Modern Physics Presented by Dante strothers

The nuclear force is a residual effect of the more fundamental strong force. The strong interaction is the attractive force that binds the particles called quarks together to form the nucleons (protons and neutrons) themselves.

The Strong nuclear force holds a nucleus together against the enormous forces of repulsion of the protons is strong. It's not an inverse square force and unlike the electromagnetic force it has a very short range

The role of the weak force in the transmutation of quarks makes it the interaction involved in many decays of nuclear particles which require a change of a quark from one flavor to another. It was in radioactive decay such as beta decay that the existence of the weak interaction was first revealed. The weak interaction is the only process in which a quark can change to another quark, or a lepton to another lepton - the so-called "flavor changes".

The weak interaction acts between both quarks and leptons, whereas the strong force does not act between leptons. Leptons have no color, so they do not participate in the strong interactions; neutrinos have no charge, so they experience no electromagnetic forces; but all of them join in the weak interactions.

The electromagnetic force holds atoms and molecules together. In fact, the forces of electromagnetic attraction and repulsion of the charges are so dominant over the other three fundamental forces that they can be considered to be negligible as determiners of atomic and molecular structure. Even the magnetic effects are usually apparent only at high resolutions, and as small corrections.

This is often called the "universal law of gravitation", the gravitational force is the weakest force of the four fundamental forces. Gravitational force is always attractive and acts along the line joining the centers of mass of the two masses. The forces on the two masses are equal in size but opposite in direction, obeying Newton's third law of action and reaction forces. Viewed as an exchange force, the massless exchange particle is called the graviton. From Einstein's treatment in general relativity, gravity is associated with the curvature of spacetime and changes in mass configuration can produce gravitational waves.

General Relativity

Einstein's theory of general relativity predicted that the space-time around Earth would be not only warped but also twisted by the planet's rotation. Gravity Probe B showed this to be correct.

When Einstein developed his theory of general relativity he determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels. As a result, he found that space and time were interwoven into a single continuum known as space-time. Events that occur at the same time for one observer could occur at different times for another.

Quantum mechanics

Quantum mechanics is the body of scientific laws that describe the wacky behavior of photons, electrons and the other particles that make up the universe.

In classical mechanics, objects exist in a specific place at a specific time. However, in quantum mechanics, objects instead exist in a haze of probability; they have a certain chance of being at point A, another chance of being at point B and so on.

Quantum mechanics developed over many decades, it began as a set of controversial mathematical explanations of experiments that the math of classical mechanics could not explain. Around the time that Albert Einstein published his theory of relativity, a separate mathematical revolution in physics that describes the motion of things at high speeds. Unlike relativity, however, the origins of quantum mechanics cannot be attributed to one scientist. Rather, multiple scientists contributed to a foundation of three revolutionary principles that gradually gained acceptance and experimental verification between 1900 and 1930. They are: Quantized properties, Particles of light and Waves of matter.


The grand unified theory is a model in particle physics in which at high energy, the three gauge interactions of the Standard Model which define the electromagnetic, weak, and strong interactions or forces, are merged into one single force.

The hunt to create a grand unified theory, or GUT, that would elegantly explain how the universe works by linking three of the four known forces together started in the 1970's. Physicists first linked the electromagnetic force, which dictates the structure of atoms and the behavior of light, and the weak nuclear force, which underlies how particles decay. Scientists began working to link the electroweak theory with the strong force, which binds quarks together into things like the protons and neutrons in our atoms.

The difference between string theory and loop quantum gravity

In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. It describes how these strings propagate through space and interact with each other.

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