A possible solution to dark matter and dark energy

A few years ago I presented a cosmological model based on Bimetric Relativity and more recently I posted a thread showing how many different models predict a similarly shaped Hourglass Universe. I would also recommend watching this video to get a deeper understanding of how the model works. In this thread I'm going to make some testable predictions about dark matter which can be compared to observations to prove or disprove this model. Unlike MOND theories this model is capable of explaining both the anomalous rotation curves of galaxies and the overly intense gravitational lensing effects of galaxies, furthermore the nature of dark energy is also revealed by the model.

For those who want a quick explanation of Bimetric Relativity; we start by assuming that negative energy was created along with positive energy during the birth of our universe, because this allows energy to be conserved, meaning the total energy in the universe is zero because the negative energy cancels out the positive energy. This idea is usually called a Zero Energy Universe by scientists. However we take it a step further and say the negative energy has a negative mass, meaning some sort of negative matter must exist. Negative matter would do the opposite of normal matter and remain in a gaseous cloud state rather than clump together, this pushes the galaxies apart and acts like dark energy.

The negative matter would also be repelled away from galaxies and create cavities around the galaxies some times called "no matters land" because they contain very little positive or negative matter. Since taking away negative matter is equivalent to adding positive matter, we can think of the cavity as a sphere of evenly distributed positive matter. This results in an increased lensing effect and produces flat rotation curves, ideally cosmologists like to model the dark matter halo as a sphere with basically uniform density, hence why this model is an extremely promising solution. Neither MOND nor weakly interacting particle models can explain the wide range of phenomena this model can.

Dr. Benoit Famaey (Universities of Bonn and Strasbourg) explains: "The dark matter seems to 'know' how the visible matter is distributed. They seem to conspire with each other such that the gravity of the visible matter at the characteristic radius of the dark halo is always the same. This is extremely surprising since one would rather expect the balance between visible and dark matter to strongly depend on the individual history of each galaxy."

Is Unknown Force In Universe Acting On Dark Matter?

Statistical analysis of mini-spiral galaxies shows an unexpected interaction between dark matter and ordinary matter. ... "We studied 36 galaxies, which was a sufficient number for statistical study. By doing this, we found a link between the structure of ordinary, or luminous matter like stars, dust and gas, with dark matter."

Unexpected interaction between dark matter and ordinary matter in mini-spiral galaxies

What this research indicates is that the amount of dark matter has a dependence on the amount of visible matter and how it is distributed. Until recently I wasn't quite sure how I could measure this relationship using Bimetric Relativity but I always knew it should be possible, and finally I was able to come up with a solution. The plan required the use of a 3D negative mass simulation, to begin with I had a cube with a diameter comparable to the distance between galaxies. The space was filled with positive mass equal to the mass of our galaxy along with an equal amount of negative mass, then I would wait until the positive mass collapsed together so I could measure the size of the cavity formed around it.

I soon realized this approach wasn't great because there was more negative mass in the corners of the cube than anywhere else and it didn't replicate the symmetric forces that would occur in an infinitely flat universe, as our universe seems to be. This is also why it makes sense to contain the matter inside a finite space, the negative matter would fly away in all directions otherwise. Instead of a cube I decided that a sphere container would probably make more sense, and the positive mass became a single large mass to save time waiting for it to collapse. To keep everything contained, if a particle reaches the wall of the container it pops out on the opposite side of the sphere (bouncing off the wall also achieves the same thing).



The only minor issue with the sphere shaped container is that the negative particles initially get repelled from the central mass because they are initially distributed in a random but uniform way, when they reach the sphere edge and head back towards the center it results in a sort of rippling effect which causes the cavity radius to cycle back and forth. However, eventually things stabilize and it's possible to make some reasonable measurements of the halo/cavity radius. The first test was to see how changing the amount of positive mass effected the size of the halo, although I realized after making this chart the x-axis units aren't really correct because I assigned the Milky Way a mass value including the estimated dark matter, but that extra mass is a gravitational illusion in this model.



Since the simulation takes time to stabilize I only took 6 different measurements to create this chart and the data points aren't separated by the same magnitude each time, but I think it still manages to demonstrate that there appears to be a relationship between the mass of all the normal matter in a galaxy and the size of its dark halo. In this model the halo size directly depends on the size and distribution of the central galaxy, it isn't just random luck that all galaxies show this dependency. Other dark matter models cannot explain this because the dark matter and normal matter are seen as two disconnected things with different histories.

