Browse Definitions:

black hole

1) The term "black hole" is sometimes used to refer to an imaginary place where objects, files, or funds go when they get lost for no apparent reason.

2) In physics and astronomy, a black hole is a region in time and space within which gravity is so strong that nothing can escape, not even electromagnetic radiation such as visible light. Black holes are thought to surround certain celestial objects.

The idea of a black hole (if not the term itself) is not new. As the intensity of the gravitational field around an object increases, so does the escape velocity. The escape velocity for a celestial mass (such as a star, planet, or moon) is the vertical speed with which an object must be hurled from the surface in order to fly forever beyond the gravitational influence of the mass. If a substantial celestial body such as a star becomes small enough in diameter, the escape velocity at the surface can theoretically exceed the velocity of light. This idea occurred to astronomers even in Isaac Newton's time. Modern astronomers believe they have observed black holes, consisting of stars that have collapsed under their own gravitation after spending their nuclear fuel. Black holes are also believed to exist at the centers of galaxies, including our own.

A black hole produces bizarre effects on time and space. As seen from outside, an object falling into a black hole would approach the so-called event horizon, which is a spherical "one-way membrane" or "Rubicon" surrounding the black hole itself. If the object were a clock, it would seem to run more and more slowly as it approached the event horizon, and would never quite make it inside the black hole. From the reference frame of the falling object, nothing out of the ordinary would take place in the rate at which time passed, and the entry to the black hole would proceed apace, although the gravitational force near the event horizon might tear the falling object apart.

Black holes have been fodder for wild ideas and science-fiction stories since the concept became well known in the mid-1900s. Some scenarios are sensational to the point of madness. For example, suppose a tiny black hole, manufactured for use as a doomsday weapon, were dropped onto the surface of the earth? It would, as the story goes, proceed to devour the planet with unstoppable and phenomenal violence.

Also see a spam-related term, blackhole list.

This was last updated in September 2005

Continue Reading About black hole

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.


File Extensions and File Formats


  • risk map (risk heat map)

    A risk map, also known as a risk heat map, is a data visualization tool for communicating specific risks an organization faces. A...

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...


  • cloud ecosystem

    A cloud ecosystem is a complex system of interdependent components that all work together to enable cloud services.

  • cloud services

    Cloud services is an umbrella term that may refer to a variety of resources provided over the internet, or to professional ...

  • uncloud (de-cloud)

    The term uncloud describes the action or process of removing applications and data from a cloud computing platform.


  • federated identity management (FIM)

    Federated identity management (FIM) is an arrangement that can be made among multiple enterprises to let subscribers use the same...

  • cross-site scripting (XSS)

    Cross-site scripting (XSS) is a type of injection security attack in which an attacker injects data, such as a malicious script, ...

  • firewall

    In computing, a firewall is software or firmware that enforces a set of rules about what data packets will be allowed to enter or...




  • bad block

    A bad block is an area of storage media that is no longer reliable for storing and retrieving data because it has been physically...

  • all-flash array (AFA)

    An all-flash array (AFA), also known as a solid-state storage disk system, is an external storage array that uses only flash ...

  • volume manager

    A volume manager is software within an operating system (OS) that controls capacity allocation for storage arrays.


  • hybrid hard disk drive (HDD)

    A hybrid hard disk drive is an electromechanical spinning hard disk that contains some amount of NAND Flash memory.