Antimatter responds to gravity like Einstein predicted, major CERN experiment confirms

[Admin]

The new study marks the beginning of detailed and direct pursuit of the gravitational nature of antimatter, which remains puzzlingly scarce in the universe.

Antimatter responds to gravity like Einstein predicted, major CERN experiment confirms : Read more

 

[rod]

"If matter and antimatter act so similarly, where's the universe's missing antimatter?
That is still an open question. During the Big Bang, the universe is believed to have been rich with pairs of matter and antimatter particles, with the latter considered matter's mirror as its particles sport the same mass except for an opposite electrical charge. If matter and antimatter particles come into contact, they wipe out each other in a violent flash that leaves behind pure energy, so matter and antimatter particles are always created and destroyed in pairs."

My note. Good question by space.com. Matter and antimatter obeying gravity the same in the BB model, the universe should be energy, we are not here today using that beginning

 

[Questioner]

This is my problem with 'dark matter',
namely its inconsistent response to gravity.
Inside a galaxy it's invariably 'immune' to gravity while it does follow external galactic gravity.

To be gravity immune it would have to be glued,
inertia free,
absolutely unmoving,
, to a location in space-time.
Really?
Not buying it at all.

 

[billslugg]

What do you mean by " 'immune' to gravity" "?

 

[Questioner]

What do you mean by " 'immune' to gravity" "?

In a disk galaxy the inner stars orbit too slowly and the outer stars orbit too fast per expected gravity.
And since we largely don't see stars & planets piling up in gravity 'gutters' from clumps of DM it must be relatively uniformly distributed ('flat') throughout.
So it's in 'faucet washer' shape.
Pulling inner stars out and outer stars in.
On the outside edge of the DM that DM has all this DM on one side and almost nothing on the other side,
Yet over the billions of years of the lifetime of a galaxy it doesn't migrate inward. It's immune to gravity to its own gravity.
Elsewhere in the formation it doesn't pile up around stars and planets so it's immune to gravity there.
Only when a galaxy orbits another galaxy does it follow that curvature of gravity.

 

[billslugg]

Dark matter does not need to be distributed in a "faucet washer" shape in order to explain why the outer stars in galaxies orbit so fast. DM is evenly distributed throughout the galaxy. It could be in disc shape or spherical, depending on the shape of the galaxy.

Here is how differential rotation occurs:

1) At one extreme we have a galaxy in which all mass is entirely at a point in the center. In this case, the classical orbit equations work perfectly. Anything close to the center orbits at a high speed. Anything far away goes much slower.

2) At the other extreme we have all of the mass of the galaxy as a disc shaped or spherical, homogenous cloud with no concentrations of mass anywhere. This cloud will not experience differential rotation, it will rotate as a solid would, same angular speed everywhere. A solid disc or sphere. You could well say "It is immune to gravity".

Here is the problem. Most of the universe's galaxies fall somewhere in between and when we go looking for the mass in that cloud, we can't find it.

 

[Helio]

I think studies have shown that there is a central bulge in DM models, but this was from years ago that I recall this.

Keep in mind that Zwicky was the first to discover DM because of the extra speed found in galaxy clusters. It probably was Vera Rubin's work with Andromeda that made DM mainstream. Gravity lensing effects, per Einstein, are additional arguments for DM, though MOND is still around to be a weaker alternative theory.

 

[Questioner]

Dark matter does not need to be distributed in a "faucet washer" shape in order to explain why the outer stars in galaxies orbit so fast. DM is evenly distributed throughout the galaxy. It could be in disc shape or spherical, depending on the shape of the galaxy.

Here is how differential rotation occurs:

1) At one extreme we have a galaxy in which all mass is entirely at a point in the center. In this case, the classical orbit equations work perfectly. Anything close to the center orbits at a high speed. Anything far away goes much slower.

