104:. If intelligent life existed it would have produced enough self-replicating spacecraft, known as von Neumann probes, to cover the universe by now, which runs counter to the knowledge that the Universe is filled with a very large number of planets, some of which likely hold the conditions hospitable for life. Life typically expands until it fills all available niches. These contradictory facts form the basis for the
1721:
1415:
1733:
1427:
62:(the conflict between the lack of obvious evidence for alien life and various high probability estimates for its existence). In this case, the solution is that there is no other intelligent life because such estimates are incorrect. The conjecture is named after astrophysicist Michael H. Hart and mathematical physicist and cosmologist
54:
titled "Explanation for the
Absence of Extraterrestrials on Earth". Assuming that the probes traveled at 1/10 the speed of light and that no time was lost in building new ships upon arriving at the destination, Hart surmised that a wave of Von Neumann probes could cross the galaxy in approximately
55:
650,000 years, a comparatively minimal span of time relative to the estimated age of the universe at 13.7 billion years. Hart’s argument was extended by cosmologist Frank Tipler in his 1981 paper entitled "Extraterrestrial intelligent beings do not exist".
142:
120:
is a special case of the Hart–Tipler conjecture which states that no other intelligent life has been discovered because humanity is the first intelligent life in the universe. According to the
445:
1664:
1338:
2691:
2760:
2071:
2061:
858:
848:
2358:
1510:
124:, the absence of interstellar probes is not evidence of life's absence, since such probes could "go berserk" and destroy other civilizations, before self-destructing.
1770:
1465:
2363:
763:
2666:
933:
1981:
1188:
1375:
2408:
2076:
1515:
868:
783:
2443:
2213:
1286:
619:
2114:
1276:
332:
2066:
2051:
1811:
1061:
853:
838:
2755:
2041:
2016:
1763:
1531:
1458:
828:
419:
287:
2676:
2519:
2046:
1390:
833:
758:
393:
2056:
1370:
1291:
843:
2750:
2613:
2208:
1395:
1228:
748:
446:"Is there evidence aliens have visited Earth? Here's what's come out of US congress hearings on 'unidentified aerial phenomena'"
1333:
1208:
948:
863:
2198:
1756:
1724:
1451:
1218:
1163:
2463:
2331:
2140:
2031:
1642:
1541:
1266:
1126:
938:
818:
576:
550:
2651:
2524:
2021:
808:
471:
2509:
2233:
1400:
1385:
1301:
978:
2301:
2223:
1474:
1233:
612:
497:
2168:
1976:
1311:
1142:
733:
2341:
1493:
1343:
364:
1431:
2036:
1238:
1004:
823:
2765:
2593:
2568:
2558:
2398:
2277:
2081:
2006:
798:
687:
2740:
2696:
2598:
2423:
2316:
2151:
2086:
1779:
1685:
1612:
1581:
1419:
1358:
1183:
878:
743:
605:
81:
2686:
2573:
2563:
2534:
2351:
2246:
1536:
1503:
1365:
1353:
1248:
1198:
1193:
1092:
1035:
1024:
928:
778:
662:
652:
531:
253:
206:
121:
117:
2745:
2499:
2346:
2326:
2272:
2238:
2133:
1805:
1793:
1632:
1498:
1348:
1173:
1732:
2621:
2478:
2428:
2218:
2146:
1178:
338:
312:
241:
196:
162:
2254:
2124:
1823:
1817:
1617:
1306:
1056:
1009:
973:
713:
692:
328:
261:
222:
35:
2701:
2641:
2588:
2494:
2468:
2368:
1945:
1799:
1705:
1675:
1607:
1576:
1566:
918:
903:
320:
214:
154:
2716:
2706:
2529:
2388:
2373:
2336:
2321:
2267:
2193:
1690:
1637:
1551:
1546:
1213:
1046:
672:
51:
1886:
535:
257:
210:
2603:
2504:
2433:
2383:
2259:
2157:
1894:
1680:
1658:
1571:
1132:
728:
667:
642:
313:"Bringing Culture to Cosmos: Cultural Evolution, the Postbiological Universe, and SETI"
47:
39:
17:
2734:
2549:
2514:
2473:
1996:
1986:
1859:
1829:
1695:
788:
519:
342:
166:
105:
75:
59:
187:
Gray, Robert H. (March 2015). "The Fermi
Paradox Is Neither Fermi's Nor a Paradox".
