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Scale of the Universe: Discover the vast ranges of our visible and invisible world.

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Scale of Universe is an interactive experience to inspire people to learn about the vast ranges of the visible and invisible world.

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What is matter? Matter is everything around you. Atoms and compounds are all made of very small parts of matter. Those atoms go on to build the things you see and touch every day. Matter is defined as anything that has mass and takes up space (it has volume).

What is mass? Mass is the amount of matter in an object. You might have a small object with a lot of mass such as a statue made of lead (Pb). You might have a large object with very little mass such as a balloon filled with helium (He). You should also know there is a difference between mass and weight. Mass is a measure of the matter in an object while weight is a measure of gravity's pull on an object.

What is volume? Volume is the amount of space something occupies. Words such as big, little, long, or short are used to describe volumes. A marble takes up a small volume while a star occupies a large volume. Different states of matter will fill volumes in different ways.

Even though matter can be found all over the Universe, you will only find it in a few forms (states) on Earth. We cover five states of matter on the site. Each of those states is sometimes called a phase. There are many other states of matter that exist in extreme environments. Scientists will probably discover more states of matter as we continue to explore the Universe.

What are the main states of matter? Everyone should know about solids, liquids, gases, and plasmas. Scientists have always known about solids, liquids, and gases. Plasma was a new idea when it was identified by William Crookes in 1879. We also like to talk about the Bose-Einstein condensate (BEC). It's a fun state of matter when you remove almost all energy from a system. The scientists (Cornell, Ketterle, and Wieman) who worked with the Bose-Einstein condensate received a Nobel Prize for their work in 2001.

What makes a state of matter? It's all about the physical state and energy in the atoms and molecules. Think about solids. Physical properties of a solid often include "hard" and "brittle." Liquids are fluidy, move around a little, and fill up containers. Gases are always around you, but the molecules of a gas are much farther apart than the molecules in a liquid. If a gas has an odor, you'll often be able to smell it before you can see it. The BEC is all about atoms that are closer and less energetic than atoms in a solid.

What is a physical change in matter? Molecules can move from one physical state to another ( phase change) and not change their atomic structure. Oxygen (O ₂) gas has the same chemical properties as liquid oxygen. The liquid state is colder and denser (less energy), but the molecules are the same. Water (H ₂O) is another example. A water molecule is made up of two hydrogen (H) atoms and one oxygen (O) atom. It has the same molecular structure whether it is a gas, liquid, or solid. Although its physical state may change because of different amounts of energy, its atomic structure remains the same.

So what is a chemical change in matter? Let's start with that glass of pure water. If the formula of water were to change, that would be a chemical change. If you could add a second oxygen atom to a water (H ₂O) molecule, you would have hydrogen peroxide (H ₂O ₂). The molecules would not be "water" anymore. In reality, there are a variety of steps that go into creating hydrogen peroxide from water.

Physical changes are related to changes in the immediate environment such as temperature, pressure, and other physical forces. Chemical changes occur when the bonds between atoms in a compound are created or destroyed. Generally, the basic chemical structure does not change when there is a physical change. Of course, in extreme environments such as the Sun, no molecule is safe from destruction.

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Chem4Kids.com: Matter: Definition and Overview

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Chem4Kids.com! This tutorial introduces basics of matter. Other sections include elements, the periodic table, reactions, and biochemistry.

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Take a break and look at some optical illusions: images, colors and patterns designed to trick the brain.

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Some History / What's new

2023-09-10 kinetic Orbison

2023-07-10 update colour game

2023-01-07 simplest oblique

2022-11-23 Diamonds/squares

More...

Optical illusions don't "trick the eye", nor "fool the brain", nor reveal that "our brain sucks", ... but are fascinating!

They also teach us about our visual perception and its limitations. My selection here emphazises beauty and interactive experiments; I also attempt explanations of the underlying visual mechanisms where possible. Returning visitor? Check →here for History/News

"Optical illusion" sounds derogative, as if exposing a malfunction of the visual system. Rather, I view these phenomena as highlighting particular good adaptations of our visual system to its experience with standard viewing situations, confronted with an atypical situation. These experiences are based on normal visual conditions, and thus under unusual contexts can lead to inappropriate interpretations of a visual scene (="Bayesian interpretation of perception").

If you are not a vision scientist, you might find my explanations too highbrow. That is not on purpose, but vision research simply is not trivial, like any science. So, if an explanation seems gibberish, simply enjoy the phenomenon 😉.

Do illusions reveal something about my personality?

NO. The web is full of claims that your personality (right- or left brain dominated, intro- vs. extroverted, stressed or sublime, or whatnot...) can be deduced from your ability to see some given illusion. However, there is no reliable scientific data that suggests this. That's just click-baiting BS. There is some influence of age, though - but you don't need illusions to know your age... So: Don't let it irk you if you don't see all the phenomena described. For many illusions, there is a percentage of people with perfectly normal vision who don't see them, mostly for reasons currently unknown.

More material

Bach & Poloschek (2006) Optical Illusions Primer (PDF, 2 pages from ACNR); on the programming: Bach 2014 (paywalled, contact me for a PDF).

Book (in German): "... Täuschungen ... Sehphänomene"

Motion & Time

Luminance/Brightness & Contrast

Colour

Geometric & Angle Illusions

Space, 3D & Size Constancy

Cognitive / Gestalt Effects

Specialties with faces

Auditory Illusions

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This huge collection of non-scary optical illusions and fascinating visual phenomena emphasizes interactive exploration, beauty, and scientific explanation.

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Start with the INTRO, then go on to the Systems. Figure out how this works and explain what you learn.

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Explore how heating and cooling iron, brick, water, and olive oil adds or removes energy. See how energy is transferred between objects. Build your own system, with energy sources, changers, and users. Track and visualize how energy flows and changes through your system.

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A guide to the energy of the Earth - Joshua M. Sneideman

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What triggers a chemical reaction? - Kareem Jarrah

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Which is stronger: Glue or tape? - Elizabeth Cox

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Watch and take some notes

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Here is another roller coaster simulation.

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Here is another roller coaster simulation.

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Roller Coaster (Work, Energy Conversion, Conservation of Energy) | Physics | Interactive Simulation | CK-12 Exploration Series

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Learn about the conservation of energy in the context of a roller coaster using our interactive simulation.

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Play this game, then take some notes on what you learned.

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exciting stem resources for parents, kids and teachers

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Play this game. Take some notes about how this game connects with your study of energy.

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Watch and take some notes