View Full Version : Dark Matter/Dark Energy

Dennis Archambault
2003-Nov-17, 09:13 PM
I don't have a problem with the concept of Dark Matter/Dark Energy. What I most want to know is "Has it been mapped throughout all the Constellations?"

As a new owner of a telescope, since I am looking at the Constellations - and trying to understand the 'symbolic pictures' (ie, LEO, etc.) with their positioning of key stars, I would also like to 'imagine' the existence, within each Constellation, of where a known Dark Matter concentration is calculated to be.

2003-Nov-17, 09:33 PM
Hello Dennis. Congratulations on your new telescope. There's a lot to observe, and a lot more to imagine, out there in the skies. As to your question regarding dark matter, the mapping you spoke about is currently underway. Unlike most conventional mapping, however, locating dark matter is mostly a question of discerning its effects on the "non-dark" matter that we can observe directly. The effects of dark matter are inferred in the orbital characteristics of stars in galactic haloes and in the clustering of galaxies. So, if you were to observe some of the stars in the outlying regions of our galaxy, you'd be seeing stars and star clusters that are orbiting more rapidly than standard keplerian/newtonian models would predict. This variance in orbital speed is attributed to the effect of dark matter.

You'd also observe this on a broader scale when looking at some of our galactic neighbors, like M31 (the Great Andromeda Galaxy), M51 (the Whirlpool in Canes Venatici), or M87 (the Virgo A galaxy). And beyond those individual galaxies, you might want to try for some of the galaxy clusters, like the Virgo cluster or the Perseus cluster, and see if you can log a few of the NGC objects in addition to the ones on the Messier list.

Good observing, and

Clear skies.


2003-Nov-18, 03:57 PM
Constellations are of little or no value in evaluating the effects of dark energy or dark matter due to the lack of mutual gravational intimacy amongst their members.

If I have done the arithmetic correctly, a Hubble constant of 72 kilometers per second per kiloparsec converts to 2.3 * 10e-19 meters/sec/meter (a tenth of a billionth of a billionth) for the current rate of expansion. Since there are 4.4e+17 seconds in 14 billion years, the cumulative expansion since the big bang is 10 centimeters/meter assuming that the current measured rate is accurate and valid. Recent measurements lead some observers to believe that the expansion rate is increasing i.e., not constant. It would not be much of a stretch to assume that the Hubble constant has always been a variable and that, due to the much greater density in the early universe and the time dilation attendant thereto, the Hubble coefficient may well have been much less than unity giving the universe a much greater age. Has anyone seen an analysis of how the enormous gravitational field strength present when the universe was 10e-30 seconds old was overcome to not only prevent a black hole type collapse but also to supply the kinetic energy associated with continuing expansion and what the time dilation characteristics of this period were?

Can there be a fractal-truncation-like effect limiting expansion effects within certain gravitational field strengths such as to prohibit expansion of space within volumes occupied by us, electrons, quarks, neutrinos, etc.,? Chances are there are attributes of potential energy as functions of electric charge and magnetic field strength distributions within galaxies that we don't currently understand that will explain some of the dark energy.

I believe we are, with respect to understanding dark energy and dark matter, where the ancient astronomers were when they were adding more epicycles to their analyses of planetary orbits. I wonder whether the Higgs boson and/or the Higgs field has a role to play here. We have lost Occam as well as his razor.