Antimatter

[DragonMaci]

Could someone who knows a bit about antimatter please tell me exactly what it is? According to this Wikipedia article GreedyCapitalist linked me to in this thread, it is the following:

In particle physics, antimatter extends the concept of the antiparticle to matter, where by antimatter is composed of antiparticles in the same way that normal matter is composed of particles. For example an antielectron (positron) and an antiproton could form an antihydrogen atom in the same way that an electron and a proton form a normal matter hydrogen atom.

It is the "anti" part of "antimatter," "antiparticles," "antielectron," "antiproton," and "antihydrogen" that confuses me. In what way are they anti. The same Wikipedia article claims this:

Furthermore, mixing of matter and antimatter would lead to the annihilation of both in the same way that mixing of antiparticles and particles does, thus giving rise to high-energy photons (gamma rays) or other particle–antiparticle pairs. The particles resulting from matter-antimatter annihilation are endowed with energy equal to the difference between the rest mass of the products of the annihilation and the rest mass of the original matter-antimatter pair, which is often quite large.

Now, while this energy creation part is quite believable, the part about them annihilating each other is not. Matter cannot simply cease to exist, so clearly they do not annihilate each other. So in what way is antimatter antimatter? The name seems to me like a contradiction.

If anyone can shed some light on this matter I would much appreciate it.

[Prometheus98876]

Now, I am not physics major as you know, but I have a little knowledge, so I will state my answer, if I am wrong Im sure someone will point it out.

I would assume that the anti in antimatter is meant to indicate that it is according to theory the reverse in terms of known attributes such as charge, of the original partcle. So positrons have the reverse charge, positive instead of negative and vice versa. If you can think of a bettter word than anti to use, by all mens use that, but you would then have to clarify what you mean.

Now..your second question...

Lets suppose that such an interaction does in fact take place. Now, the total sum of matter/energy in the universe is constant. A particle and antiparticle when they collide could in theory cause a conversion of matter to energy, so say the particle and the antiparticle could transform from their particle forms as the particle and the antiparticle to say a number of smaller particles and some energy. As long as the sum of matter and energy released from the interaction is the same as the matter energy that went into the interaction is the same, there is no contradiction.

But if one claims that there is a resultant loss of matter-energy, than this is nonsense. Though such claims have been made. And if you claim antimatter / matter appear from outside the universe and collides with its opposite (in order I assume to balance some equation which is probably based on wrong premises) then you are talking gibberish, though that too has been seriously postulated.

Edited June 5, 2007 by Prometheus98876

[DragonMaci]

I would assume that the anti in antimatter is meant to indicate that it is according to theory the reverse in terms of known attributes such as charge, of the original partcle. So positrons have the reverse charge, positive instead of negative and vice versa.

OK, that makes sense to me.

Lets suppose that such an interaction does in fact take place. Now, the total sum of matter/energy in the universe is constant. A particle and antiparticle when they collide could in theory cause a conversion of matter to energy, so say the particle and the antiparticle could transform from their particle forms as the particle and the antiparticle to say a number of smaller particles and some energy. As long as the sum of matter and energy released from the interaction is the same as the matter energy that went into the interaction is the same, there is no contradiction.

Yes, I understand that, but the wording "annihilate each other" implies they cancel each other out, resulting in less matter, which is impossible. The energy thing is certainly possible, but not the less matter.

But if one claims that there is a resultant loss of matter-energy, than this is nonsense. Though such claims have been made. And if you claim antimatter / matter appear from outside the universe and collides with its opposite (in order I assume to balance some equation which is probably based on wrong premises) then you are talking gibberish, though that too has been seriously postulated.

Yes, that is what I was saying is contradictory about Wikipedia's article and the name "antimatter".

Anyway, thanks for clearing up the meaning of the name.

[Prometheus98876]

No, what if anything rational it implies, is that the particle and antiparticle cease to exist in the sense that they could be said to be a particle and an antiparticle, but the amount of energy-matter does not decrease, what you get is smaller particles of some sort, and energy. What must not decrease is the sum of energy-matter, not just "matter". It is not a contradiction if you get less "matter", but there must not be a loss of that which exists. Energy however does exist, so if you get the equivalent amount of energy-matter, there is no less of that which exists, and no contradiction.

Note that my explanation of the name is what I consider to be a sensible use of it, not neccesarily how the physics experts use it. You would have to ask one of them about what they think is a sensible definition.

Edited June 5, 2007 by Prometheus98876

[DragonMaci]

No, what if anything rational it implies, is that the particle and antiparticle cease to exist in the sense that they could be said to be a particle and an antiparticle, but the amount of energy-matter does not decrease, what you get is smaller particles of some sort, and energy. What must not decrease is the sum of energy-matter, not just "matter". It is not a contradiction if you get less "matter", but there must not be a loss of that which exists. Energy however does exist, so if you get the equivalent amount of energy-matter, there is no less of that which exists, and no contradiction.

