In the typical parametrization, it’s the 2-3 angle that’s near 45 degrees. 45 degrees is still within the 1-sigma-ish allowed range, but the latest results from this past summer have interestingly shifted the best-fit away from maximal mixing (or, rather, sin[sup]2[/sup](2[this angle]) has a best-fit value slightly away from unity).
Note: I am not claiming it does not interact; I am speculating that if it was mostly oriented differentially in small curled up n dimensions it would mostly only interact gravitationally and an n-dimensionally symmetric particle would appear asymmetric, when it was observable. Such a speculation does not require that antimatter be the sole source of dark matter. Or that antimatter is the only substance with major projections into small curled up dimensions.
IF one accepts that there are a variety of small curled up spatial dimensions (I know a big IF to many, still very speculative and hard, but not impossible, to test, but felt to be likely true to many others) THEN the idea that all particles, especially but not exclusively n-dimensionally mirror symmetric ones, would travel within those confined dimensions in exactly the same “planes” seems ludicrous to assume, at least to me. Some of these particles could be even massive but because of being oriented differentially in n-dimensional space only weakly interactive, except by gravity.
Do the thought experiment. What would such a circumstance look like? How does that compare to what we observe? More importantly, what does it predict we would observe in the future if we looked specifically for it? Specifically what would it predict that was different than if matter and antimatter each only exist in three spatial dimensions (or alternatively, if extra curled up dimensions exist then for seem reason have the exact same projections within each one)?
Specifically, are there results different than what might be otherwise expected that could come out of the AEgIS experiment if we assume that antiprotons can travel differentially within some number of curled up dimensions? As the researchers at CERN study trapped antihydrogen could they observe some disappearing without annihilation being noted until an unexpected long distance away?
I believe the speculation makes some falsifiable predictions, but they are only falsifiable if they are looked for, and that can only be done if the ASSUMPTION that there is little antimatter in the universe is at least held up as an unproven assertion.
The behavior you propose introduces more questions than it answers. Under what formalism can matter and antimatter live in different subspaces as you describe?
While it is true that the language you’re using comes up in developed theories (i.e., discussions of extra dimensions and things that live in them), it doesn’t make sense here. If you can forgive the silly analogy, consider the following.
A cat can be lost by getting hit by a car or by running away. If someone comes up to you and says they lost a dog, you might extrapolate that a dog could be hit by a car or could run away and that maybe one of those explanations applies to the lost dog. However, if someone says they lost their keys, you would not suggest that maybe the keys ran away or got hit by a car. Keys are lost by getting left in pants pockets (unlike cats) or by falling in couch cushions. The fact that the language has parallels doesn’t matter. Keys, cats, are dogs are specific, defined things, and assuming the methods of loss translate across different objects is not always sensible.
When one says that the universe has a matter-antimatter imbalance, those two things (matter and antimatter) are very specific things. It doesn’t make sense to say that one “is oriented in” another dimension from the other. Such language does apply for certain things, but not this.
Sorry but your analogy seems only silly and not apt at all. If anything it actually illustrates my point.
We already know what keys are and where they can go; we know what dogs are and where they can go. We don’t know the same about antimatter, nor even matter relative to any possible curled up dimensions.
You are claiming that we know a priori how fundamental matter and antimatter particles can behave relative to multiple curled up spaces, as if these are imagined abstract concepts that we have defined. But they are not. If anything the imagined objects were perfectly symmetric to each other and the mental gymnastics has been to create some asymmetry between them in order to explain what we see with the assumption of the three extended dimensions being all there can possibly be. But perhaps there is no need to speculate as to why they are not actually symmetric because as objects of greater dimensionality they are.
Think of the construct I am suggesting be considered this way perhaps: icebergs and some hypothetical exact opposite that has most of its bulk above the waterline and only a small bit that can be seen from the POV of under the water.
Chronos, thanks on “knobs” and angles.
“Knobs” I had correct in my mind–it’s a pretty and useful metaphor. I wonder if non-physicists use it similarly. They should.
