Issue #18: August 22, 2025
From apples to galaxies, physics is the language of reality.
Ready to see how it all connects?
What’s Inside This Issue?
- Concepts and Terminology: Discover concepts and terminology introduced in the featured article.
- Featured Article: Dive into the world of physics and explore its ongoing quest to model and understand reality itself.
- About the Author: Join Shashir Dholakia, an American astrophysics doctoral student in Australia, who’s passionate about physics.
- Hands-On Activities: Try modeling for yourself: explore common pitfalls to avoid.
- Environmental Equity and Sustainability: Discover how physics impacts fairness in our world and its environmental footprint.
- Preparing for a Career that Uses Physics and Modeling: Explore a physics pathway and see how to get started.
- Glossary: Recap key concepts and terminology from the featured article.
1. Concepts and Terminology
- Model – a simplified view of a part of reality of interest to us. People create models to more easily understand our world. This requires making observations such as finding a root cause of an action, taking measurements, collecting and organizing the data, and using mathematics to relate two or more variables. As more is learned, the models may need refinement.
- Abstraction – the act of simplifying reality by stripping away needless details, leaving the essentials behind
- Physics – the ultimate “how-to” guide for reality and how things work; it’s the “language of reality”
- Astrophysics – the application of physics to understand and predict the world beyond us, from Earth to the farthest reaches of outer space
- Mathematics – the language of physics
2. Featured Article
What is the Point of Physics? The Endless Quest for How Reality Works.
By Shishir Dholakia
Have you ever wondered why a thrown ball follows a curved path, how a compass always points north, or why a satellite can stay in orbit without falling to Earth? These everyday questions, and the big, mind-bending ones about black holes and the very beginning of the universe, are all part of the same adventure. Physics is the ultimate “how-to” guide for reality. It is the science that seeks to understand how everything works, from the smallest particles to the largest galaxies. Think of it as a journey of discovery, where we build and test models to solve the most fascinating puzzles about our world
Background
Newton’s Laws of Motion, Einstein’s theory of relativity, the Big Bang theory, and quantum mechanics all share something in common: they’re incomplete. In fact, nearly every physicist would agree that these monumental theories are only part of a bigger story. We’ve found places—like inside black holes or in the earliest moments of the universe—where our most trusted ideas stop making sense. So, why do physicists spend their lives developing theories that they know will eventually be superseded? This isn’t a sign of failure, but the very essence of how science advances.
The beauty of physics is that it unites the big, the small, the ordinary, and the extraordinary. Physics is the study of how our reality works. Physicists use the scientific method to develop models and theories that both explain and predict our reality. To illustrate, let’s follow a strand from the history of physics and see where it leads today.
Newton’s Revolutionary Insight
It is said that Isaac Newton first got the idea for his law of gravitation by watching an apple fall from a tree. His insight was that the same force pulling on the apple also explained the motion of the Moon. He pictured the Moon as constantly “falling” toward the Earth, but also moving forward so fast that it perpetually misses, circling the planet in a continuous orbit.
This was a remarkable feat of intuition. Suddenly, one idea explained two totally different scales of reality, from a falling apple to the Moon in the sky. Newton’s real contribution was to make this idea testable and predictive. He used mathematics—the language of a physicist—to create a full-fledged theory of gravity. This mathematical model both described the motion of the planets and predicted the flight of projectiles with incredible accuracy.
Newton contemplates the universe
Image credit: Jean Leon Huens_in Our Universe
All Models Are Wrong, But Some Are Useful
However, Newton’s models began to fall a bit short in the early 1900s. The orbit of the planet Mercury, for example, was subtly but clearly different from what Newton’s model predicted. A new model for electromagnetism from James Clerk Maxwell also revealed that a universal speed of light was incompatible with Newton’s ideas. Taken together, Newton’s model for motion and gravity did not perfectly match reality.
