Anti-matter is unstable matter

[sanctus]

As usual it is all relative :)

 

If you are a bad lucky astronaut who falls into a black hole it will last a couple of nanoseconds in your time, but for an observer who is far enough, you never get into the black hole, but approache it asymptoptically. Eventually you, the bad lucky astronaut, disappear anyway, simply because the light you emit gets always more redshifted...

 

The only fishy part I see in all this is that the observer has to be infinitely far away to not havve to feel any influence...

[LaurieAG]

University News Line

 

The Universe is actually twice as bright than was previously thought, according to research conducted by a team of astronomers from Australia and Europe.

 

Apparently this is caused by particles of graphite and silica blocking half of the photons arriving. Hopefully this should shed some light on the matter:)

[alexander]

If you are a bad lucky astronaut who falls into a black hole it will last a couple of nanoseconds in your time, but for an observer who is far enough, you never get into the black hole, but approache it asymptoptically. Eventually you, the bad lucky astronaut, disappear anyway, simply because the light you emit gets always more redshifted...

right, being the person that falls in, you will not see anything different from what you would normally see, aside from increasing gravitational pressure on you that will eventually (seconds or minutes would depend on the mass of the black hole, and your relativistic velocity) kill you.

 

To an observer outside, you will approach a black hole, first of all, the closer you get, the longer the time frame for you will seem to be, and theoretically, you will never actually touch the surface, but you will appear to stretch. The closer you get, the more stretched you will appear, to a point where you will be a stream of atoms, and eventually to total disappearance to particles that the outside observer will never even be able to detect.

 

Laurie, it's a nice article, but it does not pertain to the black hole discussion... :applause: it deals with the amount of light we see in the telescopes... black holes are not just covered by by a cloud of space dust :applause: otherwise its too big of a coincidence, that just happens to be more likely found in the center of the galaxies, clusters, and just after a star collapses...

[Little Bang]

You can't make measurements on another frame of reference. As far as the astronaut is concerned if he or she is looking back at the rest of the universe the rate at which events are occurring appear to be approaching C. His clock is running very slow so that when he calculates velocity for a particle outside the event horizon, D/T, V is very large. By the time he is approaching the center of the black hole the rest of the universe will be close to total collapse or infinite expansion if that's what you believe.

[Moontanman]

This thread is so far off topic, has anyone just flat out said that antimatter is not unstable matter yet? No "matter" how you look at it twist it or confuse the issue antimatter is not unstable matter!

[Little Bang]

Moon you are right. Anti-matter is just as stable as matter, in fact you could have an anti-matter universe with humans no different from us.

[CraigD]

This thread is so far off topic, has anyone just flat out said that antimatter is not unstable matter yet?

:)

 

I think we – with the exception of HBond - said pretty much that throughout the thread. Still, it’s good to just flat out state it: antimatter is not unstable matter! (yes, I do feel much better now, thanks :bouquet:)

 

When you get down deep into theories of the origin of all matter, however, you’re confronted with a significant question - why is there mostly matter, rather than mostly antimatter? - for which a few answers come to mind:

1. Error. There is exactly as much antimatter as matter – we just haven’t spotted it yet.
    
   There are some pretty compelling reasons why this is very unlikely to be true.
    
   
2. Chance. The chance of exactly the same amounts of antimatter and matter annihilating to result in exactly no matter of either kind is very small. The chance of ending up with a little (ie: a universe worth) of one or the other is much higher. The chance of ending up with one vs. the other are exactly, or very close to exactly, equal, so the outcome we observe is a chance one. If you “replayed” the universe from the beginning several times, you’d expect to get an antimatter version of our universe about as often as a matter version.
    
   This is pretty much what Dirac though happened.
    
   
3. Something subtle. There is some basic, not-well-understood quality of the fundamental particles and interactions that leads inevitably to there being slightly more matter than antimatter in the early universe.
    
   This view – the CP violation explanation of the matter-antimatter imbalance - is the mainstream view. It has a “goldilocks” problem, however – of the two best theories for it, one predicts much more, the other much less, matter than is observed.
   

[Little Bang]

Very nice Craig. I tend to think #2 the most likely.

[HydrogenBond]

If matter and anti-matter are equally likely does this preclude some universe formation scenarios. For example, if the universe is on recycle constantly replacing matter as it loses it, here is a random generator. Based on that theory class, pockets of new anti-matter should be a common as new pockets of matter.

[alexander]

Yeah, i don't think antimatter is just unstable matter either, I also don't think there is anywhere near as much antimatter in the universe as there is matter...

[HydrogenBond]

One natural source of anti-matter is the formation of anti-protons using the particles in cosmic rays. If we do an energy balance, we get matter plus energy equals anti-matter. If both matter and anti-matter are at the same energy level, we should be able to add a similar amount of energy to that anti-matter to create matter.

 

One way to look at this, is to assume that matter and anti-matter exist on opposite sides of a transition energy hill, which separates them. They are both at the same energy level on either side of this transition hill. The idea above would imply energy from either direction pushes either up the same transition hill to rearrange the substructure and then it slides down the other side to a stable state. Have there ever been observations that show that adding energy to anti-matter to push it up the activation hill leads to matter?

 

What I picture is when matter and anti-matter approach, their mutual energy release is adding energy pushing both, up opposite sides of an activation hill. They would like to swap places and slide down opposite sides, but due to the instability in the substructure, things get all messed up and the two cancel out with a burst of energy.

 

What was never clear to me is whether the top of the hill is the best place to cancel since the transition state for both should be the same, if we assume symmetry. It makes more sense for asymmetry with one starting lower and the other higher, so they meet over the edge. What that would do is make parallel spin or whatever that messes up all the substructure.

