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Dark matter scaffolding of universe detected for the first time

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Re: Dark matter scaffolding of universe detected for the first time

#11

Post by lwat »

ok_craig wrote: post #10

There's one thing I don't understand about the mystery of dark matter. I don't understand why the simple explanation for it isn't just that it's regular matter that is not stars. Maybe there are just bajillions of planets and dust clouds out there. Matter that isn't directly circling stars, thus not reflecting light. Why is the popular assumption that if the mass isn't stars or things in orbit of stars, that it must…

We know this is not the case because intersteller dust absorbs light, while the dark matter does not emit or absorb light at all. The only effect we see is the gravity.

Re: Dark matter scaffolding of universe detected for the first time

#12

Post by derleth »

ok_craig wrote: post #10

There's one thing I don't understand about the mystery of dark matter. I don't understand why the simple explanation for it isn't just that it's regular matter that is not stars. Maybe there are just bajillions of planets and dust clouds out there. Matter that isn't directly circling stars, thus not reflecting light. Why is the popular assumption that if the mass isn't stars or things in orbit of stars, that it must…

Dust absorbs light, blocking it (creating dark spots) and getting hot (creating light spots in a different frequency range). We know what interstellar dust looks like. Dark matter doesn't look like that; it doesn't look like anything. We only know about it because its gravity affects the things we can see.

NASA has a brief page on dark matter and something else we know little about, dark energy:

http://science.nasa.gov/astrophysics/focus-areas/what-is-dar...

Re: Dark matter scaffolding of universe detected for the first time

#13

Post by derleth »

tb wrote: post #5
Xcelerate wrote: post #2

This is really cool. If you look at this graph of the Standard Model interactions http://upload.wikimedia.org/wikipedia/commons/4/4c/Elementar... you will see the ways in which all of the particles we currently know about interact. If you'll notice though, there's one interaction between ALL of the particles that is missing: gravity. Gravity affects anything with energy . Photons, leptons, quarks -- they are all attr…

> Some other particle may interact with nothing we are familiar with -- and thus we could never study it. Is it even "real" then? Philosophically, this is equivalent to the question of whether other universes, which do not interact with ours and therefore we cannot study, exist or are "real". It is not a question that Science can answer.

> It is not a question that Science can answer.

It is, though: Science suggests that they don't exist because science favors simpler models to more complex ones, as long as the simpler model still accounts for all the evidence and makes correct predictions.

Re: Dark matter scaffolding of universe detected for the first time

#14

Post by kamaal »

tb wrote: post #5
Xcelerate wrote: post #2

This is really cool. If you look at this graph of the Standard Model interactions http://upload.wikimedia.org/wikipedia/commons/4/4c/Elementar... you will see the ways in which all of the particles we currently know about interact. If you'll notice though, there's one interaction between ALL of the particles that is missing: gravity. Gravity affects anything with energy . Photons, leptons, quarks -- they are all attr…

> Some other particle may interact with nothing we are familiar with -- and thus we could never study it. Is it even "real" then? Philosophically, this is equivalent to the question of whether other universes, which do not interact with ours and therefore we cannot study, exist or are "real". It is not a question that Science can answer.

Oh well,

That question really has far reaching implications. Because if we say Science is what we observe and describe as per our interpretations of logic(And the language of logic - 'Math') then our science is really broken. Because what we can observe doesn't often turn out to be true and what is true is not often observed.

Because look at it this way. We are now saying Dark Matter doesn't interact anyway with light nor something else. Hence observing, detecting or modeling them out through conjectures manufactured through thin air is nothing more than what religion was some centuries ago.

Anything unexplainable was attributed to some form of divinity in times before.

We know it exists, but we can't show you, can't explain you what it is, how it looks is the text book definition of god throughout centuries.

Re: Dark matter scaffolding of universe detected for the first time

#15

Post by carterac »

How do these filaments stay stable and not collape under their own gravity due to instabilities? Or, if there is 0 net force causing them to collapse, why doesn't the dark matter drift apart naturally and become less dense and more diffuse over time? Either way, filaments of high density don't seem to be a natural stable state. Can someone explain this?

