Skip to comments.How Do We Know Dark Matter Really Exists?
Posted on 07/27/2018 3:36:24 PM PDT by LibWhacker
Ever since the late 1960s when Vera Rubin and Kent Ford discovered that galaxies don't behave the way they should, scientists have been looking for the mysterious substance behind that behavior. That theoretical stuff is called dark matter, and while it's invisible to telescopes, it has mass, which means it can show its might through the force of gravity. Of course, that's all theoretical. Some might even say it's a little too convenient, as if scientists just came up with a magical substance that makes the math work. What makes us so sure that dark matter is even a thing?
Hold Me Closer, Tiny Particle
"People ask this question a lot," said Katie Mack, a theoretical astrophysicist at North Carolina State University who studies dark matter. "You know, maybe dark matter is just a fudge factor or something." But for astrophysicists, dark matter is much more than that.
If you go back to high school physics class, you may remember that the more mass something has, the greater its gravitational pull. If galaxies were only made up of the stuff we can see, there wouldn't be enough gravity to keep them together, much less to keep the stars in the sparse outer edges orbiting just as fast as those in the center. In fact, scientists reckon that normal matter makes up less than five percent of the universe. Dark matter seems to make up a whopping 27 percent. (The rest is a mysterious force called dark energy.)
You can also see its mass in the warping of spacetime itself. According to Einstein's theory of general relativity, matter curves the fabric of spacetime the way a bowling ball curves the fabric of a trampoline. When light travels toward that curve, it doesn't go in a straight line. Instead, it follows the curve, bending around the massive object before continuing on its path. That warp in spacetime turns into a sort of cosmic magnifying glass in a phenomenon known as gravitational lensing. But yet again, the gravitational lensing produced by a galaxy or a galaxy cluster is too great to be explained by the matter we can see. This effect is yet another piece of evidence for the existence of dark matter.
You can even see unexpected patterns in the cosmic microwave background, the light left over from the birth of our universe, that point to the existence of dark matter. "We see patterns in that that show there had to have been something at early times that brought matter together in a way that can't work with just regular matter," Mack told Curiosity.
All Signs Point to Yes
It's not as if scientists have never tried to find an alternative. Instead of dark matter, maybe gravity just doesn't behave the same way everywhere in the universe. Researchers have tried tweaking gravity to make galaxies rotate differently than Einstein's theories say they should, sans dark matter, and it can work but then other observations we've made don't match up. In the end, Mack says dark matter is the most likely explanation we've got. "I'm not sure what it is that makes it more appealing to break general relativity and say that all these huge observations are wrong, versus 'there's a particle we can't see."
"It's kind of like if you were walking down the street and you see a plastic bag sort of move across the street in front of you," she said. "And then you see some trees lean over, and then you hear this kind of rustling sound, and then you feel a little bit of cold coming from one direction, and then you see a street sign swing, and you're like 'That's wind!' You can't see the wind, but there are all of these different pieces of evidence that air is moving.
"It's kind of the same with dark matter. We can't see it directly, but there are so many pieces of evidence that it just makes more sense than any other explanation that we can come up with."
It was Elected POTUS in 2008?
Well, there’s protons, electrons and neutrons making up Normal matter.
Normal matter is supposed to be a smaller part of all stuff according to some of these scientist.
Dark matter, is in abundance everywhere it seems, per some of those same scientist. Kinda like Stupidity.
Maybe the dominant particle of dark matter is morons ... it would explain a lot.
I guess what the article is asking, does Dark Matter matter?
Viewed an interesting utube last eve on antimatter. Said that at the moment of the big bang, there was equal amounts of matter and antimatter, and then discussed the various scenarios of what happened to the antimatter.
Other than the center of the milky way, there apparently is little antimatter in its stars and planets. Probably the same in the galaxies of the visible universes.
Perhaps there is a companion universe comprised of all the antimatter. Where that one would have a smattering of matter, just like we have antimatter here.
It’s my understanding that dark matter and anti-matter are not the same thing. What’s anti-matter?
Because the Know it all Liberals told us so.
Maybe scientists reckon wrong.
If dark matter exists why isnt my lawn covered with it?
There are folks who have argued, convincingly, that there could be a large density of small mass black holes that could account for the missing mass.
your lawn IS covered with it.
its just invisible, is all
Dark matter is that cousin whom you hardly know he’s there even when he’s there, which is somehow most of the time.
Antimatter is another cousin who is hardly ever around but when he is he’s loudmouthed, destructive, and even violent ... expect the cops to be called.
“All Signs Point to Yes”
Science by Magic 8 Ball.
Your #3 is a hoot.
Antimatter meets matter. Kablamo.
Darin matter is something else. It is the name scientist give an unknown feature of ours and other galaxies that keeps them from spinning apart. Vera Rubin discovered that the stars in the galaxy dont orbit the center like the planets in our solar system orbit the sun at different speeds. The Galaxy for the most part spins like a phonograph record as if it were a solid the only way this could happen is if there was considerably more mass that is unaccounted for. Now dark matter is physically visible as the mass warps space enough to cause stars in the background to appear elsewhere by gravitational lensing.
I knew a guy that built the best gravity meters in the world. He was hired by the military to try to measure “anti-gravity” as a solution to why the missiles weren’t landing where they were supposed to. This was years ago, and perhaps before the idea of dark matter was invented.
He couldn’t measure any anti-gravity (too difficult in actual on-site field experiments) - but he didn’t discount the idea. Although I guess that dark matter is the opposite of anti-gravity. Although the idea of anti-gravity may account for the variations that they observe?
All of the other natural forces (magnetic, electro-magnetic, etc.) have positive and negative attractions, so why wouldn’t gravity?
LOL, your use of 'reckon.' But I reckon you reckoned wrong. Ditto your other use of 'reckon.' They did much more than "reckon" how much gravity it would take to keep the stars together, and the outer stars orbiting just as fast as the stars in the central region of the galaxy.
Because we found some stuff we didn’t know what it was so we called it Dark Matter - we called it Dark Matter because it exists, it exists because we called it Dark Matter - QED.....
Dark matter is matter that travels faster than the speed of light.
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