Tuesday, January 15, 2013

Gravitational waves, what is it?


Gravitational waves, what is it?

Recently the research on cosmology has touched a level of difficulty that just a few people are able to understand. However, the cosmology is almost entirely based in the theory of general relativity. So the understanding of some points from that theory can allow us to understand a little of "classical cosmology". Current cosmology deals with multi-universes and other things like that, that is, effects that arises when are put together quantum mechanics and general relativity.

Gravitational waves are a immediate consequence of the general relativity. They are obtained even just in the classical cosmology, although its source are quantum effects. To understand what are gravitational waves we can make use of a basic analogy. Assume an electric charge and also that we are in a inertial system of coordinates in relation to the charge. Then if we are watching the charge moving, it's well known from the electromagnetism that we will to observe a electric field. Now, if we are in a accelerated motion in relation to the charge, also is well established that we will note a magnetic field as well. What we know as electromagnetic waves are just deformations on this field, called electromagnetic field.

In a complete analogy, the gravitational waves are just deformations on the gravitational field, which is our old friend since Galileo and Newton. But we need to use the general relativity to realize that. Nevertheless, we can not to measure signal of gravitational waves in a direct way yet. That happens due to the fact that the intensity of the gravitation interaction is much lower than other interactions, for instance, electromagnetic interaction. 

In the next post, I'll expose some devices which are candidates to measure directly signal of gravitational waves. Before, however, I must to show some sources from these waves.

Any question, it will be a pleasure to discuss about it.

Saturday, January 5, 2013

Two problems of exchange of knowledge


The sharing of knowledge is an important step which must be done if we wish that the world be more and more sociable. In this mechanism we have the exchange of knowledge between Professor  students in the University as well as between the "scientists" (Professor and students) and the society in general.
Of course, there are problems in all countries about it, even that it be different one of another.

I post here two little articles about this subject and I hope that they can be usefull for someone. One of them is about the exchange of knowledge between the scientists and the society and the another one is about the transfer of knowledge from Professor of physics to students of physics.

The first article, named  How to not Teach Physics shows the exchange that I have cited first, and the second exchange being discussed in the article named Social Media for Scientists Part 1: It's Our Job.

The link for the articles can be seen below:  



Just as a comment, here in Brazil we have both problems deeply. The society in general does not care if you collide two protons at a accelerator or if you is capable of moving a metal arm with your mind. Of course, the magazines most popular are not doing their job right, what makes the situation worse.

By the other hand, we have good students of science in general, particulary in physics, but unfortunately they are not valued neither by companies nor government agencies.