2) At the other extreme we have all of the mass of the galaxy as a disc shaped or spherical, homogenous cloud with no concentrations of mass anywhere. This cloud will not experience differential rotation, it will rotate as a solid would, same angular speed everywhere. A solid disc or sphere. You could well say "It is immune to gravity".

Here is the problem. Most of the universe's galaxies fall somewhere in between and when we go looking for the mass in that cloud, we can't find it.

Thanks you,
You are causing me to sharpen my thinking.
Excellent brain exercise.

The galaxy is probably more of a web work so i probably need to back off over emphasizing the 'faucet washer',
DM at a minimum must be a disk shape.
A sphere would have stars wandering out of the elliptic plane.
Remember DM is supposed to be 4 times the mass of baryonic matter.

For any/all orbits to be sustained there must be a circular gravity differential ('slope').
This must be concentrically consistent.
It could be some bare minimum.

If a galaxy's web work of gravity is the barest minimum the first passing galaxy would peel off many of the outer stars.
The Roche limit.
Just a thought.

According to reports the outer stars are orbiting too fast.
So there would need to be a sharper differential ring, 'slope' of gravity to sustain that.
That forces some source of gravity to be inside the orbits of the outer stars.
Bring on 'dark matter'.

Dark matter's outer edge has DM and its gravity on the inside and nothing much on the outside,
yet it doesn't migrate inward over a galaxy's lifetime.
So it's immune to gravity there.

Elsewhere in the disk of DM it doesn't pile up around stars and planets and amplify their gravity.
So it's immune to gravity there.

It doesn't seem to be cascading into the central black hole so gravity immunity once again.

DM does exactly one thing.
It produces gravity.
So what is the distinction between DM and simply saying gravity?
Nothing...

but neurotic reflex.

 

[billslugg]

Helio
Yes, there must be some level of bulge in DM. Stars near the edge of the galaxy go faster than visible matter would support but they are not going as fast as they would in a homogeneous model. All galaxies are somewhere in between.
I did read recently they found a galaxy with no need for DM, the velocities at the edge were slow enough.

Questioner
You are correct in that when doing rotation analysis, it cannot be a sphere. If it is rotating it will be a disc. In non-rotating clusters we can look for gravitational lensing to point us to excess gravity.
Yes, we must only consider isolated galaxies.
We recently found a galaxy that has no DM in the disc. It may have all fallen to the center. We just don't know. We can't see it, only some extra gravity.
We don't know that DM is not piling up somewhere. In some images derived from lensing studies, the DM is here and there in huge clumps.

There is no distinction between "DM" and "Extra Gravity". Both referring to the same puzzing observations. Maybe it turns out to be something other than matter, like pure energy. When we find out maybe we'll change the name.

 

[Ian]

In a disk galaxy the inner stars orbit too slowly and the outer stars orbit too fast per expected gravity.
And since we largely don't see stars & planets piling up in gravity 'gutters' from clumps of DM it must be relatively uniformly distributed ('flat') throughout.
So it's in 'faucet washer' shape.
Pulling inner stars out and outer stars in.
On the outside edge of the DM that DM has all this DM on one side and almost nothing on the other side,
Yet over the billions of years of the lifetime of a galaxy it doesn't migrate inward. It's immune to gravity to its own gravity.
Elsewhere in the formation it doesn't pile up around stars and planets so it's immune to gravity there.
Only when a galaxy orbits another galaxy does it follow that curvature of gravity.

Why would you get 'clumps' of dark matter? Normal matter tends to clump because of the electromagnetic forces that dominate their interactions. In the absence of these it is very difficult for particles of any material to shed momentum even if they are drawn to each other by gravity. Instead they would just tend to orbit the centre of mass of a cluster of 'normal' matter, forming a fairly featureless cloud.

 

[Atlan0001]

Read the lead for an article that says because antimatter falls in gravity, antigravity doesn't exist! What stupidity it is to tie one to the other!

 

[Helio]

Helio
Yes, there must be some level of bulge in DM. Stars near the edge of the galaxy go faster than visible matter would support but they are not going as fast as they would in a homogeneous model. All galaxies are somewhere in between.