2711:
2656:
2636:
2631:
2626:
2578:
2453:
2393:
2101:
2026:
1991:
1736:
1670:
813:
768:
753:
738:
723:
682:
677:
657:
647:
628:
63:
43:
958:
1929:
324:
2646:
2311:
2119:
1937:
1835:
1700:
1622:
1597:
1556:
1488:
1109:
999:
718:
708:
89:
365:"Cosmic Collisions and the Longevity of Non-Spacefaring Galactic Civilizations"
143:"Formalizing the Fermi paradox and combining consistent explanatory hypotheses"
2661:
2539:
2458:
1902:
1627:
1602:
1443:
1086:
773:
158:
265:
2681:
2418:
2413:
2228:
2203:
1910:
1223:
1080:
1041:
1019:
908:
226:
218:
2403:
2378:
2290:
2283:
2178:
2109:
1561:
1281:
1271:
1203:
994:
968:
943:
101:
1748:
2188:
2163:
1867:
1137:
963:
2671:
2183:
2091:
1380:
953:
923:
913:
873:
420:"Beyond "Fermi's Paradox" II: Questioning the Hart-Tipler Conjecture"
288:"Beyond "Fermi's Paradox" II: Questioning the Hart-Tipler Conjecture"
201:
1296:
1168:
97:
85:
27:
Idea that there is no evidence of aliens because they do not exist
394:"Beyond "Fermi's Paradox" V: What is the Aestivation Hypothesis?"
1953:
1243:
577:"Beyond "Fermi's Paradox" VI: What is the Berserker Hypothesis?"
108:, of which the Hart–Tipler conjecture is one proposed solution.
93:
1752:
1447:
601:
597:
551:"Beyond "Fermi's Paradox" X: What is the Firstborn Hypothesis?"
58:
The conjecture is the first of many proposed solutions to the
242:"Explanation for the Absence of Extraterrestrials on Earth"
1665:
1339:
Astrobiology
Science and Technology for Exploring Planets
520:"Are We All Alone, or could They be in the Asteroid Belt"
42:
evidence that no intelligent life exists outside of the
319:. Springer International Publishing. pp. 171–190.
112:
Relationship to other proposed Fermi paradox solutions
2692:
Potential cultural impact of extraterrestrial contact
46:. This idea was first proposed in opposition to the
2612:
2548:
2487:
2442:
2300:
2100:
2005:
1969:
1922:
1879:
1852:
1845:
1786:
1651:
1590:
1524:
1481:
1324:
1257:
1156:
1118:
1102:
1070:
987:
896:
887:
797:
701:
635:
524:
Quarterly
Journal of the Royal Astronomical Society
246:
Quarterly
Journal of the Royal Astronomical Society
80:There is no reliable or reproducible evidence that
2072:Habitability of F-type main-sequence star systems
2062:Habitability of K-type main-sequence star systems
859:Habitability of F-type main-sequence star systems
849:Habitability of K-type main-sequence star systems
2359:Communication with extraterrestrial intelligence
1511:Communication with extraterrestrial intelligence
784:Search for extraterrestrial intelligence (SETI)
1764:
1459:
613:
8:
764:List of microorganisms tested in outer space
2667:History of the extraterrestrial life debate
2364:Gauss's Pythagorean right triangle proposal
1982:Planetary habitability in the Solar System
1849:
1771:
1757:
1749:
1466:
1452:
1444:
1189:Enceladus Life Signatures and Habitability
893:
620:
606:
598:
363:Ostro, Steven J.; Sagan, Carl (May 1998).
141:Costa-Leite, Alexandre (18 October 2022).
34:is the idea that an absence of detectable
1376:European Astrobiology Network Association
472:"Have We Already Been Visited by Aliens?"
