ब्लैक होल
ब्लैक होल () एगो ज्यामितीय रूप से परिभाषित, स्पेस-टाइम के अइसन क्षेत्र बा, जवना के अंदर एतना ढेर गुरुत्वाकर्षण होला के ओह में से कण या इलेक्ट्रो-मैग्नेटिक रेडियेशन (प्रकाश) भी बाहर न निकल सके। रिलेटिविटी के जनरल थियरी ई बतावे ले की अगर द्रब्यमान भरपूर मात्रा में कांपैक्ट हो जाय तब ऊ स्पेस-टाइम के रूप बदल के ब्लैक होल के निर्माण करे में सक्षम हो सके ला। अइसन सीमा जहाँ से कौनों चीज फिर बहरें न निकल सके इवेंट होराइजन कहल जाला। भले एह इवेंट होराइजन के भारी परभाव एकरा के क्रास करे वाला चीज के दशा-दिशा पर पड़त होखे, कौनों लोकल फीचर इहाँ से हमनी के डिटेक्ट ना हो पावे ला। कई परकार से, ब्लैक होल सभ आदर्श ब्लैकबॉडी के रूप में बेहवार करे ला, मने की कौनों प्रकाश के रिफ्लेक्ट ना करे ला। हालाँकि, वक्राकार स्पेसटाइम के क्वांटम फ़ील्ड थियरी ई प्रेडिक्ट करे ले की इवेंट होराइजन से हॉकिंग रेडियेशन निकले ला जवन की ओही स्पेक्ट्रम में होला जवन की कौनों ब्लैकबॉडी अपना द्रब्यमान के उल्टा अनुपात वाला तापमान में करी। अब चूँकि ब्लैकहोल सभ में द्रब्यमान एतना बेसी होला की अइसन तापमान एक केल्विन के खरबवाँ हिस्सा भर होखे ला आ अइसन रेडियेशन के डिटेक्ट कइल लगभग असंभव बाटे।

Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was during the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.

Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses () may form. There is consensus that supermassive black holes exist in the centers of most galaxies.

The presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light. Matter that falls onto a black hole can form an external accretion disk heated by friction, forming some of the brightest objects in the universe. If there are other stars orbiting a black hole, their orbits can be used to determine the black hole's mass and location. Such observations can be used to exclude possible alternatives such as neutron stars. In this way, astronomers have identified numerous stellar black hole candidates in binary systems, and established that the radio source known as Sagittarius A*, at the core of the Milky Way galaxy, contains a supermassive black hole of about 4.3 million solar masses.

On 11 February 2016, the LIGO collaboration announced the first direct detection of gravitational waves, which also represented the first observation of a black hole merger. , eleven gravitational wave events have been observed that originated from ten merging black holes (along with one binary neutron star merger). On 10 April 2019, the first ever direct image of a black hole and its vicinity was published, following observations made by the Event Horizon Telescope in 2017 of the supermassive black hole in Messier 87's galactic centre.

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