There are dark arts; we have dark secrets; there is a dark side; and some things are just plain dark. In other words, the word dark carries semantic baggage.
So why is the scientifically reified source of certain astronomical effects attributed to what is called dark matter, and more specifically why is it denominated ‘dark’? There were other adjectives, even if one were to insist on the noun, and yet ‘dark’ was selected as the appropriate label for the observed effects. Why? A lot of research has been, and continues to be, expended in vain attempts to determine just exactly, or even vaguely, what dark matter might happen to be. But what has lacked attention and needs to be more fully understood are the considerations that went into selecting ‘dark’ as the adjective describing the cause of those effects. And the rationale for ‘dark’ it seems to me is that ‘invisible’, the linguistically proper description, was scientifically untenable because invisible causes smack of deus ex machina, which is what dark matter actually is – it is the unexplainable cause, without which cosmologists cannot explain certain effects
The matter of ‘matter’ itself carries some linguistic baggage, of course. But in scientific circles, that sometimes resemble logical circles, matter is fairly consistently taken to refer to ‘massive’ ensembles of objects that we believe exhibit inertial, electromagnetic, and gravitational properties, but we are sufficiently unconvinced that we often revisit that assumption that gravitation and inertia pertain to the same essential aspect of the objects to which they refer. The noun ‘matter’ is bandied about in cosmological discussions in several combined forms as baryonic matter, missing matter, dark matter, and in a related sense, dark energy, which I guess could be considered anti-gravitating matter. Baryonic matter refers to the ninety some odd naturally occurring elements about which scientific knowledge has accumulated. We know what it is. It is interactive electromagnetically, thermodynamically, and gravitationally. Antimatter is a subcategory of baryonic matter with the electric charges of constituents exchanged. Missing matter is, of course, not matter, but its absence, and how do we know that matter is missing? Well, Einstein provided us with a nominal value of the density of matter in the universe called the ‘critical density’, in excess of which the universe will gravitationally collapse. And why would we accept that? Because if the universe is thought to be expanding at a rate of H (about 73 kilometers per second per megaparsec) which is the accepted current rate of expansion of the universe, then if the density of the entire universe equals the critical density, the universe will eventually coast to a stop, neither collapsing nor expanding forever. All of which assumes that the universe is in fact finite and expanding in the first place as the responsible cause of cosmological redshift. The additional fact that observed baryonic matter falls far short of this critical value provides reason for stability seekers to welcome a new form of matter to fill that void. The more recent discovery that H has either increased, rather than diminished, at some point in the more recent history of the universe, implies that either all expansion formulas are incorrect, or there is some later introduced counter gravitational force increasing universal expansion.
The redshift of radiation is the basic reason why many classes of observed astronomical phenomena are considered to be of cosmological consequence. By distinguishing ‘cosmological’ from ‘merely’ astronomical we are buying into the cosmogony of an origin of the universe as we know it – as we observe it. Implicit in this distinction is that there is a significant difference between the past, present and future of the universe itself, totally dismissing the possibility that cosmogony may itself be superfluous – that we may exist in a stationary state universe, which is increasingly what it looks like.
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