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### Gravity as Acceleration

Einstein immediately realized that his theory of special relativity worked only when an object moved in a straight line at a constant speed. What about when one of the spaceships accelerated or traveled [more…]

### String Theory: The Uncertainty Principle

Werner Heisenberg is best known in quantum physics for his discovery of the *uncertainty principle,* which has the consequence that to make measurements of very short distances — such as those required by [more…]

### String Theory and Probability in Quantum Physics

In the traditional interpretation of quantum physics, the wavefunction is seen as a representation of the probability that a particle will be in a given location. After a measurement is made, the wavefunction [more…]

### Does Anyone Know What Quantum Theory Means?

Some physicists hope that a “theory of everything,” perhaps even string theory, may provide clear explanations for the underlying physical meaning of quantum physics. Among them, Lee Smolin has cited string [more…]

### String Theory: The Participatory Anthropic Principle

The *participatory anthropic principle* *(PAP)* was proposed by the physicist John Archibald Wheeler when he said that people exist in a “participatory universe.” In Wheeler’s [more…]

### String Theory: The Many Worlds Interpretation

In contrast to the *anthropic principle*, the *many worlds interpretation* *(MWI)* of Hugh Everett III proposes that the wavefunction never actually collapses, but all possibilities become actualities — just [more…]

### String Theory and Atomic Theory

Though several scales above the scale that string theory operates on, *atomic* theory is the study of physics at the scale of an atom. Understanding the smaller structure of matter requires some level of [more…]

### String Theory and the Atomic Model

Here is a brief exploration of the Standard Model of particle physics and how it relates to string theory. Any complete string theory will have to include the features of the Standard Model and also extend [more…]

### String Theory and the Planetary Model

There are some problems that remain from the Standard Model, which string theory hopes to resolve. In trying to figure out the atom’s structure, a natural model for scientists to look to in the past was [more…]

### String Theory and Quantum Electrodynamics

Though the principles of quantum electrodynamics were worked out by three individuals, the most famous founder of QED was undeniably Richard P. Feynman. Feynman was equally good at the mathematics and [more…]

### String Theory and Antimatter

Along with the understanding of quantum electrodynamics, there came a growing understanding that there existed *antimatter**,* a different form of matter that was identical to known matter, but with opposite [more…]

### String Theory: Virtual Particles

Quantum electrodynamics was one of the first quantum approaches to a quantum field theory, so it introduced many features possessed by string theory (which is also a quantum field theory). In quantum electrodynamics [more…]

### String Theory and Quantum Chromodynamics

As quantum physics attempted to expand into the nucleus of the atom, new tactics were required. The quantum theory of the atomic nucleus, and the particles that make it up, is called [more…]

### String Theory and Gauge Bosons

In the Standard Model of particle physics, the forces can be explained in terms of gauge theories, which possess certain mathematical properties. These forces transmit their influence through particles [more…]

### String Theory: Where Mass Comes From

Together with attempts to find new particles, such as those motivated by string theory, the inability to observe a type of particle called a Higgs boson, are among the major reasons why scientists need [more…]

### String Theory Tries to Explain Black Holes

A major motivating factor for the search for a theory of quantum gravity is to explain the behavior of black holes, and string theory appears to be one of the best methods of achieving that goal. [more…]

### String Theory's Popularity with Physicists

Many young physicists feel that string theory, as the primary theory of quantum gravity, is the best (or only) avenue for making a significant contribution to our understanding of this topic. Over the [more…]

### String Theory: The Search for M-Theory

The current version of string theory is called *M-theory,*introduced in 1995, which is a comprehensive theory that includes the five supersymmetric string theories. M-Theory exists in 11 dimensions. There’s [more…]

### Can Physicists Prove String Theory?

Even if a precise version of string theory (or M-theory) is formulated, the question then moves from the theoretical to the experimental realm. Right now, the energy levels that scientists can reach in [more…]

### String Theory and Quantum Physics

One hope scientists have is that string theory will explain some of the unusual results in quantum physics or, at the least, reconcile it with general relativity. Quantum physics traces its roots back [more…]

### String Theory: Einstein’s Nobel Idea of Light

Photons are one of the fundamental particles of physics that physicists hope to explain using string theory. Einstein received the Nobel Prize not for relativity, but instead for his work in using Planck’s [more…]

### String Theory: The Double Slit Experiment

Without quantum physics, string theory could not exist. Here is a look at how quantum theory allows objects to act as both particles and waves. The experiment that proved that light acts like a wave was [more…]

### String Theory: The de Broglie Hypothesis

The de Broglie hypothesis states that particles of matter also had wavelengths and could behave as waves, just as photons did. String theory will later say that both types of particles — matter and energy [more…]

### String Theory: The Quantum Wavefunction

The solution to the problem of the double slit experiment, a concept at the heart of string theory’s origins and a direct consequence of this early work in quantum physics, took the form of the [more…]

### String Theory: Types of Particles

Physicists have found a large number of particles, and one thing that proves useful is that they can be broken down into categories based on their properties. Physicists have found a lot of ways to do [more…]