In a stringent test of a fundamental property of the standard model of particle physics, known as CPT symmetry, researchers from the RIKEN-led BASE collaboration at CERN have made the most precise measurements so far of the charge-to-mass ratio of protons and their antimatter counterparts, antiprotons.

The work, published in *Nature*, was carried out using CERN's Antiproton Decelerator, a device that provides low-energy antiprotons for antimatter studies.

CPT invariance—which the experiment was meant to test —means that a system remains unchanged if three fundamental properties are reversed—C (charge), which distinguishes matter from antimatter, P (parity), which implies a 180 degree flip in space, and T (time). It is a central tenet of the standard model, and implies that antimatter particles must be perfect mirror images of matter, with only their charges reversed.

"This is an important issue," says Stefan Ulmer, who led the research, "because it helps us to understand why we live in a universe that has practically no antimatter, despite the fact that the Big Bang must have led to the creation of both. If we had found violations of CPT, it would mean that matter and antimatter might have different properties—for example that antiprotons might decay faster than protons—but we have found within quite strict limits that the charge-to-mass ratios are the same."

To perform the research, the team used a scheme similar to that developed by the TRAP collaboration in the 1990s. They received antiprotons and negative hydrogen ions—as a proxy for protons—from the Antiproton Decelerator, and then trapped single antiproton-hydrogen ion pairs in a magnetic Penning trap, decelerating them to ultra-low energies. They then measured the cyclotron frequency of the pairs—a measurement that allows scientists to determine the charge-to-mass ratio—and compared them to find how similar they were. In total, they measured approximately 6,500 pairs over a 35-day period.

"What we found," says Ulmer, "is that the charge-to-mass ratio is identical to within just 69 parts per trillion." This measurement has four times higher energy resolution than previous measurements of proton-antiproton pairs, and further constrains the possibility of violations of CPT invariance. "Ultimately," he says, "we plan to achieve measurements that are at least ten or a hundred times more precise than the current standard."

The work also has implications for what is known as the weak equivalence principle—the idea that all particles will be affected by gravity in the same way, regardless of their mass and charge. The team used their findings to calculate that within about one part per million, antimatter and matter behave in the same way with respect to gravity.

According to BASE member Christian Smorra, "There are many reasons to believe in physics beyond the standard model, including the mystery of dark matter and, of course, the imbalance between matter and antimatter. These high-precision measurements put important new constraints and will help us to determine the direction of future research."

**Explore further:**
Measuring the magnetism of antimatter: Researchers measure antiprotons more accurately than ever before

**More information:**
High-precision comparison of the antiproton-to-proton charge-to-mass ratio, *Nature*, DOI: 10.1038/nature14861

## Returners

Obviously, your calculations are wrong.

## malapropism

However, given that antimatter exists (it can be created in lab conditions), the question of why the universe is one type (or a mix) instead of the other rather obviously presents itself. Apart from actually observing the creation of the universe (good luck with that) to figure out the disparity, how would you suggest this be investigated, and where the researchers' calculations might be wrong, as you claim?

I suggest that there is no "obviously" about it - the calculations may indeed be wrong but I'm certain that this is far from obvious or those same calculations would have had the obvious error(s) corrected.

## docile

Aug 12, 2015## Benni

What "calculations"? There's nothing in the article about calculating anything, only making "measurements" in the production of anti-matter.

## malapropism

Yes, technically correct however I made an assumption that @Returners was referring to calculations implied in the article end-quote from Smorra about the imbalance of matter and antimatter and the "important new constraints" on the Standard Model. Perhaps I ought to have been more explicit in this; my apologies for the oversight.

## Mimath224

## Returners

Model disagrees with observation, therefore model is wrong.

Obviously.

## marcush

I'm continuously amazed by the arrogance of amateur web pundits. When you guys start getting paid to do physics research and actually publish something worthy, only then start taking yourselves seriously. Only then will the rest of us do likewise.

