Einstein's theories explained in 5 minutes: (special) relativity

Introduction

In the past I have noticed a lot of people talk about (special) relativity and other physics theories, but when you ask them a few questions, they do not seem to grasp the concept….

In this series of blog posts I will try to explain you some of his concepts the way I understand them…

The inspiration for this series has been one of Einstein’s quotes :

“Make everything as simple as possible, but not simpler”

I am no physicist by any means, nor a good mathematician, so you should never ask me any questions about the proof or maths about something, since I simply do not know. If you ask most people about these theories they usually start making it way too complicated for one of the two following reasons :

  • They do not understand it, so they try to blow you away with complicated things they heard about it, so you would stop asking questions about it…
  • They do understand it, but their explanation assumes you know the “language of physicists” - which you do not - so it seems like they are talking Jibberish all the way…

We will start with a very popular concept : the theory of special relativity.

 

The Special Theory of Relativity

This is actually one of the simpler theories, but misunderstood by a lot of people…

What is so special about it ?

And would it not be better if we got started with general relativity first ?

Actually special relativity is easier then general relativity; special relativity describes relativity for easy cases, while the general theory tries do describe all possibilities in a single theory…

Ok, so what is it all about ?

In order to explain it, I first looked at some references (i.e. wikipedia), but they seem to talk Jibberish for the most part, so I will try to explain it in my own words, using an example.

Albert Einstein used to approach Physics in a very theoretical way; he made up special cases using the extremes of physics laws, and then imagined what would happen. This theory probably started with the observation that the speed of light was constant. Think about this : no mather where you are, the light always travels at the same -albeit very high- speed. Einstein wondered what it would look like if he would fly in front of a top of a ray of light that was fired… Would you be able to see the top of the light or not ?

Why is that such a good question ? It just sounds like a lot of mumbo-jumbo to me …

Think about it; as you might know - or not, depending on your age or background - , we can see things because light reflects on it. Everything you see is because a ray of light (from a lamp or the sun) reaches your eyes, either directly, or by reflecting from another surface. You could compare it with this : the light source emits a constant flow of marbles, and these marbles hit your eyes, either directly, our by bouncing on other surfaces…

Remember that the speed of light was constant ? This would mean that all those marbles travel at the same speed, no mather where they are; either they are moving at the speed of light, or they cease to exist….

If we now go back to Einstein sitting at the rocket, flying at the speed of light, and trying to look to the top of the light, would he see it ? I suppose not; lets look at it from above. (Look at the image on the right)

If Einstein travels at the speed of light the light would never hit his eyes, because he moves as fast as the speed of light. (Two things that move at the same speed will never touch each other.) Hey, this looks like an interesting question after all… But what has this got to do with this special theory of relativity ?

 

Einstein says time and place do not exist seperately

What do you mean, “a place does not exist without time”, are you nuts ? I am at home today, and later on I will be at the shopping mall. Please tell me why a place would not exist ? Oh Man !! And, by the way, I overheard that one can never travel at the speed of light, except maybe through wormholes, so what is that all about ???

Time and it’s perception

Calm down, one step at a time… To explain it, I will take you back to the marbles example, but this time with another case. First I will try explaining this aspect to you in a simple sentence :

The exact time you see something happening is dependent on your distance from the event.

Take a good look at the sentence above; this means that if you and another person look at something, you have a different perception about the exact time it happened. I can explain this to you with a simple picture.

This picture represents a light bulb that emits yellow light, and suddenly switches to red light. Each row is a timeframe.

In the beginning a light is emitting yellow marbles, so both people see yellow light bulb… Then, a certain moment the light bulb switches from red to blue. Now, you do remember that light is like marbles who always travel at exact the same speed, do you ? What would this mean ? The moment the light switches to red, the persons would still be receiving the yellow marbles, and not the red ones. So, while the light is actually red, both the left and the right person would still be receiving the yellow version…

Next to this, you can see that when the first red marble hits the left person (i.e. the left person sees a red bulb), the right person still sees a yellow bulb, as the red ones have not reached him yet…. This means that the time when something happens at another location depends on the viewer’s distance from that event; there is a delay.

The reason we never spot this in real life is that the speed of light is very high which makes the delays really small…

What we actually showed in this part is that time is relative to the observer’s location, if you see something happening, the exact time you notice it depends on the distance you are away from it, So there is a delay….

This also imples that there is no absolute reference to “time”; while we all have the impressions that we “are in the same moment”, the “moment of another person” is slightly delayed from yours, since you are not in in same place….

In this case we consider only objects who stay in the same position relative to eachother, but what if one object would be moving away or towards another object; would that have any impact at all…. Well, I can tell you it does, in the next part I will show you how place/location/dimensions are also relative….

 

Whoa ! Place does not exist without time !!! Is this like David Copperfield when he moved the statue of liberty ???

No, it is not. (Actually Copperfield did not move the statue, he simply gave the whole tent the observers were sitting in a small twist, but that is irrelevant here…)

And now we take a break for a short commercial…

… until I am able to finish this blog post. In the mean time please do leave some comments with your opinions, remarks, improvements and suggestions as I want to make these series as good as possible… I hope you enjoyed the first part and that I will see you back again later !!!

Kind regards,

Tom

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