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Astrophysics/Does red shifting actually prove universe expansion?


Dear Dr. Stahl:
I think that red shifting measured from 1a supernovas does not prove by itself that the universe is expanding.  An INCREASING shifting (measured at different Earh times for the same source of light) would, if it were; a) measured for all 1a supernovas and b) an exponential function of distance(not linear) whose slope is continuously increasing with Earth time.
There may be alternate explanations for the red shifting: What if photons, in order to comply with 2nd law of thermodynamics lose energy and change their wavelength as a function of time (= distance), thus producing the red shifting that is misinterpreted as evidence of an expanding universe.  This would explain why the Earth seems to be the geometrical center of the universe expansion.  A lineal function of red shifting with distance or a non increasing slope either or both would support this.

Thanks for your time.



I suspect that you are actually confusing red shift measurements in two distinct contexts: 1) those to do with type Ia supernovae (which actually discloses accelerated expansion from dark energy) and 2) those to do with the redshifts measured from distant galaxy clusters, quasars etc.

In regard to the first,  the majority of plotted Type 1a supernovae data points congregated along the upper of the two plot lines (See, e.g. 'Supernovae, Dark Energy and the Accelerating Universe', Physics Today, April, 2003, p. 53) placing them firmly in the region of the graph (of observed magnitude vs. red shift) we call “accelerating universe”. On the other side of the diagonal is the "decelerating region". An additional feature of the accelerating side is 'vacuum energy'.

Perlmutter not only shows the accelerating data but also provides an explanation in terms of dark energy. Thus, Perlmutter proposes dark energy as the primary agency for the ongoing increased rate of accelerated expansion.

He does this (ibid.) by first associating the "accelerating region" with what he calls "vacuum energy". He then invokes a cosmological "equation of state" (think of something like the equation of state for an ideal gas, e.g. P = nkT) for this vacuum energy, as:

w = (p/ rho) = -1

where p denotes pressure and rho energy density.

If: p less than (rho /3) we have gravity that repels

Or (If we set: 0 = (rho + 3p))

p = (- rho)/3

This is consistent with Einstein's theory of general relativity - which one could say approaches the status of a 'basic law of physics'. In this case, the existence of a negative pressure is consistent with general relativity's allowance for a "repulsive gravity" - since any negative pressure has associated with it gravity that repels rather than attracts.

Meanwhile, the Hubble law plots the velocity of recession (v) of distant objects (galaxy clusters, quasars) vs. redshift with the Hubble constant the constant of proportionality, to yield,

v = cz = HD

where H is known as the 'Hubble constant', after Edwin Hubble who first discovered it, D is the distance, c is the speed of light and z is the red shift. In general, the red shift:

z = v /c

for the non-relativistic case. Thus, if the shift z = 0.2 then the recessional velocity is: v = 0.2c, in other words the object is moving away at one-fifth the speed of light. If the object is approaching the speed of light a different expression is needed:

v/c = (z^2 + 2z)/ (z^2 + 2z + 2)

The alternative hypothesis you propose, i.e. of photons changing their wavelength as a function of time to emulate a cosmic expansion is not novel, and has been proposed as a possible alternative way of looking at things (cf. Stahl, 'Cosmic Expansion Independent of Standard Redshift Interpretation', in Journal of Trinidad and Tobago Astronomical Society, Vol. 31, No. 1, April, 1994).

However, the problem with it is that it is more complex a hypothesis, in comparison to the simpler 'Doppler shift' analogy forming the basis of the Hubble law.  In addition, there are observational contradictions to the assumption of an unbounded photon gas - i.e. with negligible inhomogeneities (i.e. matter admixture) in a Bose-Einstein statistical regime. In addition the redshifting of the presumed photon gas must  have occurred by at least a factor of 100,000 since the de-coupling between matter and radiation.  To my knowledge, no one has been able to justify this in any published work.  


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Philip A. Stahl


I specialize in stellar and solar astrophysics. Can answer questions pertaining to these areas, including: stellar structure and evolution, HR diagrams, binary systems, collapsars (black holes, neutron stars) stellar atmospheres and the spectroscopic analysis of stars – as well as the magnetohydrodynamics of sunspots and solar flares. Sorry – No homework problems done or research projects! I will provide hints on solutions. No nonsense questions accepted, i.e. pertaining to astrology, or 'UFOs' or overly speculative questions: 'traveling through or near black holes, worm holes, time travel etc. Absolutely NO questions based on the twaddle at this Canadian site: purporting to show a "new physics". Do not waste my time or yours by wasting bandwidith with reference to such bunkum.


Have constructed computerized stellar models; MHD research. Gave workshops in astrophysics (stellar spectroscopy, analysis) at Harry Bayley Observatory, Barbados. More than twenty years spent in solar physics research, including discovery of SID flares. Developed first ever consistent magnetic arcade model for solar flares incorporating energy dissipation and accumulation. Developed first ever loop-based solar flare model using double layers and incorporating cavity resonators. (Paper presented at Joint AGU/AAS Meeting in Baltimore, MD, May 1994)

American Astronomical Society (Solar physics and Dynamical astronomy divisions), American Geophysical Union, American Mathematical Society, Intertel.

Papers appearing in Solar Physics, Journal of the Royal Astronomical Society of Canada, Journal of the Barbados Astronomical Society, Meudon Solar Flare Proceedings (Meudon, France). Books: 'Fundamentals of Solar Physics', 'Selected Analyses in Solar Flare Plasma Dynamics', 'Physics Notes for Advanced Level', 'Astronomy & Astrophysics: Notes, Problems and Solutions', 'Modern Physics: Notes, Problems and Solutions'

B.A. degree in Astronomy; M.Phil. degree in Physics - specializing in solar physics.

Awards and Honors
Postgraduate research award- Barbados government; Studentship Award in Solar Physics - American Astronomical Society. Barbados Astronomical Society award for service (1977-91) as Journal editor.

Past/Present Clients
Caribbean Examinations Council (as advisor, examiner), Barbados Astronomical Society (as Journal Editor 1977-91), Trinidad & Tobago Astronomical Society (as consultant on courses, methods of instruction, and guest speaker).

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