The next thing I wanted to measure was how the ratio of positive to negative energy impacted the size of the halo. This model predicts that different parts of the universe could have different ratios due to variations caused by quantum fluctuations in the early universe, there's also a lot of new research suggesting that the density of dark energy changes throughout the universe, which would mean the density of negative energy is changing since negative energy is dark energy in this model. We appear to live in a part of the universe where the negative energy is greater than the positive energy which causes expansion in the local universe.

For the chart above I kept the positive mass set at a constant value around the mass of the Milky Way but this time subtracting the extra dark matter mass. I started with a 50% ratio (same amount of positive and negative energy) and incremented the amount of negative energy. I found that the radius of the halo stayed roughly the same regardless of the ratio so this time I was able to calculate the data points analytically rather than make crude measurements. By subtracting the volume of the halo from the sphere container you get the volume of the "outer shell" which contains most of the negative mass, then you divide the total negative mass by that outer volume to get the density of negative matter. Multiply that density by the halo volume and you have a rough estimation of how much "fake" positive mass the halo will contain.

As mentioned it's really a gravitational illusion caused by the cavity of negative mass, but we can think of it like a sphere of uniform positive matter because it's curving space-time in an equivalent way and that also increases the effect of gravitational lensing. Obviously the main issue with this approach is deciding the radius of the outer sphere because it determines the density of negative energy, which is why I based it on the distance between large galaxies. However, it's unclear what the most appropriate value would be, especially without knowing exactly how the universe started and how the energy was distributed initially, assuming the universe is in fact infinite.

At this point I wasn't entirely happy with those charts, they involved a fair bit of guess work and I wanted something more robust. The next challenge would be to plot galactic rotation curves using the mass distribution predicted in the last chart because if it matched the unusual rotation curves we see in nature then it would be extremely strong evidence this model is on the right track. I started by asking the question "what gravitational forces would you feel travelling to the center of Earth" because the same ideas can be used to calculate the forces produced by the halo since we can treat it like a sphere of positive mass. Since the galaxy is also engulfed a large ball of gas we can also use it to calculate the forces created by the gas.



First though lets think about what a rotation curve is showing us. The above chart shows us the rotation curve for our solar system, since the strength of gravity decays exponentially with distance, called the inverse square law, the rotational/orbital velocity must also decrease with distance otherwise the orbiting object would reach escape velocity. Since the planets are much smaller than the sun the mass of the planets doesn't influence their orbital velocity, the only thing that matters is the mass of the sun and the radius from the sun. The planets in our solar system follow the inverse square law perfectly but when it comes to galaxies things get much more complicated.

Isaac Newton proved the shell theorem and stated that:

* A spherically symmetric body affects external objects gravitationally as though all of its mass were concentrated at a point at its centre.
* If the body is a spherically symmetric shell (i.e., a hollow ball), no net gravitational force is exerted by the shell on any object inside, regardless of the object's location within the shell.

A corollary is that inside a solid sphere of constant density, the gravitational force within the object varies linearly with distance from the centre, becoming zero by symmetry at the centre of mass.

It turns out the Shell theorem will help immensly with this problem because it tells us that if the Earth were hollow you wouldn't feel any gravity regardless of your location inside the shell. For a solid mass this means we can ignore all the mass beyond our current radius. So if you were halfway to the center of Earth none of the mass in the shell of the outer half of Earth would have any effect on you, only the inner part has an effect on you and it can be treated as a single point mass if it's a sphere. You would also feel no gravity at the center of Earth because all the mass is "outside" of you, or beyond your radius from the center.

We can calculate the orbital velocity at a given radius using √(GM/r) where G is the gravitational constant, r is the radius from the center of the galaxy, and M is the mass inside of our current radius. Since the fake positive mass in the halo is evenly distributed we can simply use the formula for the volume of a sphere to calculate the inner mass using a given radius. Calculating the forces produced by the disk of a spiral galaxy like the Milky Way is a little bit trickier because it's not evenly distributed in a spherical ball shape, however we can approximate it as a cylinder and swap our spherical volume formula for the cylinder volume formula. Unlike a sphere, the forces within a cylinder don't vary linearly.

