In November 1915, Albert Einstein He experienced one of the stellar moments in his career as a scientist, where he made his name known Theory of relativity before Prussian Academy of Sciences, in Berlin. Four years later, on May 29, 1919, 20th century science reached its climax with the confirmation of this theory.
but, His primary articles, in which he incorporated the world’s first relativistic ideas, which date back to 1905, published when the physicist was only 26 years old. And if you could hold a copy of these texts in your hands now, you would be surprised with a file Readability. It is that the text is simple and the equations do not overcome the complexity that some mathematical algebra problems can assume.
This is because Einstein had it A very visual way of thinking, in a manner consisting of provoking and solving small mental problems in his mind, thus raising ideas more clearly. An example of this development process is the famous twin paradox.
In its entirety, Einstein explained Two theories: general relativity, related to the gravitational field and reference systems, and special relativity, more related to the physics of motion as a function of space-time. Overall, their work completely changed the view of the universe and many phenomena and concepts such as time, space, and gravity.
Thus, although it may be difficult to understand and a little intimidating to face, it is possible to simplify it into a series of main points that bring together its results and make them accessible to anyone who wants them. So we present to you The five basic points To finally understand the theory of relativity.
The speed of light is absolute
One of the main points of the theory of relativity states that light propagates always at 300,000 km / s No matter what reference system we are observing from. What exactly does this mean? Einstein illustrates it with one of his mind games in a very simple way.
It puts a person on a train moving at 100 km/h. In parallel, another person on another train is moving in the same direction, but this person is moving at a speed of 90 km / h. Thus, for the observer of the second train, the first is moving at only 10 km/h, not the 100 km/h he would notice if his train suddenly stopped. That is, the speed at which you see the first train Depends on whether your reference system fixed or mobile. Well, with the light that’s not true.
Einstein asserts that no matter where you look from, whether you are moving or not, you will always appreciate the movement of light at the same speed: 300,000 km/s. Applying to your own game, we would have that person on the first train and the second would see the light moving at the same speed. Thus, the theory of relativity puts in constant lightthat is, a quantity that is always constant.
Time is relative
Another major consequence of this theory is that time, unlike the speed of light, Not at all It will depend on the movement of observers. That is, two events appearing simultaneously from one person’s perspective may not be from another person’s. And the strangest thing about all of this is that Both will be right.
To understand it, Einstein takes back the mental example of trains. This time it involves the first person standing next to the tracks as the train passes. Then, just as the middle car in front of him, lightning strikes the first and last cars. Since he is at an intermediate distance from both events, their light reaches his eye at the same time and he can assert, without error, that the two rays have struck them. At the same time.
Now, for another person sitting in the same central car, inside the train, things would be very different, but also true. From his point of view, the rays will also travel the same distance, but due to the relative motion of the train, the light that comes from the lightning in the tail will reach the observer later. Therefore, this person, also without being mistaken, will say that lightning strikes in different times.
this idea Very counterintuitive, because it is paradoxical logic, but it is not. Another very useful example of this relativistic estimation of the passage of time is the double discrepancy, which is somewhat more complex, but intriguing.
Time and space are not independent
Among other concepts, the theory of relativity stands out as important Redefining the concepts of space and timesince they are not independent terms, but are combined into a single term known as Free time. It is something as if both concepts were inseparable companions: what happens to one will affect the other.
Einstein in one of his classes
This statement was, for Einstein, an obvious consequence of the relativity of time: if an event, such as a train lightning strike, occurs at a different time depending on the situation in which each person is, then both concepts must be together. in this way, Neither of them can be treated independently till the end
In the words of the physicist himself: “From now on, space and time are destined to fade separately into shadows and only the union of both can part of reality“.
Mass equals energy
Do you know the famous equation e = mk2? Well, it’s probably the most common consequence of the theory of relativity. In addition, it was a scientific milestone because, with this simple and elegant equation, Einstein was able to combine two amazing conclusions.
First, you claim that Energy and mass are related And that they can become, in practice, equivalent. As an illustration, a physicist asked you to imagine an object emitting two pulses of light in opposite directions. Since each impulse carries a certain amount of energy, the body’s energy decreases, as it gives it to those impulses. Well, Einstein determined through algebraic formulas that for this to be consistent, the object must also lose mass. This means that energy and mass are directly related.
On the other hand, in a deeper way, in that equation is the key that explains another result of great importance: Why is it impossible for a moving object to reach the speed of light?. And according to the equation, if this happens, the mass of the body must be infinite, which, according to the above, would require infinite energy, which is impossible. Therefore, it is stated that objects that have no mass or, even better, waves with zero mass will be able to reach speeds comparable to the speed of light.
Gravity is simply a distortion
If all this theory is really based on concepts that are not very intuitive and almost surreal, then the concept and definition of gravity, which Einstein put as the closing point of the theory of relativity, seems to have been taken from one of Kafka’s stories. This is what triggers it Spacetime is not flatbut it is distorted by the objects placed on it.
Representative graph of gravity as a curvature of space-time
Thus, imagine a large piece of fabric suspended in the air and stretched horizontally. If we drop a small ball on it, it will sink a little bit. Now, if we place a much larger ball a little farther away, the texture will bend a lot more, so that the smaller ball will move toward it because of the tilt in the texture made by the second ball. Well, that’s what happens, according to Einstein, in the universe. We or the things we deal with will be those little balls that almost do not bend the fabric, while, for example, the Earth will be that big ball that The fabric is greatly distorted He directs us towards it.
And so Einstein shut down the theory of relativity, emphasizing that gravity was not a force, but a consequence of the curvature of the plane of space-time and left it on the table. One of the most important results of physics throughout the twentieth century, and perhaps marking science in the twenty-first century with them.
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