Looking as far as we can see . . . and some thoughts on cosmology, redshift, tired light and free-free absorption

Vast vision must improve our sight.  The Moody Blues

In 1996, the Hubble Space Telescope was used to make a series of exposures of an area of the sky in the Northern Hemisphere, which was selected as a "window" to see the most distant galaxies, quasars etc. with few stars from our own galaxy getting in the way.  Here are some images - and a second page with new theories regarding the cosmological redshift and the "Big Bang" theory.

10 March 2004: there's a new, much more ambitious image - the Hubble Ultra Deep Field:

http://hubblesite.org/newscenter/newsdesk/archive/releases/2004/07/

They believe they are seeing about 10,000 galaxies, only 400 to 800 million years after the "Big Bang".  There's a fab 62 Megabyte JPG image . . . 6200 x 6200 pixels . . . Dig it!

To the parent directory - astrophysics - from where you can reach other parts of this First Principles site - for many other things, such as the world's longest Sliiiiiiiiiiinky.  

My new site http://astroneu.com has a lengthy treatise for specialists on new theories regarding redshift of light by low-density plasmas (including coronal plasmas and the ISM / IGM) and how this may explain many things about quasars, the heating and acceleration of the solar corona, as well as the cosmological redshift.

 For more philosophical approaches to cosmology, see:

• God and Mother Nature on the imminent release of Nature 2.0  ../../eclectic/nature-2.html .
• Me on why it is scientifically (but perhaps not mystically) impossible to understand for sure why there is anything at all, any forces, any dimensions etc. (matter and energy are minor considerations by comparison!) ../../robin/
  

    Copyright 2003 Robin Whittle  rw@firstpr.com.au      2003 October 23.

Check the Wayback Machine to see earlier versions of this page: http://www.archive.org .

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The somewhat false-colour image below was created from multiple exposures through blue, red and infra-red filters.  The CCD-based (Charged Coupled Device - silicon image sensor) camera has four sensors and one of them sees a smaller section, in greater detail, because its mirror gives it twice the magnification.  A small version of the image is here:




The page with these images is: http://hubblesite.org/newscenter/archive/1996/01/ and Googling Hubble Deep Field turns up 32,000 pages.  The above image covers an area of the sky 3 x 3 arc minutes.  The Moon's or the Sun's apparent diameter from Earth is about 30 arc minutes - half a degree.

The project page with the technical details is: http://www.stsci.edu/ftp/science/hdf/hdf.html .  The field is located (J2000 coordinates) at right ascension (AKA longitude) 12h 36m 49.4000s and declination (AKA latitude) +62d 12' 58.000"   This is in Ursa Major (the Big Dipper):



(Image adapted from http://homepage.mac.com/kvmagruder/bcp/aster/constellations/UMa.htm , made with Voyager II software from http://www.carinasoft.com .)



Here is a page where you can click on another version of the above image to find information about each of the 1015 galaxies and 6 stars - their redshift (photometric estimate based on colours and in some cases based on a true spectrogram): http://nedwww.ipac.caltech.edu/level5/Deep_Fields/mirror/hdfn/

Likewise for a similar field in the south: http://nedwww.ipac.caltech.edu/level5/Deep_Fields/mirror/hdfs/ for which the project page is http://www.stsci.edu/ftp/science/hdfsouth/hdfs.html .

Here is the full resolution .jpg - 3069 pixels square - 2 Megabytes: 1996-01-c-full_jpg.jpg .

From the bottom left section, a 1024 pixel wide section is available as a .jpg (572 kbytes) Hubble-Deep-Field-1024-wide.jpg and as a .BMP (3.2 Megabytes) suitable for using as a Windows desktop wallpaper: Hubble-Deep-Field-1024-wide.bmp (To use this, shift click on the link and save it somewhere on your hard drive.  Then use Start > Settings > Control Panel > Display > Background > Browse to select it.)

Here is my own selection, from the bottom right section, including what I assume is one local star.  I have rotated it clockwise 90 degrees.

This image is 1024 pixels wide x 767 pixels high. 
It covers an area of the sky 1.5 arc-minutes wide and 1.125 arc-minutes high.
(1 arc minute = 1/60th of a degree.  1 radian = 57.3 degrees. )

1.5 arc-minutes wide x 1.125 arc-minutes
    = 0.00044 x 0.00033 radians.
    =1.43 x 10^-7 square radians (steradians, of which there are 4pi in a complete sphere).
    = 1/88,000,000 of the sky. 

Looking at one such area per second, it would take 2.79 years to see the whole sky.

(Below, I call this the BIG image.)

The "galaxy 204" should appear directly below here.