For the gas we again use the sphere formula but we set a maximum radius which extends out slightly further than the disk but is still smaller than the halo radius. If the current radius is higher than the maximum it means we're no longer inside the gas cloud and can treat it as a normal mass where the force of gravity drops off exponentially with distance. We also need to take into account the fact the gas will probably not have a uniform density, gravity will pull together the gas and cause it to be denser closer to the center and more diffuse as you increase in distance from the center. This can be achieved by varying the density based on the radius, and gives it a logarithmic shape similar to the cylinder.

A similar thing actually should be done to the halo calculation because the density of the halo can change, not all of the negative mass stays away from the galaxy, especially if the galaxy is small or highly diffuse. Again we can just vary the density based on distance but because the radius of the halo is so massive the resulting curve is still mostly linear. Lastly we need to account for the central bulge of the galaxy which contains a lot of mass due to the black hole, we can use the same ideas used so far and treat it like a sphere with uniform density. Obviously it's not that simple but we're not really interested in knowing about the orbital velocities inside the bulge anyway, we want to see if the rotation curve drops, grows, or stays flat at large distances.



That is the rotation curve for a spiral galaxy somewhat like the Milky Way or Andromeda, produced using parameters derived from the ideas discussed so far. You can even download the chart I made and mess around with it using this nice open source graph tool. The separate curves are combined to form the final rotation curve and we see the dark halo curve help keep it flat. Compared to the real rotation curves shown in the chart below I'd say it's a fairly good match. It's even got a bit of the waviness seen in some of these real curves, however I think we're not seeing so many waves because I simplified the spiral arms into a uniform cylinder. In reality the density of the disk would vary as you move away from the center and pass through the spirals.

Of course this is the part where I admit there's still a little bit of a problem. You may have noticed from an earlier chart that the fake mass produced by the halo isn't very high unless the negative energy ratio is really high, and that presents a problem because I discovered you need a ratio of around 90% negative energy to get the desired flat rotation curve. I said that the ratio can vary throughout the universe but I didn't expect to see such a large imbalance between positive and negative energy and I still don't think it's very sensible. A large benefit of this model is the way it's built up from simple principles without needing to fine-tuning things like dark energy, but here we are tuning ratios to fit the requirements.

I suspect there is still a piece of the puzzle missing or something I'm overlooking. It will probably take someone smarter than me to figure it out though. One thing I do know is that after staring at rotation curves for hours I can understand them to the point where I can visualize where the forces are coming from to produce the anomalous curves. There is clearly some spherical mass with uniform or close to uniform density which holds galaxies together, whether it's a weakly interacting particle or a gravitational illusion remains to be seen, but hopefully this thread will play a role in resolving the mystery once and for all.

a reply to: ChaoticOrder

I have a thought when you see the absence of stars what do you see black or dark energy. Another thought wheres the energy to spin up atom rotation close to the speed of light. What powers it?
So my thought what if we were inside a black hole out side is the positive and inside is the negative that keeps getting compressed into black holes in to the infinite . And the spinning black hole is forming the galaxies along with the energy for the big bang.From the massive compression to begin with. And that's what dark energy is the black hole the black we see or can't see.

a reply to: Joeshiloh

I have a thought when you see the absence of stars what do you see black or dark energy.

You see an absence of photons.

Another thought wheres the energy to spin up atom rotation close to the speed of light. What powers it?

I'm not sure what you mean by this, what atoms are you talking about? In terms of how a Zero Energy Universe could could contain any object with motion or spin, well it's actually a fairly interesting topic. In my simulation all the positive and negative matter starts off randomly distributed and they all have no velocity, no motion. But the repulsive gravity of the negative particles makes everything start moving around in random ways. If you add up the velocity of all the particles you find it all adds up to zero, all the motion vectors cancel each other out. It's the same basic logic this model uses to explain how a zero energy universe can come from nothing, positive and negative energy exist as real things but it all adds up to nothing.

a reply to: ChaoticOrder

Its just a thought. You asked I gave my thoughts .

When you say negative matter, are you inferring an opposite to baryonic matter, or a descriptor for a new state of interactive matter?

How would this be different from anti-matter?

originally posted by: ChaoticOrder
Compared to the real rotation curves shown in the chart below I'd say it's a fairly good match.

The reason the match doesn't look that great to me is the real curves are relatively flat after a certain radius.
The theoretical curves don't look flat to me, but seem to reach a peak, and are then declining. So it seems to be a not very good match to me.

Matt O'Dowd mentioned the bimetric gravity idea of Jean-Pierre Petit at the 16 minute mark in this episode of his PBS space-time series, which is a pretty interesting look at supporting evidence for the Big Bang model.

