Could there be parallel universe(s) right before our eyes (or at least telescopes)?

First off, your theory is killed stone dead by the fact that the masses of galaxies can be measured, and dark matter (or anything else) does NOT neatly balance out the visible components of each galaxy so as to make them all have the same overall mass. Anything but.

Furthermore, there seems to be no good reason to single out galaxies. Galaxies are themselves arranged into clusters on very large scales, so why not count galaxy clusters as your 'parallel universes'? On the other end of the scale, why not count star systems, or planets, or even subatomic particles? Thinking about it, the idea that each particle is a 'parallel universe' makes a lot more sense that applying the same idea to galaxies. It seems to me that the only reason you're specifying galaxies is that they are neatly far enough away for us to not be able to get to them yet. However, that perception is based on our own highly subjective timescales which, quite frankly, the Universe doesn't care about. Objectively, there is no incredibly important distinction between your lifespan, the length of time the Sun takes to orbit the Milky Way, or the length of time it takes an electron to orbit a hydrogen atom. And there is no good reason in physics that we couldn't travel to other galaxies, if we had the necessary technology and were willing to put in the necessary amount of time. Under your idea this would seemingly violate the causal distinction between 'parallel universes', even assuming that light and gravity had not done so already, which they have.

Incidentally though, there are some ideas in cosmology which do sort of relate to your idea, only a far, far larger scale. See, back in the 1960s it was discovered that there is a 'haze' of radiation, called the Cosmic Microwave Background, that covers the entire sky. Although there are slight variations in the CMB, overall it is incredibly uniform and there is no bias in any particular direction. However, the cosmological theories at the time didn't explain why this should be the case. In the 1980s, Alan Guth proposed a model called 'cosmic inflation' by which the very early Universe expanded extremely rapidly as the four basic forces 'crystallized' out of space itself. This would increase formerly small regions to enormous sizes and carry different parts of the Universe far away from each other, explaining why the CMB is so uniform. However, it also implies that there could be other regions of the Universe carried away from us by inflation, which could possess different physical laws and constants but which would be causally disconnected from us by the expansion of space. Furthermore, recent studies have shown that all the matter in the observable universe seems to be (on average) moving at a small but statistically significant speed relative to the CMB, suggesting that our region of the Universe may have once been located near some region containing a vast amount of mass that imparted an impulse on us before being removed beyond the cosmic event horizon. This idea of causally disconnected regions with different physics is similar to your idea, although on a far larger scale (and very importantly, on a large enough scale that we specifically CAN'T see them, because that's what allows them to be different in the first place).

the difference between just an imaginative idea, which you have, and a scientific idea it this:

you must have evidence observation or experiment to support or deny the idea

the idea must make logical sense

the terms used must mean the same to everyone who studies the topic

you have so may mixed up ideas in the one suggestion that it is hard to sort them all out

take one: "Parallel Universe" that does NOT mean side by side like two sticks lay parallel to one another

It is the Idea that entire Universes exist in a dimension Outside our 3 D and time universe. they are unreachable because they are NOT "IN" our universe

However you are thinking and asking questions and that is the first and most important step in learning new things

This concept you have is actually an accepted theory in physics known as M theory. Its a plausible theory, however, it requires a redundant amount of dimensions that we cannot prove. The LHC is on a mission and is trying to find gravitons to prove this theory to be correct. If it is true, we could find out any day.

big bang THEORY, string THEORY, multiverse THEORY, dark matter and dark energy none of which are grounded in reality all of which make so many assumptions they are almost worthless, even the closest star is 4 light years away, trying to conclude what is now from a star several billion light years away is impossible, it all comes from mathematical games but in the real world for example there are no negative numbers you can't take three chairs away from two and actually have minus one chair

Nope.

If there are 'parallel universes', they are different 'space time continuae',

what makes you think light could travel between them? (It can't.)

Yes its called heaven

it cant be in front of our telescopes if its a Parallel universe..it needs to be beside us...