## docile

Aug 13, 2015## docile

Aug 13, 2015## Mike_Massen

There is another possibility given what we know of uncertainty & variance...

That there was an almost equal amount of matter/antimatter at the point of initiation which produced enough energy for the 'so called' big bang like event but, the variance in amount, although of many millions of a % difference show one type of matter is left over after all the annihilation conclude.

Although appears Vast in our matter based universe, what we may be seeing is just that small % left over, then as such, there is no problem re where anti-matter went etc.

The CMBR fine details & other clues founded at deepest level of QM which shares part of the paradigm may well cover this satisfactorily, in that case the variance although very small still results in a net amount of matter we observe.

I don't see a problem with that.

## docile

Aug 13, 2015## docile

Aug 13, 2015## docile

Aug 13, 2015## docile

Aug 13, 2015## docile

Aug 13, 2015## docile

Aug 13, 2015## docile

Aug 13, 2015## Mike_Massen

Awful narrow simplification not worthy of intelligent cognition

In Science, especially Physics one learns early on issues of uncertainty in any & all measurements but, along with mathematics of limits & calculus & especially integration one can produce a valid model which carries through those measurement errors and through equivalent calculations as per the data pass through and generate valid "Error Bars"

One direct & practical application of the value of modelling & how it deals with obvious chaos & integration is the petrol spark ignition engine & its modelling performed by an engine computer

ie Chaotic process of combustion but, integration re heat/power is not. There is however an error bar/range which pops out & is measurable directly Eg Lambda/stoich, the feedback is fed back as Eg, same paradigm re AGW

Continued

## docile

Aug 13, 2015## Mike_Massen

swordsman states BH attracts matter/anti-M re gravitation & afaik mass of both protons <-> anti-protons is (so far) same

swordsman claims No. Although, from your earlier posts I see where your opinion originates

Consider Protons/anti-P fall into BH & annihalate but, after they've crossed the event horizon, all energy released eg gamma etc will be unable to escape thus be drawn to the massive center which may after-all be a sea of energy ie not as particles

Mass/energy in BH conserved whether anti-P or not, gravitation continues unabated

I don't accpet center of BH has zero size, likely n-planck relationship

BH gravitation confirmed re observation

## Hyperfuzzy

Maybe we should rethink anti-matter is not anti- at all! In fact, we haven't began to define charge; but do we have some cool tools!

## Hyperfuzzy

If it is only charge, is charge transparent? The fields overlay and add in this vector space, so ... each point has a set of attributes. Define each element's possible state. then we try to define matter.

## Benni

Dark Matter Enthusiasts would disagree with you......but then again, how many of them have ever seen a Differential Equation they could solve?

## Mike_Massen

You seem to be tangentially implying your maximum level of education is DE's, so is this taken as confirmation you have missed out on uni studies so therefore your implication of higher study in may other posts are false ?

Benni I've challenged you on a few occasions over the past months as have others & especially so re this DE re heat/climate

https://en.wikipe...transfer

In respect of your jibe re claiming unknown people cannot do what you imply you can, then why have you never been able to; address it, manipulate or even pursue some evaluation under appropriate conditions.

Eek a real DE - oh no !

Lol

## TheGhostofOtto1923

Getting sober is the hard part eh Lrrrkrrrr?

## antialias_physorg

Particles that aren't indivisible (electron? quarks?) will be torn apart/decay long before they reach the center. Forces like the weak force (and the strong force) are limited to below the speed of light. So any kind of spatial imbalance (nucleons within a nucleus or even the quarks within nucleons) means that some will stop feeling the forces of their brethren that are further 'in' once the event horizon is crossed.

(Actually this means that such composite particles as protons, neutrons - and of course entire nuclei - will already disintegrate ever so slightly before they hit the event horizon whne the imbalance grows large enough)

## Hyperfuzzy

How do you know this? PhD does not know truth, for them its a search. Common sense not included. did anyone find anything other than charge? Anti-matter, huh? Nonsensical!