Sound Waves from the Beginning of Time

In a previous episode, he mentioned the theoretical problem with negative mass that caused it to yield runaway acceleration, and a commenter pointed out that Petit's idea gets around that. O'Dowd points out Petit's idea is speculative, so I'm not sure how we can get from speculative to backed by observation in this case, especially since I don't see the match in those graphs that you apparently see.

My take on there being some kind of negative mass, is always that lensing will be an issue.

If it is created equal and opposite to normal matter, it logically should give a negative lensing affect. The caviat that 'it doesn't clump' is in my opinion a little bit of a weak assumption. If it repels normal matter... and repels itself, preventing clumping... then the properties are not being conserved at all... despite energy being conserved. It makes logical sense that negative matter should clump with itself, especially in wide 'open' space.

We should see this. Where there are huge voids or known spaces between filaments there should be HUGE negative lens affects. That is not what we see. Same for galaxy clusters. Galaxies embedded in this negative mass, if it is enough to provide the extra force to push the outer edges of galaxies to rotate faster, you would expect anomolies to be present in the deconvolved lens shapes for clusters as you would simply need it to be there... not only to keep the galaxy rotation curves in check, but the clusters held together too.

Lets not forget that the original discovery of the issue was in a cluster of galaxies... NOT the rotation curves (about 60 years later)

a reply to: Archivalist

It's all explained in my previous threads. It's negative energy, and the equivalence principle states all energy has mass, so we're talking about negative mass. Anti-matter only has an opposite electrical charge, it still has normal positive mass, or at least we're pretty sure it does. It's a very hard thing to test, but this year we have several new experiments which are designed to test the gravity of anti-matter and we will get a definite answer soon. It will be a very important result because if anti-matter turns out to have negative mass it will have large implications for this theory and a lot of other models. The Feynman-Stueckelberg interpretation says anti-matter is equivalent to normal matter moving backwards through time, and this model predicts negative mass would experience negative time, so there's a possibility anti-matter is negative matter, but I'm skeptical, I think anti-matter is most likely not the same thing.

originally posted by: Arbitrageur

originally posted by: ChaoticOrder
Compared to the real rotation curves shown in the chart below I'd say it's a fairly good match.

The reason the match doesn't look that great to me is the real curves are relatively flat after a certain radius.
The theoretical curves don't look flat to me, but seem to reach a peak, and are then declining. So it seems to be a not very good match to me.

You're obviously looking at the separate curves in my chart, the combined curve is clearly flat and even rises near the end, and that's the curve you should be looking at. You can view the full sized image here. The other curves represent the different components of the galaxy, the bulge, the disk, the gas, and the halo. For example here's a chart from this stackexchange question which shows a similar thing:

The dark matter component in this chart shows quite a strong curve shape, which would imply the dark matter density is increasing sharply near the center of the galaxy, but in reality we know this isn't the case, we measure dark matter to be distributed in a very uniform way and most theories have trouble modeling this, it's called the Cuspy Halo problem. The model presented here is fully able to explain the uniformity. Also I don't fully understand why this chart shows the disk curve without a peak before the drop, I don't think that is correct but I could be wrong, I haven't looked deeply into how scientists generate these curves and I may have got something wrong with my curves.

In a previous episode, he mentioned the theoretical problem with negative mass that caused it to yield runaway acceleration, and a commenter pointed out that Petit's idea gets around that. O'Dowd points out Petit's idea is speculative, so I'm not sure how we can get from speculative to backed by observation in this case, especially since I don't see the match in those graphs that you apparently see.

I've seen that video, you may even be referring to a comment I made because it annoys me how quick scientists are to brush over these concepts without even trying to understand them properly or see what predictive power they have. Yes negative mass is a strange thing and it's hard to believe but it's clear none of our current theories are cutting the mustard and we need to start considering more radical options.

a reply to: ErosA433

If it is created equal and opposite to normal matter, it logically should give a negative lensing affect.

This is true, however if the negative mass is uniformly distributed through space then the only thing we will see is the lensing relative to distribution. In other words we only notice a lensing effect in areas where the uniformity of negative mass changes, and the only place it really changes is around galaxies. If we're using the space outside of the galaxy as our reference point, then the cavity around the galaxy will appear to have some positive mass. Another way to imagine it is as you get closer to the edge of the halo you're experiencing an increasingly strong repulsive force pushing you back towards the galaxy center, which is the same effect as a uniform sphere of positive mass. If there was a clump or higher density of negative energy in one part of space it would cause negative lensing, but taking away negative mass from a uniform field of negative mass is equivalent to adding positive mass. A similar sort of thing applies to particles in a lattice, a hole in the lattice will act like its anti-particle.