I am aware of that. You wasted your time and effort in pointing it out. I meant energy-matter, despite my wording. I was talking about a canceling out of existence of them, not a cancelling of the existence in a particular form by the changing of state from matter to energy.

Edited June 5, 2007 by DragonMaci

[Prometheus98876]

Oh..opps..well at least now you have a slightly better version of that part of the explanation :-P

But anyway, its pretty weird stuff, and a lot of physicists have found it difficult to accept and fully understand in the past. It isnt exactly the most intuitive of ideas, but I guess that points out that intuition really isnt much good when it comes to science.

[D'kian]

When a particle collides with it's anti-particle, say a proton against anti-proton, they mutually cause each other to disintegrate into various other kinds of particles and energy. That's what's meant by the term "they anihilate each other."

Matter and energy are equivalent, that is to say they are different manifestations of the same thing. that's expressed in Einstein's equation e=mc^2 (energy equals mass times the square of the speed of light). from this you can see that small amount of matter is equivalent to a very large amount of energy.

There's a practical demostration of this principle. By the late XIX Century Newton's theory of universal gravitation checked out for every known body, except for Mercury. To make a long story rather short, only an unkown mass lying between the Sun and mercury would epxplain the aberration (either that, or Newton's law was wrong). The mass was found by Einstein in the XX Century. It was the mass made up from the Sun's own gravitational field. The Sun's mass has a gravitational field. This field is energy. Given the Sun's large mass, the energy in its field has a mass of its own, and that adds to the overall pull of the Sun. Clear?

BTW, antimatter has been known to exist for a while now. I think positrons (anti-electrons) were first detected in the 1930s

[DragonMaci]

When a particle collides with it's anti-particle, say a proton against anti-proton, they mutually cause each other to disintegrate into various other kinds of particles and energy. That's what's meant by the term "they anihilate each other."

Prometheus98876 already clarified that for me.

BTW, antimatter has been known to exist for a while now. I think positrons (anti-electrons) were first detected in the 1930s

Yes, I read about that in the Wikipedia article.

[Prometheus98876]

BTW, antimatter has been known to exist for a while now. I think positrons (anti-electrons) were first detected in the 1930s

Indeed...but assuming that was directed at me...I mean way back in the past back to arond the 30's. I realize these days pretty much no physicist doubts the existence of antimatter.

[DragonMaci]

According to a friend I spoke to last week said real life experiments using controlled matter-antimatter reactions used lithium to control the reaction, which means Gene Rodenberry's dilithium crystals was surprising close, especially since my friend says these experiments were done after Rodenberry created Star Trek and since he was no scientist. So if he my friend is correct then what Rodenberry done was impressive.

Edited June 5, 2007 by DragonMaci

[Prometheus98876]

Yes, well Star Trek used dilithuim crystals (whatever the heck they are meant to be ) which I am pretty sure dont exist. :-P The way its explained on the show seems pretty far-fetched anyway, but at least its a relatively beleivable "explanation".

[DragonMaci]

Yes, well Star Trek used dilithuim crystals (whatever the heck they are meant to be ) which I am pretty sure dont exist. :-P The way its explained on the show seems pretty far-fetched anyway, but at least its a relatively beleivable "explanation".

I would assume they are crystallised dilthium, dilithium being a molecule with 2 lithium atoms I presume. Sort of the lithium equivalent of O2. Whether or not dilithium can crystallise, I do not know, but by using such a particle he was close to the real life succesful usage. It is a shame the production of antimatter makes it cost a ridicously high amount just to power a simple 40 watt light bulb.

[Prometheus98876]

Yeah, I too assume that, but apparently such crystals dont exist.

Imagine if you had a antimatter generator in your home and it exploded like they do in Star Trek...ouch that wouldnt be pleasent. However whether anyone has any theories on a workable antimatter-matter generator at the moment...and how far off such might be in terms of working units..I dont know, probably not in my lifetime.

[DragonMaci]

Yeah, I too assume that, but apparently such crystals dont exist.

Well, as I understand it, they do not occure naturally in Star Trek. As I recall Star Fleet has to artifically create them. Whether or not that is realistic, I do not know. However, in using a lithium based system was has surprising and impressively close to the real life system that came over a decade later.

[Robert J. Kolker]

Yeah, I too assume that, but apparently such crystals dont exist.

Imagine if you had a antimatter generator in your home and it exploded like they do in Star Trek...ouch that wouldnt be pleasent. However whether anyone has any theories on a workable antimatter-matter generator at the moment...and how far off such might be in terms of working units..I dont know, probably not in my lifetime.

Yodah says: Do not your breath hold until in your home anti-matter is used , else blue turn you will.