200:
2761:Search for extraterrestrial intelligence
2409:Search for extraterrestrial intelligence
2077:List of potentially habitable exoplanets
1516:Search for extraterrestrial intelligence
869:List of potentially habitable exoplanets
2214:Living Interplanetary Flight Experiment
1287:Living Interplanetary Flight Experiment
133:
498:"Fermi and the Hart-Tipler Conjecture"
470:Kolbert, Elizabeth (14 January 2021).
2115:Biological Oxidant and Life Detection
1277:Biological Oxidant and Life Detection
147:International Journal of Astrobiology
7:
2067:Habitability of yellow dwarf systems
2052:Habitability of neutron star systems
1812:Viking lander biological experiments
1426:
854:Habitability of yellow dwarf systems
839:Habitability of neutron star systems
549:Williams, Matt (27 September 2020).
2042:Habitability of binary star systems
2017:Catalog of Nearby Habitable Systems
1532:List of interstellar radio messages
829:Habitability of binary star systems
2677:Nexus for Exoplanet System Science
2520:Hypothetical types of biochemistry
2047:Habitability of natural satellites
1391:Nexus for Exoplanet System Science
834:Habitability of natural satellites
759:Hypothetical types of biochemistry
88:. No transmissions or evidence of
25:
2057:Habitability of red dwarf systems
1371:Center for Life Detection Science
1292:Mars Astrobiology Explorer-Cacher
844:Habitability of red dwarf systems
575:Williams, Matt (23 August 2020).
2209:Life Investigation For Enceladus
1731:
1720:
1719:
1425:
1414:
1413:
1396:Ocean Worlds Exploration Program
1229:Life Investigation For Enceladus
749:Extraterrestrial sample curation
518:Papagiannis, Michael D. (1978).
392:Williams, Matt (7 August 2020).
240:Hart, Michael H. (1 June 1975).
1334:Astrobiology Society of Britain
1209:Explorer of Enceladus and Titan
864:Habitable zone for complex life
2199:Journey to Enceladus and Titan
1219:Journey to Enceladus and Titan
496:Williams, Matt (6 June 2021).
418:Patton, Paul (8 August 2015).
1:
2332:Berkeley SETI Research Center
2032:Extraterrestrial liquid water
1267:Astrobiology Field Laboratory
819:Extraterrestrial liquid water
2652:Extraterrestrials in fiction
2525:Interplanetary contamination
2022:Circumstellar habitable zone
1906:(unusual light fluctuations)
1898:(unusual light fluctuations)
1890:(unusual light fluctuations)
1401:Spanish Astrobiology Center
809:Circumstellar habitable zone
325:10.1007/978-3-030-41614-0_12
2510:Extraterrestrial hypothesis
1475:Interstellar communications
1386:NASA Astrobiology Institute
286:Patton, Paul (2015-04-08).
92:extraterrestrial life have
2782:
2756:Astronomical controversies
2224:Mars sample-return mission
1234:Mars sample return mission
73:
1977:Earliest known life forms
1714:
1409:
1312:Terrestrial Planet Finder
734:Earliest known life forms
159:10.1017/S1473550422000374
94:been detected or observed
2342:Breakthrough Initiatives
1494:Breakthrough Initiatives
1344:Breakthrough Initiatives
311:Dick, Steven J. (2020).
