The Theory of Special Relativity Space and Time

The Theory of Special Relativity Space and Time

Special Relativity – Space and Time • Space-time – two parts of one whole. Your position in the universe can be described by 4 coordinates. Three of them are your position (x, y, z) and the last one is time (t) • Motion in space affects motion in time. The faster you move, the slower time moves

Special Relativity – Space and Time • Two Points: • Motion is Relative – The position and speed we measure motion affects out results. Objects have different speeds relative to different frames of reference • The speed of light is a constant – in all reference frames, the speed of light will always be the speed of light

Special Relativity – Space and Time • The first postulate of special relativity All the laws of nature are the same in all uniformly moving frames of reference. • This means we can only detect accelerating motion, and not uniform motion. This is why it is difficult to measure the Earth’s motions while on the Earth.

Special Relativity – Space and Time • The second postulate of special relativity The speed of light in empty space will always have the same value regardless of the motion of the observer. • The constancy of the speed of light is what unifies space and time. All measures of the speed of light, c, will be the same no matter what.

Special Relativity – Space and Time • Time dilation – time becomes stretched when objects move near the speed of light. • The faster you move, the more time stretches. This effect is even measureable on an airplane. • Time stops when an object moves at the speed of light, for that object.

Special Relativity – Space and Time • Videos then a derivation of the time dilation equation

Special Relativity – Space and Time •

Special Relativity – Space and Time • According to the time-dilation equation. If v = 0. 995 c, 10 earth years will pass for every 1 year on the space ship. • Consider a pair of twins: if one twin travels away in a rocket ship near the speed of light, and one twin stays at home on Earth, the twin on the ship will age less than the one at home. This is the twin paradox.

Special Relativity – Space and Time • Time travel – traveling near the speed of light makes the future approach you at a quicker rate. • In theory, if one was to travel faster that the speed of light, they would be going back in time… • A hypothetical particle proposed to move faster than the speed of light is the tachyon. None have been discovered

Special Relativity – Space and Time • Homework • Pg 230: 1, 2, 7, 8, 9, 19 • Extra Credit: 16