What the universe is made of
Dark energy: 75%
Dark matter: 21%
Normal matter: 4%
Source: NASA / CXC / M.Weiss
Both Dark Matter and Dark Energy are so entirely outside my actual daily experience that it seems like a pretty gigantic leap to conclude that the universe is almost totally made up of the stuff. Don't get me wrong, I'm okay with things I can't perceive (gravity, radio waves, etc...) but sometimes when I read articles like this - as I often do to see where modern astrophysics is at - I don't get a deep feeling of satisfaction.
I guess I just need to spend a few more years living in closely controlled laboratory conditions with a strict diet of detailed data or something to really 'get' it.
What's Your Universe Made Of?
On
2007-05-17
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comments
8 comments:
I've yet to be convinced that dark matter is really something special. Who says that it's simply not normal matter that we just can't see?
I'm no expert, but if two light-emitting bodies are moving away from each other travelling at, say, half the speed of light, then light emitted by one body moves towards the other AT the speed of light. But that other body is moving away from the incoming light at half the speed of light, so the incoming light is only moving at half the speed of light relative to the other body, so it takes way longer to reach it. What if "dark matter" is just normal matter whose light emissions/reflections just haven't caught up to us yet?
Sounds pretty reasonable.
Therefore.
Cannot be true.
;)
Yeah, well, I actually have no idea if galaxies (let alone individual stars) are moving at even close to that speed relative to each other. This is where it all falls apart, you see ;)
Sometimes I wish I had gone into astrophysics. It's so cool.
Kyro, has Seeing Red planted some doubts in your mind?
angryparrot, with the speed of light being ~300,000 km/s, we wouldn't see anything more than redshift with galaxies and super-clusters moving around 1100 km/s.
Dark matter is troublesome because they can't see it even though it is between us and the normal matter with which it is associated. It is only detected by gravitational observations of galaxies which are inexplicable under the standard model.
I guess astronomers thought that calling it 'Inferred Matter' might make the whole thing sound silly.
Readers of Van Flandern and Arp will know that the anomalous gravitational effects purportedly explained by dark matter evaporate if gravity is modelled as a force with finite speed and range rather than infinite speed and infinite range.
The able are directed to this article.
A detailed review of Halton Arp's Seeing Red can be found nearby.
'Inferred Matter' might make the whole thing sound silly.
Umm.. yeah, and "Dark Matter" is just so dinner table accessible. Sure.
We should get a copy of Seeing Red to Angry Parrot though, just for his reading pleasure.
And how about some board games dammit!
Also, before reading the article on The Speed Of Gravity, it is helpful to look at the LR article, so it all makes sense.
I urge everyone to click on over to Abebooks and order used copies of both Van Flandern's Dark Matter, Missing Planets and New Comets and Arp's Seeing Red. I'll be re-reading mine in July and perhaps more discussion will ensue.
In fact, the missing matter is just the styrofoam chips that all the telescope equipment was packed in.
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