In more recent times, it has been determined that dwarf galaxies have a higher DM ratio than spirals. One was found to have about 99% DM.

I'm not sure what that suggests, though I would guess that DM anisotropy was instrumental in forming the first galaxies (dwarfs), so perhaps a higher concentration makes sense.

Regarding the OP, I think the take-a-way isn't that antimatter obeys the laws of gravity, but that it doesn't behave with antigravity.

 

[billslugg]

Helio
I also believe DM anisotropy can help explain the early formation of galaxies. There is no reason I can think of antimatter might have antigravity.

 

[Helio]

Helio
I also believe DM anisotropy can help explain the early formation of galaxies.

Agreed. But would normal QM explain this, or must DM particle’s formation require a little extra lack of homogeneity!

There is no reason I can think of antimatter might have antigravity.

But you can guess how many will, and likely have, wax fancy to impress others with this idea.

 

[Slayter]

Can someone explain to an ordinary (non science) person how the article can say that it "conclusively demonstrated that gravity causes the antihydrogen to fall downward" when it also said 20% wandered upward? No one has commented on this so obviously I am missing something and would like to understand what? Thank you for any clarification!

 

[Pogo]

Consider a column of air, or any gas, tall enough, gravity will cause the bottom to be at a higher pressure than the top. The atmosphere is an example. In this experiment, since there were only a small handful of anti hydrogen atoms and nothing else, they would normally lie along the bottom. But, moleculer motion causes a few to be bounced up to the upper regions, just as any gas would. Then they would naturally fall back down and others would take their place.
This could be further proven if they could build a cylinder of sufficient diameter about 100 km high or so and fill it up to standard atmospheric temperature and pressure of the anti equivalent atoms and molecules of our atmosphere.

 

[Unclear Engineer]

And, for what its worth, here is an article that says that our own Milky Way galaxy looks like it doesn't need any "dark matter" to explain its stellar velocities. See https://phys.org/news/2023-09-revisited-mass-milky-smaller-cosmology.html .

Going back to the theories about how dark matter behaves, it does seem to behave differently than regular matter. If it did not, I would expect it to just follow the densities of regular matter, and we would be thinking that regular matter was more massive than we currently think it is, because we would be measuring the same ratio of dark + regular matter everywhere.

But, without being able to detect or explain theoretically what dark matter is and why it has the distributions that it seems to have, we can postulate just about anything and have a hard time disproving it. Hence, conjectures about "dark photons" etc. , and even entire ecosystems of dark matter objects composed of a variety of types of dark matter, not just one form, with all sorts of potential interactions that we simply cannot observe. There are just too many free parameters in the theories to make any real progress in understanding why dark matter behaves the way we think it behaves. And then we get measurements like what is in the link that seem to say we are not immersed in it here, anyway. That would make it even harder for us to detect it, especially in a laboratory - unless we can figure out how to "make" some of it.

 

[Helio]

And, for what its worth, here is an article that says that our own Milky Way galaxy looks like it doesn't need any "dark matter" to explain its stellar velocities. See https://phys.org/news/2023-09-revisited-mass-milky-smaller-cosmology.html .

That's interesting, but look at those error bars! Those look unusual given the quality of the data I would assume they have to work with.

 

[Unclear Engineer]

Are you sure those are "error bars"? I was expecting them to be the actual variability in the measured values, showing ranges of the velocities measured for individual stars at the various distances. If the stars are not in circular orbits, then those at the apogalacticon and perigalacticon of individual orbits would be going at different velocities. If stars are born in "stellar nurseries" with a lot of massive bodies forming and then kicking individual members out of the region by gravitational "collisions", I would expect a lot of non-circular orbits. It would not surprise me if the stars in the outer edges of the disks are in the most elliptical orbits. Actually, since this is really a [huge number] body problem in orbital mechanic, I don't even expect the orbits to be classically elliptical.

 

[Questioner]

DM is hypothetical matter to explain unexpected (by all appearances) gravity.

