Albert Einstein

Albert Einstein -------------------------------------------------------------------------------Think Like Einstein by Rick Groleau Ever since Einstein revealed his special theory of relativity, we've known that time travel�at least moving forward through time�is possible. Einstein didn't pull this theory, or even the notion that time travel is possible, out of thin air. Rather, he took the knowledge of the day, saw an inconsistency�a piece of a puzzle that didn't fit, so to speak�and thought about possible explanations. On the following pages you'll have to think like Einstein. You'll take a look at the same puzzle and see the problem, and you'll have to think about the same things Einstein had to think about to resolve the problem. Maybe you've heard the recent reports about how physically unique Einstein's brain was. Don't panic�you won't need a superhuman brain to grasp the concepts presented. And when you finish, not only will you understand the special theory, you will have reasoned it out for yourself, just as Einstein did. Think Like Einstein Part 1: Adding Velocities We begin with a basic concept�one that sets the scene... You're on a train that's moving forward at 50 mph. You throw a ball in the direction that the train is moving. Relative to you and the train, the ball leaves your hand travelling at 20 mph. Question: From the point of view of someone standing alongside the tracks, how fast is the ball moving? 20mph 30mph 50mph 70mph Part 2: The Speed of Light OK. Everything so far makes sense. Let's move on to the speed of light for a moment. In 1887 two American scientists performed a now-famous seemed to show that the speed of light was independent that light always travelled at the same speed: 186,000 matter if the source of the light was moving or if the

experiment. The experiment of motion. In other words, miles per second. It didn't observer was moving.

There was another indication that the speed of light was constant, too�one that Einstein found especially difficult to ignore. James Clerk Maxwell, the mind behind electromagnetic theory, had developed equations that described the nature of electricity, magnetism, and even light. These equations, the predictions of which were confirmed by experiment, by the way, implied that light always travelled at the same speed.

Which brings us to the next question... Think Like Einstein Part 2: The Speed of Light OK. Everything so far makes sense. Let's move on to the speed of light for a moment. In 1887 two American scientists performed a now-famous seemed to show that the speed of light was independent that light always travelled at the same speed: 186,000 matter if the source of the light was moving or if the

experiment. The experiment of motion. In other words, miles per second. It didn't observer was moving.

There was another indication that the speed of light was constant, too�one that Einstein found especially difficult to ignore. James Clerk Maxwell, the mind behind electromagnetic theory, had developed equations that described the nature of electricity, magnetism, and even light. These equations, the predictions of which were confirmed by experiment, by the way, implied that light always travelled at the same speed. Which brings us to the next question... Again, you're on a train. This time, though, the train is moving much faster�at half the speed of light, or 93,000 mps (miles per second). And instead of throwing a ball, you turn on a flashlight. Question: How fast is the light travelling relative to the observer standing alongside the tracks? 93,000 mps 186,000 mps 279,000 mps

Think Like Einstein Part 3: The Speed of Light Here's our last question. This one's like the previous one, but with a twist. Again, you're on a train moving at 93,000 mps, and again, you turn on your flashlight. Question: How fast does the light travel relative to you? 93,000 mps 186,000 mps 279,000 mps

Part 4: The Solution By now you probably understand the conflict: How is it possible that light always travels at the same speed, no matter how fast its source is moving? Einstein, when he was 16, thought about the same thing. Are you familiar with the equation v=d/t? All it says is velocity (speed) equals distance travelled divided by time.

Here's an example of how it can be used...

And here are two more examples that show how speed can stay the same even though distance and time can change...

See the relationship between speed, distance and time? If we use this equation in our first scenario�the one where you threw the ball�it works out fine. For you, within the train, as well as for someone standing by the tracks, we can calculate the speed of the ball by adding the distance the train travelled and the distance the ball travelled. The equation does not work out so well in the second scenario, though, because we're dealing with the speed of light, so the "v" in the equation always has to be 186,000 miles per second. Something has to give. Question: What can we infer from what we've seen so far? That the results of various experiments and that Maxwell's equations must be incorrect, and that the speed of light can vary, depending on the situation. That time (and maybe even distance as well) is not the same for all observers.