Re: Dark matter scaffolding of universe detected for the first time

#16

Post by archgoon »

carterac wrote: post #15

How do these filaments stay stable and not collape under their own gravity due to instabilities? Or, if there is 0 net force causing them to collapse, why doesn't the dark matter drift apart naturally and become less dense and more diffuse over time? Either way, filaments of high density don't seem to be a natural stable state. Can someone explain this?

Well, the particles also have no way to radiate away energy, so the dark matter particles just whisk around each other under the gravitational force.

You can check out something like this on your computer

http://http.developer.nvidia.com/GPUGems3/gpugems3_ch31.html

To see what pure 1/r^2 interactions look like. You can download the simulations from here:

http://developer.nvidia.com/cuda/cuda-toolkit-40

Re: Dark matter scaffolding of universe detected for the first time

#17

Post by lloeki »

syncerr wrote: post #3

It is worth noting that there was no direct detection of dark matter. It comes from a measurement of gravitational lensing, which has been going on for awhile˟˟. Critical response: http://www.scilogs.eu/en/blog/the-dark-matter-crisis/2012-07... Source: http://www.nature.com/nature/journal/v487/n7406/full/nature1... ˟˟ http://physicsworld.com/cws/article/news/2006/aug/25/gravity...

Indeed, it's more like observing a magnetic field by dropping iron dust on a sheet of paper, and gently hit/shake it until the field lines "appear".

It makes me wonder why we can't observe dark matter (which seems to emit only pure gravitation, and no light nor electromagnetic radiation). Could it be because there's no actual matter (i.e pure gravitational waves, like the magnet+iron+paper experiment)? Or are they massive clouds overloaded with Higgs bosons?

Re: Dark matter scaffolding of universe detected for the first time

#18

Post by lloeki »

lwat wrote: post #11
ok_craig wrote: post #10

There's one thing I don't understand about the mystery of dark matter. I don't understand why the simple explanation for it isn't just that it's regular matter that is not stars. Maybe there are just bajillions of planets and dust clouds out there. Matter that isn't directly circling stars, thus not reflecting light. Why is the popular assumption that if the mass isn't stars or things in orbit of stars, that it must…

We know this is not the case because intersteller dust absorbs light, while the dark matter does not emit or absorb light at all. The only effect we see is the gravity.

Not only just light (photons) but no other radiation as well (electromagnetic, like X or gamma rays), except gravity.

Re: Dark matter scaffolding of universe detected for the first time

#19

Post by mattheww »

Xcelerate wrote: post #2

This is really cool. If you look at this graph of the Standard Model interactions http://upload.wikimedia.org/wikipedia/commons/4/4c/Elementar... you will see the ways in which all of the particles we currently know about interact. If you'll notice though, there's one interaction between ALL of the particles that is missing: gravity. Gravity affects anything with energy . Photons, leptons, quarks -- they are all attr…

There are a lot of people thinking about what kind of structure the model of dark matter particles could have. And there are a lot of different ways for there to be more than one dark matter particle, and even if the only way those other particles interact with normal matter is through gravity, there are still ways for us to understand things about them.

At the moment, the most popular dark matter theory comes from supersymmetry. In this case, there's only one dark matter particle, and all of the rest of the particles interact with normal matter, in pretty much the normal way, since all of the underlying structure of the model is almost identical.

Re: Dark matter scaffolding of universe detected for the first time

#20

Post by ordinary »

lloeki wrote: post #18
lwat wrote: post #11

Earlier quoted context omitted.

We know this is not the case because intersteller dust absorbs light, while the dark matter does not emit or absorb light at all. The only effect we see is the gravity.

Not only just light (photons) but no other radiation as well (electromagnetic, like X or gamma rays), except gravity.

Gamma rays and X-rays are photons.[0]

_____

[0] http://en.wikipedia.org/wiki/File:EM_Spectrum_Properties_edi...

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