In physics, chemistry, and electronic engineering, an electron hole (often simply called a hole) is the lack of an electron at a position where one could exist in an atom or atomic lattice. Since in a normal atom or crystal lattice the negative charge of the electrons is balanced by the positive charge of the atomic nuclei, the absence of an electron leaves a net positive charge at the hole's location. Holes are not actually particles, but rather quasiparticles; they are different from the positron, which is the antiparticle of the electron. (See also Dirac sea.) Holes in a metal or semiconductor crystal lattice can move through the lattice as electrons can, and act similarly to positively-charged particles.

Electron hole

The caviat that 'it doesn't clump' is in my opinion a little bit of a weak assumption. If it repels normal matter... and repels itself, preventing clumping... then the properties are not being conserved at all... despite energy being conserved. It makes logical sense that negative matter should clump with itself, especially in wide 'open' space.

One of the main challenges of this model is figuring out exactly how negative matter would behave. The Newtonian laws of gravity (F=GMm/r^2) tell us that negative mass would repel other negative mass, however since negative mass is attracted to positive mass but positive mass is repelled from negative mass, it allows runaway motion to occur. Runaway motion is often seen as a huge problem but I don't really think it's that bad, my simulations still work fine using the Newtonian laws because runaway motion can only occur under perfect conditions, any little disturbance will move the positive and negative mass into different trajectories. In the real world quantum mechanics would prevent runaway motion from ever occurring, the Newtonian approach is mathematically valid and performs sensibly in simulations using randomly distributed mass. Only if you start with a single positive particle and single negative particle will you see runaway motion occur.

However the Newtonian laws do have a problem, mainly that negative mass gets attracted to galaxies and that diminishes the lensing effect and doesn't really help with the rotation curves either. That's why this model instead uses Bimetric Relativity, and also because relativity is obviously a more accurate description of how gravity works. The rules of Bimetric Relativity state that negative mass and positive mass both repel each other, however negative mass is attracted to other negative mass and that's a problem I mentioned in my previous threads. The way I basically deal with this is to say that the negative mass would behave like a super fluid or perfect fluid, admittedly it's not the greatest solution but scientists have speculated that dark energy could be a 'dark fluid' with negative mass and researchers have even managed to create a so called negative-mass fluid that flows against the force applied to it. It has also been shown that negative mass only makes sense within certain frameworks of the universe if it's treated like a perfect fluid:

The crucial breakthrough by Mbarek and Paranjape is to show that negative mass can produce a reasonable Schwarzschild solution without violating the energy condition. Their approach is to think of negative mass not as a solid object, but as a perfect fluid, an otherwise common approach in relativity.

And when they solve the equations for a perfect fluid, it turns out that the energy condition is satisfied everywhere, just as in all other solutions of general relativity that support reasonable universes.

Cosmologists Prove Negative Mass Can Exist In Our Universe

originally posted by: ChaoticOrder

The dark matter component in this chart shows quite a strong curve shape, which would imply the dark matter density is increasing sharply near the center of the galaxy, but in reality we know this isn't the case, we measure dark matter to be distributed in a very uniform way and most theories have trouble modeling this, it's called the Cuspy Halo problem. The model presented here is fully able to explain the uniformity.

Just to make something else clear, the halo density would be very uniform in a galaxy like ours, the edge to the halo is quite well defined, so the dark matter "curve" wouldn't be a curve at all, it's just a straight line because the shell theorem states the gravitational force changes linearly with distance inside a solid sphere of uniform density. In my opening post I did mention that I gave it a little bit of a curve but it remained still mostly linear. My point is I didn't do that to make it flat, the final combined rotation curve looks almost exactly the same even when the halo component changes linearly. That is because it's still mostly linear, it's only really curved near the start, and the mass of the central bulge overpowers everything else at close distances. It's also worth pointing out that because my rotation curves are mathematically generated they have sharp points that obviously wouldn't exist in nature, you basically you have to imagine the curve slightly smoothed out.