Re angles: I’m stunned, but I actually understand your post. Again, thanks, it opened up my mind. Beautiful math concept for me, hair-raising physics.
I’ll let you boys go back to your play now.
Oh shit I just read Pasta. And DSeid.
Pasta let me turn your question around. Assuming some number of small curled up spatial dimensions under what formalism would the truly n-dimensional fundamental particles of matter and antimatter, or even of all matter particles have to travel within those dimensions in exactly the same ways? Why would one assume that? If one does not assume that what would an n-dimensional universe with equal parts of perfectly symmetric (in greater dimensionality) look like, especially to creatures who can observe only the three extended spatial dimensions and a particular slice of the curled up ones that they, beings of matter, tend to travel within?
To go back to your keys analogy, the fact that there are no keys where the light is good, under the lamp post, where I have been looking, is not solid evidence that the keys do not exist. Maybe such was a reasonable presumption if we assume that all of the universe is contained under the view of the lamp post’s light, but once we assume that some world exists beyond the range of the good light we must remain open to the possibility that keys exist where we cannot see them. Of course such is not proof they do exist either, but I can remain open to the possibility that they do. The question then becomes how to test it. What predictions does it make, if any, that would be different than few antimatter particles with asymmetries that exist for some reason?
It sounds like you’re assuming we exist at a point in the curled up dimensions. For example, if there were only a single curled up dimension, that we exist at some (possibly time varying) angle of that tube, phi(t). And that you’re wondering about some other matter that’s at some other angle on the tube, theta(t), which only intersects our angle now and then (and with more curled up dimensions, they would only rarely intersect). Am I understanding this right? Because that’s not how tiny dimensions are expected to work.
No, not right.
I am speculating that objects project into various curled up dimensions and travel within them in not exactly the same ways. Each object can and does exist as an object with multiple (greater than 3) dimensions, not as points.
DSeid, any such explanation must contend with the fact that we have produced antiprotons and positrons in the lab, and so far as we can tell, those produced antiparticles appear to interact with spacetime in exactly the same way as their more familiar partners (in fact, they appear to do everything symmetrically to their more familiar partners, or at least to come extremely close to symmetry). So you’d not only have to posit that antimatter behaves differently with respect to the extra dimensions, but you have to posit that only some antimatter behaves differently. You might argue that the antimatter particles all got “re-oriented” or whatever at some early stage of the Universe’s evolution, and subsequently got stuck that way, but then you have to explain why that same re-orientation event didn’t happen to the matter particles.
Really? So far those produced antiparticles have NOT been so well studied and most of the focus is indeed on noting the ways in which they are (other than mass) different than particles. The big deal was that CERN has kept some in one place. And the only way they know any were there was to detect annihilation events when they came into contact with matter as they were released.
Here’s an experiment I’d propose:
Create a defined population of anti-atoms multiple times, carefully measuring annihilation events around the bottle the whole time from creation until release. Release at various points in time from a few ms to the current record of 15 minutes. IF anti-atoms must travel in the same exact dimensions to the same degree as matter then the total annihilation events from creation to release will be the same at all time points. IF some can escape by way of travel “above” or “below” regular matter then there will be fewer total events the longer they are held. Yes it would require enough trials to average out the noise from background annihilation events.
BTW your “re-oriented” word choice reveals to me that I am doing a poor job expressing myself. I am sorry.
No, not “re-oriented.” Taking to a different orientation by their very nature. Just picture that in regards to one or more curled up dimension one tends to slightly sink up and down and the other tends to slightly float up and down, in mirror images of each other
That line of research uses the word “antimatter” in a rather specific way, namely to mean an anti-atom. Antimatter in the general sense (and in the sense that is relevant for cosmology) is any antiparticle, even in isolation. Antimatter in this more general sense is extremely well-studied and is created, manipulated, utilized, and kept around for long periods of time regularly, often in scenarios where its relation to spacetime is manifest. The low-temperature niche studies (like those at CERN) of bound states of antiprotons and antielectrons to make antihydrogen are difficult, which is why it is a big deal overall, but it’s not reflective of our knowledge of “antimatter” meaning all antiparticles.
