Category archives: Cosmology

The brightest end of the Lyman alpha luminosity function

The brightest end of the Lyman alpha luminosity function

AstrophysicsCosmologyDIPC Astrophysics

By DIPC

The Javalambre-Photometric Local Universe Survey, J-PLUS, is an unprecedented photometric sky survey of 8500 deg2 visible from Javalambre (Aragón, Spain), using a set of 12 broad, intermediate and narrow-band filters. The J-PLUS photometric system is well suited to study the properties of nearby galaxies (z < 0.015). However, there are a few redshift windows beyond […]

The road to quantum gravity (4): The flow of time for massive objects

The road to quantum gravity (4): The flow of time for massive objects

CosmologyHistoryTheoretical physics

By Daniel Fernández

We started this series discussing the basic ingredients of the Universe: events, spacetime, causality. In the last chapter, we introduced massive objects (and thus, matter), which appear as a generalization of the so-called photon box. As it moves, any object traces a path. Physicists call it worldline. We established that a massive object never moves […]

The road to quantum gravity (3): The speed of light and the origin of mass

The road to quantum gravity (3): The speed of light and the origin of mass

CosmologyHistoryTheoretical physics

By Daniel Fernández

In the previous chapter of this series, we went over the subjective, relative separation of the network of events known as Spacetime into space and time. The speed of light played a major role in the discussion. In particular, we divided Spacetime into three regions (with respect to a particular event) defined by the existence […]

The Road to Quantum Gravity (2):  The emergence of Space and Time

The Road to Quantum Gravity (2): The emergence of Space and Time

CosmologyHistoryTheoretical physics

By Daniel Fernández

The division of past and future In Part 1 of this series, we presented the empirical fact that under extreme circumstances, a certain observer’s past can be in another observer’s future. To explain this, we introduced the network of cause and consequence relations as the fixed background structure of reality. This network constitutes Spacetime. Causality […]

The road to quantum gravity (1):  Spacetime as the network of causality

The road to quantum gravity (1): Spacetime as the network of causality

CosmologyHistoryTheoretical physics

By Daniel Fernández

Observations vs intuitions Einstein’s Theory of Relativity introduced us to the concept of Spacetime, as a unified entity. This stands in contrast with the intuition that we develop since birth, which leads to naturally separate space and time. Human intuition is a way to understand how the world works, our brain processes our daily experiences […]

Hawking’s information preservation and weather forecasting mess

Hawking’s information preservation and weather forecasting mess

AstrophysicsCosmologyPhysics

By Mario Herrero-Valea

Last month, a lot of newspapers and websites have been promoting this article on Nature referring to a recent preprint uploaded by Stephen W. Hawking to the internet repository ArXiv. In this work, summarizing what he talked about in a conference given last August, the English physicist argue that, since event horizons, the definitory property […]