2012-07-09, 18:09 | Link #1001 | |
Absolute Haruhist!
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But I have one burning question I've always wanted to ask: Why can't dark matter just be normal matter like hydrogen and helium which are abundant but spread so thinly that they do not get detected by our instruments? As far as I know, if telescopes don't point at the right spot for a long enough exposure time, things can skip detection. Or that there are not enough matter or radiation sources to reflect light in the region, stuff can be invisible on various wavelengths. I always see alot of crazy theories that try to introduce a bunch of whole new particles to describe dark matter.
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2012-07-09, 18:26 | Link #1003 |
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Even if something is spread extremely thin, with the huge volumes of space, that light has to pass through, a lot of photons would hit some of that thinly spread gas and bounce off it.
And when that happens we get those absorbtion lines, which are easy to detect. Also, with all the needed mass it would have to account for, it can't be spread that thin. My understanding is, that with the amount of mass that has to be there for gravity equations to work out, so that our galaxy does not fly apart, we would see it. I saw some people mention, that if you calculate the galaxy spin with relativity in mind (gravity does not propagate FTL), which makes it a whole lot more complex, then 'dark matter' would not be needed to match our observations. But I have not found any scientific sources on that yet. |
2012-07-09, 22:59 | Link #1004 | ||
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There was, however, an article about half a year back that talked about errors in estimation of planets (so regular matter) in our galaxy: Nomad Planets. The research talked about how previous estimations (for our galaxy) of the planet count per star could well have been off by 4 to 5 orders of magnitude (ie we'd have not a few tens of planets per star but hundreds of thousands floating about in loose orbits). I haven't seen any follow up, unfortunately, but these things take time. That said, you could consider these 10000:1 planets to amount to quite a bit of the mass of our galaxy that we'd previously chocked up to Dark Matter. Then you have releases like this Dark Matter Baffles, that really make the whole enterprise very confusing.
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2012-07-10, 05:21 | Link #1005 |
Absolute Haruhist!
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Hmmm are you suggesting that undetected nomad planets can make up a large portion of mass and gravity to account for dark matter? Do they not have gravity and give off radiation enough to be detected?
If large undetected planets can account for alot of mass, I'm sure smaller objects like asteroids, dust and even gas spread over huge regions of space can account for significant mass.
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2012-07-10, 06:19 | Link #1006 | |
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Moreover, dark matter has observable results to it that doesn't fit standard matter. So there's most certainly something exotic out there that isn't just scattered hydrogen, helium, and Li-7.
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2012-07-10, 12:08 | Link #1007 |
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Nomad planets are planets that got ejected from a solar system.
The idea, that those are quite numerous came up recently. They ran a lot of simulations on planets forming around a sun from a dustdisc according to current models. Turned out, that the average number of planets was much higher than expected, but the resulting system would be unstable. It would eject planets into interstellar space until a stable configuration was reached. This includes gas giants too. If this was true, then the amount of planets zipping through space while being almost undetectable, should be pretty high. |
2012-07-10, 14:01 | Link #1009 |
Absolute Haruhist!
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Yea I'd think that there would be alot of massive brown dwarfs with extremely weak radiation that makes them extremely hard to detect.
I personally think that the missing mass of dark matter is the result of underestimation from the lack of data and instrument limitations. I guess I'm just following Occam's Razor, I don't want to think that they are weird particles and mysterious invisible masses.
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2012-07-10, 15:53 | Link #1010 | ||
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We'd need better ways of detecting aged brown dwarfs though, to really be able to say how many are floating about unaccounted for... There are some observational results, I'm pretty sure, that cannot be answered (as of now) with standard matter. There's some weird stuff out there.
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2012-07-12, 11:36 | Link #1011 |
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FARNBOROUGH: Virgin Galactic takes wraps off LauncherOne:
"Sir Richard Branson stole the show yesterday - swooping in by helicopter and all but renaming the event the Farnborough space show with a star-studded presentation of his Virgin Galactic SpaceShip2 and a bold plan to use the system to slash the cost of launching small satellites." See: http://www.flightglobal.com/news/art...herone-374271/ ------------------------------------------------------------------------------------------------------ Hubble finds fifth moon orbiting Pluto: "The Hubble Space Telescope has found yet another moon orbiting what used to be the last planet in the Solar System. The moon, the fifth that's been spotted orbiting Pluto, is an irregularly shaped lump around 6 to 15 miles across and orbits in a plane 58,000 miles around the dwarf planet. It was spotted in nine images taken with the Hubble's Wide Field Camera in June and July." See: http://www.theregister.co.uk/2012/07...to_moon_fifth/ |
2012-07-21, 04:57 | Link #1015 | |
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CBS: Drones That May Fly ‘Indefinitely’ Can Be Recharged By Lasers
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2012-07-21, 14:17 | Link #1016 | |
NYAAAAHAAANNNNN~
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Age: 35
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2012-07-23, 06:16 | Link #1019 |
Absolute Haruhist!
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That is technically a nanomachine, I wonder how it gets energy to fuel its movements.
I think in the future, history texts would be calling the 21st century as the 'nano age'. EDIT: actually I think its still at micro level so it can't be called a nanomachine.
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