The universe is kinda held together by duct tape and string.
Except the tape is actually a handful of numbers that never change. We call these the constants of nature. If you tweaked just one of them—literally just nudged a decimal point a tiny bit to the left—stars would stop burning, atoms would fly apart, and we definitely wouldn't be sitting here reading articles on the internet. It sounds like sci-fi, but it’s the most grounded reality there is.
Physicists like Max Planck and Richard Feynman spent their lives obsessed with these figures. Why? Because they represent the "hardware settings" of our reality. They aren't things we invented; they are things we discovered.
The Big Three: Speed, Gravity, and Smallness
Let’s talk about the speed of light, denoted as $c$. It’s exactly 299,792,458 meters per second. Not a bit more, not a bit less. People often think of it as just a speed limit, like something a cosmic highway patrol enforces. But it’s actually a fundamental property of how space and time relate to each other. If light moved at a different speed, the famous $E=mc^2$ equation would break. Energy and mass would have a different relationship, and the way stars generate heat through fusion would be totally unrecognizable.
Then there’s $G$, the gravitational constant. Honestly, gravity is surprisingly weak compared to the other forces. Think about it: a tiny fridge magnet can defy the pull of the entire Earth to hold up a postcard. But $G$ dictates how planets orbit and how galaxies form. If $G$ were slightly stronger, the universe would have collapsed back in on itself long ago in a "Big Crunch." If it were weaker, gas clouds would never have clumped together to form stars. We’d just be a boring, thin mist of hydrogen floating in the dark.
And we can't forget the Planck constant ($h$). This is the "graininess" of the universe. It tells us that energy isn't a smooth ramp; it’s a set of tiny, discrete stairs. It’s the reason why your chair feels solid instead of you just falling through the floor.
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The Fine-Structure Constant: The Number That Scares Scientists
There is one number that keeps physicists up at night: $1/137$.
Specifically, it's the fine-structure constant, or $\alpha$. It’s a dimensionless number, which basically means it’s just a pure ratio—no meters, no seconds, no kilograms attached. It governs the strength of the electromagnetic interaction between elementary charged particles.
Richard Feynman famously called it a "cursed" number. He said all good theoretical physicists should have it written on their wall and worry about it. Why? Because we have no idea where it comes from. Most other constants have units, but 1/137 is just... there. It’s a fundamental part of the "source code" of the universe, and we can't explain why it isn't 138 or 136. If it were even 4% different, carbon wouldn't be produced inside stars. No carbon means no organic life. No us.
Are the Constants of Nature Actually Constant?
This is where things get weird.
We assume these numbers are the same everywhere and for all time. But some researchers, like John Webb at the University of New South Wales, have looked at light from distant quasars—basically looking back billions of years into the past. Some of his data suggested that the fine-structure constant might have been slightly different billions of years ago in different parts of the sky.
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The scientific community is still fighting about this. Most experiments, like those using ultra-precise atomic clocks at NIST (National Institute of Standards and Technology), show that if the constants are changing, they’re doing so at a rate smaller than one part in $10^{18}$ per year. That is incredibly stable.
But the mere possibility that they could change suggests that our "laws" of physics might just be "local bylaws."
Why This Matters for Technology
You might think this is just for people in lab coats, but your phone relies on these numbers. GPS satellites have to account for both General and Special Relativity to stay synced with your handset. That involves $c$ and $G$ working exactly as predicted.
In 2019, the world of metrology (the science of measurement) underwent a massive revolution. We stopped defining the "kilogram" as a physical hunk of metal sitting in a vault in France. Instead, we redefined the entire International System of Units (SI) based on the constants of nature.
The kilogram is now defined by the Planck constant. The meter is defined by the speed of light. This means that if an alien civilization on the other side of the galaxy wanted to trade blueprints with us, we wouldn't need to send them a ruler. We’d just tell them the value of the constants, and they could recreate our exact measurements using their own atoms.
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The Anthropic Principle: A Lucky Coincidence?
Some people look at these perfectly tuned numbers and see a "Fine-Tuned Universe." This leads to the Anthropic Principle.
Basically, it says that the reason the constants are so perfect for life is because if they weren't, we wouldn't be here to observe them. It’s a bit of a circular argument, but it’s a big part of the Multiverse theory. If there are trillions of universes with different settings, we just happened to end up in the one where the "radio" is tuned to the right station.
Others, like theoretical physicist Sabine Hossenfelder, argue that we shouldn't get too caught up in "naturalness" or why these numbers are what they are. Science is about describing what we see, and what we see are these specific, unchanging values.
How to Internalize This Knowledge
Knowing about the constants of nature changes how you look at a sunset or a piece of toast. You’re seeing the result of a very specific set of mathematical rules playing out in real-time.
If you want to dive deeper, don't just read pop-science summaries. Look into the actual data.
- Audit the CODATA values: The Committee on Data for Science and Technology (CODATA) publishes the officially recommended values for these constants. Check their latest 2022/2023 updates to see how our precision is improving.
- Explore the "Natural Units" concept: Look up Planck Units. This is a system of measurement where the constants are all set to 1. it makes the math of the universe look surprisingly clean and reveals how the constants are interconnected.
- Track the "Variation of Constants" research: Follow journals like Physical Review Letters for any updates on those quasar studies. If we ever find definitive proof that $G$ or $\alpha$ is shifting, it will be the biggest news in the history of science.
The universe isn't a chaotic mess. It’s a highly tuned machine. We’re just the passengers trying to figure out how the engine works by listening to the hum of the constants.
Practical Next Steps for Further Exploration:
- Download a "Physics Constants" app: Having the precise values of the Boltzmann constant, the electron mass, and the vacuum permittivity in your pocket makes it easier to fact-check science news.
- Read "The Constants of Nature" by John D. Barrow: It’s an older book but remains the gold standard for explaining how these numbers define our reality without needing a PhD in math.
- Use the NIST Reference on Constants: Visit the NIST website to see how these numbers are actually measured using experiments like the Kibble Balance. It’s far more fascinating than just seeing a number on a page.