Einstein Theory of Relativity.

Theory of Relativity

Einstein's idea that space and time are connected, and strange things happen at high speeds or near heavy objects. Example: A clock on a spaceship runs differently than one on Earth.

General Relativity

Gravity is not a force but the curvature of spacetime caused by mass and energy. Objects move along paths (geodesics) in the curved spacetime. Massive objects bend spacetime, affecting how other objects and even light move near them. The Sun's mass curves spacetime, and Earth orbits along this curved patch.

Special Relativity

Spacetime behaves differently at high speed. It states that the laws of physics are the same for all observers in uniform motion and the speed of light is constant. Example: A fast-moving train appears shorter, and its clock ticks slower due to time dilation and length contraction.

Speed of Light

A constant speed of 299,792,458 m/s, the fastest anything can go. Example: A flashlight beam travels around Earth 7 times in 1 second.

E=mc²

Energy equals mass times the speed of light squared. Ex: In the Sun, nuclear fusion converts tiny amounts of mass into massive energy, powering the Sun's light and heat.

Time Dilation

Time slows down for fast-moving objects. Example: An astronaut moving near light speed ages slower than people on Earth.

Length Contraction

Objects appear shorter when moving close to light speed. Example: A spaceship moving very fast looks squished.

Simultaneity

Two events happening at the same time for one observer may occur at different times for another moving observer. Ex: a person standing still might see two lightning strikes as happening together, but someone on a moving train would see one strike before the other.

Spacetime

A combination of space and time that forms the fabric of the universe (a 4D framework). Ex Imagine space and time as a stretchy rubber sheet.

Gravity in General Relativity

Gravity bends spacetime around heavy objects. Example: The Sun curves spacetime, keeping Earth in orbit.

Geodesics

Paths objects naturally follow in curved spacetime. Example: A satellite follows a curved path around Earth.

Lorentz Transformation

Equations that explain how space and time change for moving observers. Example: A moving clock ticks slower than one at rest.

Inertial Frame

A frame where objects move in a straight line at constant speed. Example: A car moving at steady speed on a highway.

Non-Inertial Frame

A frame where acceleration happens. Example: A roller coaster accelerating downward.

Gravitational Time Dilation

Time runs slower in stronger gravity. Example: A clock at sea level ticks slower than one on a mountain.

Twin Paradox

A fast-traveling twin ages slower than the one staying home. Example: One twin travels on a spaceship and returns younger.

Relativistic Mass

Mass increases as an object moves faster. Example: A speeding particle in a collider feels heavier to an observer.

Photon

A particle of light with no rest mass. Example: Light from the Sun travels as photons.

Black Hole

A region in space where gravity is so strong that not even light can escape. Example: A black hole swallows a nearby star.

Event Horizon

The "point of no return" around a black hole. A spaceship crossing it can’t escape.

Gravitational Waves

Ripples in spacetime caused by moving massive objects. Example: Two merging black holes create waves detected on Earth.

Equivalence Principle

Gravity and acceleration feel the same. Example: Standing in an elevator feels the same as being pulled down by gravity.

Curvature of Spacetime

Mass bends spacetime, affecting objects and light. Example: Light bends around the Sun during an eclipse.

Redshift

Light stretches to longer wavelengths when moving away. Example: Distant galaxies look red due to the universe expanding.

Perihelion of Mercury

Mercury’s orbit shifts because of spacetime bending. Example: Mercury doesn’t orbit in a perfect ellipse.

Michelson-Morley Experiment

Proved there’s no "aether," supporting Special Relativity. Example: Light travels the same speed in all directions.

Relativistic Doppler Effect

Light changes color due to motion. Example: A star moving away looks red, moving toward looks blue.

Proper Time

Time measured by a clock moving with you. Example: Your wristwatch shows your time, even on a fast train.

Rest Energy

Energy an object has due to its mass. Example: A stationary rock contains energy according to E=mc^2.

Relativistic Momentum

An object’s momentum increases with speed. Example: A speeding car is harder to stop.

Gravitational Lensing

Light bends around heavy objects, acting like a lens. Example: A star looks brighter when light bends around another star.

Spacetime Diagram

A graph showing events in space and time. Example: A movie timeline for where and when things happen.

Cosmological Constant

A number added to explain the universe's behavior. Example: Helps explain why the universe is expanding.

Experimental Confirmation

Tests like observing light bending confirm relativity. Example: Scientists saw starlight bend during a solar eclipse.

GPS and Relativity

GPS systems account for time differences due to motion and gravity. Example: Without relativity, GPS would give wrong locations.

Relativistic Velocity Addition

Adding speeds under relativity rules. Example: A fast spaceship’s speed plus another doesn’t exceed light speed.

Invariant Interval

A spacetime "distance" that stays the same for everyone. Example: Like measuring the shortest path between two points.

Rest Frame

A frame where an object is stationary. Example: Sitting on a park bench, you’re in the rest frame.

Warped Spacetime

Massive objects distort spacetime. Example: A bowling ball stretches a trampoline.

Hafele-Keating Experiment

Proved time dilation by flying clocks on airplanes. Example: Plane clocks ran slower than ones on the ground.

No Absolute Time

Time isn’t universal and depends on the observer. Example: Two clocks can tick differently in space and on Earth.

Relativistic Energy

Energy of an object moving close to light speed. Example: A fast-moving asteroid has more energy than a slow one.

Cosmic Rays

High-energy particles from space showing relativistic effects. Example: Cosmic rays hit Earth’s atmosphere and create showers.

Light Cone

Shows all possible light paths from a point. Example: A flashlight beam spreading out in all directions.

Schwarzschild Radius

The size of a black hole’s event horizon. Example: The "edge" of a black hole where light can't escape.

Time Travel in Relativity

Relativity allows for time dilation, enabling "time travel" effects like slower aging. Example: An astronaut traveling near light speed returns to Earth much younger than their twin.

Relativity and Causality

Causality is preserved in relativity, ensuring cause precedes effect. Example: If you drop a ball, it always hits the ground after you let go, no matter the observer.

Einstein Field Equations

Equations in General Relativity that describe how matter and energy influence spacetime. Example: These equations predict black holes and how spacetime bends near heavy objects.

Tests of Relativity

Experiments like gravitational lensing and time dilation support Einstein's theories. Example: During an eclipse, scientists saw starlight bending around the Sun, proving General Relativity.

Relativity and Universe

Relativity plays a key role in understanding cosmology, including the Big Bang and black holes. Example: Relativity explains how galaxies formed after the Big Bang.