There’s a saying, attributed to statistician George E.P. Box “All models are wrong, but some are useful.” Even after physicists knew Newton’s models were incomplete, engineers used them to guide the rockets that sent a dozen people to walk on the Moon. Newton’s theory was sufficient because it works perfectly fine at speeds much less than the speed of light and for weaker gravitational fields. Mercury, on the other hand, orbits much closer to the massive Sun, where gravity is enormously strong. Good predictions of the orbit required Einstein’s later insights.
Where Newton’s laws are sufficient (between the Earth and the Moon), and where they aren’t (tiny Mercury’s close orbit around our massive Sun).
Image credits: Astronaut on Moon and Mercury
Einstein’s Spacetime and the Next Breakthrough
Einstein’s theories of Special and General Relativity were built on some incredibly complex math, but they gave us amazing new insights, like how mass and energy are two sides of the same coin (E=mc2). This single idea is what powers the sun and makes things like nuclear energy possible.
These new models predicted incredible things, like the bending of light by a gravitational force. To test this radical claim, British astronomers Sir Arthur Eddington, Edwin Cottingham, and their colleagues organized two expeditions, one to the tropical island west of Africa called Príncipe and another to Brazil, to observe a total solar eclipse in 1919. Telescope photos were taken at the two spots. The position of stars nearest the Sun were then compared to those from images taken at night without the sun’s presence. The teams’ stunning discovery was that the starlight bent around the Sun by precisely the amount that Einstein’s model predicted—a deflection twice as large as people believed it would be under Newton’s laws. While many other predictions of the theory were confirmed over time, such as the existence of black holes, their confirmation was not immediate. The eclipse of 1919, however, was the dramatic first step that established general relativity as a remarkable new component of the model of gravity. Why did they bother doing the confirmation? Because math and science are genuinely cool.
Image credits: Britannica: Sir Arthur Eddington and European Southern Observatory: 1919 Solar Eclipse
The Modern Quest for a Unified Theory
Almost immediately after Einstein introduced relativity, a new field of physics was also taking shape: quantum mechanics. This theory, which describes the bizarre behavior of very small particles, was also incredibly successful at explaining and predicting experimental results. However, as both theories developed, a deep incompatibility became clear. We have since learned that neither theory can explain everything; each one has its limits. We know that in extreme situations, our current understanding breaks down. Even now, we still have no single, complete theory that works for both the smallest particles and the largest scales of the universe.
This is the great challenge of modern physics. Experimental physicists are constantly probing the universe, hoping to find new data that conflicts with existing models—to falsify them—or to find something completely new and unexpected. This work has already uncovered a mountain of strange phenomena, like dark matter, dark energy, and puzzling details about the early universe, that existing theories cannot fully explain. Modern theoretical physicists are hard at work to develop new models and theories that might unify these concepts. The goal of physics is this beautiful, unending interplay between experiments and models, which pushes us ever closer to a more complete understanding of our fascinating universe.
What are Models and Why Make Them?
Models in physics are simplified representations of real-world systems or phenomena, but they can be simplified in different ways. Some models are reductionist, where the goal is to strip away all but the most essential components to explain a specific phenomenon. Others are comprehensive, aiming to include as many factors as possible to reproduce a full range of behaviors. For example, general relativity (GR) is a complex and comprehensive model because it attempts to account for a wide range of gravitational phenomena.
A great example of a reductionist model is a cartoon drawing of a person—it captures the most important features of just a part of the universe, while leaving out the complicated details. This is a crucial concept because it’s how physicists make sense of the world.
Your goal with model making is to look at the real thing, grab enough of the important features, throw away all the fluffy details, and keep the essential parts. Albert Einstein is said to have said something like: “Everything should be as simple as possible, but not simpler.”
In the images below, we first take a fun photo of Albert (we’re on a first-name basis now!) and successively remove details, going left-to-right, to show in pictures what we mean when we say we create a “model.” Here, our model on the far right has the minimum number of details that still let us identify Albert. Simplifying things further might not help, and may actually hurt us.