## Mimath224

## Da Schneib

## antialias_physorg

Good catch...I was trying to write indivisible...but wanted to change to "not divisible"...and stuff got jumbled.

It is currently uncertain whether electrons or quarks can be split given sufficiently high energies. If they can't be split then they would (presumably) survive inside a black hole.

Forces are mediated via force carriers (photons, gluons, W/Z bosons....possibly gravitons, but the latter has, as of yet, no experimental evidence to back it up). As such the force carriers are limited to the speed of light (or below). Put that together with the fact that at - or within - the event horizon nothing can move further away from the center of a black hole and you get the conclusion I have outlined above.

## Da Schneib

There might be unicorns in there, but if there are, we'll never know.

Personally my opinion is that all the mass a black hole "eats" is trapped in the region just outside the event horizon. The shell theorem means that this cannot be distinguished from it being inside the event horizon; the gravity effect will be the same. Nothing, in this view, ever passes the event horizon; it just keeps getting more and more infinitesimally closer to the event horizon.

contd

## Da Schneib

This is dictated by the fact that as things come closer and closer to the event horizon, their apparent time grows slower and slower according to relativity.

Thus, my answer to "what's inside a black hole" is "nothing." All the mass the hole has, as we see it, is concentrated into the region just outside the event horizon, going slower and slower, and never quite crossing the event horizon because it can never get there due to time dilation.

I am surprised that no one ever notes this as a possibility in the literature.

If there is any material inside the hole, it is what was already inside the event horizon at the time the hole was formed; everything else the hole has "eaten" since that time is, as I say, concentrated just outside of the horizon.

That is, if relativity is correct in the ultraviolet limit.

contd

## Da Schneib

For reference, the shell theorem states that if all the material supposedly inside the radius of a sphere were concentrated on that sphere's surface, outside the sphere no difference could be told between that situation and the situation where the material is evenly distributed within the sphere, nor the situation where all the material is concentrated at the center of the sphere. This theorem has been known since the seventeenth century, and was first proved by Sir Isaac Newton. https://en.wikipe..._theorem

Since it is a theorem, not a theory, it is capable of mathematical proof, and Newton provided that proof.

See conclusion #1 in the introduction of the Wikipedia article.

## antialias_physorg

However the subjective time of someone approaching the event horizon does not change. So they definitely would cross over (if they could cross over whole, that is).

What an outside observer sees is just the last few seconds stretched out to infinity (well..not even that. As the number of photons emitted prior to crossover is finite. So there is a time by which the last photon - severly redshifted and at a much later date as it may be - is recieved)

The shell theorem comes about because all paths that cross the event horizon end up at the singularity. So however you are looking at the event horizon you are always looking in direction of the singularity. But the way I see it that in no way says that stuff stays at the event horizon (that is only an apparent effect...it would also go counter to all kinds of conservation laws, like conservation of momentum).

## Da Schneib

I'm not quite clear on how it would violate momentum conservation. Can you explain that more carefully, please?

contd

## Da Schneib

I should be careful here to note that the shell theorem merely explains why we couldn't tell if this situation (all the mass that's supposedly past the event horizon is actually packed just outside it) were correct, or if the mass had actually passed the EH; the gravity effects would be essentially the same. It's time dilation as you approach the EH that is the actual cause of this (assuming of course that I'm right, and I can't see, given that time dilation, how I can be wrong).

Suppose, for the sake of argument, again ignoring spaghettification by tidal forces, we could send a probe in very close to the EH, and then have it come back. Wouldn't it come back to find out millions or billions of years had passed in the outside universe? My understanding is that at the actual EH, time dilation is infinite, from the POV of the rest of the universe. Is that not correct?

## Da Schneib

Note that I rearranged the equation to give coordinate time instead of proper time as the output.