The problem is when one plugs in matter where the gravity indicates (in a galaxy) one ends up with ridiculous, self contradicting properties for matter.
Notably intra-galactic immunity to gravity and exo-galactic attraction/response to gravity.

So far all and the only evidence is of gravity.
And gravity on its own explains what is seen,

perfectly.

It may be higher dimensional vectors of gravity or some exo-universal caused gravity,
but for all appearances is some kind of curvature.

I guess one needs to differentiate between expected matter caused gravity and other sourced curvature that maybe needs identifying distinction (name, adjective, label).

Saying
'Dark gravity'
'extra gravity'
or
'unexplained gravity'
would be much more precise
and not misleading.
It would address the actual issue head-on.

Matter is, however, a failed hypothesis.

 

[Helio]

Are you sure those are "error bars"? I was expecting them to be the actual variability in the measured values, showing ranges of the velocities measured for individual stars at the various distances.

Yes, that makes more sense. Having a ton of data at those distances should justify their result, but a small inaccuracy would reveal a DM result. The evidence of the great abundance of DM in dwarf galaxies, and the two or more that the MW is currently absorbing, should be evidence that we have more DM than their findings. But it's interesting, regardless.

It would be interesting to see how many DM theories are still on the table. I recall reading one author who listed about 24 DE theories, each by their own name, even though DE is still quite dependent on only a small number of difficult observations, unlike DM effects.

If the stars are not in circular orbits, then those at the apogalacticon and perigalacticon of individual orbits would be going at different velocities. If stars are born in "stellar nurseries" with a lot of massive bodies forming and then kicking individual members out of the region by gravitational "collisions", I would expect a lot of non-circular orbits. It would not surprise me if the stars in the outer edges of the disks are in the most elliptical orbits. Actually, since this is really a [huge number] body problem in orbital mechanic, I don't even expect the orbits to be classically elliptical.

Yep, that's logical, but without knowing their orbits, only statistical efforts can be applied, and it may be less accurate than implied.

 

[Helio]

I guess one needs to differentiate between expected matter caused gravity and other sourced curvature that maybe needs identifying distinction (name, adjective, label).

Yes. And it has a name given it by Fritz Zwicky... Dark Matter.

 

[Unclear Engineer]

. . . Having a ton of data at those distances should justify their result, but a small inaccuracy would reveal a DM result. . . .

It would have been nice if the link I posted had included a graphical comparison of the data against the results that would be expected from both the Keplerian and the DM theories, instead of just showing the fit to the Keplerian model.

 

[Helio]

It would have been nice if the link I posted had included a graphical comparison of the data against the results that would be expected from both the Keplerian and the DM theories, instead of just showing the fit to the Keplerian model.

Yes, but I think that what DM has shown is somewhat flat velocity profiles with galactic radii. That's what Vera Rubin had found with Andromeda.

 

[Questioner]

Yes. And it has a name given it by Fritz Zwicky... Dark Matter.

Let's call a square 'the less rounded circle',
not even the isometric rectangle.
Obfuscation not information.

Academics, 'authorities' and government officials do favor impenetrable obfuscation over clear, bell like clarity. It makes them indecipherable.
A party to the condescending exclusionist 'information priesthood'.

'Dark matter' as a tag explicitly indicates matter.
Matter is NOT what ANY of the evidence identifies.
It's gravity, gravity, gravity & nothing else.

Oh dear, the Universe doesn't fit into the neat little magic boxes in our imaginations...

Gee, isn't science there to understand things based on the evidence and not our neurotic presumptions?

If we pay attention we learn new things,
maybe things we don't like to believe,
maybe scary things.
Not with the absolute certainty of magic & religion,
but with the working handle of rational evidence.

Prediction & determinism are nice,
but real science has never had a guarantee of that.
Only arrogant dimwits who have religious faith the universe is an absolutely closed, deterministic system presume that.

Sorry,
Godel already nixed that nonsense.