Dark Matter question

The physicists on observing that the outer solar systems (stars) off galaxies spin as fast around the core of the galaxy as the inner stars. From that they extrapolate the theory of Dark matter, a hypothetical form of “matter” they can’t even see!

Now they base this extrapolation (the existence of this hidden Dark Matter) on the analogous phenomenon that in our solar system the inner planets rotate faster around the sun than the outer planets, therefore if that doesn’t occur in galaxies (where both outer and inner stars rotate at the same speeds) than dark matter an unseen, unknown hypothetical force must cause this.

A question. Has it occurred to them that a galaxy may have more dynamic elements to it than a mere solar system?

As it occurred to them that the analogy is out of whack: planets rotating around suns analogous to stars rotating around galaxy cores. Parenthetically, since they don’t know galaxy cores like they do suns, therefore is their extrapolation faulty?

"The physicists on observing that the outer solar systems (stars) off galaxies spin as fast around the core of the galaxy as the inner stars."

Citation please.... impossible for an outer point to spin as fast as an inner point of a singularity.....

That's why they came up with dark matter

In 1933, Swiss astrophysicist Fritz Zwicky, first noticed this studying certain galaxy clusters, then years later a woman physicist named Vera Rubin later confirmed his theories.

a reply to: Willtell

Dark matter is just a term for unknown. We have observed differences in galaxies that can only be explained by the presence of an unknown force.

a reply to: Vector99

I get that. According to this How the universe works documentary, they base that on the rotation of the bodies around the galaxy core.


A related point. Science always criticizes religious ideas because God is not empirical neither is Dark energy, nor Dark Matter.

originally posted by: Willtell
a reply to: Vector99
I get that.

It does not seem that you do?

Dark energy, Dark Matter are guesses. Should someone come up with a better explanation, they would be tossed aside.

Ever heard of a Religion tossing their God aside for a better explanation?

Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

Displaced supersolid dark matter is curved spacetime.

In the Bullet Cluster collision the dark matter has not separated from the ordinary matter. The collision is analogous to two boats that collide, the boats slow down and their bow waves continue to propagate. The water has not separated from the boats, the bow waves have. In the Bullet Cluster collision the galaxy's associated dark matter displacement waves have separated from the colliding galaxies, causing the light to lense as it passes through the waves.

originally posted by: Willtell
a reply to: Vector99

I get that. According to this How the universe works documentary, they base that on the rotation of the bodies around the galaxy core.


A related point. Science always criticizes religious ideas because God is not empirical neither is Dark energy, nor Dark Matter.

The standard come back is that the effects of Dark Matter and Dark Energy are observable, while God is not.

The rotation curves are not modelled on our solar system.

Basically if you think of the simplest structure that relates to how matter is distributed in our galaxy, and in other galaxies, based on the luminous matter we can see... spiral galaxies are structured with a ellipsoidal bulge in the middle and an approximately flat disk.

If you apply Newtonian gravitational dynamics to this structure, you expect that objects orbiting or moving within it, should follow a roughly linear rise in the bulge and then a 1/sqrt R fall off in velocity when you transition from the bulge to the disk.

What they observe is that the disk remains almost uniformly flat and this is observed in the vast majority of spiral galaxies. THIS observation was made by Vera Rubin of first Andromeda by observing stars and Hydrogen and then other galaxies.

Fritz Actually looked first at Clusters of galaxies (Coma cluster) and applied the Virial Theorem, which basically says that "If a system is gravitationally bound and approximately spherical its the average Kinetic energy of the objects should be roughly half the total gravitational energy. This is a kinematic supposition which works on small scale rotating systems.

He applied this and basically it gives you a measure of mass from kinematics and mass from observable light... they where different by a factor of... i think 500. Which means, something is very wrong. He didn't really accept that the observation made sense, but accepted the contention. That number came down as observations where made of the cluster in different EM spectrum but it still doesn't match, that and other clusters have had the same treatment and they find the same.

So here you have two different measurements made at two different scales both pointing at something unknown. Fritz coined the label Dark Matter.

The supposition that galaxies are more dynamic objects is fine, except, we have become far better at mapping and observations and for a structure like a galaxy to be stable in its configuration, it still does't work without actually making the maths way harder and having way more fudge factors. Dark Matter is actually a rather elegant solution. There are other objects such as the bullet cluster which thus far cannot be explained by any other model that point at particulate Dark matter as a tenable solution.