Image credits, left to right: 1. colorized photo, 2. actual photo, 3. & 4.: Ideogram and Foundation, 5. Pixabay and Foundation
We could take similar steps to try to figure out how a bird or a jet plane flies, for example. Let’s try this with a plane and show the forces on the main lifting part, the wing – their magnitudes and directions – so that we can calculate the resulting force, and therefore predict the plane’s path through the sky. Once we identify all of the different kinds of forces, we let them act on a single point on our model, and next find or derive the equations that go with each force to find out how big they are, expressing them mathematically in terms of everything else important that’s going on, like speeds, directions, angles, and gravity. In physics, we learn how to combine many forces that point in different directions into one. This work usually requires us to first take some courses in school in several areas, but hey, learning is fun! Given some time and effort, we can do it!
Bottom Image: A simplified model of just the wing with the basic forces acting at a point on the jet.
From those, and perhaps a little bit more, we can predict where the jet’s headed!
Image credits: free image and this Foundation
Students in classes like physics, fluid mechanics (possibly in a department of mechanical engineering), and aeronautical engineering will study problems like that one with the jet.
When we do problems in astrophysics, we approach things pretty much the same way. Only in astrophysics, we’re dealing with planets and stars and galaxies and black holes and whew! And, there’s nothing holding them still! When you have two celestial bodies, like the Earth and the Moon, you can predict their paths accurately using formulas dating back to Newton. However, when you have three bodies, things can get rather complicated quickly. But that does not mean we don’t try to figure out what’s going on – we find ways to proceed!
Image credit: Star Wars™ sunset
We create models because they allow us to:
- Simplify problem-solving: Without a model, every physics problem would be impossible to solve.
- Predict the future: A model can help us predict where a thrown ball will land or how long it will take for a car to stop.
- Test our understanding: If our model makes inaccurate predictions, it means our understanding of the system is flawed, and we need to refine our model or our theories.
The idea of making models of our world is not only a cornerstone of physics, but it is also a fundamental human activity that extends into almost every field, from engineering and video game design to economics and urban planning. It’s clear that making models is a very valuable skill to learn!
The quest to understand our universe is a journey with no end, and every new discovery brings us closer to a more complete picture of reality. Physics is everywhere, from the planets in the sky to the phone in your hand, and the questions it asks are some of the biggest and most exciting there are. So, what’s your question? What will your discovery be?
3. About the Author
Hello! My name is Shishir, and I am excited to share the wonders of the universe with you. Although we attended different schools, I first met Paul Jr. at the Santa Clara County Science Fair when I was in middle school, where we bonded over our shared love of science and technology. I completed my bachelor’s degree in Astrophysics at the University of California, Berkeley, where I met up with Paul again, and even took a class with him! I am now a PhD researcher at the University of Southern Queensland in Australia trying to learn more about exoplanets – planets around stars other than our Sun. Although my job has advanced beyond stargazing, I’m still passionate about going out on a dark night and looking up at the beautiful night sky. Often, I’ll bring a telescope and a camera to enjoy even better views and take photographs of distant nebulae and galaxies. In my free time, I also enjoy playing badminton and taking photographs of nature.
4. Hands-on Activities
The Pitfalls of Modeling
When we create a model, we often start by gathering data to find patterns. We might use a spreadsheet to plot the information and see if one variable could be the cause of another. But if we’re not careful, our work can lead to some surprising errors. Here are a few of the most common pitfalls:
a) Correlation does not mean Causation.
Take a look at the chart below showing planetary distance and Amazon rainforest cover over time. What do you see? It appears that as the distance between two distant planets goes down, so does the amount of plant coverage in the Amazon! If you plot one variable against the other, you’ll get a nearly straight line.
