[fruser1]

I never got far enough into physics to comprehend dark matter, other than it seemed to be a “convenience” to account for “missing” matter to account for the gravitational forces needed, by calculation, to hold galaxies together.

As such, thinking back to the physics I did have (perhaps demonstrating I only know enough to screw things up) I wonder about the 19th century classical concept of the “ether”.

The ether was supposed to be the medium on which electromagnetic waves propagate. When physicists determined that light was just an electromagnetic wave, they wondered how, as a wave, it managed to propagate through space (vacuum) since other waves, like sound or water, needed a medium. So, they figured there was a mysterious “ether” that served this purpose.

They ultimately rejected this concept and basically said that light needs no medium on which to propagate.

So I wonder: is it possible that the old dudes were right and that the ether exists and it is made of dark matter?

[peteyd]

As far as I’m concerned ,dark matter presently resides in the WH.

[kjam22]

When the second sentence in an article says.... "Dark matter makes up 80 per cent of the universe's matter ".... I pretty much move on to something else.

[arthurus]

Dark Matter and Dark Energy seem to be the wheels within wheels devised to continue to prop up the rotten old mythology in the face of the new Copernicus.

[zeugma]

I do not believe that GPS satellites actually have on-board atomic clocks. Might be wrong, but I’d be surprised if they do.

[Rebel_Ace]

"Dark Matter" and "Dark Energy" are placeholders in Physics for "We don't really know yet, but we can tell something is there."

So, how can they tell "something" is there? By observing the effects from the unseen agent. There are simple examples in the everyday world. You see a flag fluttering. You see leaves rustling. You see fields of grass waving. You see all the EFFECTS of wind, but you do not see the WIND itself.

So, what effects are seen from the "invisible" Dark Matter? Well, there are 2 that readily come to mind:

(1) The measured spin of distant galaxies seems to be too fast for the visible matter measured. There needs to be more "stuff" there holding it together. So, either the spin measurements are wrong, or the mass measurements are wrong, or the equations for gravity are wrong. If you check and recheck each one, eventually you must conclude that there is stuff there you can't see.

(2) The presence of mass in space causes it to curve. Enough mass will bend space enough to produce an effect called "gravitational lensing". From the amount of the bend, you can calculate the amount of "stuff" needed to produce it. So, when you find areas exhibiting gravitational lensing in telescopic images, you run the numbers and come to the conclusion that there must be more stuff there than you can see to produce the effect, or Einstein's relativity equations are wrong.

"Dark Energy" is the name for the force that seems to make empty space "springy". Why should empty space even "want" to flatten out and "expand"? You can measure the effects on a large scale (Galactic Red Shifts) and on a small scale (Quantum Vacuum Energy Effects) but what is causing that? Well, some "Dark Energy". Again, a placeholder for "I don't know".