The other support for it is the Lambda Cold Dark Matter Model which looks at the anisotropy scale of the Cosmic Microwave background and from that predicts what distribution of matter and energy there should be for it to have originated from the big bang. This model also predicts that observable baryonic mater is only a small percentile.

a reply to: Vector99

"can only be explained" usually ends up being too limited.
Could be that the "force" of gravity is an illusion at the quantum level.
We probably don't have the tools necessary to map quantum space time geometry directly.
They haven't simplified the mathematical models much either.

a reply to: Willtell

Yeah you're quite right those 1000's of cosmologists with IQ's 10 times bigger than yours all forgot to think about your point.

How about you study what your talking about first before making claims

a reply to: ziplock9000

How about refuting the point on your own and have a discussion.

And when you go out on Sunday to worship all those scientists don't forget to do 1000 hail Einsteins!

The rotation curves are not modelled on our solar system. Basically if you think of the simplest structure that relates to how matter is distributed in our galaxy, and in other galaxies, based on the luminous matter we can see... spiral galaxies are structured with a ellipsoidal bulge in the middle and an approximately flat disk. If you apply Newtonian gravitational dynamics to this structure, you expect that objects orbiting or moving within it, should follow a roughly linear rise in the bulge and then a 1/sqrt R fall off in velocity when you transition from the bulge to the disk. What they observe is that the disk remains almost uniformly flat and this is observed in the vast majority of spiral galaxies. THIS observation was made by Vera Rubin of first Andromeda by observing stars and Hydrogen and then other galaxies. Fritz Actually looked first at Clusters of galaxies (Coma cluster) and applied the Virial Theorem, which basically says that "If a system is gravitationally bound and approximately spherical its the average Kinetic energy of the objects should be roughly half the total gravitational energy. This is a kinematic supposition which works on small scale rotating systems. He applied this and basically it gives you a measure of mass from kinematics and mass from observable light... they where different by a factor of... i think 500. Which means, something is very wrong. He didn't really accept that the observation made sense, but accepted the contention. That number came down as observations where made of the cluster in different EM spectrum but it still doesn't match, that and other clusters have had the same treatment and they find the same. So here you have two different measurements made at two different scales both pointing at something unknown. Fritz coined the label Dark Matter. The supposition that galaxies are more dynamic objects is fine, except, we have become far better at mapping and observations and for a structure like a galaxy to be stable in its configuration, it still does't work without actually making the maths way harder and having way more fudge factors. Dark Matter is actually a rather elegant solution. There are other objects such as the bullet cluster which thus far cannot be explained by any other model that point at particulate Dark matter as a tenable solution. The other support for it is the Lambda Cold Dark Matter Model which looks at the anisotropy scale of the Cosmic Microwave background and from that predicts what distribution of matter and energy there should be for it to have originated from the big bang. This model also predicts that observable baryonic mater is only a small percentile.

Thanks for that. This post is about learning and you have contributed to that. I am grateful for your input and the details about Rubin and Fritz.

We, laymen, are learning but we can’t assume because we aren’t experts that everything these physicists are saying is the truth.

Even now, they’re claiming Einstein’s CC may have been correct! While at that time even Einstein mocked his own theory as nonsense yet it may be the answer to this mystery, after all.

originally posted by: Teikiatsu

originally posted by: Willtell
a reply to: Vector99

I get that. According to this How the universe works documentary, they base that on the rotation of the bodies around the galaxy core.


A related point. Science always criticizes religious ideas because God is not empirical neither is Dark energy, nor Dark Matter.

The standard come back is that the effects of Dark Matter and Dark Energy are observable, while God is not.

Then the effects of God are also observable

Then God is a form of Dark matter, conceptually speaking.

Iv been heavily involved in building a Ton scale dark matter experiment, soooo id say iv been quite intimately involved in the search for WIMP dark matter, as such, have a above average level of knowledge in the history of the subject.

The issue in the transfer between layman and scientists is that the media play the middle man, and typically science correspondence and the translation from Science to popular science is often not done at the correct level.

As an example, I can explain how each of the measurements worked, down to the kinds of data and observations are made. But that would be very very long, and so we summarize to a few paragraphs cutting out a lot of gory detail. Then someone asks a follow up question relating to a measurement and their idea or assumptions are completely wrong, or partially wrong. That then is the tricky part because often, especially in places like these, people don't like to be told they are incorrect, people like to believe they fundamentally know what is happening, when in actual fact even the experts wouldn't say they fundamentally know what is occurring.

