a precise formula that describes how electromagnetic radiation is delayed by free-floating electrons.

Aha. This might be akin to the Fritz Zwicky theory of 'Tired Light". Light that is red shifted has less energy. There may be other causes for a difference in red shifts other than velocity increases ??

Hubble made a law out of it.

https://www.cfa.harvard.edu/~dfabricant/huchra/hubble/

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Yes Hubble made the first guess and it has been refined over the years but it is still based on standard candles for distance and redshift for velocity calculations.

What the essence of my idle musing was : is there any other cause for redshift that causes the light to change frequency as it travels through astronomical distances. Learned people have said no--the redshift is caused by receding galaxies and the fact that the farther out they are the faster that they are going.

However, The farther out we go the earlier in time we are observing them when perhaps gravity did not have time to reign in the expansion of the big bang. Hence the contradiction among the struggle between the "energy of the vacuum" and "gravity".

a precise formula that describes how electromagnetic radiation is delayed by free-floating electrons.

Aha. This might be akin to the Fritz Zwicky theory of 'Tired Light". Light that is red shifted has less energy. There may be other causes for a difference in red shifts other than velocity increases ??

Reminds me of this.
A team of Scottish scientists has made light travel slower than the speed of light.
They sent photons - individual particles of light - through a special mask. It changed the photons' shape - and slowed them to less than light speed.
http://www.bbc.com/news/uk-scotland-glasgow-west-30944584

Sláinte.

Yes Hubble made the first guess and it has been refined over the years but it is still based on standard candles for distance and redshift for velocity calculations.

https://www.youtube.com/watch?v=anGkkQ0WtYc

From the 2006 album "Super Colossal" comes the track "Redshift Riders". I envision an interstellar journey through spacetime, when I hear this song. Maybe even picturing the Silver Surfer on one of his outings.

Magnetic field discovery gives clues to galaxy-formation processes

I reckoned this article might fit here. Dark Matter has a great influence on the rotation of the galaxies in space. Unlike our solar system, the outside regions of galaxies have the same speed as the inside regions due to the presence of dark matter in between the arms (where globular clusters can also be found).

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Very interesting article on dark energy!

http://arxiv.org/pdf/astro-ph/0403687.pdf

The 'ever famous' quintessence is also mentioned..

Okaay, printed the article here at work, will have some reading matter for tonight..

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Very interesting article on dark energy!
http://arxiv.org/pdf/astro-ph/0403687.pdf
The 'ever famous' quintessence is also mentioned..

The 'ever famous' quintessence:)
Yes there is no such thing like empty space.
The greeks was perhaps right.
The more I read about modern science it appears that they "only" confirm their theories.
Whatever. Empty space are full of virtual particals.
They exist only for a fraction of time but thats enough to create Hawkin's Radiation and eventually a black hole will cease to exist.

Now dark energy that's very weird.
When our universe expands dark energy are also increasing.
Sounds like a contradiction to thermodynamics laws but there it is.
Does that mean that the universe expansion is a form of energy?

Seti posted a video on dark matter on facebook, too bad I cannot hear it, here at work..

Do WIMPs rule? The LUX and LZ Experiments and the Search for Cosmic Dark Matter - Dan Akerib

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Black holes may make ideal dark matter labs


Source:
NASA/Goddard Space Flight Center
Summary:
A new computer simulation shows that dark matter particles colliding in the extreme gravity of a black hole can produce strong, potentially observable gamma-ray light. Detecting this emission would provide astronomers with a new tool for understanding both black holes and the nature of dark matter, an elusive substance accounting for most of the mass of the universe that neither reflects, absorbs nor emits light.

http://www.sciencedaily.com/releases/2015/06/150623161109.htm

The First Signal from Dark Matter? --"Could Usher in a New Era in Astronomy"

The signal comes from a very rare event in the Universe: a photon emitted due to the destruction of a hypothetical particle, possibly a "sterile neutrino".

Interesting..

http://lss.fnal.gov/conf/C0911181/Petraki_CosPA09.pdf

Full text here:

http://arxiv.org/pdf/1411.0311.pdf

The identity of the dark matter remains unknown. The detection
of a series of unexplained lines in the X-ray spectra
of a number of different astrophysical targets are suggested
to be consistent with the decay of light dark matter particles

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It will be interesting to see the follow up to all this. Scientists are fairly sure now that there is such a thing as dark matter, and dark energy, in that they can detect something there that apparently glues the galaxies together, but at present they don't know exactly what it is.

The signal comes from a very rare event in the Universe: a photon emitted due to the destruction of a hypothetical particle, possibly a "sterile neutrino".

There are two ways to do science. You either come up with a theory that something exists because of the effects it has upon things that you can see. That is how we found the outer planets in the solar system. Or, you can observe a happening and then go looking for the cause of it. So we are now looking for more sterile neutrinos to try to explain dark matter and energy. At least we know what to look for which is half the battle!

True :)

Neptunus has been found purely thanks to Math.

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strange...

By illuminating dark matter with quasar light from around a super-massive black hole, astronomers have seen for the first time ever the strands that constitute a cosmic web and hold the universe together. Scientists in the US and Germany have been able to confirm what has long been suspected, but only before “observed” via computer simulations. Filaments or threads of dark matter have long been presumed to link together the phenomenal voids across intergalactic space. As these don’t emit light though, they have not been possible to see.

http://guardianlv.com/2014/01/the-skeleton-of-the-universe-illuminated/

I saw that today on Yahoo news. Was watching a program on the subject Saturday night. It struck me that the big picture view of the universe looks a lot like the maps of the human brain.

exactly my thought, as I was reading the text... ;)

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non-profit org. Play4Life in Zagreb, Croatia, EU

The matter we know and that makes up all stars and galaxies only accounts for 5% of the content of the universe! But what is dark matter? One idea is that it could contain "supersymmetric particles" – hypothesized particles that are partners to those already known in the Standard Model. Experiments at the Large Hadron Collider (LHC) may provide more direct clues about dark matter.

What is supersymmetry?
http://profmattstrassler.com/articles-and-posts/some-speculative-theoretical-ideas-for-the-lhc/supersymmetry/supersymmetry-what-is-it/