Astronomy and Cosmology

  • Thread starter Dotini
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http://www.eso.org/public/news/eso1217/
The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighbourhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts. But a new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful.

“Despite the new results, the Milky Way certainly rotates much faster than the visible matter alone can account for. So, if dark matter is not present where we expected it, a new solution for the missing mass problem must be found. Our results contradict the currently accepted models. The mystery of dark matter has just become even more mysterious.

Respectfully submitted,
Steve
 
It seems another wheel has fallen off the dark matter wagon.

http://www.ras.org.uk/news-and-pres...ways-companions-spell-trouble-for-dark-matter

http://arxiv.org/abs/1204.5176

http://www.youtube.com/watch?v=nUwxv-WGfHM <--Very peculiar (anisotropic) motion of vast, polar structure (disc) rotating in step with the Milky Way.

http://www.scilogs.eu/en/blog/the-d...ing-in-many-places-a-crisis-of-modern-physics
Here, in the personal blog of Marcel Pawlowski one can find serious doubts as to the validity of General Relativity and Newtonian gravity at the scale of galaxies and larger. This is a shaking of the very foundation of modern physics!

Respectfully submited,
Steve
 
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Could be MOND be slightly further to be being a viable alternative to the Lambda-CDM theory now. Every time I see it mentioned in either papers or online, it is normally discredited in favour of dark matter. However it does explain rotation curves if galaxies very well, which after all, is what dark matter was invented for. Maybe if everyone wasn't so keen to stick to Newton there might be more research into possible alternatives to continual dark matter pushing.
 
Dotini
Yes. Pavel Kroupa is highly enthused over MOND.
http://www.scilogs.eu/en/blog/the-d...1-03-21/question-c.ii-mond-works-far-too-well

Respectfully,
Steve
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Indeed he is, he positively enthuses in that article that MOND is a better solution to our gravity problems than L-CDM. It's interesting to note the way general relativity is designed specifically for our galaxy, whilst MOND is designed for the universe. The article is certainly persuasive, and it might be worth invoking Occam's razor at this point, and in that case MOND makes more sense. Another issue is the lack of a fundamental theory describing the true nature of gravity as a force. As always in cosmology, only more data will suffice.
 
Members in Hawaii should wake up soon and get that #14 welder's glass out.
While the VENUS TRANSIT takes place on the 6th in the Eastern Hemisphere, it happens a day before that (5th) in N. America, but of course afterwards.

This event won't happen again till December 2117. Even if you're from Mars, try to see it; it's a once-in-a-lifetime opportunity.

Cheers,
Harry.
 
Emptyone
Voyager is almost out of the Solar System!
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I heard about that! It will be very exciting to see what information it sends us after it leaves. I personally would love to see a second set of voyager missions more focused on exploring the area outside of our solar system and interstellar space. With our current technology we could easily send something very quick that would last longer than the Voyager probes, which are expected to run out of energy in 10-15 years.
 
Wikipedia says that the power from the nuclear power should be enough to support some systems until 2025, which is another 40AU or so. Plenty enough to tell if it gets to interstellar space hopefully.
 
Technically it doesn't leave the solar system until it's left the Sun's hill sphere, which is still about a lightyear away. But at this point it's passed the Kuiper belt and the scattered disc, so their isn't much left out there apart from CBR and the occasional comet from the Oort Cloud.
 
Never thought we'd see the last of Voyager . . . hupefully not too soon.

In other news: Atlas 5 takes off with a classified payload.
 
Hipster.




Oh! Are you talking about the fish?:dopey:

We saw some big ones, too (shower meteors, not fish); I swear one passed right before my nose. Funny how close they seem sometimes. Not as good as the year before last - which had a ZHR of about 60 - 80 for us. While there was no moon this year to spoil the fun, there was some cloud and the light pollution from our viewpoint (we were on a seven-story building rooftop) interfered with what could have been a better show. On tomorrow, too, and plenty of viewing parties all around the town, including the Science center that's a block away from me - so maybe another skyfall tomorrow.

Touring Mars
Except for viewers in Scotland :ouch:
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You have Andy Murray. He's meteor enough. ;)
 
Just read that 26% of the Americans still believe that the sun revolves around the earth.
 

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