"The Milky Way spins so fast it would fly apart if the gravity of some invisible matter weren't holding it together. Clusters of galaxies, buzzing around one another like angry bees, would similarly fragment and disperse. And when you run the gravitational numbers, the mysterious matter that keeps all that cosmic disintegration from happening should outweigh the familiar stuff by about four-to-one."


I'm just a lowly engineer, but It sounds like they just make up stuff like this to try to make sense of the order of the universe that we can't understand. Surely it has to be an invisible force or matter that we can't yet detect.....

(*spoiler alert*)
God's spinning the galaxy on a big stick.

So, FTA they are detecting positrons.  They think the decay of dark matter could produce positrons.

They also think pulsars could be a source of positrons.

IIRC, positrons can be spontaneously produced is a photon with sufficient energy has a specific interraction with a nucleus.

They say it is like looking for bears by looking for bear tracks.

I would say they are looking for Michael Jordan by examining foot prints left by Nike shoes. There are lots of Nike prints out there.

mcgreggers99: "The Milky Way spins so fast it would fly apart if the gravity of some invisible matter weren't holding it together. Clusters of galaxies, buzzing around one another like angry bees, would similarly fragment and disperse. And when you run the gravitational numbers, the mysterious matter that keeps all that cosmic disintegration from happening should outweigh the familiar stuff by about four-to-one."


I'm just a lowly engineer, but It sounds like they just make up stuff like this to try to make sense of the order of the universe that we can't understand. Surely it has to be an invisible force or matter that we can't yet detect.....

(*spoiler alert*)
God's spinning the galaxy on a big stick.

[coloring.thecolor.com image 554x565]

Well, yes... oddly that's kind of what science IS.  Don't understand something?

1) Create a theory (aka make stuff up)
2)  test your theory to see if it's true.
3) If not true goto 1

Dingleberries?

Lionel Mandrake: I thought it was closer to Urectum.

Urectum? Damn near Killed em!

mcgreggers99: "The Milky Way spins so fast it would fly apart if the gravity of some invisible matter weren't holding it together. Clusters of galaxies, buzzing around one another like angry bees, would similarly fragment and disperse. And when you run the gravitational numbers, the mysterious matter that keeps all that cosmic disintegration from happening should outweigh the familiar stuff by about four-to-one."


I'm just a lowly engineer, but It sounds like they just make up stuff like this to try to make sense of the order of the universe that we can't understand. Surely it has to be an invisible force or matter that we can't yet detect.....

(*spoiler alert*)
God's spinning the galaxy on a big stick.

[coloring.thecolor.com image 554x565]

Dark matter always sounded like luminiferous aether to me.

revrendjim: Tricky Chicken:
They say it is like looking for bears by looking for bear tracks.

I would say they are looking for Michael Jordan by examining foot prints left by Nike shoes. There are lots of Nike prints out there.

There's a little more to it. They are finding positrons in the energy range they expected, and they are coming from all directions, which indicates a diffuse source. To use you analogy, it's more like they are finding Nike footprints in Michael Jordan's shoe size.

Come to think of it, dont all positrons from pair production have the exact same energy when produced?  It should be fairly simple to rule those out then.

I have always been a bit leery of dark energy/matter theories.  And since I have a somewhat less than rudimentary understanding of what they are talking about, my opinion on the matter is unimportant.

Telos: 1) Create a theory (aka make stuff up)

AGGGGGGGGGG, No no no no no.

1) Create a HYPOTHESIS
2) Observe/test
3) yada yada
4) Profit.

Tricky Chicken: Come to think of it, dont all positrons from pair production have the exact same energy when produced?

No. There is a characteristic energy of gamma ray produced when a positron and electron annihilate (511 keV), but going the other way any excess energy in the incoming photon just ends up as kinetic energy in the new particles.

Article says 'dark matter' is 80% of the universe.

Latest data:

Dark energy:  68.3%
Dark matter:  26.8%
Normal matter:  4.9%

What the fark are they blathering about?

Precision Boobery: Article says 'dark matter' is 80% of the universe.

Latest data:

Dark energy:  68.3%
Dark matter:  26.8%
Normal matter:  4.9%

What the fark are they blathering about?

I was wondering that myself, I don't think they had a very good grasp of what the study, the theory behind it or the results was about.

Precision Boobery: Article says 'dark matter' is 80% of the universe.

Latest data:

Dark energy:  68.3%
Dark matter:  26.8%
Normal matter:  4.9%

What the fark are they blathering about?

Came here for this.  Journalists are idiots.

Precision Boobery: Article says 'dark matter' is 80% of the universe.

Latest data:

Dark energy:  68.3%
Dark matter:  26.8%
Normal matter:  4.9%

What the fark are they blathering about?

No, they stated 80% of the matter in the universe. You're describing the distribution of mass-energy.

hawcian: Precision Boobery: Article says 'dark matter' is 80% of the universe.

Latest data:

Dark energy:  68.3%
Dark matter:  26.8%
Normal matter:  4.9%

What the fark are they blathering about?

No, they stated 80% of the matter in the universe. You're describing the distribution of mass-energy.

26.8/(26.8+4.9) = 85%.  So same ballpark.

hawcian: No, they stated 80% of the matter in the universe. You're describing the distribution of mass-energy.

I...guess that could be what they mean, even though they say "up to 80%" when the actual number is 84.5%.  Meanwhile, the headline is "80% of the universe's mass".

Precision Boobery: up to 80%" when the actual number is 84.5%

These are the same number to one significant figure.

If dark matter passes through normal matter, yet is affected by gravity, wouldn't this cause any local gravity well to have a large chunk of dark matter at its core?