Image credit: spurious correlations
But does one of these things actually cause the other? Of course not! This is a perfect example of how just because two variables correlate—meaning they move together—it doesn’t mean that one causes the other. The correlation is just a coincidence. When you’re building a model, you’re on the lookout for a real cause, not just a coincidence.
Your turn: Can you think of another example of two things that correlate but don’t have a cause-and-effect relationship?
b) Good Data and Smart Models
Even after you’ve avoided the first pitfall, there are still a few more to watch out for. Your model will only be as good as the data it’s based on—a principle computer scientists call “Garbage In, Garbage Out.” You can have the perfect model form, but if you derived it using bad data, your results will be useless.
You also have to be careful not to make your model too simple. As we saw in the main article, a model is a simplified representation of reality, but if you oversimplify it, you lose the ability to make accurate predictions. Finally, always remember that the map is not the territory. Your model is a guide, not reality itself. The conditions that your model is based on can change, so you need to be ready to change your model too.
Your turn: Can you think of examples of garbage-in/garbage out, oversimplification, and ‘the map is not the territory’?
5. Environmental Equity and Sustainability
The following projects show that physics is much more than just a subject in a textbook. It’s a powerful tool for building a more sustainable and equitable world. By using the same principles that help us understand the stars, physicists and engineers are tackling real-world problems right here on Earth, from making clean energy available to everyone, to fighting for clean air in every neighborhood.
It’s much more powerful to see how these ideas are being applied in the real world. Here are some of those projects presented in a way that’s easy to understand, along with links for you to explore more.
1. Using Satellites to Fight Pollution: NASA’s Air Quality Maps 🛰️
- The Challenge: We can’t see the air pollution around us, but it can be a lot worse in some neighborhoods than others, especially in communities near factories or busy highways.
- How Physics Helps: Physicists and engineers use sensors on satellites orbiting Earth to measure and map air quality. These devices rely on the physics of light to detect different gases and particles in the atmosphere. By combining this data with demographic information, they can create powerful models that reveal exactly where pollution is a bigger problem.
- The Project: Researchers at George Washington University and NASA have used satellite data to create maps that show how air pollution disproportionately affects communities of color and low-income areas. This data isn’t just for science—it’s a powerful tool that communities can use to push for change and demand cleaner air.
- Learn More: NASA SVS Air Quality Visualization
Higher values are represented with dark purple and lower values are represented with light blue.”
Text and Image Credit: NASA Scientific Visualization Studio
2. Power from the Earth: Geothermal Energy in Kenya 🌍
- The Challenge: Many countries rely on fossil fuels for energy, which is expensive and harms the environment. How can we find a sustainable, reliable power source that’s also locally available?
- How Physics Helps: Physicists who study geology and Earth sciences help locate “hot spots” beneath the ground where the Earth’s core heat is close to the surface. They use the physics of heat transfer and thermodynamics to design and model power plants that can turn this underground heat into a constant flow of electricity.
- The Project: Kenya has become a world leader in geothermal energy, which now provides a huge portion of its electricity. This has reduced the country’s dependence on fossil fuels and made power more reliable. It’s a fantastic example of a nation using physics to create a clean, sustainable, and energy-independent future for its citizens.
- Learn More: IMF on Kenya’s Geothermal Energy
Image Credit: IMF: Kenya Taps the Earth’s Heat
3. Community Solar: A Team Approach to Clean Energy 🏡
- The Challenge: Making a solar panel is a great start, but making sure everyone can use them is a whole other problem. How can communities work together to get the benefits of clean energy, especially if they can’t put panels on their own roof?
- How Physics Helps: The physics behind a solar panel turning sunlight into electricity is just the beginning. The success of community solar relies on modeling and system design to ensure that the energy generated from a central location is fairly and accurately distributed to everyone who subscribes. The National Renewable Energy Laboratory (NREL) uses these models to help communities get the most from their shared solar arrays.
