And yet, a small amount of matter survived. We ended up with a world filled with particles. And not just any particles--particles whose masses and charges were just precise enough to allow human life.
Here are a few facts about the particle physics of you that will get your electrons jumping. About 99 percent of your body is made up of atoms of hydrogen, carbon, nitrogen and oxygen. You also contain much smaller amounts of the other elements that are essential for life.
While most of the cells in your body regenerate every seven to 15 years, many of the particles that make up those cells have actually existed for millions of millennia. The hydrogen atoms in you were produced in the big bang, and the carbon, nitrogen and oxygen atoms were made in burning stars. The very heavy elements in you were made in exploding stars. The size of an atom is governed by the average location of its electrons.
By contrasting this model with what is variously called the continuous, continuum, or plenum model, this session shows how the particle model is useful for making accurate predictions about a variety of behaviors of matter on a macroscopic scale. Then, children in the Science Studio divide a piece of aluminum foil into the smallest pieces possible and are asked: Is it possible to go on dividing forever?
Is there ever a point at which the pieces no longer have the properties of the aluminum foil? Science historian Dr. Al Martinez recounts the history of the continuous model originally proposed by the Greeks, explains its appeal, and later tries to use this model to explain the expandability and compressibility of gases.
Back in the Science Studio, children continue to reveal their models of matter, which support what science education research says about the difficulty children sometimes have connecting their ideas about macroscopic matter with the particles that make it up. We return to the Science Studio one last time, where we find children further developing their models to explain the compressibility of gases and proposing a model to explain an everyday change of state—boiling.
In both classrooms the students express a variety of macroscopic rationale for what is happening. What is matter? This question at first seems deceptively simple — matter is all around us. Yet how do we define it?
What does a block of cheese have in common with the Moon? What are the characteristics of matter that set it apart from something that is definitely not matter? Matter is one of the big ideas in science. Tell students that an atom is the smallest building block of matter and a molecule is two or more atoms connected together.
Scientists use models to try to understand the behavior of atoms and molecules and to help explain the properties of matter. Note: Even though atoms and molecules are different, for the purpose of this lesson, they both will be represented in the same way as a circle or sphere. In later lessons, they will be shown using different models.
Show the animation Particles of a Solid. Explain that the particles in a solid are very attracted to each other and vibrate in place. The strong attraction between particles keeps them close together and makes solids, such as the metal in the hammer, solid. Students will record their observations and answer questions about the activity on the activity sheet.
Explain that the bottle has air in it and that air is made up of different gases like oxygen, nitrogen, and carbon dioxide that we breathe every day. Explain that a gas is made up of extremely tiny particles.
Tell students that a gas is very different from a solid. Tell students that if they still doubt that there is anything in the bottle, they can put a balloon on it and see what happens when they squeeze the bottle.
Show the animation Particles of Gas in a Bottle. Explain that the spheres represent the particles of a gas. Explain that the particles of a gas are not very attracted to one another and just hit each other and bounce off. The particles are also much farther apart than they are in a solid. Explain that when the bottle is squeezed, the gas molecules move from the bottle into the balloon, making the balloon expand.
Show the animation Observing Gas in a Bottle. Explain that with the lid on, the bottle can still be squeezed because gas molecules have a lot of space between them and can be compressed. Show the animation Liquid in a Bottle. Explain that the particles of a liquid are attracted much more than the particles of a gas and that they are much closer together. They are almost as close together as a solid but they can slide past each other.
They are so close together that they are very difficult to squeeze. Students have been introduced to the idea that matter, whether solid, liquid or gas, is made from tiny particles called atoms and molecules. Explain to students that the illustrations and animations of atoms and molecules they have seen are models used to represent atoms and molecules. Explain that the actual size of atoms and molecules is incredibly tiny, trillions of times smaller than the dots or spheres we use to represent them.
In fact, atoms and molecules are so small that millions of them would fit in the space of a single period at the end of a sentence. Show the animation Atoms are Small—Really Small. Tell students that the animation is about how incredibly small atoms and molecules are.
It is based on the number of water molecules in a tablespoon of water, which is about ,,,,,,, — About billion trillion, so they are very small.
Tell students that some books and other resources may define states of matter more simply in the following way:. Careers Launch and grow your career with career services and resources.
Communities Find a chemistry community of interest and connect on a local and global level. For instance, they can carry different amounts of electric charge. While particles with color are representations of the symmetry group SU 3 , particles with the internal properties of flavor and electric charge are representations of the symmetry groups SU 2 and U 1 , respectively. The Standard Model reigns half a century after its development. In the s, Glashow, Nanopoulos and others tried fitting the SU 3 , SU 2 and U 1 symmetries inside a single, larger group of transformations, the idea being that particles were representations of a single symmetry group at the beginning of the universe.
As symmetries broke, complications set in. Other, less appealing possibilities remain in play. Researchers placed even higher hopes in string theory: the idea that if you zoomed in enough on particles, you would see not points but one-dimensional vibrating strings.
You would also see six extra spatial dimensions, which string theory says are curled up at every point in our familiar 4D space-time fabric. The geometry of the small dimensions determines the properties of strings and thus the macroscopic world. In their absence, other ideas have blossomed. Over the past decade, two approaches in particular have attracted the brightest minds in contemporary fundamental physics.
Both approaches refresh the picture of particles yet again. Qubits are probabilistic combinations of two states, labeled 0 and 1. Qubits can be stored in physical systems just as bits can be stored in transistors, but you can think of them more abstractly, as information itself. Through these contingencies, a small number of entangled qubits can encode a huge amount of information. In the it-from-qubit conception of the universe, if you want to understand what particles are, you first have to understand space-time.
In , Van Raamsdonk, a member of the it-from-qubit camp, wrote an influential essay boldly declaring what various calculations suggested. He argued that entangled qubits might stitch together the space-time fabric. But the lower-dimensional system that encodes information about that bendy space-time is a purely quantum system that lacks any sense of curvature, gravity or even geometry.
It can be thought of as a system of entangled qubits. Under the it-from-qubit hypothesis, the properties of space-time — its robustness, its symmetries — essentially come from the way 0s and 1s are braided together.
The long-standing quest for a quantum description of gravity becomes a matter of identifying the qubit entanglement pattern that encodes the particular kind of space-time fabric found in the actual universe. Our universe, by contrast, is positively curved. But researchers have found, to their surprise, that anytime negatively curved space-time pops up like a hologram, particles come along for the ride.
That is, whenever a system of qubits holographically encodes a region of space-time, there are always qubit entanglement patterns that correspond to localized bits of energy floating in the higher-dimensional world.
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