Lubang hitam

Lubang hitam adalah bagian dari Ruang Waktu yang merupakan gravitasi paling kuat, bahkan cahaya tidak bisa kabur. Teori Relativitas Umum memprediksi bahwa butuh massa besar untuk menciptakan sebuah Lubang Hitam yang berada di Ruang Waktu. Di sekitar Lubang Hitam ada permukaan yang di sebut Event Horizon. Lubang ini disebut "hitam" karena menyerap apapun yang berada disekitarnya dan tidak dapat kembali lagi, bahkan cahaya. Secara teoritis, lubang hitam dapat memliki ukuran apa pun, dari mikroskopik sampai ke ukuran alam raya yang dapat diamati. Teori Medan Quantum dalam Ruang-waktu melengkung memprediksi bahwa Event Horizon memancarkan radiasi disekitarnya dengan suhu yang terbatas. Suhu ini berbanding terbalik dengan massa Lubang hitam, sehingga sulit untuk diamati Lubang hitam bermassa bintang atau lebih.

Sejarah

Teori adanya lubang hitam pertama kali diajukan pada abad ke-18 oleh John Michell and Pierre-Simon Laplace, selanjutnya dikembangkan oleh astronom Jerman bernama Karl Schwarzschild, pada tahun 1916, dengan berdasar pada teori relativitas umum dari Albert Einstein, dan semakin dipopulerkan oleh Stephen William Hawking.
Istilah lubang hitam mulai populer ketika John Archibald Wheeler menggunakannya pada ceramah-ceramahnya pada tahun 1967. Walaupun ia dianggap luas sebagai pencetus pertama istilah ini, namun ia selalu menampik dengan pernyataan bahwa ia bukanlah penemu istilah ini.

Asal-mula lubang hitam

Lubang Hitam tercipta ketika suatu obyek tidak dapat bertahan dari kekuatan tekanan gaya gravitasinya sendiri. Banyak obyek (termasuk matahari dan bumi) tidak akan pernah menjadi lubang hitam. Tekanan gravitasi pada matahari dan bumi tidak mencukupi untuk melampaui kekuatan atom dan nuklir dalam dirinya yang sifatnya melawan tekanan gravitasi. Tetapi sebaliknya untuk obyek yang bermassa sangat besar, tekanan gravitasi-lah yang menang.

Mendeteksi Lubang Hitam

Lubang hitam memang tak nampak, bahkan cahaya tak bisa lepas dari tangkapan gravitasinya. Meski begitu, batasan lubang hitam bisa terlihat dari pancaran radiasi materi yang jatuh ke lubang hitam. Proyek bernama Event Horizon Telescope mengombinasikan kekuatan bermacam-macam antena dari jaringan teleskop radio global untuk menangkap objek yang seringnya terlalu kecil untuk bisa dilihat.

This crescent-shape image is the best fit to observations of Sgr A*, the supermassive black hole at the center of our galaxy, according to a January 2013 study.

This NASA/ESA Hubble Space Telescope image shows the bright star-forming ring that surrounds the heart of the barred spiral galaxy NGC 1097, a Seyfert galaxy. The larger-scale structure of the galaxy is barely visible. Its comparatively dim spiral arms, which surround its heart in a loose embrace, reach out beyond the edges of this frame. This face-on galaxy, lying 45 million light-years away from Earth in the southern constellation of Fornax (The Furnace), is particularly attractive for astronomers. Lurking at the very centre of the galaxy, a supermassive black hole 100 million times the mass of our Sun is gradually sucking in the matter around it. The area immediately around the black hole shines powerfully with radiation coming from the material falling in. The distinctive ring around the black hole is bursting with new star formation due to an inflow of material toward the central bar of the galaxy. These star-forming regions are glowing brightly thanks to emission from clouds of ionised hydrogen. The ring is around 5000 light-years across, although the spiral arms of the galaxy extend tens of thousands of light-years beyond it. REUTERS/NASA/ESA/Hubble/Handout

An artist's illustration of a newfound large star cluster near the center of the Milky Way that may be a breeding ground for intermediate black holes

A supermassive black hole powers jets of cosmic rays on either side the elliptical radio galaxy Hercules A.