- The Project: Community solar projects are being built all over the world, allowing people to subscribe to a large solar farm and get credit for the energy it produces on their own electricity bill. This makes clean energy accessible to renters, apartment dwellers, and people with homes in shady areas, making sure the benefits of solar are shared by the whole community.
- Learn More: U.S. Department of Energy on Community Solar
Image Credit: U.S. Department of Energy_Community Solar Basics
6. Preparing for a Career that Uses Physics and Modeling
Preparing for a career that uses both physics and modeling is an excellent goal. This combination of skills is incredibly valuable because it teaches you not only how the world works, but also how to predict it. The key is to focus on building a strong foundation in both the principles of physics and the tools of computation.
Build Your Core Skills
The most important thing you can do in high school is master the fundamentals. Physics is the language of reality, and math is the language of physics.
- Math is a Must: Don’t just get through math. Explore it! The deeper you go, the more you’ll uncover its hidden beauty and find that the effort is truly rewarding. Taking calculus, for example, gives you a unique way to model and understand the world around you.
- Embrace Computer Science: Modern modeling is done with computers. Learning to code in languages like Python is essential. It’s the skill you’ll use to build, test, and analyze your models.
- Understand the Principles: Take physics classes to learn the core concepts, like energy, motion, and gravity. These are the building blocks for every model you’ll create, whether it’s for a rocket or a financial market.
Get Hands-On Experience
The best way to learn modeling is by doing it.
- Start with Projects: Look for projects that involve creating a model to solve a problem. This could be a science fair project where you use a mathematical model to predict the flight of a paper airplane, or a robotics club where you program a robot to navigate a maze.
- Explore Extracurriculars: Join clubs like robotics or coding clubs. These groups are full of opportunities to work with others on real-world problems that require building and refining models.
Discover Career Paths
A career that uses physics and modeling isn’t just one job; it’s a way of thinking that is valued in many fields. Here are a few examples:
- Climate Scientist: These professionals build complex computer models of the Earth’s atmosphere and oceans to predict the effects of climate change.
- Aerospace Engineer: They use physics and modeling to simulate how a rocket will perform in different conditions before it is ever built.
- Financial Analyst: Many financial analysts build mathematical models to predict market trends and manage risk for banks and investment firms.
- Data Scientist: The demand for data scientists is huge. They use statistical models to analyze massive datasets and find patterns in everything from customer behavior to disease outbreaks.
- Medical Physicist: They use modeling to design and optimize medical equipment, such as MRI machines and radiation therapy systems, to ensure safe and effective patient treatment.
7. Glossary
- Model – a simplified view of a part of reality of interest to us. People create models to more easily understand our world. This requires making observations such as finding a root cause of an action, taking measurements, collecting and organizing the data, and using mathematics to relate two or more variables. As more is learned, the models may need refinement.
- Abstraction – the act of simplifying reality by stripping away needless details, leaving the essentials behind
- Physics – the ultimate “how-to” guide for reality and how things work; it’s the “language of reality”
- Physicist – A person who models the world in order to understand how it works
- Astrophysics – the application of physics to understand and predict the world beyond us, from Earth to the farthest reaches of outer space
- Mathematics – the language of physics
- Newton’s Laws of Motion – A framework for understanding and predicting the motions and gravitational attractions of simple classes of objects. His laws work very well when the objects are not too heavy and their speeds do not approach the speed of light
- General Relativity Theory – A modification of Newton’s Laws, created by Albert Einstein, which take into account massive objects and how they affect local gravity.
- Correlation – When two or more measurements (variables) change in a pattern that might suggest one causes the effect of the other. They could move upwards together or opposite one another, but the bottom line is that sympathetic movements don’t necessarily mean that when one moves, it causes the other(s) to move.
- Causation – A much stronger relationship than correlation alone. Here, a change in one variable definitely causes another variable to change. In a physics problem, we try to understand the root causes (the mechanisms for the behaviors), explain them with math, and put the results in our model.
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