Black holes Lake Shank A/B45

Stellar black hole Formed by the gravitational collapse of a massive star This star ranges from the mass of about three to several tens of solar masses Also referred to as a collapsars The milky way galaxy has more than a million stellar black holes and weigh about ten times as much as our sun Some of these black holes have a star orbiting them, which are slowly bleeding matter into the black hole The mass of these black holes can be determined by the velocity of their companion star

Super-massive black hole Largest type of black hole in the galaxy Most galaxies are assumed to have a super- massive black hole in the center A super-massive black hole can have a density less than that of water People say the origin of super massive black holes are conglomerations of many star-size black holes that were formed during the history of a galaxy, or that galaxies formed around large black holes that then grew by accreting matter.

Micro black hole Micro black holes are like mini black holes The micro black hole is theorized and it is also theorized a mini black hole could be created but would soon evaporate The minimum energy of a microscopic black hole is GeV Theorized that high energy collisions in the LHC generate micro black holes They have next to no mass, exert a near-zero gravitational pull on matter, and therefore do not grow. In fact, they most likely do the opposite; they evaporate.

Event Horizon Boundary marking the limit of the black hole At the event horizon, the escape velocity is equal to the speed of light Since general relativity states that nothing can travel faster than the speed of light, nothing inside the event horizon can ever cross the boundary and escape beyond it, including light. The event horizon is not a material surface a mathematically defined demarcation boundary, nothing prevents matter or radiation from entering a black hole, only from exiting one. When the surface reaches the event horizon, time stands still, and the star can collapse no more - it is a frozen collapsing object

Schwarzschild Radius Also called the gravitational radius The radius below which the gravitational attraction between the particles of a body must cause it to undergo irreversible gravitational collapse This is thought to be the final fate of massive stars The Schwarzschild radius (R g ) of an object of mass M is given by the following formula, in which G is the universal gravitational constant and c is the speed of light: R g = 2GM/c 2 For a mass as small as a human being, the Schwarzschild radius is of the order of cm, much smaller than the nucleus of an atom for a typical star such as the Sun, the Schwarzschild radius is about two miles

Kerr Black hole Kerr black holes were postulated by the theorist, Roy Kerr in the 1960s This is spinning black hole He postulated that a rotating star could collapse into a black hole with a rotating ring of neutrons at its center Kerr believed that since there wasn't a singularity at the center, one might be able to travel through the black hole without being crushed by the singularity He theorized that at the end of the black hole was a “white hole” which would push matter away Theorists also think even if such a thing were possibly then one would be torn apart by tidal forces

Singlarity In astronomy, a term often used to refer to the center of a black hole, where the curvature of space time is maximal. At the singularity, the gravitational tides diverge; no solid object can even theoretically survive hitting the singularity at the center of a black hole space time has infinite curvature and matter is crushed to infinite density under the pull of infinite gravity At a singularity, space and time cease to exist as we know them. The laws of physics as we know them break down at a singularity

Time travel Gravity is a result of the bending of this space time in response to the presence of matter, this means space time could be changed somehow Time travel in some sort could be possible In 1937, Scottish physicist W. J. van Stockum first applied general relativity in a way that opened the door for time travel. By applying the equation of general relativity to a situation with an infinitely long, extreme dense rotating cylinder (kind of like an endless barbershop pole). The rotation of such a massive object actually creates a phenomena known as "frame dragging," which is that it actually drags space time along with it. Van Stockum found that in this situation, you could create a path in 4-dimensional space time which began and ended at the same point - something called a closed time like curve - which is the physical result that allows time travel. You can set off in a space ship and travel a path which brings you back to the exact same moment you started out at In 1963, New Zealand mathematician Roy Kerr used the field equations to analyze a rotating black hole, called a Kerr black hole, and found that the results allowed a path through wormhole in the black hole, missing the singularity at the center, and make it out the other end. This scenario also allows for closed time like curves, as theoretical physicist Kip Thorne realized years later.

Time travel (cont.) In 1963, New Zealand mathematician Roy Kerr used the field equations to analyze a rotating black hole, called a Kerr black hole, and found that the results allowed a path through wormhole in the black hole, missing the singularity at the center, and make it out the other end. This scenario also allows for closed time like curves, as theoretical physicist Kip Thorne realized years later. In the early 1980s, while Carl Sagan worked on his 1985 novel Contact, he approached Kip Thorne with a question about the physics of time travel, which inspired Thorne to examine the concept of using a black hole as a means of time travel. Together with the physicist Sung-Won Kim, Thorne realized that you could (in theory) have a black hole with a wormhole connecting it to another point in space could be held open by some from of negative energy.

Where do they come from? When stars are big enough they will collapse into a black hole after a super nova. In principle, low mass black holes should be able to be created in a particle accelerator Low mass stars does not collapse into black holes It is unknown how some black holes are formed and there is no real evidence on how they are

Strangelet A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks Strangelets are only theorized It has been hypothesized that strangelets (sub-stellar agglomerations of strange matter) may be able to exist independently from the quark stars which created them. If so, there may be many strangelets in this universe, a possible explanation for the dark matter problem. Since strangelets maintain such deep gravity wells for objects of their size, calculations show that strangelets coming in contact with ordinary matter would overwhelm this matter with their gravitational fields, breaking down the ordinary matter into strange matter.

Strangelet(cont.) If strangelets exist and keep coming into contact with ordinary matter indefinitely, it may be only a matter of time (albeit a cosmologically long duration of time) before strangelets swallow all the conventional matter in the universe. there exist observed stars too dense to be conventional neutron stars yet too sparse to be black holes thestrangelet remains a theoretical construct until we develop instruments fine enough to either verify or disprove their existence.

Citations no-braner.html Discovery Communications, LLC. The number-one nonfiction media company no-braner.html event-horizon. Encyclopædia Britannica, Inc event-horizon areas/black-holes/. NASA areas/black-holes/ tm. About.com tm Conjecture Corporation