It says the ratio of coordinate time (far away from the black hole) to proper time (falling into the black hole) is:

t[c] = t[p] / ⎷(1 - r[s]/r)

Where,

t[c] is coordinate time

t[p] is proper time

r[s] is the Swartzchild radius (i.e. radius of the EH)

r is the distance of the close in observer from the center of the BH

Now, if r = r[s], then r[s]/r = 1, 1 - 1 = 0, and ⎷0 = 0. Thus, an observer far from the BH sees the proper time of the observer at the EH as stopped; any amount of proper time is an infinite amount of coordinate time. I was pretty sure I was right about that. I think I'm right here. I might not be for a Kerr BH (rotating) and I'd be interested to know by how much I'd be off, say at the equator of the BH.

## antialias_physorg

I agree with the observation part. We see the not-quite-crossing-over forever...in theory. In practice we see the object fading so far into the low end of the electromagnetic spectrum that it becomes undetectable by even theoretical receivers due to th massive redshift almost instantly.

Also remember that 'seeing' is the act of receiving at least one photon. The object doesn't suddenly start emitting more photons just because it gets close to the event horizon.

If the matter were truly stuck at the event horizon then all motion would be reduced to a tangential trajectory. Any kind of radial momentum it had would somehow go 'poof'...and I'm not sure by which mechanism that would be possible.

## antialias_physorg

I agree with this. My point is:

From the outside we don't see stuff pass the event horizon.

From the outside we cannot tell whether stuff is on the event horizon or inside by any kind of measurement.

However: Stuff does pass the event horizon nevertheless.

Still that does not prevent the probe itself from crossing over (if it chose to do so instead of coming back). It is accelerated inwards on its trip and would cross over in finite time in its own reference system (i.e. send out a finite number of photons before it crossed over).

## antialias_physorg

So we could get to the paradoxical situation that stuff resides on the horizon but the horizon grows...which means having that stuff move further away from the singularity. which - I think - isn't allowed.

## Hyperfuzzy

## Hyperfuzzy

## Da Schneib

But it's still, from our POV, just outside the EH. And I can't see, if the equations I posted or correct, how it can ever actually pass it in our universe.

Sure but the question is whether the mass ever actually crosses the EH, and the answer appears (from those equations) to be "no."

contd

## Da Schneib

If the matter were truly stuck at the event horizon then all motion would be reduced to a tangential trajectory. Why? Just because the BH and EH are rotating doesn't impart rotation to infalling matter.

## Da Schneib

But it will never happen according to our POV.

contd

## Da Schneib

I agree with this, but point out that (again, if the equations from the Wikipedia article are correct, and I believe they are, with, again, the proviso that it may not be so for a real (i.e. Kerr) BH), nothing ever actually "falls in" past the EH according to coordinate time (that is, our time as observers far from the BH).

I'm really interested in whether the exposure of the ergosphere has any impact on this situation.

## Da Schneib

OTOH, perhaps the mechanism is that the EH "grows past" the matter, at the last moment due to the addition of mass *even though it starts out past the EH*. After all, the location of the EH is determined by X mass within R radius, and you can't keep adding mass to a shell just outside the radius without increasing the radius. I suspect this is the answer to my conundrum.

## antialias_physorg

But we don't observe all the events that happen in the frame of the thing passing the event horizon. We only observe the part until it reaches the event horizon - and that part stretched out over, for us, infinity. The rest of the journey is cut off from our perception (but not from what actually happens). The arbiter of what is real is not a far off observer but the object.

All paths at the EV are almost completely radial.

If the stuff truly did not cross the EV then the radial component relative to the EV must be reduced to zero (or as close as makes no difference). This would mean all radial momentum would have to become zero and only tangential momentoum would (could) remain. I can't get that to work with conservation of momentum.

## Hyperfuzzy

So infinite density is fantasy! It makes no sense!

## Da Schneib

No, that's a constraint on all stable orbits. Better double-check your references on that one.

## Hyperfuzzy

The way I see it, everyone seems to know all this yang makes no sense!