Cubicle Jockey: If dark matter passes through normal matter, yet is affected by gravity, wouldn't this cause any local gravity well to have a large chunk of dark matter at its core?

Not necessarily, but maybe. Consider the bullet cluster of galaxies. They were galaxies that did have a lot of dark matter in them (like any galaxy), but when the two clusters collided, the ordinary matter slowed down more than the dark matter, causing separation.

If you're talking about a local gravity well like the sun, it might be too small to make a difference on galactic scales, kind of like wondering if you have a lot of dark matter in you because you're a local gravity well.

Noted Dark Matter researcher can't deny

Precision Boobery: hawcian: No, they stated 80% of the matter in the universe. You're describing the distribution of mass-energy.

I...guess that could be what they mean, even though they say "up to 80%" when the actual number is 84.5%.  Meanwhile, the headline is "80% of the universe's mass".

I'd forgive them saying "mass." Most people think of actual matter when you say mass, not equivalent mass-energy. And yea, they're in the ballpark, at least, though I'd be curious as to where they got their numbers from.

bingethinker: Near Uranus? What happens if the universe takes a massive dump?

I've been trying to come up with a "cosmicstipation" joke, but it just won't emerge.

Epicanis: bingethinker: Near Uranus? What happens if the universe takes a massive dump?

I've been trying to come up with a "cosmicstipation" joke, but it just won't emerge.


Too hard to come out with?

And now, a relevant musical interlude:

Dark Matter

Telos: mcgreggers99: "The Milky Way spins so fast it would fly apart if the gravity of some invisible matter weren't holding it together. Clusters of galaxies, buzzing around one another like angry bees, would similarly fragment and disperse. And when you run the gravitational numbers, the mysterious matter that keeps all that cosmic disintegration from happening should outweigh the familiar stuff by about four-to-one."


I'm just a lowly engineer, but It sounds like they just make up stuff like this to try to make sense of the order of the universe that we can't understand. Surely it has to be an invisible force or matter that we can't yet detect.....

(*spoiler alert*)
God's spinning the galaxy on a big stick.

[coloring.thecolor.com image 554x565]

Well, yes... oddly that's kind of what science IS.  Don't understand something?

1) Create a theory (aka make stuff up)
2)  test your theory to see if it's true.
2.5) tweak data and results until you get the outcome your want
3) If not true  accepted by "consensus" of same thinking scientists goto 1

Fixed

/from experience

There is no dark side in the moon, really. As a matter of fact it's all dark.

MilesTeg: Telos: mcgreggers99: "The Milky Way spins so fast it would fly apart if the gravity of some invisible matter weren't holding it together. Clusters of galaxies, buzzing around one another like angry bees, would similarly fragment and disperse. And when you run the gravitational numbers, the mysterious matter that keeps all that cosmic disintegration from happening should outweigh the familiar stuff by about four-to-one."


I'm just a lowly engineer, but It sounds like they just make up stuff like this to try to make sense of the order of the universe that we can't understand. Surely it has to be an invisible force or matter that we can't yet detect.....

(*spoiler alert*)
God's spinning the galaxy on a big stick.

[coloring.thecolor.com image 554x565]

Well, yes... oddly that's kind of what science IS.  Don't understand something?

1) Create a theory (aka make stuff up)
2)  test your theory to see if it's true.
2.5) tweak data and results until you get the outcome your want
3) If not true  accepted by "consensus" of same thinking scientists goto 1

Fixed

/from experience

I did not know you worked in climate science.

/ducks

MilesTeg: Telos: mcgreggers99: "The Milky Way spins so fast it would fly apart if the gravity of some invisible matter weren't holding it together. Clusters of galaxies, buzzing around one another like angry bees, would similarly fragment and disperse. And when you run the gravitational numbers, the mysterious matter that keeps all that cosmic disintegration from happening should outweigh the familiar stuff by about four-to-one."


I'm just a lowly engineer, but It sounds like they just make up stuff like this to try to make sense of the order of the universe that we can't understand. Surely it has to be an invisible force or matter that we can't yet detect.....

(*spoiler alert*)
God's spinning the galaxy on a big stick.

[coloring.thecolor.com image 554x565]

Well, yes... oddly that's kind of what science IS.  Don't understand something?

1) Create a theory (aka make stuff up)
2)  test your theory to see if it's true.
2.5) tweak data and results until you get the outcome your want
3) If not true  accepted by "consensus" of same thinking scientists goto 1

Fixed

/from experience

You sound unsuccessful.

Gijick: Epicanis: bingethinker: Near Uranus? What happens if the universe takes a massive dump?

I've been trying to come up with a "cosmicstipation" joke, but it just won't emerge.


Too hard to come out with?

You need to relaxative.

I found the missing mass on your Mom last night subby.

Is there any reason 3/4 of the matter in our galaxy couldn't consist of planets flung out of orbit, dark stars that have already burned through their fuel, and entire "solar systems" we cannot see because the accretion discs never formed any bodies massive enough to go nuclear?

revrendjim: Tommy Moo: Is there any reason 3/4 of the matter in our galaxy couldn't consist of planets flung out of orbit, dark stars that have already burned through their fuel, and entire "solar systems" we cannot see because the accretion discs never formed any bodies massive enough to go nuclear?

Yes. We would "see" that stuff because it would block the light from sources behind it.

ZAZ: Tommy Moo

Dark planets and such go by the collective name "massive compact halo objects" or MACHOs for short. There are experiments to detect them, e.g. searches for microlensing events. We don't see enough.

Ah, thanks guys. That has always had me curious.

FTFA:  The new findings come from a team of physicists led by Samuel Ting, of the European Organization for Nuclear Research,

Sounds like the Sam Ting over and over again to me.