Singularity

Want to stay on top of all the space news? Follow @universetoday on Twitter

Ever since scientists first discovered the existence of black holes in our universe, we have all wondered: what could possibly exist beyond the veil of that terrible void? In addition, ever since the theory of general relativity was first proposed, scientists have been forced to wonder, what could have existed before the Big Bang? Interestingly enough, these two questions have come to be resolved (after a fashion) with the theoretical existence of something known as a gravitational Singularity. It is now the consensus among scientists that beneath veil of an event horizon, and at the beginning of the universe before the Big Bang, this was what existed.

In scientific terms, a gravitational singularity (or space-time singularity) is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system. In other words, it is a point in which all physical laws are indistinguishable from one another, where space and time are no longer interrelated realities, but merge indistinguishably and cease to have any independent meaning. The two most important types of space-time singularities are curvature singularities and conical singularities. Singularities can also be divided according to whether they are covered by an event horizon or not; these are known as naked singularities.

A curvature singularity is best exemplified by a black hole. At the center of a black hole as described by general relativity lies a gravitational singularity, a region where the space-time curvature becomes infinite. Conical singularities occur when there is a point where the limit of every general covariance quantity is finite. In which case, space-time looks like a cone around this point, where the singularity is located at the tip of the cone. An example of such a conical singularity is a cosmic string, a type of hypothetical 1-dimensional topological defect that is believed to have formed during the early universe when symmetry breaking phase transitions were commonplace. In addition, there is the naked singularity, a type of singularity which is not hidden behind an event horizon. These were first discovered in 1991 by Shapiro and Teukolsky using computer simulations of a rotating plane of dust that indicated that general relativity might allow for “naked” singularities. This remains theoretical however, as it remains a mystery what these objects would look like.

The Penrose–Hawking singularity theorems are a set of theoretical results based on general relativity which attempt to answer the question of when gravitation produces singularities. The first situation is where matter is forcibly compressed to a point (a space-like singularity), the second is a situation where certain light rays come from a region with infinite curvature (time-like singularity).

We have written many articles about singularity for Universe Today. Here’s an article about what was before the Big Bang, and here’s an article about black holes.

If you’d like more info on singularity, check out these articles from NASA and Physlink.

We’ve also recorded an entire episode of Astronomy Cast all about Singularity. Listen here, Episode 113: The Moon, Part 1.

Sources:
http://en.wikipedia.org/wiki/Gravitational_singularity
http://en.wikipedia.org/wiki/Coordinate_system
http://en.wikipedia.org/wiki/Big_Bang
http://en.wikipedia.org/wiki/Black_hole
http://en.wikipedia.org/wiki/Event_horizon
http://en.wikipedia.org/wiki/General_covariance

Tagged as: Big Bang, Black Holes, singularity