2751:Astronomical hypotheses
2446:extraterrestrial beings
2037:Galactic habitable zone
1005:Mars Science Laboratory
824:Galactic habitable zone
317:Space, Time, and Aliens
2594:Planetarium hypothesis
2584:Hart–Tipler conjecture
2569:Dark forest hypothesis
2559:Aestivation hypothesis
2278:Venus In Situ Explorer
2082:Planetary habitability
1871:(misidentified quasar)
1863:(misidentified pulsar)
1184:Enceladus Life Finder
1164:Breakthrough Enceladus
688:Planetary oceanography
32:Hart–Tipler conjecture
18:Hart-Tipler conjecture
2697:Post-detection policy
2599:Rare Earth hypothesis
2424:Voyager Golden Record
2317:Allen Telescope Array
2152:Enceladus Life Finder
2087:Superhabitable planet
1780:Extraterrestrial life
1686:Extraterrestrial life
1613:Sebastian von Hoerner
1582:Voyager Golden Record
1359:Breakthrough Starshot
959:Lunar Micro Ecosystem
879:Superhabitable planet
744:Extraterrestrial life
219:10.1089/ast.2014.1247
2687:Planetary protection
2574:Firstborn hypothesis
2564:Berserker hypothesis
2535:Mediocrity principle
2352:Breakthrough Message
1970:Life in the Universe
1537:A Message from Earth
1504:Breakthrough Message
1366:Carl Sagan Institute
1354:Breakthrough Message
1194:Enceladus Orbilander
929:Biosatellite program
779:Planetary protection
663:Evolutionary biology
653:Atmospheric sciences
122:Berserker hypothesis
118:firstborn hypothesis
96:anywhere other than
2500:Directed panspermia
2479:Reptilian humanoids
2347:Breakthrough Listen
2327:Arecibo Observatory
2273:Titan Mare Explorer
1846:Signals of interest
1806:Murchison meteorite
1794:Shergotty meteorite
1633:Linda Salzman Sagan
1542:Across the Universe
1499:Breakthrough Listen
1349:Breakthrough Listen
536:1978QJRAS..19..277P
258:1975QJRAS..16..128H
211:2015AsBio..15..195G
50:in a 1975 paper by
2622:Ancient astronauts
2219:Mars Geyser Hopper
2147:Enceladus Explorer
1787:Events and objects
1179:Enceladus Explorer
36:Von Neumann probes
2725:
2724:
2255:SpaceX Red Dragon
2170:Rosalind Franklin
1965:
1964:
1824:Allan Hills 84001
1818:Allan Hills 77005
1746:
1745:
1643:Aleksandr Zaitsev
1618:Nikolai Kardashev
1441:
1440:
1320:
1319:
1144:Rosalind Franklin
1057:Trace Gas Orbiter
714:Allan Hills 84001
693:Planetary science
334:978-3-030-41613-3
16:(Redirected from
2773:
2702:San Marino Scale
2642:Brookings Report
2589:Neocatastrophism
2495:Cosmic pluralism
2469:Little green men
2444:Types of alleged
2369:Astrolinguistics
1958:
1950:
1949:(unknown origin)
1946:Fast radio burst
1942:
1934:
1915:
1914:(unknown origin)
1911:HD 164595 signal
1907:
1899:
1891:
1872:
1864:
1850:
1800:Nakhla meteorite
1773:
1766:
1759:
1750:
1735:
1723:
1722:
1706:San Marino Scale
1676:Astrolinguistics
1608:Hans Freudenthal
1577:Teen Age Message
1567:Hello from Earth
1468:
1461:
1454:
1445:
1429:
1428:
1417:
1416:
894:
789:Yamato meteorite
622:
615:
608:
599:
592:
591:
589:
587:
572:
566:
565:
563:
561:
546:
540:
539:
515:
509:
508:
506:
504:
493:
487:
486:
484:
482:
467:
461:
460:
458:
456:
450:The Conversation
444:Tingay, Steven.