Here is the same image as a .BMP for use as desktop wallpaper in a Windows machine hubble-deep-field-northern-detail-rw.bmp  (2.3 Megabytes).  As a .JPG with a caption at the bottom, giving the above details: hubble-deep-field-northern-detail-rw-caption.jpg  (224 kbytes).


Conventional theory is that the Universe is expanding, after a Big Bang about 15 billion years ago.  In this theory (which is generally taught and believed as fact in the last few decades) the nature of galaxies, stars etc. several billion years ago will be different from that we see at current times.  So the expectation is that by looking at galaxies a very long way away (as the Hubble Deep Field does as never before) we would see galaxies which look rather different from those which we see nearby.  But this expectation was not entirely realised. Some seem to be different but many have familiar shapes.  From http://hubblesite.org/newscenter/archive/1996/01/text :

Gazing into this small field, Hubble uncovered a bewildering assortment of at least 1,500 galaxies at various stages of evolution.

Most of the galaxies are so faint (nearly 30th magnitude or about four-billion times fainter than can be seen by the human eye) they have never before been seen by even the largest telescopes. Some fraction of the galaxies in this menagerie probably date back to nearly the beginning of the universe.

"The variety of galaxies we see is amazing. In time these Hubble data could turn out to be the double helix of galaxy formation. We are clearly seeing some of the galaxies as they were more than ten billion years ago, in the process of formation," said Robert Williams, Director of the Space Telescope Science Institute Baltimore, Maryland.

The above-mentioned page goes on to speculate that some of these galaxies are seen as they were merely a billion years after the Big Bang. 

What we see, apart from the star, are galaxies and perhaps some quasars - compact sources of light which produce very different spectra than stars or galaxies, and have high redshifts.  (A quasar has been identified in the HDF South: http://www.stsci.edu/ftp/science/hdfsouth/hdfs.html .) 


Some galaxies (or are they quasars . . . ?) in the field have spectrographically measured redshifts of 3 or more.  The data is here:  http://nedwww.ipac.caltech.edu/level5/Deep_Fields/mirror/hdfn/HDFNpzmag.dat  One of the papers describing spectroscopy of some of the high redshift objects, with one of the massive (33 foot diameter) Keck telescopes in Hawaii, is here: http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v481n2/35317/35317.pdf .





Consider the barred spiral galaxy near the top edge of the BIG image above:

This is called "Galaxy 204" in this image, and some details are here: http://nedwww.ipac.caltech.edu/level5/Deep_Fields/mirror/hdfn/pages/204.html

This looks somewhat like a nearby barred spiral - NGC 1365: http://antwrp.gsfc.nasa.gov/apod/ap990624.html which is believed to be about 60,000,000 light years from Earth (http://www.seds.org/hst/96-21a.html) :




According to http://antwrp.gsfc.nasa.gov/apod/ap991008.html NGC 1365 is 200,000 light years in diameter, and may have a massive black hole at its centre.  This is called a "supergiant" galaxy.

(Our Galaxy, the Milky Way, may have a bar too, though probably not as prominent: http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992ApJ...384...81W . Our Galaxy may also have a massive black hole at its centre. )

Lets say this "Galaxy 204" is about 100,000 light years across - about the same size as own galaxy the Milky Way.  In this image (the "BIG" image above), Galaxy 204 is about 48 pixels in diameter, and in this image 1024 pixels is 0.00044 radians.  So this barred-spiral galaxy is about 0.00002 radians across, from where we are. 

If you hold a piece of human hair (lets assume a thickness of 0.07 mm) at arm's length (0.7 metres) then the thickness of the hair subtends 0.0001 radians.  So a hair's breadth at arms length would be this wide on the scale of the above image, 5 times wider than the angle subtended by Galaxy 204:

With these assumptions:

Diameter = 100,000 light years

Angle from Earth 0.00002 radians = 1 / 50,000 radians

we can calculate the distance as 100,000 x 50,000 = 5,000,000,000 light years.

So the light from this galaxy has been travelling since about the time the Earth was formed (according to currently accepted theories of the Earth's formation, which seem reasonable to me). 

Of course, if Galaxy 204 is actually the same diameter as NGC 1365, then it is about 10 billion light years away.

There are many galaxies subtending smaller angles in this image, so presumably many of those are further away than Galaxy 204.

The redshift page linked to above has these details for Galaxy 204: http://nedwww.ipac.caltech.edu/level5/Deep_Fields/mirror/hdfn/pages/204.html and it has a spectrographically measured redshift of 0.9600. 

So the frequency of light we see is 1/1.96 of what it was originally - and the wavelengths of the light 1.96 times longer. (Based on the reasonable assumption that the physics of that galaxy were the same as here now when the light was generated.)