The most common thing i hear on ATS is the old "Dark matter is just a fudge factor" when it is so clearly a more complicated issue than just adding a random fudge factor. It is observed at different scales and with different methods of observation and requires a model, not a simple offset. It then by definition says there is something going on we don't understand. We such want to find out.



Again Einstein's cosmological constant isn't some miracle of a model, it is the fact that the mathematically to get to the end point of the equation there is an integration. Anyone who has done differentiation and integration will tell you, that when you differentiate, all your constant terms vanish, while when you integrate the result of the differentiation, you doing regain your constants. THUS it is more a technicality that when you integrate you should always add a constant term... exactly what it is, is not known from a mathematical standpoint. Einstein added the CC for completeness, his mocking was more over... "I added this because technically i should... but its a problem because i think its not a real thing"

Then with the discovery of accelerating expansion it looked clearly as though the CC could/would easily play the part of providing that in the field equations.

I was watching the documentary how the universe works and they say they don’t know what dark matter is at all, they admit that and some physicist even said it might not even be one form of matter. They just don’t know. Then again they go on to explain so much about dark matter and one wonders how they cannot know something yet extrapolate so minutely on it.
But being well versed in metaphysics, and computer technology I can understand the challenge of describing complex matters to laymen where one has to leave out the nuances.
Learning the nuances is the challenge

Dark matter and dark energy are very exciting topics and one gets the feeling humankind may be at the crust of learning something real deep

It is an open question. Though with any open question complex stipulation should be done with some caution. It is true that dark matter can be more than one form of matter, it in truth could be many things. It however isn't the truth to say we have no idea about it for example.

From our observations we have the following phenomenological understanding or knowledge, presented with evidence

1) It has electrostatic neutral charge.
Evidence - We do not observe its presence in the EM spectrum
We do not observe any drag effect indicative to a high strength interaction such as with the EM spectrum... - Bullet Cluster)
2) It interacts gravitationally
Evidence
- We observe large lobes of matter in gravitational lensing far beyond the observable stars in galaxies
- We observe universal rapid rotation out to large distances in spiral galaxies
- We have observed Galaxies with very very few stars, but significant mass... so called Dark matter galaxies in which the stars rotate around a central point but there doesn't really appear to be enough stars or gas in that galaxy to support it at all in comparison to say... the milky way
- Clusters of galaxies move too quickly to be bound. This would mean that when we look into the sky, we should not see any observable families of galaxies, and more just a totally random distribution. Again, something is holding it all together in a gravitational well.
3) - Tenable statement - It is probably particulate in nature. This means it could be a particle of some kind rather than a weird field or simply a force.
Evidence
- Objects like the Bullet cluster show how the matter concentration of a cluster can be separated from the particle concentration. This object is two clusters that have passed through each other. The result from gravitational lensing places the centre of mass ahead of the observable mass from optical and X-ray measurements. Optical measures show how hot gas stripped from the clusters drags behind in a shock front structure. What this suggests is that Dark Matter is some kind of particulate matter that experiences gravitation but not electrostatic effects. If it did, it would be dragged back similarly to the hot gas stripped from the clusters.

SO what are the candidates?

Well again we can imagine many, here are a few models...

a reply to: ErosA433

I get most of what you’re saying in one reading but I'll read the rest closely.

Interesting it doesn’t interact with radiation; that in itself has implications

well yes, this is largely the issue in that there are not many other candidate particles that can fit the bill...when i say doesn't interact with radiation, it might not be strictly true, but largely what i mean is its electrostatically neutral. One model is that it is a particle that interacts via the weak interaction only... which places the interaction strength at an extremely low level.

these would be WIMP like particles in the diagram above (supersymmetry) (largest area of search at this point in time)

The other breed might be an axion like particle in which photons propagating in a magnetic field can convert into a new particle of low mass. (second largest area of search at this point in time)

The other interesting area could be a dark sector or sterile neutrino of high mass. The concept of a sterile neutrino is basically that it would be a large mass neutrino with opposite chirality to a regular neutrino meaning interactions are highly forbidden, making it extremely weakly interacting.

Its a vibrant and exciting field

A little scary too… All that darkness is very mysterious and doesn’t interact with light…!
The same documentary talked about how Dark matters mate, Dark energy, may, or can eventually keep the universe expanding into cold oblivion.

Then they say, maybe not, since some mechanism might reset all the way back to the Big bang

Now inst that interesting


Indeed it's exciting
It all makes me wish I had taken physics instead of chemistry which was hard enough.