The world we live in is strange, but it becomes even stranger when we travel at the speed of light, you see.
It is not the first time that we are going to talk about theory of Einstein relativity and what happens when we travel at the speed of light, but this time we are going to go slowly explaining everything carefully. To begin with, it must be clearly understood that time and space are not constant as we think; The distance between two points varies according to the speed at which we move, and the same happens with the speed at which time passes, it is not always the same.
This is the most important thing that happens when we go to the speed of light and the cause of all the rare effects that we are going to see next. As always we have to mention that it is impossible for us to travel at the speed of light because we need infinite energy, but since we can get as close to that speed as we want and the effects are the same, we are not going to get technical or picky throughout this article.
What do we feel when we travel at the speed of light?
The quick answer is: NOTHING. One of the oldest principles of physics (the Galileo’s relativity) states that it is impossible to distinguish between two frames of reference moving at constant speed. This means that as long as we do not accelerate, it does not matter the speed at which we move, we We won’t have a sense of speed nor can we do any experiment that lets us know that we are traveling at the speed of light. That is why the effects should always be compared to another person, one who for example stays on Earth.
We will assume that the speed of light is reached with a smooth acceleration, which does not kill us; Or directly that we are already traveling at the speed of light since we thus avoid a lot of problems with acceleration that are mathematically complicated, but are much less interesting from the informative point of view. So the situation is as follows: We travel at the speed of light, we have a friend who is on Earth and who will serve as a reference, the difference between our time and our space and his will lead to very curious situations .
Time and space and how they change when we travel at the speed of light
When we travel at the speed of light or almost at the speed of light time passes much slower for us than for our friend on Earth. It is not that we notice it, because we have seen before that everything remains the same for us, but when we come across him we will see that he has aged much more than us. In addition the distances we see different, for us the distances between points become shorter, but this is something that, once again, we cannot see because any rule we carry will also shrink in the same proportion as the rest of the distances.
Remember that this does not mean that we see reality distorted by a failure of our senses, but that when we travel at the speed of light distance and time really vary. For almost a century since Einstein left us his theory of relativity, hundreds of experiments have confirmed that these effects are real and measurable, not an illusion or a mathematical trick. But of all the effects that occur when we travel at the speed of light, the most curious of all is what happens when our friend and we contemplate the same event.
The train paradox and the blades in the tunnel
Let’s put ourselves in the following situation: we are on a train and we travel at the speed of light and we approach a tunnel that measures exactly the same as the train. From the outside our friend, who is still, sees us. The tunnel has blades placed at the entrance and exit; the blades will go down and up instantly when the train is in the tunnel. The question that matters to all of us is: Will the blades cut the train or will we escape unscathed because we travel at the speed of light?
The answer is complicated because from our friend’s point of view, as we travel at the speed of light, the train is smaller than the tunnel (which is still) and therefore we will fit inside the tunnel without problem and the blades will not prevent us from continuing our way in peace. However, from our perspective, the tunnel is the one that moves towards us and therefore it seems much shorter than the train, which makes us suspect that our trip will have a sudden end. But although strange things happen when we travel at the speed of light, what can never happen is that the blades cut and do not cut the train at the same time. What really happens then?
Reality is very strange and the solution is that the blades do not cut off the train (take a deep breath, now the strange thing is coming) for our friend outside everything happens as we expect: the train enters the tunnel, the blades go down and up while the train is inside the tunnel and we continue our way without problem. For us, however, what happens is that when we enter the tunnel the first blade closes and opens, without cutting the train, and when the end of the train has already entered the tunnel, the second blade goes down and rises without cutting us. And is that when we travel at the speed of light the concept of simultaneity becomes too flexible. To better understand this paradox, I recommend watching the video of Sixty Symbols on these lines.
