Welcome to my fourth “Science Answers” post! If you have a question, you can ask it in the comments here, or ask it in an email. Or find me on Facebook!
Q: (1) How did scientists find elements in the first place? Could there be more undiscovered elements? (2) How did scientists create the periodic table? (3) How do we know that everything is made up of atoms, when atoms are so small that they can’t even reflect light (a necessity for seeing them)? (asked by Mukesh Garbyal)
Really good questions! I was asked these in a comment on my post “Types of Atoms,” and chose to answer them in a post of their own.
Let’s take this apart. I actually want to address the third part of the question first, since it contains a misconception: atoms can reflect light. Their interaction with light is actually why we can see anything in the world.
Depending on their mass, stars can remain stable for millions and even billions of years. The most massive stars live for “only” about 10 million years, but models predict that the least massive live for much longer—longer than cosmologists believe the universe has existed.
As stars exhaust their fuel, their internal structures change drastically. Their cores contract, but their outer layers are forced to expand, and they become giants. You’d think the next thing we’d cover would be what happens to these giant stars, right?
Well…not quite! At this point, something downright weird is going on in their cores, and it’s well worth a closer look…
Well, I guess now you have. But what exactly is a neutrino?
Don’t worry, they’re not harmful. They’re passing through you this very second and you’ll never notice them, not in your whole life. They’ll never hurt you because they just don’t interact with matter—including you—in the way you’d expect.
I’ll bet now you’re wondering where they even come from.
Well, as the diagram illustrates, they come from the sun. They’re kind of a side-effect of the nuclear reaction that powers the sun, and they radiate out from the sun in droves. But that’s not even the coolest bit.
We know how many neutrinos should come from the sun if our theories about its power generation are right. So if we can count them, we can prove those theories correct.
That’s when we encounter a bit of a problem. We can’t actually detect neutrinos.
Take a wild guess: how much energy do you think the sun generates?
Think about it. It definitely generates enough energy to power a world.
Humans depend on the photosynthesis of plants, which converts sunlight into energy. And that’s not all. Without energy from the sun, our atmosphere would behave very differently, and so would our oceans.
Everything that moves on Planet Earth does so because it has energy. And a lot of that energy comes from the sun. It doesn’t even stop there—obviously, the sun has plenty of energy to spare, if the recent influx of solar power means anything.
The sun is incredibly powerful. And it’s powerful enough to keep generating that kind of massive energy supply for billions of years.
Everything we know about space comes from radiation.
Now wait just a moment here. That statement explains how astronomy is such a successful field of science—it’s based entirely on the information we can glean from radiation, after all. But how does that make sense?
I mean, it’s one thing to study radiation. It’s quite another thing to study matter, the “stuff” in the universe. How does one have anything to do with the other?
Well…that’s where atoms come in. Radiation does, in fact, have a lot to do with the “stuff” it comes from. And if it weren’t for that basic principle, astronomy as a science wouldn’t work.
Thankfully for astronomers, it does. So what’s the secret, then? What does radiation have to do with matter?
I’m going to venture a wild guess and say you haven’t, since scientists have only recently been able to take this kind of image. I learned about it in my biology class this semester, and the professor said that it was a landmark achievement.
It might, or it might not. If it does, you might recognize it as the periodic table of the elements—more often known as simply the “periodic table.” It’s an ingenious way to organize elements that has worked for scientists for quite some time.
To fully appreciate the ingenuity of the periodic table, I’d have to take you through a few chemistry lessons. Never fear, I have every intention of doing so—later. For now, though, I just want to address enough of the world of atoms to talk about stellar spectra.
That just means the spectrums we get from stars, by the way. (Spectra is plural for spectrum.) And that means…well…we’ll talk about it later. Let’s talk about the different types of atoms first.
“The Building Blocks of the Universe.” When you put it that way, atoms sound less like a topic specifically for a chemistry class and more like something astronomers might discuss.
They really are. I’ve got a fantastic reason to include atoms under astronomy, and its name is stellar spectra.
We’ve encountered stellar spectra before in these astronomy posts. When I wrote about the spectrograph, an instrument astronomers use to study data, I talked about spectral lines. I also promised we’d come back to elaborate on that later.
We’re not actually going to talk about the spectrograph in this post. I’m saving that for another time. For now, I’m going to cover atoms in a little more detail.