Understanding Cosmology (Post 4)

[Meow Mix]

The standard gravitational idea of "lumping atoms together", i.e. "condensing or accreting" is a very assumptive and false way of explaining formative cosmology in general.
It is the strong EM force which binds atoms and nucleus together and when it comes to form stars this happens i connection with the overall E&M force in the galactic centers and out in the galactic arms.
Bides this "dark matter" isn´t needed in order to explain the galactic rotations as this is a logical formation and rotation in all electromagnetic currents and their perpendicular and circuital fields.

What do you mean by the "strong EM force," do you just mean the strong force? Are you assuming it's electromagnetic in nature? Or are you referring to GUT stuff like with the electroweak force?

 

[Meow Mix]

I'm curious, if dark matter neither reflects radiates or absorbs... What happens when something bumps into it... Does it just magically occupy the same space and time of another particle while passing through? You said dark matter can't clump because it can't radiate, seems like dark matter being absorbed by a black hole is clumping.

Thanks!

Almost nothing happens depending on what dark matter is. You may get some elastic scattering.

If dark matter is largely WIMPs (weakly interacting massive particles), then they'd be a lot like neutrinos. It could pass through miles of baryonic matter without interacting with a single thing. Some searches for WIMPs work the same way searches for neutrinos go: freeze dense stuff as much as possible and check it for the extremely rare collisions that aren't neutrinos.

It's possible that there is dark anti-matter, but it would probably be as rare as anti-matter. If so, dark matter could collide with its dark anti-counterpart and annihilate into photons, the one case in which it would do so. Some searches check for this, too.

But the answer is that dark matter just doesn't really interact. It'd pass through baryonic stuff without a sweat, even if it's weakly interacting.

 

[Meow Mix]

So dark matter mostly exists to explain why inner parts of our galaxy doesn't spin faster than the outer parts as our solar system does?

Not quite. The galactic rotation curve was one of the first pieces of evidence that there was dark mass out there somewhere, but dark matter explains all of the observations I've been making mostly in Post 4 and Post 5 now.

Difference I see is the Galaxy has a super massive black hole, the solar system does not. Seems clear the solar system coalesced from a glass cloud, so math makes sense. If the math doesnt make sense for the galaxy, perhaps the galaxy evolved given a supermassive black hole to start with? Not sure what the age of the universe is these days, but seems to me the time it takes to create a supermassive black hole via stellar evolution and orbital decay would sure take a long long time to add up to billions and billions of solar masses?

I find these threads fun cause I can just make stuff up and someone eventually feels obliged to correct me so I learn a lot.

Galactic supermassive black holes are still being studied re: their formation mechanism. What you describe, depending on exactly what you're saying, is one possibility (that they've just accreted from a bunch of stellar clusters at the beginning of galactic formation). Galactic star formation and death (what we call quenching) are still open fields of research, and in fact, that's where my thesis research is going to be until I move back to dark energy for my PhD.

 

[Meow Mix]

Seems gravity is the key to "showing" dark matter exists in cosmology, so I ask has it been proven that gravity is not instantaneous? Instantaneous gravity would explain why stuff falling off the particle horizon doesn't violate conservation of energy, right? If gravity were instaneous then seems to me the only way to prove it would be to pluck a big chunk of matter out of the universe and note if all points in the universe experienced a change of gravity instatenously. Of course I know we can't do that, yet, but can we rule out instanteous gravity with complete confidence today or does the possibility remain open? How would instantaneous gravity change the dark matter discussion?

Thanks!

@Heyo beat me to this. Instantaneous gravity would break GR; but we already detect gravitational waves.

 

[Native]

Ok, I'm finally at a keyboard.

Welcome back

We use offshoots of the Schwarzschild metric to describe black holes (t goes to infinity at the horizon with your "basic" Schwarzschild metric, so we use Eddington-Finkelstein [EF] metric. We call the EF metrics particular to holes with angular momentum some variation of Kerr metrics, and so we call such holes Kerr black holes). There are four Killing fields, one being time-like and the other three are related to the spherical symmetry. (Actually for a Kerr hole there are only two Killing fields; but the time-translation one is the one we care about). The time-like Killing vector becomes null on the horizon, and inside the horizon is spacelike. This is associated with a spatial momentum component as a conserved quantity (translation: it can be negative).

This can actually occur outside the event horizon in the case of Kerr black holes (which I see the video notes). And this is how we technically define the ergoregion: it is a region where its time translation Killing vector at infinity becomes space-like.