Bob Kolker

[Prometheus98876]

Yodah says: Do not your breath hold until in your home anti-matter is used , else blue turn you will.

Bob Kolker

Hahaha, even in Star Wars, a much more futuristic (and albiet fantasy ) setting they are still waiting. I indeed better not hold my breath. :-P

[D'kian]

Well, as I understand it, they do not occure naturally in Star Trek. As I recall Star Fleet has to artifically create them. Whether or not that is realistic, I do not know. However, in using a lithium based system was has surprising and impressively close to the real life system that came over a decade later.

As much as I like Star Trek and with all the respect I have for Roddenberry, I have to say it's nothing more than a coincidence.

BTW, the source of dilithium in Trek varies according to series and various books. In one book, "Prime Directive," the narrator claims a portion of Earth's quartz crystals were actually dilithium. And, no, I don't want to get into a canon vs non-canon discussion.

[Prometheus98876]

As much as I like Star Trek and with all the respect I have for Roddenberry, I have to say it's nothing more than a coincidence.

BTW, the source of dilithium in Trek varies according to series and various books. In one book, "Prime Directive," the narrator claims a portion of Earth's quartz crystals were actually dilithium. And, no, I don't want to get into a canon vs non-canon discussion.

Good point, the alleged sources differ. Also I dont recall what the alien races apparently use or where they apparently get their stuff from.

[DragonMaci]

As much as I like Star Trek and with all the respect I have for Roddenberry, I have to say it's nothing more than a coincidence.

Of course it was a coicidence! As I said he was no scientist, so it could not of been anything else.

BTW, the source of dilithium in Trek varies according to series and various books. In one book, "Prime Directive," the narrator claims a portion of Earth's quartz crystals were actually dilithium. And, no, I don't want to get into a canon vs non-canon discussion.

I know nothing about that, as I have never read any of the Star Trek books. As for canon vs non-canon, it is not really all that important to this discussion since this dicsussion is on real world anitmatter, so I agree with you that we should leave canon vs non-canon out of it.

Also I dont recall what the alien races apparently use or where they apparently get their stuff from.

I do not know either, which is why I only mentioned Star Fleet.

Edited June 6, 2007 by DragonMaci

[Prometheus98876]

Hey, in that Star Trek movie where they had the Klingon vessel did that not have dilithium crystals as well? I know it was some sort of crystals that they had to find some way to refuse using nuclear energy (Star Trek 4 I believe, about the worst due to its environmental overtones and general implausability).

By the way DragonMaci:

As I said he was no scientist, so it could not of been anything else.

Is poor wording fior what you perhaps meant. It implies that because he was not a scientist he had no way of knowing about a particular aspect of it that might have taken place (OK, in this case he didnt, as the experiment in question took place afterwards). This is false, non-scientists are capable of learning about particulars in science and emulating them in science fiction, so it need not in theory have been a coincidence.

[DragonMaci]

Hey, in that Star Trek movie where they had the Klingon vessel did that not have dilithium crystals as well? I know it was some sort of crystals that they had to find some way to refuse using nuclear energy (Star Trek 4 I believe, about the worst due to its environmental overtones and general implausability).

Yes, they used dilithium crystals, but Scotty could of adapted the engines to use them so that the ship would be of continual use to them. However, I doubt it.

This is false, non-scientists are capable of learning about particulars in science and emulating them in science fiction, so it need not in theory have been a coincidence.

True, but irrelevant since I am obviously talking about the context of him using it before the experiment. He had no means of knowing what the scientists of the future would do. Given the obvious context my wording was not bad, because in that context it does not imply what you said it does. In the context of it coming after the experiment it would imply that, but in the context of before. So, you see, my wording was not flawed at all.

[Prometheus98876]

No, my point was not the engines or such, but the fact that the Klingons apparently had dilithium, which definetely calls in question the theory that they came from Earth (im pretty sure they wouldnt trade dilithium with the Klingons whom were their enemies at the time).

[Plasmatic]

Anti-matter is an anti conceptual abstraction,invented to justify ,the absence of the required matter to exert the amount of gravity,Enstiens fantasies required, In other words the equations are 95% lacking in their attempt to describe the world. This dark matter anti matter non sense,is a result of the strongest and most pervasive force,being absent from Newtons gravity only Celestial mechanics. Which Einstein was building on. Now 99.9 percent of matter in the universe is in the 4th state,Plasma. An electrified gas which has been used in the laboratory to demonstrate the very things you see in your telescopes. Laboratory Plasma physics,Has far surpassed the gravity only cosmology in its efficacy as a successful model of the heavens. And it does this without the imaginary other dimensional fantasy abstractions of the quantum mystics!!

http://thunderbolts.info/tpod/2006/arch06/...dark-matter.htm

http://thunderbolts.info/tpod/2006/arch06/...assumptions.htm

Edited January 18, 2008 by Plasmatic

[DragonMaci]

