# Physics

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### String Theory For Dummies Cheat Sheet

String theory, often called the “theory of everything,” is a relatively young science that includes such unusual concepts as superstrings, branes, and extra dimensions. Scientists are hopeful that string

### Quantum Physics Workbook For Dummies Cheat Sheet

When solving quantum physics problems, you need to keep plenty of information in mind. This Cheat Sheet is all about giving you a framework from which to start. Here, you see the essentials for tackling

### The Basic Elements of String Theory

Five key ideas are at the heart of string theory. Become familiar with these key elements of string theory right off the bat. Read on for the very basics of these five ideas of string theory in the sections

### What String Theory Attempts to Accomplish

To many, the goal of string theory is to be a “theory of everything” — that is, to be the single physical theory that, at the most fundamental level, describes all of physical reality. If successful, string

### The Successes of String Theory

String theory has gone through many transformations since its origins in 1968 when it was hoped to be a model of certain types of particle collisions. It initially failed at that goal, but in the 40 years

### Considering String Theory’s Setbacks

Because string theory has made so few specific predictions, it’s hard to disprove it, but the theory has fallen short of some of the hype about how it will be a fundamental theory to explain all the physics

### Einstein's Special Relativity

In 1905, Albert Einstein published the theory of special relativity, which explains how to interpret motion between different inertial frames of reference

### Einstein's General Relativity Theory: Gravity as Acceleration

General relativity was Einstein’s theory of gravity, published in 1915, which extended special relativity to take into account non-inertial frames of reference

### Einstein's General Relativity Theory: Gravity as Geometry

General relativity was Einstein’s theory of gravity, published in 1915, which extended special relativity to take into account non-inertial frames of reference

### String Theory's Idea of an Expanding Universe

Albert Einstein was influenced by the concept of an unchanging universe. His general theory of relativity predicted a dynamic universe — one that changed substantially over time — so he introduced a term

### String Theory's Notions of The Big Bang Theory

Soon after astronomer Edwin Hubble proved the universe was expanding, it became evident that the universe was once very much smaller. The theory that the universe started from a single point

### The Universe's Dark Matter and Dark Energy

Two of the biggest mysteries of both string theory and cosmology are the presence of unseen dark matter and of repulsive gravity in the form of dark energy.

### String Theory: Defining a Black Hole

One of the consequences of Einstein’s general theory of relativity was a solution in which space-time curved so much that even a beam of light became trapped. These solutions became called

### The Start of the Universe with String Theory

The big bang theory doesn’t offer any explanation for what started the original expansion of the universe. This is a major theoretical question for cosmologists, and many are applying the concepts of string

### String Theory and the Thermodynamics of a Black Hole

When Stephen Hawking described the Hawking radiation emitted by a black hole, he had to use his physical and mathematical intuition, because quantum physics and general relativity aren’t reconciled. One

### String Theory and the Black Hole Information Paradox

One of the important aspects of the thermodynamics of black holes relates to the black hole information paradox. This paradox may well have a solution in string theory, either in the string theory analyses

### The Theory of Parallel Universes

The multiverse is a theory in which our universe is not the only one, but states that many universes exist parallel to each other. These distinct universes within the multiverse theory are called

### Slowing Time to a Standstill with Relativity

In physics, time travel is closely linked to Einstein’s theory of relativity, which allows motion in space to actually alter the flow of time. This effect is known as

### General Relativity and Wormholes: Doorways in Space and Time

In general relativity, the fabric of space-time can occasionally allow for worldlines that create a closed timelike curve,which is relativity-speak for time travel. Einstein himself explored these concepts

### Physics Equations for Electricity and Magnetism

Electricity and magnetism make up one of the most successful fields of study in physics. When working mathematically with electricity and magnetism, you can figure out the force between electric charges

### Light Wave and Optics Formulas

Light waves — that is, electromagnetic waves — behave like other waves: They can reflect, refract (bend), and interfere with each other. Here are some wave formulas that are useful when you’re working

### Formulas from Einstein’s Theory of Special Relativity

Einstein’s theory of special relativity describes what happens as things near the speed of light. Here are some important special-relativity equations that deal with time dilation, length contraction,

### Quantum Mechanics and Other Modern Physics Topics

Modern physics includes all sorts of topics, such as quantum mechanics, matter waves, radioactivity, the spectrum of hydrogen, and more.

### Physics II For Dummies Cheat Sheet

Here’s a list of some of the most important equations in Physics II courses. You can use these physics formulas as a quick reference for when you’re solving problems in electricity and magnetism, light

### Metric System Unit Prefixes

For building circuits or other electronics, a system of prefixes is used to make managing and reading metric easier. Use this chart to learn the metric prefix, its symbol, and the decimal value.