441:
435:
434:
432:
430:
415:
409:
408:
406:
404:
389:
383:
382:
380:
378:
372:academic.oup.com
369:
360:
354:
353:
351:
349:
308:
302:
301:
299:
298:
283:
277:
276:
274:
272:
237:
231:
230:
204:
184:
178:
177:
175:
173:
138:
21:
2781:
2780:
2776:
2775:
2774:
2772:
2771:
2770:
2731:
2730:
2728:
2726:
2721:
2717:Xenoarchaeology
2707:Technosignature
2608:
2544:
2530:Kardashev scale
2483:
2445:
2438:
2434:Xenolinguistics
2399:Project Phoenix
2389:Project Cyclops
2374:Lincos language
2337:Bracewell probe
2322:Arecibo message
2303:
2296:
2194:Icebreaker Life
2096:
2008:
2001:
1961:
1956:
1948:
1940:
1932:
1918:
1913:
1905:
1897:
1889:
1875:
1870:
1862:
1841:
1782:
1777:
1747:
1742:
1710:
1647:
1638:Iosif Shklovsky
1586:
1552:Bracewell probe
1547:Arecibo message
1520:
1477:
1472:
1442:
1437:
1405:
1326:
1316:
1259:
1253:
1214:Icebreaker Life
1152:
1114:
1098:
1072:
1066:
983:
889:
883:
800:
793:
697:
673:Geomicrobiology
631:
626:
596:
595:
585:
583:
574:
573:
569:
559:
557:
548:
547:
543:
517:
516:
512:
502:
500:
495:
494:
490:
480:
478:
469:
468:
464:
454:
452:
443:
442:
438:
428:
426:
417:
416:
412:
402:
400:
391:
390:
386:
376:
374:
367:
362:
361:
357:
347:
345:
335:
310:
309:
305:
296:
294:
285:
284:
280:
270:
268:
239:
238:
234:
186:
185:
181:
171:
169:
140:
139:
135:
130:
114:
78:
72:
52:Michael H. Hart
28:
23:
22:
15:
12:
11:
5:
2779:
2777:
2769:
2768:
2763:
2758:
2753:
2748:
2743:
2733:
2732:
2723:
2722:
2720:
2719:
2714:
2709:
2704:
2699:
2694:
2689:
2684:
2679:
2674:
2669:
2664:
2659:
2654:
2649:
2644:
2639:
2634:
2629:
2624:
2618:
2616:
2614:Related topics
2610:
2609:
2607:
2606:
2604:Zoo hypothesis
2601:
2596:
2591:
2586:
2581:
2576:
2571:
2566:
2561:
2555:
2553:
2546:
2545:
2543:
2542:
2537:
2532:
2527:
2522:
2517:
2512:
2507:
2505:Drake equation
2502:
2497:
2491:
2489:
2485:
2484:
2482:
2481:
2476:
2471:
2466:
2461:
2456:
2450:
2448:
2440:
2439:
2437:
2436:
2431:
2426:
2421:
2416:
2411:
2406:
2401:
2396:
2391:
2386:
2384:Pioneer plaque
2381:
2376:
2371:
2366:
2361:
2356:
2355:
2354:
2349:
2339:
2334:
2329:
2324:
2319:
2314:
2308:
2306:
2298:
2297:
2295:
2294:
2287:
2280:
2275:
2270:
2265:
2257:
2252:
2244:
2236:
2234:Northern Light
2231:
2226:
2221:
2216:
2211:
2206:
2201:
2196:
2191:
2186:
2181:
2176:
2175:
2174:
2161:
2158:Europa Clipper
2154:
2149:
2144:
2137:
2130:
2122:
2117:
2112:
2106:
2104:
2102:Space missions
2098:
2097:
2095:
2094:
2089:
2084:
2079:
2074:
2069:
2064:
2059:
2054:
2049:
2044:
2039:
2034:
2029:
2024:
2019:
2013:
2011:
2003:
2002:
2000:
1999:
1994:
1989:
1984:
1979:
1973:
1971:
1967:
1966:
1963:
1962:
1960:
1959:
1957:(radio signal)
1951:
1943:
1941:(inconclusive)
1935:
1933:(radio source)
1926:
1924:
1920:
1919:
1917:
1916:
1908:
1900:
1895:EPIC 204278916
1892:
1883:
1881:
1877:
1876:
1874:
1873:
1865:
1856:
1854:
1847:
1843:
1842:
1840:
1839:
1833:
1827:
