From the ‘Dark side’, why do we need Dark Energy?
I really don’t understand this: Greatest Mysteries: Where is the Rest of the Universe?
The say about ‘dark matter’ in one breath “that light doesn’t interact with it”, then three paragraphs later “Another hallmark of dark matter is gravitational lensing, similar to the effect of light passing through a piece of polished glass.” What gives? Either dark matter and light interact or they do not, no?
Here’s the problem: If light interacts with ‘dark matter’ supposedly comprising 22% of the universe energy budget, then why not simply accept that light is gravitationally redshifted as it passes through these large parts of the intergalactic cosmos? If this redshift is gravitational, either because light is passing through dark matter, with which it ONLY interacts gravitationally (whether from a Machian totality of ‘dark matter’ gravity well in line of sight, or from dark space-vacuum encounters), then why need ‘dark energy’ at all? Wouldn’t this disallow for Doppler space expansion, if redshift is ‘dark matter’ gravitational instead? That’s where I’m stuck, as to either or: we either accept ‘dark matter’ interacts gravitationally with light, or we reject it, meaning we cannot use it for gravitational lensing. But we know the latter is false, because we can observe gravitational lensing. So we are left with only one conclusion, logically, that space gravity of dark matter must interact to cause redshifting gravitationally. All that gravitatinally massive 'dark matter' in the universe, therefore, is giving us the illusion, line of sight, as if it were expanding Doppler like, which may only be the ‘Dark side’ fooling us.
The corollary to this conundrum is then, what do we do with the balance of the matter/energy budget, the remaining 74% now ascribed to ‘dark energy’? If E = mc^2 is correct, then where is that energy hiding, if dark matter lensing and gravitational redshifting for intergalactic light is accounted for? Could that energy budget be locked up inside the dark matter itself somehow? Could this other missing energy be 'eaten up' by the process of redshift itself, if due to dark matter BIG gravity?
I don’t know, but I can’t go over to the Dark side yet, not unless I can understand where the rest of that energy went in the universe. Please help me see the light!