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Jens
2015-Nov-24, 06:04 AM
I read this post in IFL Science where they talk about the idea that there is a "resolution limit" in the universe, where it might be impossible to clearly see things beyond a certain distance, no matter how large the telescope, because of an inherent limit due to quantum fluctuations. The post is here:

http://www.iflscience.com/space/universe-s-resolution-limit-why-we-may-never-have-perfect-view-distant-galaxies

On one hand it would be disappointing. I wonder what it means, though. Does it mean that even if the universe is infinitely large and eternal, we would still not see far into the distance because of the resolution limit?

mkline55
2015-Nov-24, 01:08 PM
I believe the idea is that over a great enough distance, those sparse photons which reach the observer will have individually encountered slightly different conditions along their paths, so that it becomes impossible to determine, for example, whether two consecutive photons actually came from the same star or from two different stars in a far-away galaxy.

antoniseb
2015-Nov-24, 01:50 PM
... Does it mean that even if the universe is infinitely large and eternal, we would still not see far into the distance because of the resolution limit?
That isn't what the authors meant to say, because they aren't assuming an infinite eternal universe. It is hard to say what something intended to describe things that we will see in this universe of finite duration would mean in a universe with different laws.

efanton
2015-Nov-24, 02:07 PM
Conspiracy theory time :D
They are preparing excuses in case the JWST has a duff mirror


But back to reality
I would imagine at the distances they are talking it is unlikely we will be seeing a perfectly clear galaxy even if everything works perfectly.
We are more likely to see a minuscule blur or smudge, so although what they say makes sense it seems to me to be a mute point.

Jens
2015-Nov-24, 02:17 PM
We are more likely to see a minuscule blur or smudge, so although what they say makes sense it seems to me to be a mute point.

Mute -> moot?

efanton
2015-Nov-24, 02:48 PM
Mute -> moot?

Yes, I know, Typo, mea culpa

Although “moot” by itself means “debatable, or subject to discussion,” the opposite of its general use. So maybe we should all be saying 'mute point' rather than 'moot point'

kzb
2015-Nov-25, 12:46 PM
I've got to ask the question:

If it is accepted that photons interact with virtual particles in the way proposed, does this open the door to "tired light" theories?

Shaula
2015-Nov-25, 05:34 PM
I've got to ask the question:

If it is accepted that photons interact with virtual particles in the way proposed, does this open the door to "tired light" theories?
Nope. Because the end result is one of two things - the virtual particle is promoted to a real one or the photon has the same energy coming out as in. In QM energy is globally conserved (and has to be unless there is a time asymmetry we have never seen)

kzb
2015-Dec-01, 12:59 PM
Nope. Because the end result is one of two things - the virtual particle is promoted to a real one or the photon has the same energy coming out as in. In QM energy is globally conserved (and has to be unless there is a time asymmetry we have never seen)

From the article I am not sure that is the proposed mechanism. It is about multiple tiny gravitational lensing events.

Quote:
Any mass, no matter how small, is predicted to warp space-time. This is Einstein’s description of gravity. The most dramatic example of this phenomenon in nature is in the gravitational lensing of distant galaxies by massive clusters. Photons – particles of light – travelling through such foaming space-time would be affected by such fluctuations in a similar manner to light passing through our thick and turbulent atmosphere.

Of course, the effect is tiny – almost negligible. But a photon emitted from a distant galaxy making the journey across the universe has to travel a long way. On this journey, the countless “phase perturbations” caused by the foamy nature of space-time might add up.


However, that seems to say that photons are scattered rather than lose energy, which is what is required for tired light.

Cougar
2015-Dec-01, 01:17 PM
Photons particles of light travelling through such foaming space-time would be affected by such fluctuations in a similar manner to light passing through our thick and turbulent atmosphere....

that seems to say that photons are scattered rather than lose energy....

But such scattering is rather disproven by observation. We can detect galaxies that are billions of lightyears away. If those photons were being "scattered" by virtual particles, the images would be out of focus. They're not.

I believe our lack of understanding of the implications of virtual particles led to the famous MIScalculation by 120 orders of magnitude of the mass of the universe's dark energy....

mkline55
2015-Dec-01, 02:53 PM
I am not convinced that the article has much value.
But if the theory is correct then this cosmic blurring might be apparent in images of distant galaxies made by next-generation telescopes.
There are more significant known issues to consider. As I understand it, the images of the most distant galaxies can only be made by observing a tiny patch of the cosmos over an extended period of time. What I infer is that only relatively few photons reach the telescope from that entire distant galaxy. So, what is the resolution limit? Could a "big enough" telescope differentiate meter-sized rocks on a planet around a star in a 10-GLR distant galaxy? How fast would photons have to be collected to do so, and how dense are they (i.e. How many photons per hour coming from that 1-meter rock pass through a 100-square meter plane perpendicular to that distant source, assuming the rock is illuminated brightly by its nearby sun? Keep in mind that your telescope has to differentiate photon sources before they move significantly - think rotational and orbital motion.

John Mendenhall
2015-Dec-01, 03:08 PM
But such scattering is rather disproven by observation. We can detect galaxies that are billions of lightyears away. If those photons were being "scattered" by virtual particles, the images would be out of focus. They're not.

I believe our lack of understanding of the implications of virtual particles led to the famous MIScalculation by 120 orders of magnitude of the mass of the universe's dark energy....

I missed that mis, Cougar. Link?

antoniseb
2015-Dec-01, 03:12 PM
... What I infer is that only relatively few photons reach the telescope from that entire distant galaxy. So, what is the resolution limit? Could a "big enough" telescope differentiate meter-sized rocks on a planet around a star in a 10-GLR distant galaxy? ...
I'm going to say no to this specific example... regardless of whether the premise of the OP is true, there are other blurring influences that would impact something that angularly small (resolving better than 10^-26 radians). If the effect in the OP is valid, it would probably mean that we could never resolve a face-on accretion disk from the earliest unshrouded AGNs... which would be much broader and brighter than the rocks you were asking about.

kzb
2015-Dec-02, 12:41 PM
But such scattering is rather disproven by observation. We can detect galaxies that are billions of lightyears away. If those photons were being "scattered" by virtual particles, the images would be out of focus. They're not.

<EDIT>....

But that's the whole point of the article.
It is saying that as telescopes get bigger they will come up against this scattering (if that indeed is what it is) and images of very distant objects will be blurred. The effect is not serious for the current generation but could be for the next.

trinitree88
2015-Dec-02, 06:13 PM
I missed that mis, Cougar. Link?


John. Posted similar long ago....SEE:
http://phys.org/news/2012-03-weve-cosmological-constant-wrong.html

pete