# On Antimatter

## Main Question or Discussion Point

Hi! I'm completely new to this website, and I have no background. I'm just a curious kid who googles stuff for the fun of it, and I've just had this burning question for a while now. I watched this interview with Michio Kaku on YouTube, and he discussed how we shouldn't exist. Anti-matter and matter cancel eachother out, but in the process releases the most energy possible for the amount of matter that was destroyed. Thus, there is no reason for anything to exist; however, we do exist, and for some reason there is more normal matter than anti-matter. To me that made a lot of sense, because all matter is made out of energy, right? If E=mc^2, then all matter comes from energy, thus explaining why we have more regular matter than anti-matter. I know it is possible for us to convert matter into energy via nuclear fission, but can we do the reverse? And if so, isn't it plausible that the reason why we have more regular matter than anti-matter, is because the energy released produces even more regular matter? If this is the case, then how come energy didn't naturally translate into anti-matter at the start of the universe? Are there naturally occurring processes that convert energy into matter? And are there holes in my theory, or false facts? I am just a stupid kid who doesn't have any background or credibility; sitting here asking questions that probably sound stupid to experts.

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phinds
Gold Member
... because all matter is made out of energy, right? If E=mc^2, then all matter comes from energy, thus explaining why we have more regular matter than anti-matter.
I cannot fathom how you conclude that is any kind of "explanation". We have no idea why there is was more matter than anti-matter in the early universe.

I know it is possible for us to convert matter into energy via nuclear fission, but can we do the reverse?
It's done all the time at CERN.

And if so, isn't it plausible that the reason why we have more regular matter than anti-matter, is because the energy released produces even more regular matter?
No, it also produces anti-matter.

Nugatory
Mentor
Anti-matter and matter cancel eachother out, but in the process releases the most energy possible for the amount of matter that was destroyed.
It's not so much that they "cancel each other out" as that they react together in a way that turns all of the mass of both into energy according to $E=mc^2$. Say you have an electron; call its mass $m_e$. That's also the mass of an anti-electron (often called a "positron"); its mass is also $m_e$. If an electron and a positron collide, they will both be converted into energy and we'll end up with $2m_ec^2$ of energy in the form of gamma radiation and no particles at all. You can also run this process in reverse (google for "pair production") but clearly this won't explain why we have more regular matter than antimatter because it produces equal amounts of both.
Thus, there is no reason for anything to exist; however, we do exist, and for some reason there is more normal matter than anti-matter.
"For some reason" is the key phrase here. The universe had to start with more matter than antimatter, but we don't know why.

Oh, and be cautious about videos, even those made by competent scientists like Michio Kaku or Brian Greene. They're entertainment, not science.

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It's not so much that they "cancel each other out" as that they react together in a way that turns all of the mass of both into energy according to $E=mc^2$. Say you have an electron; call its mass i$m_e$. That's also the mass of an anti-electron (often called a "positron"); its mass is also $m_e$. If an electron and a positron collide, they will both be converted into energy and we'll end up with $2m_ec^2$ of energy in the form of gamma radiation and no particles at all. You can also run this process in reverse (google for "pair production") but clearly this won't explain why we have more regular matter than antimatter because it produces equal amounts of both.

"For some reason" is the key phrase here. The universe had to start with more matter than antimatter, but we don't know why.

Oh, and be cautious about videos, even those made by competent scientists like Michio Kaku or Brian Greene. They're entertainment, not science.
Thank you for explaining things for me, it was very satisfying to finally get an answer. I have another quick question that popped up if you don't mind answering. Why do we assume matter and anti-matter came into existence in equal quantities?

Nugatory
Mentor
Why do we assume matter and anti-matter came into existence in equal quantities?
We don't assume that. In fact, we know the opposite: we know that they didn't come into existence in equal amounts because our universe contains much more matter than anti-matter. The question is why it is that way. All the known processes that create particles from energy produce a particle and an anti-particle together so there's no way of ending up with more of one than the other.

phinds
Gold Member
Thank you for explaining things for me, it was very satisfying to finally get an answer. I have another quick question that popped up if you don't mind answering. Why do we assume matter and anti-matter came into existence in equal quantities?
You're not quite getting what Nugtatory already told you. We do NOT assume that, we assume just the opposite. If they had been equal we would not be here.

EDIT: OOPS. I see Nugatory beat me to it.

CWatters
Homework Helper
Gold Member
I wondered if the OP meant the following sequence might be what occured....

Firstly equal amounts of matter and anti matter are created.

The matter and anti matter react to produce energy.

E=mc^2 means all that energy could turn into a lot of matter which is what we see today.

Nugatory
Mentor
E=mc^2 means all that energy could turn into a lot of matter which is what we see today.
That's pretty much what I thought he was suggesting - not realizing that those reactions have to produce as much antimatter as matter.

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Mister T
Gold Member
To me that made a lot of sense, because all matter is made out of energy, right?
No. Energy is a property of matter.

If E=mc^2, then all matter comes from energy, thus explaining why we have more regular matter than anti-matter.
The $m$ stands for mass, not matter. Mass is also a property of matter.

$E_o=mc^2$ tells us that rest energy and mass are equivalent, two different names for the same thing. Thus when you measure the mass of a piece of matter you are also measuring its rest energy.

You don't convert matter into energy. Matter-antimatter annihilation is a conversion of matter to electromagnetic radiation.

You can say you convert mass into energy, but all you're really doing is choosing to call what you have before the annihilation mass, and what you have afterwards energy. Before the annihilation you have matter, afterwards you have electromagnetic radiation. The mass before the annihilation equals the mass afterwards, the energy before equals the energy afterwards.

I know it is possible for us to convert matter into energy via nuclear fission, but can we do the reverse?
Yes, it is called fusion.

Nugatory
Mentor
Yes, it is called fusion.
That's not right. Fusion and fission both convert matter into energy: there is less mass after the reaction than before, and the missing mass has been converted into energy according to Einstein's $E=mc^2$.

To turn energy into matter you need something like pair production or very high-energy collisions.

To turn energy into matter you need something like pair production or very high-energy collisions.
Touche.
But that wasn't really "that specific question", it was "convert matter into energy" and fission releases * some* of the atomic energy, and the opposite is *release* some atomic energy, voila, fusion... up to iron and then it *costs* some energy.

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I know it is possible for us to convert matter into energy via nuclear fission
The key word here is *some* of the matter. Nothing under Fe can be gained upon though fission. Antimatter annihilates all matter.

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destroyed.
The only word that names that "thing" is annihilated. And if you kept up that means converted to E.