what is antimatter? Does it exist? How does it matter to us?
In: Physics
To understand antimatter I feel like you should first try to understand the concept of nothing.
Imagine someone digging a hole as they are digging a hole they are also creating a small hill with the dirt they are moving. As they continue to dig the hole, the hole gets bigger and as a result so does the dirt Hill. In short summary the hill was only created because the hole was dug.
Matter is very similar to this. Matter is created by the imbalance of nothing, when that imbalance occurs there is both matter and antimatter created at the same time. When matter and antimatter meet they annihilate each other and disappear. Just like putting the dirt back in the hole the hole was never there.
Regular matter consists of the particles that most people have heard of: electrons, protons, neutrons (the latter two consisting of quarks). These make up atoms, molecules and so on.
Antimatter works exactly the same way, however the particles have an inverted charge. While an electron has a negative charge, an anti-electron (called positron) has positive charge. And while a proton has positive charge, an anti-proton has negative charge. Other than that antimatter can build atoms, melocules etc. just like regular matter
When matter and anti-matter touch, they annihilate each other, releasing a huge amount of energy in the process.
Antimatter is real and it can actually be synthesized in really tiny amounts using large quantities of energy, or it can be created in radioactive decay. However in the environment around us we basically see no meaningful amounts of antimatter at all. To my knowledge, physics has not found out yet why the universe around us is made of matter instead of antimatter.
In quantum mechanics, there is something called the Schrödinger equation. Quantum mechanics is really hard to ELI5, but the basic gist is that the equation is kinda like Newton’s Third Law – for every action there is an equal and opposite reaction – but applied to particles. For example, electrons are negatively charged, so there should exist an equivalent particle (the positron) which is positively charged. This logic is also extended to posit the existence of anti-protons and anti-neutrons.
Antimatter does exist, albeit in very tiny quantities and never for long. It is usually created through some kind of radioactive decay or particle accelerator. A rather common example is the potassium in a banana. About every 75 minutes a potassium atom decays, releasing a positron.
Should matter and antimatter ever interact, the result would be the conversion of matter into energy as they annihilate each other. If done with any meaningful mass, it would result in a very big boom.
Matter is made up of things that are positively and negatively charged…and no matter what we looked at, they always had the same charge. We wanted to know why they were charged this way and considered, “What if the charges were flipped? Is that possible?”
We found this was possible (antimatter), but it can’t really exist naturally around us because the moment it touches normal matter, the combination creates and explosion releasing a lot of energy.
This is important because there doesn’t seem to be a reason for matter to exist, other than by accident. Antimatter is just as likely to be created as matter, and the combination of the two would cancel each other out leaving a hot universe full of energy. Somehow, the universe created a tiny amount more of matter than antimatter, allowing the rest of the universe to appear like it does today.
Like a million balloons being dropped on a million tacks, the expectation would be a popped balloon. And yet, at the end, there was somehow a balloon or two that survived. We’re interested in knowing how that happened, and that requires a better understanding of antimatter, which is difficult to study while preventing it from touching any normal matter.
Antimatter is normal matter, but with the opposite charge, and it very much does exist.
When it touches normal matter, they annihilate each other and turn into pure energy (usually in the form of light) according to E=mc^2
The easiest example of antimatter is a positron, or anti electron. We can see this come from anything that is radioactive and undergoing β+ decay. Bananas contain potassium, and some of that potassium is potassium-40, which undergoes beta plus decay, which emits positrons.
Another example is a PET scan. PET stands for positron emission tomography. You are given an isotope (carbon-11, nitrogen-13, oxygen-15, or fluorine-18) which undergoes β+ decay, and they use a machine to detect where the positrons are coming from in your body, so they can see what parts of the body are using resources.
Anti protons and anti neutrons have to be made in a lab with a particle accelerator. Basically, we smash together particles with so much energy that we create matter (E=mc^(2)) and it is always created as a matter-antimatter pair. So if we make a proton, we also make an anti proton.
There’s also an entire class of particles made of both matter and antimatter called mesons. Protons and neutrons (baryons), which you’re familiar with, are made of quarks, 3 quarks each. Mesons are made of a quark and antiquark pair.
We have made a few grams of anti hydrogen, and we have just recently used some to prove that antimatter is affected by gravity in the same way as normal matter
Antimatter is like matter, but with almost all properties equal but flipped. Where for matter something would be a plus, for antimatter it’s a minus. The one exception is mass, sadly we have not discovered negative mass here, it’s exactly the same as matter.
Because of that, when a particle and it’s antiparticle (the have to match) meet, they cancel eachother out and annihilate. All that’s left is some energy in the form of light.
And yes, it exists, it’s regularly produced by some natural decays as well as made in particle colliders. There’s just very, very little made in this way.
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