as you know I think humanity can do better than the metric system---which is antiquated and awkward.

part of the the prospective struggle between systems has to do with how the most basic conditions of existence are stated, such as the energy density throughout space that is estimated now to be about half a nanojoule per cubic meter.

In the *erg* energy unit of the centipace ounce system (a planckian system with most of the main natural constants exactly equal to powers of ten), the same estimate is about 1 millionth of an erg per cubic pace.

The figure I most often see actually amounts to 0.54 nanojoule per cubic meter, or 1.17 microerg per cubic pace. But I've rounded these off to half and one because it is mainly the orderofmagnitude size that matters.

this dark energy is the wild card that makes things work out right in cosmology----it explains both the observed flatness (not enough ordinary and dark matter to do that) and it explains the observed acceleration in expansion.

people have different theories about it and models of it but chief facets include the fact that, unlike ordinary and dark matter, it does not bunch together gravitationally, and that as time goes on it becomes a larger and larger part of the total energy in the universe.

dark matter forms concentrations just like ordinary matter does and the dark matter in galaxies is one of the things that holds them together. dark matter is like ordinary matter in this gravitational bunching together, the main difference is we can't see it.

dark energy (aka vacuum energy, quintessence, cosmological constant) whatever it is has the property of not bunching but being more or less uniformly spread out---as if (as many people suggest) it is a property of empty space itself. The simplest models of it have no bunching or variation---just a constant density thru all space and time.

and as space expands there gets to be more space and so more dark energy but dark and ordinary matter spreads out more and more.

so a few billion years ago when there was all this matter concentrated in space the dark energy was not so important---could be like 10 percent of the mix---but now after so much expansion the dark energy is, they estimate, over 70 percent of the mix and that can only increase.

there is a kind of cute explanation why dark energy has this expansive effect that accelerates the U's expansion and I will get to it in a subsequent post.

I need to paste the url of Ned Wright's cosmology FAQ and tutorial here, or at least of his "cosmic calculator" which lets you calculate distances from redshift with the assumption of 73 percent dark energy.
Wright teaches cosmology at UCLA and is unusually good as an explainer. (however even he says "yoctograms per cubic meter" instead of nanojoules.)

What a koinkydink. I studied Astronomy & Cosmogeny as a minor at UCLA and Claremont GS. Did a lot of it at UCLA!! Too bad i did not run into Ned Wright!!

http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0202/0202008.pdf


try downloading this pdf paper by Michael Turner
of UChicago. 17 pages survey.
paper is well organized description of the new
cosmology as of feb 2002. first two pages say
what is known
then open questions are analysed and last two
pages summarize what current programs (observations
on ground and in space) may be expected to clarify.

there is also a shorter survey article by Turner
at, I think,
http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0202/0202007.pdf

I can't check that url right now, it is probably an earlier verion of the same article.

Ned Wright's FAQ and cosmo tutorial is fun to read because it has a whole lot of links and pictures and the calculator and a partly playful attitude.
but Turner's article is valuable because it is very concise and lays it all down very orderly.

I will get a Ned Wright link, the calculator has links to everything else of his so that should suffice.

but at least see if you can get the Turner article to print out, looks less fun but valuable because concentrated and factual.

http://www.astro.ucla.edu/~wright/CosmoCalc.html

that has links to other stuff

I like his homepage which has a picture of the guy

I like the introduction page to his tutorial
where he has his (frequently updated) "News of the Universe"
and where he sounds off on various periferal issues
like religious fundamentalists
the guy suffers less from normal restraints than many of the rest of us
but mainly a lot of his site is pitched to the 101 level (upperdivision undergrad) and he is a good teacher.


John Baez has a great intuitivization of general relativeity also

I am in clover.

I think that cosmology----starting when Aristarchus circa 270 BC figured out that stuff goes round the sun---is the noblest human enterprise.

And I think that the units system is part of the mental toolkit with which humanity takes the measure of the universe and that there is a deep linkage between cosmology and units-sense---a kind of resonance between them.

Actually this is why it worries me that half a nanojoule per cubic meter sounds good to me. for the allimportant dark energy density. I trust my ear (as a parttime writer and poet) and when a major fact about nature sounds good in metric to me then it constitutes a hunch that metric is wellsized and fitting to the universe in at least that department

maybe this is good news for you (since all you want is to trim metric) but it is bad for me because i want
a radical readjustment to make the basic constants all be powers of ten.

well we will see how that turns out.

great scot pint drinker the hits for march are
already approaching what they were for feb and
it is not the end of the month yet.

what an increase since the handful in january.

I really think you should describe your trimmed metric in concise orderly way. Give old metric equivalents our to 4 or 5 decimal places. Present it as a coherent and completely worked out system for use in undergrad physics course. And post it here.

Science teachers might come here and see it.

what is the use of thinking up trimmed metric if you
dont put it out on the web where it can

1. contribute to the dissatisfaction and impatience of hs and college students who see it and wonder why they did not get to have speed of light and planck's const be exact

2. plant the idea in teacher's heads that they might let their students work physics problems in trimmed units

it seems obvious to me that this would be a constructive first step----something I should be doing in the case of planckian alternatives to metric.

NO ! Trimming metric is NOT "all i want to do". I think your planckian system of units is superior to the trimmed metric for the simple elegant reason that having NO DIGITS whatsoever in the coefficients is up to 100X better than having TWO DIGITS in the coefficients (which in turn is better than having umpteen-and-a-half.12345... digits in those coefficients). Trimmed metric is NOT competitive with but a precursor to the planck system. It is a matter of natural units. And a metric system with 2 digit coefs can certainly be seen to be more natural than SI with its ubiquitous haze of coefficients which serve no purpose other than to obscure the dynamics of the phenomena which it is designed to elucidate. And it is also true that the Planck system with NO cefficients for the natural constants is 100X better yet.

Hello p.d., it is really interesting that you see
trimmed metric and planckian as parts of a single
drive to improve on metric. there may be something to it.

Also in another post you pointed out an objection to "grade" for temperature step, but gave qualified approval.
(I was using it for the 141 kelvin temperature which is E-30 of the planck temperature, which as you mentioned in your post made "centigrade" come out to be the more familiarsize 1.41 kelvin. Another drawback is that Germans already say "Grad" for the kelvin or celsius temperature degree. And you point out the *grade* which is one percent of a right angle.)

Keeping an eye out for a good replacement word is a background task---for now it does not seem terribly urgent so I just keep using grade for E-30 of the natural temperature unit or reasonable facsimile thereof.

I'll copy part of your post here for reference:
[...you noted your "grade" temperature scale to be "not good for everyday life". I do not think this to be at all true. How about "centigrade"? Wouldn't that be just fine? Although i [personally would probably pout and] do not particularly like that term "grade" to denote temperature because i would like to use it on another project that i am quite serious about, the concept [or referent] of "centigrade" would seem utterly practicable. Although it is self-evident that "grade" represents a unit that is too large to be practical [for everyday life], i do not believe "centigrade" to be so... neither "milligrade"...]

Somehow one of us should get a concise description of trimmed metric posted. Questions of strategy and motive are actually secondary to the need for objective clarification---what does it look like if you tabulate a representative sample of its basic units.

OK Leonard. Now to get organized. For me that is a terribly unpleasant job.

I know, me too.
But it will be easy
as long as clearly your initiative I will
be happy to help for what that's worth
go ahead when you feel like it and get something
down

I think bryan parry's temp degree is almost
exactly half of reaumur btw

I'm off to the garage for the usual oilchange stuff
the logistics are complicated so wont be here for
a while