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Old 05-17-2019, 07:16 PM
 
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This still raises the question of what dark matter really is?
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Old 05-17-2019, 08:00 PM
 
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Originally Posted by elnina View Post
Oh, I read the abstract and other info available on the net. Still - there are astronomers (incl. hobby astronomers) that are observing the visible parts of the Space pretty much all the times. They use many different types of telescopes to observe objects in the Universe. Some are located right here on earth and some are sent into space. In fact, a large number of observatories have been launched into orbit.
You would think they have the round of the hour observations covered.



In other words, this event occurred a very long time ago but was just discovered lately...
The news headlines made it sound like this just happened.
Yeah, reporters sometimes give misleading information. If an event, say, 10,000 light years away from us actually did happen today, we wouldn't know about it until 10,000 years from now. It's a big universe and on a universal scale light is a relative slow-poke.

Last edited by Mike555; 05-17-2019 at 08:09 PM..
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Old 05-17-2019, 08:12 PM
 
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Pretty sure the Earth if flat and that is just a bunch of CGI video game graphics to keep you all ooh-ing and ahh-ing, but, I suppose it could also be a big swimming pool of dark matter as an interesting alternate theory.
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Old 05-17-2019, 08:14 PM
 
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Originally Posted by Milky Way Resident View Post
This still raises the question of what dark matter really is?
That's true, but unless dark matter can actually be directly detected and analyzed we can't really tell what it is. But how do you detect and then analyze something that doesn't interact with ordinary matter except gravitationally?
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Old 05-17-2019, 08:22 PM
 
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Originally Posted by UrbanAdventurer View Post
Pretty sure the Earth if flat and that is just a bunch of CGI video game graphics to keep you all ooh-ing and ahh-ing, but, I suppose it could also be a big swimming pool of dark matter as an interesting alternate theory.
Open two windows on your computer and bring up two live real-time beach sunset cams; one on the gulf coast of Florida and one on the California Pacific coast. If when the sun is still a ways over the horizon on the California cam while the sun has just set below the horizon on the Florida cam at the exact same time, then the earth isn't flat. Simple. You don't even have to leave your seat.

I probably shouldn't have even replied to this.
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Old 05-18-2019, 04:18 AM
 
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Originally Posted by Mike555 View Post
That's true, but unless dark matter can actually be directly detected and analyzed we can't really tell what it is. But how do you detect and then analyze something that doesn't interact with ordinary matter except gravitationally?
So far most of the “detections” have been through gravitation as you mentioned. Is it possible that dark matter forms gigantic invisible solid objects? What if there’s something the size of a galaxy that cannot be directly observed?
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Old 05-18-2019, 09:27 AM
 
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Originally Posted by Milky Way Resident View Post
So far most of the “detections” have been through gravitation as you mentioned. Is it possible that dark matter forms gigantic invisible solid objects? What if there’s something the size of a galaxy that cannot be directly observed?
Close to your suggestion, but not quite, there is a galaxy called Dragonfly 44 which is believed to be 99.9 percent dark matter. Though its mass is about that of our own Milky Way, it omits only one percent the amount of light and looks like this.


PIETER VAN DOKKUM, ROBERTO ABRAHAM,
GEMINI, SLOAN DIGITAL SKY SURVEY
The dark galaxy Dragonfly 44. The image on the left is a
wide view of the galaxy taken with the Gemini North
telescope using the Gemini Multi-Object Spectrograph
(GMOS). The close-up on the right is from the same
very deep image, revealing the large, elongated galaxy,
and halo of spherical clusters of stars around the
galaxy’s core, similar to the halo that surrounds our
Milky Way Galaxy. Dragonfly 44 is very faint for its
mass, and consists almost entirely of Dark Matter.

''. . . only one hundredth of one percent of that is in the form of stars and “normal” matter; the other 99.99 percent is in the form of dark matter. The Milky Way has more than a hundred times more stars than Dragonfly 44.''

Scientists Discover Massive Galaxy Made of 99.99 Percent Dark Matter – W. M. Keck Observatory

If not for small number of stars and normal matter in Dragonfly44, the galaxy would be unobservable. That suggests to me that there very well could be huge clumps that are 100 percent dark matter and not able to be observed directly.
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Old 05-22-2019, 06:20 PM
 
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Quote:
Originally Posted by Mike555 View Post
Open two windows on your computer and bring up two live real-time beach sunset cams; one on the gulf coast of Florida and one on the California Pacific coast. If when the sun is still a ways over the horizon on the California cam while the sun has just set below the horizon on the Florida cam at the exact same time, then the earth isn't flat. Simple. You don't even have to leave your seat.

I probably shouldn't have even replied to this.
That proves that the sun sets first in Florida and later in California. But I was not disputing that was the case.
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Old 05-26-2019, 09:41 AM
 
7,255 posts, read 3,979,650 times
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Quote:
Originally Posted by elnina View Post
Oh, I read the abstract and other info available on the net. Still - there are astronomers (incl. hobby astronomers) that are observing the visible parts of the Space pretty much all the times. They use many different types of telescopes to observe objects in the Universe. Some are located right here on earth and some are sent into space. In fact, a large number of observatories have been launched into orbit.
You would think they have the round of the hour observations covered.



In other words, this event occurred a very long time ago but was just discovered lately...
The news headlines made it sound like this just happened.
Taken in total there is probably someone, somewhere, looking at something all the time. It takes bigger and more capable telescopes to see further out. And the further out you look, the less you look at. Taken all together the total area being observed at any one time compared to the total area of sky to observe is kind of like watching a football game through a soda straw.
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Old 05-26-2019, 02:29 PM
 
Location: Ohio
20,723 posts, read 14,670,694 times
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Originally Posted by UrbanAdventurer View Post
Pretty sure the Earth if flat and that is just a bunch of CGI video game graphics to keep you all ooh-ing and ahh-ing, but, I suppose it could also be a big swimming pool of dark matter as an interesting alternate theory.

Pretty sure you have no understanding of spherical geometry.
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