If you were to theoretically send a particle into the ergoregion where it could decay, and were careful to make sure some decay product with negative energy fell into the hole while the rest escaped the ergoregion, the only place the energy could be paid back from is the hole's angular momentum (so, consequently, we know that the escapee must have angular momentum opposite to that of the hole)

I´m pretty familiar with these theories, but . . .

This actually has a lot of consequences for classical conceptions of black hole thermo, because it's possible to extract energy from the hole without affecting the size of the horizon . . .

Of course it is theoretically as the entire formation process in galaxies is a circuit of attractive and repulsive formation - which ONLY can be achieved by the qualities in the E&M. This entire E&M motion MIRRORS the fact of energi of coming out and going in.

Now the main point I want to make here after this (probably too thorough) explanation of the Penrose process is that it has pretty much nothing to do with E&M, so I don't know why you've brought it up with respect to E&M/plasma physics.

It´s beyond me that modern scientists - or students - can ignore an E&M Plasma cosmological affect as huge E&M gamma- and x-rays are beaming out from the galactic poles.

If you maybe have "gravity" to make these strong nuclear rays in galaxies, you STILL and logically also have to accept E&M to have a huge influence - and maybe even the most influence too since (the assumed and unexplained) "gravity" per definition is the weakest of the fundamental forces.

This is also pretty well-understood as with the Penrose process, and I cannot see what it would have to do with a proposed E&M or plasma-based cosmology, either.

Would you say the Penrose Process theory is the final and consensus one in the subject of formative motions in galaxies?

Just because some theorists ignores and exclude the E&M fundamental forces, it doesn´t mean the E&M forces have no influence.

 

[Native]

Not quite. The galactic rotation curve was one of the first pieces of evidence that there was dark mass out there somewhere,

Please be more scientific nuanced and correct Meow Mix.

Dark matter was assumed to be a cause for the rotation anomaly and this assumption have been so long at place that it apparently has become "the whole truth and nothing but the truth" - but in fact, it is nothing more than a biased gravity circumstantial assumption.
Even more so as no one can describe gravity dynamically as a force = it´s just an assumption in the first place.

 

[Native]

What do you mean by the "strong EM force," do you just mean the strong force? Are you assuming it's electromagnetic in nature? Or are you referring to GUT stuff like with the electroweak force?

I am referring to the EM in generally. I don´t differ between the three fundamental electromagnetic descriptions as the EM works with all kinds of charges, frequencies, ranges and in both polarities - and it works in all four elementary (plasmatic) stages as ONE Force.

Galactic star formation and death (what we call quenching) are still open fields of research, . .

You don´t have to re-invent anyting of this. This formative process was already known in ancient times and described by three eternal principles:

Quote from - BBC - Religions - Hinduism: Brahma
"Brahma is the first god in the Hindu triumvirate, or trimurti. The triumvirate consists of three gods who are responsible for the creation, up-keep and destruction of the world. The other two gods are Vishnu and Shiva. Vishnu is the preserver of the universe, while Shiva's role is to destroy it in order to re-create. Brahma's job was creation of the world and all creatures. His name should not be confused with Brahman, who is the supreme God force present within all things".
-----------------
All ancient cultures had this perception of an eternal creation principle via formation, dissolution and re-formation. Sadly, modern science have forgot most of the human intuitive knowledge.

 

[JoshuaTree]

@Heyo beat me to this. Instantaneous gravity would break GR; but we already detect gravitational waves.

Thank you for being so patient, this is a very instructive thread for me, thanks for starting!

Didn't Einstein favor a static non expanding universe because he thought it would break GR? Now we have a universe with accelerating expansion and stuff falling off the edge of the particle horizon, seems already broke to me.

Didn't Einstein reject spooky action at a distance for the same reason?

If I move a mass from point A to point B then I totally understand the effects of the distortion will not propagate faster than light.

If I remove a mass from the known universe I punch a hole in the fabric of space time, wouldn't the effects be measured across the entire universe at the same time?

We can't remove a mass from the known universe because it violates conservation of energy and breaks GR, right? Yet isn't that exactly what is happening when stuff falls over the edge of the particle horizon when gravity is limited by the speed of light?

Another question... If the universe is expanding and the particle horizon is real, why do we see cosmic background radiation on the horizon no matter which direction we look? Shouldn't we see... "Nothing"? Maybe the CBR is misunderstood and has nothing at all to do with the big bang?

Does anyone know how gravity works???

Thanks again!

 

[JoshuaTree]

Not quite. The galactic rotation curve was one of the first pieces of evidence that there was dark mass out there somewhere, but dark matter explains all of the observations I've been making mostly in Post 4 and Post 5 now.