The galaxy cluster PKS 0745-19 is shown in this NASA composite image containing X-rays from Chandra (purple) and optical date from the Hubble Telescope (yellow) released December 19, 2012. The black hole at the center of this galaxy is part of a survey of 18 of the biggest known black holes in the universe. Researchers found that the black holes in the survey may be about ten times more massive than previously thought. REUTERS/NASA/CXC/Stanford/Handout

Hubble's panchromatic vision, stretching from ultraviolet through near-infrared wavelengths, reveals the vibrant glow of young, blue star clusters and a glimpse into regions normally obscured by the dust in this image taken in July 2010 with Hubble's Wide Field Camera 3 and released on June 16, 2011. The center is home for a supermassive black hole that ejects jets of high-speed gas into space. REUTERS/NASA

This composite photo provided by NASA shows A powerful jet from a supermassive black hole is blasting a nearby galaxy in the system known as 3C321, according to new results from NASA. This galactic violence, never seen before, could have a profound effect on any planets in the path of the jet and trigger a burst of star formation in the wake of its destruction. (AP Photo/NASA)

This undated image provided by the Gemini Observatory via the journal Nature shows an artist's conception of stars moving in the central regions of a giant elliptical galaxy that harbors a supermassive black hole. (AP Photo/Gemini Observatory, AURA artwork by Lynette Cook via Nature)

NASA's Spitzer Space Telescope has imaged a coiled galaxy with an eye-like object at its center, shown in this photograph released by NASA July 23, 2009. The galaxy, called NGC 1097, is located 50 million light-years away. It is spiral-shaped like our Milky Way, with long, spindly arms of stars. The "eye" at the center of the galaxy is actually a monstrous black hole surrounded by a ring of stars. In this color-coded infrared view from Spitzer, the area around the invisible black hole is blue and the ring of stars, white. REUTERS/NASA

This artist's depiction, provided by NASA, demonstrates what scientists believe is happening very close to the Sagittarius A* black hole in the Milky Way. The supermassive black hole is surrounded by a disk of gas (yellow and red). Massive stars, shown in blue, have formed in this disk, while small disks represent where stars are still forming. Results from the Chandra X-ray Observatory show that stars have formed locally in this disk, rather than being deposited there by a star cluster. The mysterious black hole has helped give birth to a new generation of stars, new observations suggest. (AP Photo/NASA, CXC, M. Weiss)

This still from a computer animation shows a simulation of a giant space cloud falling into Sagittarius A*, the supermassive black hole at the center of our own Milky Way galaxy, in mid-2013. Image added on July 2, 2012

Simulation of the formation of a galaxy similar to our Milky Way. Massive black holes lurk in the centers of many of the building blocks that merge to assemble the galaxy, and a black hole also inhabits the final galaxy. Still from video releas

Three of these galaxies (top right, bottom left, and bottom right) are normal and show no signs of past collisions, while the top left galaxy's irregular shape suggests it collided with a neighbor, in these photos from the Hubble Space Telescop

This undated composite image provided by Lynette Cook and Andrea Ghez via the journal Nature shows an image of the center of our Galaxy from laser-guide-star adaptive optics on the Keck Telescope. More massive black holes have larger event horizons, the region within which even light can not escape. If a ten billion solar mass black hole resided at the Galactic center, its immense event horizon would be visible (illustrated by the central black disk). The actual black hole at the Galactic center is 2500 times smaller. (AP Photo/Lynette Cook and Andrea Ghez via Nature)

Artist's impression of gravitational waves from two orbiting black holes.

Hot iron gas rides a wave of space-time around a black hole in this computer image taken from a Rossi X-ray Timing Explorer observation.