Another interesting thing worth noting is that in galaxies with low mass cores or no core at all, the curve at the start will be much less steep. You can see this effect when you look at the other chart with the real rotation curves, UGC 2885 is a massive spiral galaxy with a large core and has a very typical rotation curve with a sharp rise followed by a steep decline and then it slowly climbs back up. NGC 801 and NGC 2998 are smaller spiral galaxies with a less sharp rise at close distances, meaning they must have smaller cores. The Wikipedia page on dark matter halos provides the following chart which apparently shows the rotation curve for our own galaxy. The predicted curve is red and the observed curve is blue. The core of the Milky Way appears to have quite a strong effect on the rotation curve, however I'm a little bit confused why that sharp rise wouldn't be predicted because it doesn't require anything unusual to be explained.

If negative mass exists but just isn't present in the solar system then could it be replicated in lab or particle accelerator?

As I understand it not having this is the primary obstacle to the alcubierre "warp" drive.

Actually Newtonian physics doesn't state what you said it does

F is a force observed between the two masses M and m.

IF both M and m are negative, you will expect that negative mass will clump exactly like positive mass does. This was my point, you cannot just say it doesn't based on that equation because it is algebraically incorrect to do so. The negative will cancel and you are still left with a positive force, which in that equation means, attraction.

All that equation would mean is that, negative and positive mass will repel.


On the distribution of dark matter, the plot is misleading as it is showing velocity, not mass but the cuspy halo problem which you talk about isn't an issue for all galaxies, BUT is an interesting issue. There are a few different solution to it which are not completely off the wall. having for example... Dark Matter having a weak self interaction can solve it, the model of thermalizing Dark Matter into almost mono-energetic and cold distribution also can be quite wrong. There could easily something going on that produces the observed cusps.
Dark matter being more than one particle type for example... 'structured dark matter'

a reply to: ErosA433

It wouldn't sound farfetched to me if dark matter was just as if not more complex than baryonic matter. So that could explain variations when we detect it.

Funny I was watching a youtube video where the host was questioning if we're approaching the dreaded "end of physics" where we've explained almost everything we can observe. Something that happened in Einsteins time and then boom relativity and quantum physics happened. What if we're at the cusp of opening up another window and finding out everything we knew was once again just a minority of what's out there?

a reply to: ErosA433

IF both M and m are negative, you will expect that negative mass will clump exactly like positive mass does.

That is true however I forgot that it's a little bit more complicated than that, you use that force to calculate the velocity change of a particle as force/mass. In a particle simulation you can do that every iteration to update the position of the particle. Since the mass is negative the resulting velocity vector becomes negative. I didn't just make up these rules, these are the runaway motion rules and as I said I'm not using those rules anyway.

Runaway motion

Although no particles are known to have negative mass, physicists (primarily Hermann Bondi in 1957,[6] William B. Bonnor in 1964 and 1989,[12][13] then Robert L. Forward[14]) have been able to describe some of the anticipated properties such particles may have. Assuming that all three concepts of mass are equivalent according to the equivalence principle, the gravitational interactions between masses of arbitrary sign can be explored, based on the Newtonian approximation of the Einstein field equations. The interaction laws are then:

* Positive mass attracts both other positive masses and negative masses.
* Negative mass repels both other negative masses and positive masses.

Negative mass - Wikipedia

So is the up in the air question here, whether the negative matter's mass interaction is such with gravity that as it accumulates it either creates a gravitational repulsion, or has the same interaction with gravity as regular mass?

Interesting ideas, but I was certain these possibilities have been explored as thought science for some time.

You're just claiming that experiments that are occurring soon will give us that practical answer?

What will we really do with this knowledge when we know the difference? Refine a model?

Doesn't seem very helpful on the day to day.

a reply to: Archivalist

You're just claiming that experiments that are occurring soon will give us that practical answer?

Like I said the experiments are with antimatter and there's a good chance negative matter is something different than antimatter. Dr. Becky recently uploaded a well made mini doco on the topic of anti-matter, at around the 12:20 mark she speaks to a CERN physicist who mentions they have two experiments designed to test the gravity of antimatter.

What will we really do with this knowledge when we know the difference? Refine a model?

If anti-matter proves to have normal positive mass then it wont really impact anything, our standard models will remain unchanged. If however antimatter does produce anti-gravity then it will basically force us to overhaul our understanding of the universe, and if we accept the existence of negative mass then any new theories we come up with will probably be similar to what I've presented in this thread.

Yep they are going to test it, I actually know the instrument being used for it, as it was being put together on the bench next to our area in the lab when I was working at TRIUMF