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#### Relativity

A little intro with a bit of text

### 1. The Michelson-Morley Experiment

It was thought that light must travel through a medium called the ether. If this really existed then light would travel slower in the direction the Earth moved through space, compared to light that travelled at right angles to this. Michelson and Morley used an intererferometer to see if they could measure this change.

### 2. Special Relativity

In this video I introduce Einstein's ideas of special relativity, his two postulates and what he meant by a frame of reference.

### 3. Gamma Factor and Time Dilation

You don't have to derive the gamma factor (also known as the Lorentz factor) for relativity, however, it is something that you should be able to follow. This factor tells us how much time, length and mass change by.

### 4. Muons and Time Dilation

I use the muons created by cosmic rays as an 'everyday' example of where special relativity must be considered and time dilation must be used to explain our observations.

### 5. Length Contraction

As objects travel closer to the speed of light length appears to contract, once again I use the example of muons to demonstrate this.

### 6. The Twins Paradox

This is a well known paradox about two twins and which one should age more than the other.

### 7. Relativistic Mass

Mass is not always a constant - in fact as an object increases is velocity its mass also increases.