Re: Dark Matter, dark eneggy, & conservation

From: Joao Leao <>
Date: Mon, 03 Nov 2003 10:18:35 -0500

Wow Ron! That is a lot of answer for me!
I will have to split mine in two installments
if you don't mind.

Ron McFarland wrote:

> Thank you list for the welcome. I look forward to many congenial
> debates!
> ....
> >
> > I am sorry but you seem to contradict yourself below!
> > You state, quite correctly as far as I can tell, what the
> > outcome of the most recent cosmic observations on
> > our universe is. But them you state that
> >
> > >
> > > Neither dark energy nor dark matter has been proven by experiment
> or
> > > measurement to exist. Both seem as pure postulates at this
> writing.
> >
> > Both "dark matter" and "dark energy" express little more than our
> > puzzling with two sets of consistently observed effects which we
> > aren't able to accommodate in the so-called "concordance model" of
> > standard cosmology. What these terms designate are not (yet)
> definite
> > entities so it is a bit early to even call them postulates.
> Theorists
> > have sought to explain these effects along several distinct
> > hypothetical lines but the word is still out on which one of those
> > will prevail.
> Correct, and I did not define my terms.

I am not sure I follow you here. Your terms are surely not the
conventional ones, but that is not necessarily objectionable. Let us

> By "postulate" I mean the
> expression of an idea not yet represented by a defining mathematical
> statement.

In that case I can't agree that "dark matter" and "dark energy" are
"postulates". They both have no lack of mathematical expression,
the problem is that we don't really know which one describes them
fully or integrates with what else we know.

> By theory I mean an idea supported by mathematical
> statement but not yet verified in all possible ways by apparent
> empirical evidence.

Again there are serveral many theories (called "scenarios") that
try to account for either one, and they all aim to match the available
empirical evidence. But, as data from better probes comes along, the
small disparity between the scenarios should favor some over others.
That is already the case, for example, when you compare the WMAP
data with the Type Ia supernova surveys, for dark energy evidence...

> By law I mean an idea supported by a mathematical
> statement that can not be ruled out by empirical evidence.

I am not sure that you can say that about any law of physics with
much conviction. Conservation laws are associated with global
symmetries and even these can be broken (think of Parity and CP
for example), and consequentially ruled out by empirical evidence.

> > > To me, dark energy seems to be the more important postulate. It
> > > appears to me that if the universe will forever keep expanding at
> an
> > > ever increasing rate then within a non infinite time period no
> > > elementary particle of matter will be able to interact with
> another.
> >

Will get to the other part later...


Joao Pedro Leao  :::
Harvard-Smithsonian Center for Astrophysics
1815 Massachussetts Av. , Cambridge MA 02140
Work Phone: (617)-496-7990 extension 124
Cell-Phone: (617)-817-1800
"All generalizations are abusive (specially this one!)"
Received on Mon Nov 03 2003 - 10:20:18 PST

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