the oldest light we can observe in the sky) is also uniform on large scales in all directions. More importantly, it seems that physics as we currently understand it has many satisfactory explanations for the structure that the CMBR exhibits. Since the CMBR can be thought of as a surface, behind which we cannot see directly, we infer the properties of regions further away/older than this surface due to the fine detail that this surface exhibits. We continue construct ever more precise methods of measuring the detail of this surface to refine our understanding of the early universe.

For a good visualisation of how accurately we can view such a distant 'suface' and how we continue to refine the resolution of that image, take a look at this comparison of two images of it.

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So in summary, yes our 'picture' of the universe becomes less accurate the further back we look, but that hasn't stopped us from seeing it with exquisite detail.

By farther I mean light years away, when we concentrate our telescopes to a certain area light years away, could we be looking at a star that we aren't seeing but is there or vice versa?

I think this question also deals with the complexities of relativity. We can only infer what the current state of an object like a star might be based on our theories of their evolution. We can make a decent guess as to the state of that star at our currently measured age of the universe, but we cannot possibly make an observation of the state of that star 'as it is now'. This is because the only way we have of measuring the state of that star is via the photons (or perhaps graviational waves) it emits, which travel at the speed of light. It makes no difference if we send a craft to physically investigate that region of space, since it's messages to us will also be limited by the speed of light. All measurement of objects (whether they are 1mm away from the measuring device, or 1 million light years) will be a measurement of that object at some time in the past.

Determining what is 'there' is subject to the limits of the speed of light and our detector sensitivity.

Another interesting thing for you to look up is 'Angular resolution'. Which deals with our ability to distinguish between two separate sources of light. For example, due to increasing telescope resolution we have discovered that many stars previously observed as one star, turned out to be two-stars, making up a binary star system. We have discovered that these binary stars are much more common than had been observed.