The theory of relativity
In 1915 Albert Einstein published the “general relativity”. In 1925 he published the “special relativity”. The central thought of these theories is as follows “if two observers move relativity to each other they can measure different space and time intervals, but the laws of physics is absolute for everything”. And that is very broadly speaking. And there is a lot more to it than this. Because this theory explains phenomenon in space, things like looking back in time due to high speed or high gravitation. I am going to explain the phenomenon and how the theory of relativity can explain these things in space. Let’s start with a journey to a black hole.
What is a black hole?
Black holes is created due to stars running
out of fuel and then collapse under its own weight, then turning into a black
hole with a massive gravitational power that drags in more mass creating an
even bigger mass and the bigger the mass, the stronger the gravitational force
becomes.
So a black hole is capable to have the
biggest gravitation force that is currently known, and this makes finding a
black hole easier, because if the black hole is dragging things towards itself
it will show in the space, because in this area stars and other orbs will spin
around it, creating a spinning circle around the black hole due to the massive
gravitational force, and the other way is to detect radiation in an area. And we would of course not see a black hole
because it traps all light due two curved space-time, and I will explain curved
space later.
And all light gets trapped in a black hole,
and this is interesting and there are three reasons why light can’t escape a
black hole, so light is made by photons witch doesn’t have any mass which
allows it to travel at the speed of light, and actually anything with mass can’t
travel as fast as light. Because particles require energy, and the faster you
go the heavier you get so these particles in let’s say your space shuttle would
require an infinite source of energy, which doesn’t exist or hasn’t been found
yet .
Another reason is even though photons (light consists out of photons) have no mass, they
are still affected by gravity.
And because they are affected by gravity they can’t
just pop in and out of a black hole, and another reason is that within the
event horizon space is curved to the point that all directions are pointing
inside. And the escape velocity within a black hole’s event horizon is faster
than the speed of light. Hence light cannot go at that speed and thus cannot
escape, so it is completely dark.
An interesting scenario is if we would travel to a black hole, the nearest black hole is actually in our galaxy. So imagine if we would have a space ship that could travel very long distances in space, and we then arrive at the black hole, but wouldn’t we get sucked in? First of all, black holes doesn’t “suck” it pulls. Sucking and pulling are two different forces, so that is a big misconception. And no, we wouldn’t get pulled in. We are just going to drive in an orbit around the black hole. And now let’s say we would do some experiments, we have to watches and a robot. So we send the robot down to the black hole, and as the robot gets closer to the event horizon, you, from the space shuttle would see him freeze when he passes the event horizon, the robot would in its own perspective just keep on falling towards the middle, speed is relative, when you ask someone how fast something is going, you always have to ask from which perspective. And so, you in your space shuttle would see the robot standing completely still on the event horizon. But how is that possible? The time goes slower in high gravitation. Since the black hole has a massive gravitational force the time goes slower in a black hole according to you, the robot wouldn’t “feel” any difference, you would just measure different time, so what about the watches? If we had a mega telescope that could see the robot’s clock down there in the black hole we would simply see that the arms of the clock are going slower that our own, and if we would have colors on the clock.
Let’s say the watches has a blue color, and now we send it down to our robot In the black hole, now, the blue color is red, and that further proves that time goes slower in a high gravitation, because colors is just how fast frequencies are going, and since blue have a very high frequency and red a slightly slower frequency and since time goes slower in a black hole, the frequency slows down and it turns red.
And now since the time goes slower in a black hole, and faster on our own earth, can we see into the future? If I would to fall with my back towards the black hole’s center, with other words, I’m watching earth while falling down to a black hole, then my time in the black hole would pass slower than earth’s time. And since earth’s time is passing faster than my own time that I’m experiencing in the black hole, I would see it like someone is “fast forwarding” a movie, and then I would see the future of space and our earth, it’s like magic, and then if we would pull me out I would be several years younger than before I went in. Because growing old is due to cell’s tumbling around and getting destroyed, and that’s very broadly speaking, and when the time goes slower the cell’s doesn’t vibrate as much. And I will be younger because my time went slower, so less time went by for me. And so we can conclude that in higher gravitational time goes by slower.
