Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!bronze!anachem
From: anachem@bronze.ucs.indiana.edu (mark s gilstrap)
Newsgroups: sci.electronics
Subject: Re: How to tell distance of Stars
Message-ID: <1991May10.201924.23524@bronze.ucs.indiana.edu>
Date: 10 May 91 20:19:24 GMT
References: <8937@crash.cts.com> <7480021@hpfcso.FC.HP.COM>
Organization: Indiana University, Bloomington
Lines: 49

In article <7480021@hpfcso.FC.HP.COM> mll@hpfcso.FC.HP.COM (Mark Luce) writes:
>
>     Uh, not trying to be picky, but you have the Doppler relation bass-
>ackwards. Things whose light is blue-shifted are moving *towards* us; the
>light from things which are moving away is red-shifted. Around about 1920
>or so, Edwin Hubble discovered that the light from nearly all galaxies is
>red-shifted; they are all moving away from us. There are some exceptions,

	some recent theories are questioning the certainty with which
	we can know location, mass / velocity of large astronomical
	bodies - sort of a macro (or mega) Heisenberg uncertainty prin-
	ciple.

	But more interesting is the idea that gravitation does in fact
	affect the energy of escaping photons. Photons escaping from
	large galaxies lose more energy than from lone stars in our
	galaxy and therfore by that process alone are red-shifted (and
	doppler can also be operative but the magnitude of its effect
	is an unknown percentage of the whole - possibly even negative -
	such as in the case of a massive quasar or black hole region moving
	rapidly towards us (blue-shifted) and still appearing red-shifted
	by the large effect of gravitational loss of photon energies.)

>most notably some galaxies in our own Local Group, such as the giant spiral
			^^^^^^^^^^^^^^^^^^ why would that be?

>Andromeda galaxy. Quasars have extremely large red-shifts. Hubble's 
				^^^^^^^^^^^^^^as expected if powered by
				monstrous gravity sourecs such as black holes

>discovery led quite naturally to the Big Bang theory. The Hubble constant

	if correct, the new ideas would - quite naturally - dispel the 
	Big Bang theory (as first postulated anyway)

>is the relation between the distance of a galaxy and its red-shift. It is
>very difficult to pin down with any precision, which is why estimates of
>the age of the universe range from ten to twenty billion years.

	I wonder what the new age estimates might be?  maybe the scien-
	tific creationists are right (~6000 b.c?) :*)

	With the uncertainty of the meaning of red-shifts occurring in 
	quasars and other massive gravitational fields, it has even been
	postulated that we can't say for sure that the universe isn't
	collapsing.

	disclaimer: I read this in American Laboratory magazine which is
	not a periodical of the astronomical sciences.