Relativity Lite

Cosmology | 87 Geller and John P. Huchra found by mapping the distribution of galaxies. * The reader may measure the red-shift velocities of some 200 galaxies in a telescope simulator called CLEA, available from Gettysburg College, † and plot this information against their angular posi- tions (called right ascension [RA] and equivalent to longitude on the Earth’s surface) in a small slice of the other angle (called declination [Dec.] and equivalent to latitude). Even with just 200 galaxies, the bubble structure is apparent, and it grows more marked with larger numbers of galaxies and adjacent declinations. Those desiring to plot thousands of galaxies may access the Las Campanas Redshift Sur- vey Catalog, ‡ the results of which are shown in figure 10. This is a composite of a trio of three-degree slices of the sky that one may see stacked not quite edge-on in figure 9 as red, green, and blue fans of galaxies. Figure 9. Three slices of red-shift velocities of 4,000 galaxies at declinations from −46 to −43 degrees shown in blue, −43 to −41 in red, and −40 to −38 in green, seen almost edge on. * M. J. Geller and J. P. Huchra, Science 246 , 897 (1989). † The original Windows version is at http://​www3​.gettysburg​.edu/​~marschal/​clea/​univlab​.html, and the version bottled for Macintosh by Joel Cranston is at http://​archives​.pdx​.edu/​ds/​psu/​15113. ‡ In the search page at https://​heasarc​.gsfc​.nasa​.gov/​db​-perl/​W3Browse/​w3table​.pl​?tablehead​=​name​%3Dlcrscat​&​Action​= ​ More​+Options, one types “−46 .. −44” in the “dec” box and “> 1045” in the “radial velocity” box and hits “Start Search.” The automatic result is to limit the search to 1,000 galaxies. One may then change “Maximum Rows”: to “4,000” and hit the “Reissue Query” button. I changed the download from the default “Tabbed” to “Excel-compatible” and saved the file. I rearranged the columns so that “ra,” “dec,” and “radial_velocity” were in columns a, b, and c, and in cell K2 entered the equation “= “{“&RADIANS(A2)&”,”&C2&”},”.” I filled down to cell K4001 and copied the results into a Mathematica notebook. The four-term version would read “k45: = {{1.20937371982484,31150},{1.09713211922786,36760},{1.113329 64735099,42616},{0.989954765988463,13140}},” where I have replaced the last comma with a curly bracket. The Math- ematica instruction, “ListPolarPlot[k45, PlotStyle −> Directive[PointSize[Tiny], Magnification −> 0.1, Blue]]” gives the blue plot.