Thanks to Brilliant for  supporting this SciShow video.

To keep building your STEM  skills beyond this video, check out Brilliant.org/SciShow. You’ll get 20% off an annual premium  subscription when you use that link! [ intro ] Imagine putting a house on a really  big scale and weighing the whole thing.

And then you break it down and weigh all of the individual pieces separately. And then you find one brick that’s  heavier than the whole house. That can’t be right, that’s impossible.

But in the weird world of subatomic physics it could totally happen, and new research has found  evidence for it inside protons. So, if the proton is a proverbial  house, that brick is a charm quark, and learning more about it  might help us understand the biggest mysteries in particle physics. Every atom in the universe has at  least one proton inside of it.   In fact, protons make up most  of the regular matter out there.

And thanks to decades of  particle physics research, we know that protons are made of  even smaller particles called quarks. Specifically, protons are made of  two fundamental ‘flavors’ of quark: ‘up’ flavored quarks and ‘down’ flavored quarks. Or at least, that’s what  we’ve thought until recently.

Because new research says this  may not be the whole story. Some physicists have proposed  that in addition to those quarks, There is another fundamental  component to the proton: a charm quark. A charm quark is another flavor of  quark, behaving exactly like an up quark, only with a lot more mass.

A single charm quark is more  massive than an entire proton! So yeah, the idea of protons being  built from them sounds a little bizarre. But it’s physically plausible  because of another strange rule.

On this teeny tiny scale of reality,  everything comes down to probabilities. Physicists use equations to  describe the possible outcomes for which quarks they will see  when they observe a proton. They do this by smashing  protons together at high speeds and watching what particles are  formed from all that energy.

About 99.5% of the time, when they  observe a proton in these situations, they see it’s made of up quarks  and down quarks as expected. But the other 0.5% of the time, they see it’s made of a charm quark, too. Because the charm quarks are there so  infrequently and they’re short-lived, they only contribute a small  amount of their enormous mass to the overall mass of the proton in the  equations that describe these things.

That is how the brick can  weigh more than the house. So, physicists do see short-lived charm  quarks come out of protons all the time. But they call them extrinsic charm quarks, because they’re not thought  to be a component of protons when we’re not smashing them together  and creating all kinds of new particles.

Some physicists, however, have theorized that there are also intrinsic charm quarks fundamental building blocks that exist whether we are tinkering with  protons in a particle accelerator or not. And finding evidence that protons  are really made of charm quarks turns out to be a lot more difficult. Physicists have been chasing after subtle hints of intrinsic  charm quarks for decades, but there’s a big effect that may be masking it.

Every proton also has a roiling ‘sea’ of  particles popping in and out of existence, buzzing around at all times. Physicists have to hunt through that  noise to find intrinsic charm quarks. If you don’t go into the data analysis  with a particular model in mind, you can’t really wade through all that noise.

And there are lots of plausible  models of intrinsic charm, so generally physicists have  to go through each model one at a time to see if the data match. But research published in  August 2022 used a new trick: machine learning. The team fed 30 years of particle  collision data into a computer, including hot-off-the-press data from  the Large Hadron Collider in Switzerland.

Then they told the computer to look  for evidence of intrinsic charm quarks, using whatever model it needed to. But it was also allowed to assume  there was no intrinsic charm quark. Because that’s always a possibility, too.

By looking at loads of different models at once, it could identify which ones fit the data best  way more effectively than previous attempts. And sure enough, the researchers did  find evidence for intrinsic charm quarks. They even calculated the probability of  spotting one of them: around 0.6%.   But is this evidence actual proof?

The team says there’s only a one in  one thousand chance they’re wrong. But in the world of particle physics, that is not good enough. Before anyone can actually  claim a discovery has been made, they have to show there’s only a one  in three million chance they’re wrong.

I mean we are talking about the  fundamental rules of reality here. The standards should be pretty high! Whether or not protons really do  have this intrinsic charm quark, these sorts of ultra-precise tests are  crucial for the future of particle physics.

Researchers are probing ever-deeper  into the smallest parts of reality, and that requires an extreme level of accuracy… both in the experimental design, and the understanding of laws of nature. That way, if experiments don’t match  what those laws predict will happen, they can be sure it’s because  of something new and exciting, not some kind of accounting error. And if this new evidence holds up, then we’ve learned a new fact  about the nature of reality… and about a particle that we are all made of.

That’s an idea that really  has some intrinsic charm. You made it to the end of the video, so you  probably think quantum objects have some merit. But if we lost you at any point along the way, you might want to check out the  Brilliant course on quantum objects.

Brilliant is an online learning platform that offers guided problem-solving based  courses in math, science, and engineering. They’ve supported SciShow for many years and we’re happy to have them  support this video as well. Their quantum objects course  has 18 interactive lessons that cover over 100 concepts and exercises.

And that is just one of their courses! In this course, you’ll learn things  like how sneaky tiny objects can be. The first lesson explains how they can  still be mixed up even after you sort them.

And at the end of the course, you’ll have a new appreciation  for the small physics that enables lasers, transistors, and other defining technologies  of the modern world. To try this course or any other  Brilliant course for free, click the link in the description down  below or visit Brilliant.org/SciShow. That link also gives you 20% off  an annual Premium subscription. [ outro ]