Movement is relative
What is relative in the general theory of relativity? All movement is relative, and that is what the theory is relaying on. And the other two absolute statements are that the laws of nature are absolute for everyone and that the speed of light is absolute for everyone.
How can scientist prove this? And how speed is relative? You have to put all speed in a frame of reference. If a plane is going around the globe, what is actually moving? We from earth would see the plane move, people from the moon would see the plane move as fast as the earth is rotating, and people watching the plane from another galaxy will see the plane going as fast as our galaxy is rotating, and which one is right? And that is why speed has to be put in a frame of reference. And if the plane would go just as fast as the earth rotates the plane would according to the people on earth stand still. But it is moving as fast as the earth rotates. And why is light absolute for everyone? Let’s do a kind of “mind experiment”. I and you are floating around weightless in space in our separate space shuttles. And since we are in space there are no up and down because we are weightless. And now we can test why speed is relative and why light is absolute for everyone. I will throw a ball at you at 100 km/h. I am in rest (rest means that I am not moving), while you are going at 90 km/h, so now, the ball is going 100 km/h towards you. You are going at 90 km/h, and so I will see the ball pass you at 10 km/h faster than your speed, so the ball will in time pass you, according to me.
According to you, I am moving and you are in rest! And this changes everything, you see the ball going at 100 km/h minus my speed and since you say you are in rest and that I am moving away from you in 90 km/h it is 100 – 90 km/h, and so you see the ball coming at you in 10 km/h. Both perspectives are right, the ball is going at 10 km/h towards Helmer. Now we know that speed is relative.
The speed of light is absolute
One good way to test this is another “mind experiment”. “The speed of light is absolute” means that you can never travel as fast as your own light. So what if we were going at the speed of light and we turned on the headlights? What would happen? The light would go faster than us, because the light will always travel faster than us, and if someone would watch us from a planet or something in space, they would see the light traveling in front of us, and then because it is in front of us we must be traveling slower, and so, you can never travel faster than the light, and therefore the light is absolute.
One more example, if a sprinter would compete against the speed of light, what would happen? Let’s say that the sprinter is 9.999c fast and he is running against the speed of light witch is 1c. And they are off, the race only takes a small part of a second, and the light wins, it goes 0.0001c faster than the sprinter, and so the light wins, the crowd is amazed because he almost beat the light, but the sprinter is not happy, because the sprinter thought the light travelled the whole of the light speed faster than him, but the crowed thought that the light was almost as fast as the sprinter. Why? The speed of light is absolute for everyone. So the sprinter thought the light was 1c faster, the whole of the light speed. Meanwhile the crowd sees both the light and the sprinter almost go at the speed of light because the speed of light is absolute for them.
Time Dilation
Time dilation can explain how time can bend and expand and decrees. And why nothing can travel at the speed of light. Imagine that you are sitting in a space shuttle and you placed a mirror on the opposite sides of the shuttle, and the laser now create a line, like in the A picture. But that will only happen if you sit in the space shuttle, but if someone was observing you from a far distance, that person would see the laser go in a triangle shape like in the picture B. The triangle shaped course is longer than the straight course. So if these two persons would measure the time it takes for the laser to travel back and forth. The A alternative would be faster than the B alternative, so it must pass less time in the space shuttle.
The triangle shaped course is created when the space shuttle moves forward. And if the space shuttle would move faster, maybe at 0.9C(C= speed of light) the difference in time would be even bigger. The faster something travels the bigger the triangle gets. And the reason we don’t realize this on our earth is because we can’t see something with a fast enough speed. If we would like to experience this on our own earth you have to find something that can travel in C.
And this explains why nothing with mass can travel at C. The time would go slower the faster you are accelerating. Witch in theory would mean that when traveling in C, time would completely stop,
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