Galactic supermassive black holes are still being studied re: their formation mechanism. What you describe, depending on exactly what you're saying, is one possibility (that they've just accreted from a bunch of stellar clusters at the beginning of galactic formation). Galactic star formation and death (what we call quenching) are still open fields of research, and in fact, that's where my thesis research is going to be until I move back to dark energy for my PhD.

And why couldn't supermassive black holes be cast out from the big bang? If expansion in big bang was uniform then everything uniformly expanded faster than light quenching any black holes but if not uniform couldn't big bang produce black holes?

 

[JoshuaTree]

Almost nothing happens depending on what dark matter is. You may get some elastic scattering.

If dark matter is largely WIMPs (weakly interacting massive particles), then they'd be a lot like neutrinos. It could pass through miles of baryonic matter without interacting with a single thing. Some searches for WIMPs work the same way searches for neutrinos go: freeze dense stuff as much as possible and check it for the extremely rare collisions that aren't neutrinos.

It's possible that there is dark anti-matter, but it would probably be as rare as anti-matter. If so, dark matter could collide with its dark anti-counterpart and annihilate into photons, the one case in which it would do so. Some searches check for this, too.

But the answer is that dark matter just doesn't really interact. It'd pass through baryonic stuff without a sweat, even if it's weakly interacting.

Ok, if dark matter is subject to gravitational effects, how can it pass through normal matter without interacting with it gravitationally?

 

[JoshuaTree]

Debating cosmology is almost as exciting as debating free will! Almost.

 

[Meow Mix]

Didn't Einstein favor a static non expanding universe because he thought it would break GR? Now we have a universe with accelerating expansion and stuff falling off the edge of the particle horizon, seems already broke to me.

Einstein was thinking from a static universe perspective, but he understood that a static universe is unstable: all it takes is for one thing to move to begin a cascade of instability that would lead to a universe that's no longer static. Thence came his original attempt at "fixing" this by imagining the cosmological constant as a sort of ad-hoc correction pulling against the push of gravitation. If indeed dark energy comes from GR (that is still open research), then he'll have been right for the "wrong" reason basically.

Didn't Einstein reject spooky action at a distance for the same reason?

Einstein rejected this because he wanted to preserve both realism and locality in quantum theory; this was more of a philosophical preference than an attempt to fix anything.

If I move a mass from point A to point B then I totally understand the effects of the distortion will not propagate faster than light.

If I remove a mass from the known universe I punch a hole in the fabric of space time, wouldn't the effects be measured across the entire universe at the same time?

No, the effects would ripple out at the speed of light. If the Sun poofed from existence right now, we'd peacefully have no idea for a little under 9 minutes: we'd still see a glowing ball in the sky and Earth would continue to orbit the spot where it was for the same amount of time.

Are you familiar with force carriers? Gauge bosons like gluons, photons, W and Z bosons; in QM and gauge theories these carry the forces: a magnetic force uses photons to carry the force for instance, so magnetism "travels" at the speed of light, though the field is infinite and permeates all space. Likewise with gravity, the graviton would be the gauge boson in this case, so it would be fair to oversimplify it and say the gravitons already "emitted" from the sun would "still be traveling" for the 8+ minutes until the last one that was emitted before the Sun disappeared arrives.

That's simplified, but perhaps helps conceptualize.

We can't remove a mass from the known universe because it violates conservation of energy and breaks GR, right? Yet isn't that exactly what is happening when stuff falls over the edge of the particle horizon when gravity is limited by the speed of light?

The cosmological horizon is specific to reference frame. Where we see a horizon, someone in Andromeda would see a different horizon. People on the edges of the visible universe (with Earth as the reference frame, to define the "edges") see vastly different horizons (like venn diagrams barely overlapping). So nothing is truly "leaving existence" in this way. It's just leaving our causal frame.

Another question... If the universe is expanding and the particle horizon is real, why do we see cosmic background radiation on the horizon no matter which direction we look? Shouldn't we see... "Nothing"? Maybe the CBR is misunderstood and has nothing at all to do with the big bang?

Does anyone know how gravity works???

Thanks again!

The furthest CMB we see is the time of last scattering, a period when the universe went from being opaque (photons having a mean free path* greater than their horizon at the time) to translucent: it is the furthest "back" that it's possible to "see" because of this.

(* -- the mean free path of something is the average distance it takes for a moving particle to collide; so a very short mean free path means that the particle is interacting very often; for photons this would mean scattering, absorbing, emitting, etc. So a very short mean free path or having a mean free path proportional to a horizon would mean you have something opaque).

