de Sitter meets Planck

by Adriana V. Araujo, Diego F. López and José G. Pereira

The Quest for Consistency in Spacetime Kinematics

Newton’s inception of the theory for the gravitational interaction in 1642 was a landmark for modern physics. In addition to explaing all known gravitational phenomena of that time, Newton’s gravitational theory was consistent with the kinematic rules of the Galilei group, known as Galilei relativity. Such consistency provided an atmosphere of intellectual comfort, which lasted for more than two centuries.

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From left to right, José, Adriana and Diego. Click here to see the authors taking advantage of all dimensions of a space section of the universe.

By the mid nineteenth century, most secrets of the electric and  magnetic fields were already unveiled. Those advancements culminated with the publication by Maxwell of a comprehensive treatise on the unification of electricity and magnetism, which became known as Maxwell’s theory. This theory brought to the scene the first inconsistency of our tale. In fact, it became immediately clear that the electromagnetic theory was inconsistent with the Galilei relativity: electromagnetism was claiming for a new relativity. In response to this claim, and with contributions from Lorentz and Poincaré, Einstein published in 1905 the basics of what is know today as Einstein special relativity. According to this theory, for velocities near the velocity of light, spacetime kinematics would no longer be ruled by Galilei, but by the Poincaré group. Most importantly, electromagnetism was consistent with Einstein special relativity! Mission accomplished? Not quite! Continue reading

Gravitational Wave Neurons

by Serena Vinciguerra 


A neuroscience perspective on the gravitational wave community.

INSIDE OUT is not only a Pixar cartoon, but also a very intelligent slogan. I am not talking about emotions, but more generally about our brain. A more common view of our brain might be OUTSIDE IN: we use the brain to interpret the inputs we receive from outside. However, the brain is also the most powerful computer ever known, so why not try the INSIDE OUT modality, and be inspired by our brains as computational models?

The brain is a biological network composed of nerve cells (neurons) connected to each other. We can imagine neurons as calculation units which compute a weighted sum of the received electric inputs. If this sum reaches a particular threshold, a new electric signal is generated, propagated and finally transmitted to other neurons.

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Serena hiking on the Forra del Lupo (Folgaria) trail – Italy

Artificial neural networks (ANNs) and their success clearly represent the strength of applying the mechanisms which drive our mind to other subjects. ANNs find many applications in research, including in the science of gravitational waves (GW). In searches for un-modelled GW transients, ANNs have been used to classify noisy events, to search for GWs associated with short gamma ray bursts as well as for signal classification. What are the eyes, the ears, the nose and the mouth which make up an identifiable face in GW transients or glitches? These are the kind of questions ANNs have to answer to perform classification/identification tasks. To find out how good they are, take a look to these papers [1, 2]

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