Because matter and antimatter are intimately related in ways that are also intimately tied to spacetime, Lorentz invariance, etc. If you want something that’s not matter that can live in the bulk(*), then that thing isn’t antimatter.
(*) bulk = the higher dimensional space of which we experience a subspace
I’m not saying that multidimensional theories aren’t related to the baryon assymetry. In fact, there are many cromulent ones out there that attempt to shed light on the asymmetry. But the characters in the play are somewhat constrained by their very definitions. It is also true that multidimensional theories often get reduced into intuitive-sounding stories as the elevator pitch, but it is not always (in fact, usually not) mathametically valid to generalize the story.
This is way harder than you need. If you just want antimatter and matter to annihilate, you can just use protons/antiprotons or electrons/antielectrons rather than trying to get them to join up into atoms first (which is an experimental tour de force, to be sure). And that’s exactly what several decades of colliders (Tevatron, LEP, KEK-B, PEP-II, etc.) have been doing, recordings billions upon billions of matter/antimatter annihilation events.
Cromulent. I had to look it up.
Ditto embiggen:
The first occurrence of the word was in the journal High Energy Physics in the article “Gauge/gravity duality and meta-stable dynamical supersymmetry breaking”, which was published on January 23, 2007.[12] For example, the article says: “For large P, the three-form fluxes are dilute, and the gradient of the Myers potential encouraging an anti-D3 to embiggen is very mild.”
You guys, you.
Antimatter galaxies, even if they exist, couldn’t be the same as dark matter. First, antimatter is known to experience the electromagnetic force, so it should emit light. Second, many of the observations that have been seen as the strongest evidence for dark matter (galactic rotations curves, the bullet cluster) require it to be right next to the regular matter. If the dark matter were antimatter, we’d see it annihilating.
We actually know quite a lot about antimatter. I do not think your suggestions are consistent with what we know about antimatter. For one thing, if antimatter traveled along additional dimensions that regular matter can’t, I think we would expect its apparent mass to be different than for regular matter, like with Kaluza-Klein particles.
Please don’t take this as an insulting comment, but what kind of background do you have in physics? I am pretty sure both Chronos and Pasta are professional physicists. If you are working from a popular-level understanding (e.g., haven’t actually taken courses in quantum field theory, etc.) then possibly you’re out of your depth.
At the risk of being whooshed, surely the first occurrence of the word was in “The Simpsons”?
No insult received. And indeed I am not a physicist. At the same time I have had these discussion with friends who are (well one still is and works at Fermi, including on the antiproton project … the other was downsized) and have not been laughed out of the room.
Yes though, my level is that of the elevator pitch. What I am looking for is an understanding, and perhaps pasta can provide it, of how we know that some portions of individual matter and some of antimatter particles are not within the bulk and differentially so.
No I am not just interested in annihilation. More in the annihilation that should occur but that does not. But I’ll stop now. But let’s check back after ten more years of the antimatter study and see if someone with the actual chops comes up with a more generalizable mathematically valid version of something similar. And know then, you heard it here first!
Ugh. Nasty typos.
Toward this, take a look at the wiki page on Dirac spinors. This wiki entry is obviously way too technical, but if you skim it (even just the words), you’ll see hints of the sort of relationship that particles and antiparticles have. These aren’t like two different species, say charm quarks and electrons, that could do very different things without too much fuss. Particles and antiparticles are two sides of the same coin, and they show up in parallel in all the formalism we have at hand, including multidimensional theories. That is, their spacetime relationships are fundamental and are preserved even in multidimensional theories that do put things into the bulk. Breaking that isn’t a quick fix to explain baryon asymmetry; it’s a discarding of all of the theoretical groundwork back to the birth of relativistic quantum field theory. Maybe that’s what’s needed, but if we throw all that out, the first question isn’t “Did we get the baryon asymmetry right?” but rather “How do particles work? What’s energy? What’s an interaction?”