Anti-matter is an anti conceptual abstraction,invented to justify ,the absence of the required matter to exert the amount of gravity,Enstiens fantasies required, In other words the equations are 95% lacking in their attempt to describe the world. This dark matter anti matter non sense,is a result of the strongest and most pervasive force,being absent from Newtons gravity only Celestial mechanics. Which Einstein was building on. Now 99.9 percent of matter in the universe is in the 4th state,Plasma. An electrified gas which has been used in the laboratory to demonstrate the very things you see in your telescopes. Laboratory Plasma physics,Has far surpassed the gravity only cosmology in its efficacy as a successful model of the heavens. And it does this without the imaginary other dimensional fantasy abstractions of the quantum mystics!!

Dark matter and anti-matter are different things. Anti-matter such as anti-deuterium (anti-heavy hydrogen) is reverse in terms of known attributes such as charge, of the original partcle. Dark matter is meant to be undetectable because it is cold and dark. It is meant to be undectable because it is cold and dark (the scientists wrongly assumed that because we cannot detect cold dark matter that we never will be able to; just because we cannot detect somthing in one time period doesn't mean we never will be able to, as has been proven with atomic and sub-atomic partticles) Anti-matter isn't cold and dark, it can be detected. We can detect reverse charge particles and molecules. What we cannot detect is cold and dark things.

Furthermore, scientists have made anti-matter in the labs and used it to try produce energy. The problem with that matter anti-matter reaction is that due to the high cost of artifically producing anti-matter makes it to expensive with current technology. With that method it costs the same amount to power a light bulb as it does to power a large city. But the important thing is that they could detect it. They wouldn't of been able to do the experiment if they couldn't detect it.

It can't be an anti-concept if it was made in the labs and experiemented with. You can't even make expensive means of power production using anti-concepts; you can make no means of power production. So what was your mistake? You mistake was to lump together two seperate ideas, one an anti-concept (dark matter), one a valid concept that has been used to make an expensive means of power production. I hope I've painted the picture clearly enough to make you realise that dark matter and anti-matter are very different. One is pure theory, pure speculation - and rather ridiculous. The other us real; it has been artifically produced in labs.

Furthermore, one of the articles you linked to makes the mistake of implying that we have to see matter to know it is real. That isn't true. We only know sub-atomic particles exist because we have observed the effect they have on other particles; we cannot see them even with the most powerful microscope. This illustrates how there is other means of using our senses - with the aid of technology - to sense something is there. Here is an analogy for you: you are watching a nature documentary and you hear a bird in the video but cannot see it in the trees. You still know it was real at least at the time of filming even though you cannot see the bird in the video. Even if it dead you know its corpse is real. Either way you know something that you never saw is real. Detecting things like sub-atomic particles that we cannot see is the same. So, while the article is right to criticise people for believing in dark matter without evidence of it, the implication that the theory is wrong because we cannot see dark matter is invalid.

As for spiral galaxies, they exist as spirals because they have a supermassive black hole in their galactic cores. A supermassive black hole easily produces enough gravity to cause a galaxy to be a spiral. So, we already have a known means to explain spiral galxies without dark matter.

Furthermore, I think it needs to be asked: can the plasma they refer to be detected with current means and if not do they have an explanation for that? One that makes sense? I think those are important questions that need to be asked when people try to explain such things.

As for quantum mechanics, it is mostly mystic, but like all other fields of science, not all of it is. Some of it has been used in used to make advanced technology like computers, so it is just as valid as complex numbers (a complex number is a number that when multiplied by itself equals -1; this is a valid mathematical concept, it has been used in computations to solve problems). Therefore it isn't all mystic: you can't use mysticism to make computers and other advanced technology.

[DavidOdden]

Anti-matter is an anti conceptual abstraction,invented to justify ,the absence of the required matter to exert the amount of gravity,

It seems that you don't understand the notion of "concept". Let's take the case of the anti-electron, i.e. the positron. They were captured about 75 years ago, so there can't be any serious doubt of their existence. Science has long had the valid concept of "charge", and there is nothing anti-conceptual in conjecturing that if there is charge, spin, and mass, that there could be a lepton with the 1/2 spin and mass of an electron but a +1 charge. There's nothing nonsensical or anti-conceptual in conjecturing a baryon that looks and smells like a proton but has a negative charge, which is a good thing given that some guys got a Nobel prize for discovering that they do actually exist. It also okay to conjecture the existence of antihydrogen, both conceptually and, as of 1995, empirically.

If your objection is that we don't find antimatter cats walking around, I don't recall Einstein or any other scientist claiming that there are actually antimatter life forms on Earth. So I really don't know what your objection is.

Edited January 18, 2008 by DavidOdden