The inflationary period actually did blow apart the CMB, but the CMB permeates space. It's precisely because of inflation that we can look on one side of the universe and find a patch of CMB anisotropy that's the same temperature as a patch on the other side of the sky: because those patches were once causally related (close enough to each other) prior to inflation.

 

[Meow Mix]

And why couldn't supermassive black holes be cast out from the big bang? If expansion in big bang was uniform then everything uniformly expanded faster than light quenching any black holes but if not uniform couldn't big bang produce black holes?

Supermassive black holes weren't around during the inflationary period; but primordial black holes may be hanging around from that time (same with magnetic monopoles, but those are predicted to be so diffuse from inflation that we wouldn't expect even one to be in the visible universe that we can see).

 

[Meow Mix]

Ok, if dark matter is subject to gravitational effects, how can it pass through normal matter without interacting with it gravitationally?

It does interact gravitationally, that just isn't very strong with such tiny masses as diffuse particles; it's completely negligible for instance in the presence of a planet.

 

[JoshuaTree]

@Meow Mix , !

 

[Native]

Supermassive black holes weren't around during the inflationary period;

Dear Meow Mix,
With this (IMO strange) "inflation theory", one could just as well conclude everything was coming from a primordial "black hole".

It does interact gravitationally, that just isn't very strong with such tiny masses as diffuse particles; it's completely negligible for instance in the presence of a planet.

It must be very scientifically convenient to have a force which works according to the human consensus ideas.
It (dark matter) can be very strong, holding lots of stars in galaxies and when it comes to explaining this human invented force dynamically, it also can be very weak and even not affecting anything at all.

In fact "dark matter", is just a sign and result of not understood cosmic motions in general and this should be clearly underlined under every article titles about cosmological theory and understanding.

 

[Meow Mix]

Dear Meow Mix,
With this (IMO strange) "inflation theory", one could just as well conclude everything was coming from a primordial "black hole".

There are ideas about universes coming from black holes in other universes (I know these are solutions in LQG, loop quantum gravity for instance); but that's not what's being said here.

It must be very scientifically convenient to have a force which works according to the human consensus ideas.
It (dark matter) can be very strong, holding lots of stars in galaxies and when it comes to explaining this human invented force dynamically, it also can be very weak and even not affecting anything at all.

In fact "dark matter", is just a sign and result of not understood cosmic motions in general and this should be clearly underlined under every article titles about cosmological theory and understanding.

Individual particles have negligible gravity; it takes a lot to have a gravitational influence. Thus in the galactic center where baryons accreted you're not going to find much dark matter to have significant gravitational effects, especially at a local level.

 

[Native]

Individual particles have negligible gravity; it takes a lot to have a gravitational influence. Thus in the galactic center where baryons accreted you're not going to find much dark matter to have significant gravitational effects, especially at a local level.

Can´t you se yourself how this "dark matter multi-tasking rubber-like idea" is a very weak scientific idea in itself?

This "thing" is assumed on the assumption of gravitational celestial motions which de facto was contradicted in galactic realms - and the dark matter assumptions now builds up in all cosmological directions and fills about 28 % of the Universe according to consensus science.

(An the other invented "energetic dark thing" fills almost the rest 68 % leaving only 4 % of known particles and gas)

Nothing much to brag of is it?

 

[Meow Mix]

Can´t you se yourself how this "dark matter multi-tasking rubber-like idea" is a very weak scientific idea in itself?

This "thing" is assumed on the assumption of gravitational celestial motions which de facto was contradicted in galactic realms - and the dark matter assumptions now builds up in all cosmological directions and fills about 28 % of the Universe according to consensus science.

(An the other invented "energetic dark thing" fills almost the rest 68 % leaving only 4 % of known particles and gas)

Nothing much to brag of is it?

I recommend reading posts probably 3 through 5 one more time, as it doesn't seem that you picked up the parts about how accurately dark matter and dark energy predicted from first principles why large scale structure looks the way it does and why baryon acoustic oscillations look the way they do when we plot the multipole moment from the CMB.

Is there anything I can clarify about those facts to impress just how astoundingly strong they are, and why cosmologists don't find dark matter controversial anymore?

 

[Native]

Is there anything I can clarify about those facts to impress just how astoundingly strong they are, and why cosmologists don't find dark matter controversial anymore?

No not really as the very invention is based on former inventions which didn´t work on cosmological scales. IMO you´re driving yourself far astray out in space by accepting such unsubstantiated and unexplainable ideas.

Once you i. e. the stranding cosmological science begin to work strictly with the scientific method of revising or discarding contradicted laws and investigate if other fundamental forces could be at play, we can have a debate which is nuanced compared to the standing one-force discussion.