[Little Bang]

To answer your first question Hydro, (and this is my opinion) there can be only four types of universe (all of which come from an EM pulse BB) an anti-matter, a matter, a positive electron proton, and a negative electron proton universe. I do not like the latter two because both those universes would expand forever implying that the place the BB came from is losing energy that it can never get back.

 

As to your second question your right. If the universe is being recycled as you suggest then there would be just as much matter as anti-matter and the universe should eventually disappear.

[Moontanman]

If matter and anti-matter are equally likely does this preclude some universe formation scenarios. For example, if the universe is on recycle constantly replacing matter as it loses it, here is a random generator. Based on that theory class, pockets of new anti-matter should be a common as new pockets of matter.

 

I'll say that is a possible scenario but it doesn't necessarily mean that pockets of anti matter are close enough to us in this universe to have any real connection with our pocket of matter.

[Moontanman]

One natural source of anti-matter is the formation of anti-protons using the particles in cosmic rays. If we do an energy balance, we get matter plus energy equals anti-matter. If both matter and anti-matter are at the same energy level, we should be able to add a similar amount of energy to that anti-matter to create matter.

 

It's already been said that this is exactly the situation. If I recall correctly the idea was that if you bombard a steak made of matter with the correct particles at the correct energy level you get antimatter particles, and if you bombarded an anti matter steak with anti particles of the correct energy level you would get matter particles.

[Moontanman]

To answer your first question Hydro, (and this is my opinion) there can be only four types of universe (all of which come from an EM pulse BB) an anti-matter, a matter, a positive electron proton, and a negative electron proton universe. I do not like the latter two because both those universes would expand forever implying that the place the BB came from is losing energy that it can never get back.

 

I've never heard of the positive proton&electron/negative proton&electron versions of possible universes' Does mirror matter figure in this possible universes' scenario?

[Little Bang]

When the proton anti-proton pairs were made in the early universe they would have annihilated each other except that about one collision in every billion would have involved say two anti-protons and one proton colliding at exactly the same instant leaving one extra proton. This picture would have produce enough protons to make the universe. The energy released from the annihilations would have created the electron anti-electron pairs with the above process leaving the electrons to make the universe but this process could also have left anti-electrons instead and all the particles in the universe would just race apart.

[CraigD]

One natural source of anti-matter is the formation of anti-protons using the particles in cosmic rays.

It’s important to note that cosmic ray antiprotons, the first-detected and, AFAIK, most numerous kind, are produced in fundamentally the same way as one created artificially in facilities such as CERN’s “antimatter factory”. In the case of cosmic rays, the interaction ([math]p + A \to p + p + \overline{p} + A[/math]) is believed to involve the particles in a high-velocity proton ([math]p[/math]) interacting with those in a heavy atomic nucleus ([math]A[/math]) in a low-density interstellar cloud, resulting in the production of an proton-antiproton pair ([math]p + \overline{p}[/math]). In the case of a “manufactured” antiproton, the reaction is the same, but the heavy nucleus is in a high-density solid target. One could, in principle, manufacture antiprotons using low-density interstellar gas, but the rate of production would be much less, and given that proton accelerators like CERN’s cost a lot to build and operate regardless of what’s used as a target, and lots of researchers want as many antiprotons as they can get, high production rates are desired.

If we do an energy balance, we get matter plus energy equals anti-matter.

…

One way to look at this, is to assume that matter and anti-matter exist on opposite sides of a transition energy hill, which separates them. They are both at the same energy level on either side of this transition hill. The idea above would imply energy from either direction pushes either up the same transition hill to rearrange the substructure and then it slides down the other side to a stable state. Have there ever been observations that show that adding energy to anti-matter to push it up the activation hill leads to matter?

I believe “matter + energy [math]\to[/math] antimatter” is too great a simplification of actual antimatter-producing interactions. Adding energy to a proton – for example, by interacting with it with photons of magnetic force to accelerate it – results in a higher energy and higher relativistic mass proton, but will not result in the proton undergoing a “phase transition” to become an antiproton, as your analogy appears to suggest.

 

Rather, what is believed to occur in the [math]p + A \to p + p + \overline{p} + A[/math] reaction is that conditions briefly resemble those believed to have existed within the first [math]10^{-12}[/math] s after the Big Bang, with temperature greater than [math]10^{10}[/math] K. In these conditions, the fermions (quarks) in the protons and neutrons no longer exist, but are some sorts of “grand unified” bosons (force carriers, such as photons). On a tiny scale, they replay the Big Bang creating roughly equal numbers of quarks and antiquarks, most of which annihilate to produce photons, but, in rare (about 1 in [math]10^6[/math]) cases, some of which become confined into protons and antiprotons.

 

AFAIK, the same interactions that can produce antiprotons can also produce neutrons and antineutrons. Since both lack net charge, they can’t be easily contained or distinguished from other post-collision interactions, so are pretty much ignored.

If both matter and anti-matter are at the same energy level, we should be able to add a similar amount of energy to that anti-matter to create matter.

In principle, I think this is true. If one had a large collection of heavy anti-atoms – say a sheet of nice, cool anti-copper, suspended, of course, in a near perfect vacuum with not physical contact with its container – one could use an accelerator like CERN’s to collide antiprotons into it to generate proton-antiproton pairs, just like ordinary matter – in our previous notation: [math] \overline{p} + \overline{A} \to \overline{p} + p + \overline{p} + \overline{A}[/math].

 

Practically, however, the best present-day technology can barely manufacture and contain cool antihydrogen gas in quantities measured in the thousands of atoms ([math]10^{-24}[/math] kgs), so the prospect of actually carrying this out seems remote – not to mention that macroscopic quantities of antimatter of any kind is simply scarey!