1821:
1815:
1809:
1803:
1797:
1790:
1788:
1784:
1783:
1778:
1776:
1775:
1768:
1761:
1753:
1744:
1743:
1741:
1740:
1728:
1715:
1712:
1711:
1709:
1708:
1703:
1698:
1693:
1688:
1683:
1681:Drake equation
1678:
1673:
1668:
1661:
1659:Alien language
1655:
1653:
1649:
1648:
1646:
1645:
1640:
1635:
1630:
1625:
1620:
1615:
1610:
1605:
1600:
1594:
1592:
1588:
1587:
1585:
1584:
1579:
1574:
1572:Pioneer plaque
1569:
1564:
1559:
1554:
1549:
1544:
1539:
1534:
1528:
1526:
1522:
1521:
1519:
1518:
1513:
1508:
1507:
1506:
1501:
1491:
1485:
1483:
1479:
1478:
1473:
1471:
1470:
1463:
1456:
1448:
1439:
1438:
1436:
1435:
1423:
1410:
1407:
1406:
1404:
1403:
1398:
1393:
1388:
1383:
1378:
1373:
1368:
1363:
1362:
1361:
1356:
1351:
1341:
1336:
1330:
1328:
1322:
1321:
1318:
1317:
1315:
1314:
1309:
1304:
1302:Northern Light
1299:
1294:
1289:
1284:
1279:
1274:
1269:
1263:
1261:
1258:Cancelled and
1255:
1254:
1252:
1251:
1246:
1241:
1236:
1231:
1226:
1221:
1216:
1211:
1206:
1201:
1196:
1191:
1186:
1181:
1176:
1171:
1166:
1160:
1158:
1154:
1153:
1151:
1150:
1149:
1148:
1135:
1133:Europa Clipper
1130:
1122:
1120:
1116:
1115:
1113:
1112:
1106:
1104:
1100:
1099:
1097:
1096:
1089:
1084:
1076:
1074:
1068:
1067:
1065:
1064:
1059:
1054:
1053:
1052:
1039:
1032:
1031:
1030:
1017:
1016:
1015:
1002:
997:
991:
989:
985:
984:
982:
981:
976:
971:
966:
961:
956:
951:
946:
941:
936:
931:
926:
921:
916:
911:
906:
900:
898:
891:
885:
884:
882:
881:
876:
871:
866:
861:
856:
851:
846:
841:
836:
831:
826:
821:
816:
811:
805:
803:
795:
794:
792:
791:
786:
781:
776:
771:
766:
761:
756:
751:
746:
741:
736:
731:
729:Drake equation
726:
721:
716:
711:
705:
703:
699:
698:
696:
695:
690:
685:
680:
675:
670:
668:Exoplanetology
665:
660:
655:
650:
645:
643:Astrochemistry
639:
637:
633:
632:
627:
625:
624:
617:
610:
602:
594:
593:
581:Universe Today
567:
555:Universe Today
541:
510:
488:
476:The New Yorker
462:
436:
424:Universe Today
410:
398:Universe Today
384:
355:
333:
303:
292:Universe Today
278:
232:
195:(3): 195–199.
179:
153:(2): 111–117.
132:
131:
129:
126:
113:
110:
74:Main article:
71:
68:
48:Drake equation
40:contrapositive
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
2778:
2767:
2766:Fermi paradox
2764:
2762:
2759:
2757:
2754:
2752:
2749:
2747:
2744:
2742:
2739:
2738:
2736:
2729:
2718:
2715:
2713:
2710:
2708:
2705:
2703:
2700:
2698:
2695:
2693:
2690:
2688:
2685:
2683:
2680:
2678:
2675:
2673:
2670:
2668:
2665:
2663:
2660:
2658:
2655:
2653:
2650:
2648:
2645:
2643:
2640:
2638:
2635:
2633:
2630:
2628:
2625:
2623:
2620:
2619:
2617:
2615:
2611:
2605:
2602:
2600:
2597:
2595:
2592:
2590:
2587:
2585:
2582:
2580:
2577:
2575:
2572:
2570:
2567:
2565:
2562:
2560:
2557:
2556:
2554:
2551:
2550:Fermi paradox
2547:
2541:
2538:
2536:
2533:
2531:
2528:
2526:
2523:
2521:
2518:
2516:
2515:Fermi paradox
2513:
2511:
2508:
2506:
2503:
2501:
2498:
2496:
2493:
2492:
2490:
2486:
2480:
2477:
2475:
2474:Nordic aliens
2472:
2470:
2467:
2465:
2462:
2460:
2457:
2455:
2454:Energy beings
2452:
2451:
2449:
2447:
2441:
2435:
2432:
2430:
2427:
2425:
2422:
2420:
2417:
2415:
2412:
2410:
2407:
2405:
2402:
2400:
2397:
2395:
2392:
2390:
2387:
2385:
2382:
2380:
2377:
2375:
2372:
2370:
2367:
2365:
2362:
2360:
2357:
2353:
2350:
2348:
2345:
2344:
2343:
2340:
2338:
2335:
2333:
2330:
2328:
2325:
2323:
2320:
2318:
2315:
2313:
2310:
2309:
2307:
2305:
2304:communication
2299:
2293:
2292:
2288:
2286:
2285:
2281:
2279:
2276:
2274:
2271:
2269:
2266:
2264:
2262:
2258:
2256:
2253:
2251:
2249:
2245:
2243:
2241:
2237:
2235:
2232:
2230:
2227:
2225:
2222:
2220:
2217:
2215:
2212:
2210:
2207:
2205:
2202:
2200:
2197:
2195:
2192:
2190:
2187:
2185:
2182:
2180:
2177:
2173:
2171:
2167:
2166:
2165:
2162:
2160:
2159:
2155:
2153:
2150:
2148:
2145:
2143:
2142:
2138:
2136:
2135:
2131:
2129:
2127:
2123:
2121:
2118:
2116:
2113:
2111:
2108:
2107:
2105:
2103:
2099:
2093:
2090:
2088:
2085:
2083:
2080:
2078:
2075:
2073:
2070:
2068:
2065:
2063:
2060:
2058:
2055:
2053:
2050:
2048:
2045:
2043:
2040:
2038:
2035:
2033:
2030:
2028:
2025:
2023:
2020:
2018:
2015:
2014:
2012:
2010:
2004:
1998:
1997:Life on Titan
1995:
1993:
1990:
1988:
1987:Life on Venus
1985:
1983:
1980:
1978:
1975:
1974:
1972:
1968:
1955:
1952:
1947:
1944:
1939:
1936:
1931:
1928:
1927:
1925:
1921:
1912:
1909:
1904:
1901:
1896:
1893:
1888:
1885:
1884:
1882:
1878:
1869:
1866:
1861:
1858:
1857:
1855:
1853:Misidentified
1851:
1848:
1844:
1837:
1834:
1831:
1830:Yamato 000593
1828:
1825:
1822:
1819:
1816:
1813:
1810:
1807:
1804:
1801:
1798:
1795:
1792:
1791:
1789:
1785:
1781:
1774:
1769:
1767:
1762:
1760:
1755:
1754:
1751:
1739:
1738:
1734:
1729:
1727:
1726:
1717:
1716:
1713:
1707:
1704:
1702:
1699:
1697:
1696:Fermi paradox
1694:
1692:
1689:
1687:
1684:
1682:
1679:
1677:
1674:
1672:
1669:
1667:
1666:
1662:
1660:
1657:
1656:
1654:
1650:
1644:
1641:
1639:
1636:
1634:
1631:
1629:
1626:
1624:
1621:
1619:
1616:
1614:
1611:
1609:
1606:
1604:
1601:
1599:
1596:
1595:
1593:
1589:
1583:
1580:
1578:
1575:
1573:
1570:
1568:
1565:
1563:
1560:
1558:
1555:
1553:
1550:
1548:
1545:
1543:
1540:
1538:
1535:
1533:
1530:
1529:
1527:
1523:
1517:
1514:
1512:
1509:
1505:
1502:
1500:
1497:
1496:
1495:
1492:
1490:
1487:
1486:
1484:
1480:
1476:
1469:
1464:
1462:
1457:
1455:
1450:
1449:
1446:
1434:
1433:
1424:
1422:
1421:
1412:
1411:
1408:
1402:
1399:
1397:
1394:
1392:
1389:
1387:
1384:
1382:
1379:
1377:
1374:
1372:
1369:
1367:
1364:
1360:
1357:
1355:
1352:
1350:
1347:
1346:
1345:
1342:
1340:
1337:
1335:
1332:
1331:
1329:
1323:
1313:
1310:
1308:
1305:
1303:
1300:
1298:
1295:
1293:
1290:
1288:
1285:
1283:
1280:
1278:
1275:
1273:
1270:
1268:
1265:
1264:
1262:
1256:
1250:
1247:
1245:
1242:
1240:
1237:
1235:
1232:
1230:
1227:
1225:
1222:
1220:
1217:
1215:
1212:
1210:
1207:
1205:
1202:
1200:
1199:Europa Lander
1197:
1195:
1192:
1190:
1187:
1185:
1182:
1180:
1177:
1175:
1172:
1170:
1167:
1165:
1162:
1161:
1159:
1155:
1147:
1145:
1141:
1140:
1139:
1136:
1134:
1131:
1129:
1128:
1124:
1123:
1121:
1117:
1111:
1108:
1107:
1105:
1101:
1095:
1094:
1090:
1088:
1085:
1083:
1082:
1078:
1077:
1075:
1069:
1063:
1060:
1058:
1055:
1051:
1049:
1045:
1044:
1043:
1040:
1038:
1037:
1033:
1029:
1027:
1023:
1022:
1021:
1018:
1014:
1012:
1008:
1007:
1006:
1003:
1001:
998:
996:
993:
992:
990:
986:
980:
977:
975:
972:
970:
967:
965:
962:
960:
957:
955:
952:
950:
947:
945:
942:
940:
937:
935:
932:
930:
927:
925:
922:
920:
917:
915:
912:
910:
907:
905:
902:
901:
899:
895:
892:
886:
880:
877:
875:
872:
870:
867:
865:
862:
860:
857:
855:
852:
850:
847:
845:
842:
840:
837:
835:
832:
830:
827:
825:
822:
820:
817:
815:
812:
810:
807:
806:
804:
802:
796:
790:
787:
785:
782:
780:
777:
775:
772:
770:
767:
765:
762:
760:
757:
755:
754:Extremophiles
752:
750:
747:
745:
742:
740:
737:
735:
732:
730:
727:
725:
722:
720:
717:
715:
712:
710:
707:
706:
704:
700:
694:
691:
689:
686:
684:
681:
679:
676:
674:
671:
669:
666:
664:
661:
659:
656:
654:
651:
649:
646:
644:
641:
640:
638:
634:
630:
623:
618:
616:
611:
609:
604:
603:
600:
582:
578:
571:
568:
556:
552:
545:
542:
537:
533:
529:
525:
521:
514:
511:
499:
492:
489:
477:
473:
466:
463:
451:
447:
440:
437:
425:
421:
414:
411:
399:
395:
388:
385:
373:
366:
359:
356:
344:
340:
336:
330:
326:
322:
318:
314:
307:
304:
293:
289:
282:
279:
267:
263:
259:
255:
251:
247:
243:
236:
233:
228:
224:
220:
216:
212:
208:
203:
198:
194:
190:
183:
180:
168:
164:
160:
156:
152:
148:
144:
137:
134:
127:
125:
123:
119:
111:
109:
107:
106:Fermi paradox
103:
99:
95:
91:
87:
84:have visited
83:
77:
76:Fermi paradox
69:
67:
65:
61:
60:Fermi paradox
56:
53:
49:
45:
41:
37:
33:
19:
2741:Astrobiology
2727:
2712:UFO religion
2657:Extremophile
2637:Biosignature
2632:Astroecology
2627:Astrobiology
2583:
2579:Great Filter
2394:Project Ozma
2302:Interstellar
2289:
2282:
2260:
2248:Perseverance
2247:
2239:
2169:
2156:
2139:
2132:
2125:
2027:Earth analog
2009:habitability
1992:Life on Mars
1737:Space Portal
1730:
1718:
1671:Astrobiology
1663:
1430:
1418:
1327:and programs
1325:Institutions
1143:
1125:
1103:Heliocentric
1091:
1079:
1047:
1034:
1026:Perseverance
1025:
1010:
814:Earth analog
801:habitability
769:Ocean planet
739:Earth analog
724:Biosignature
683:Paleontology
678:Microbiology
658:Biochemistry
648:Astrophysics
629:Astrobiology
584:. Retrieved
580:
570:
558:. Retrieved
554:
544:
527:
523:
513:
501:. Retrieved
491:
479:. Retrieved
475:
465:
453:. Retrieved
449:
439:
427:. Retrieved
423:
413:
401:. Retrieved
397:
387:
375:. Retrieved
371:
358:
346:. Retrieved
316:
306:
295:. Retrieved
291:
281:
269:. Retrieved
249:
245:
235:
192:
189:Astrobiology
188:
182:
170:. Retrieved
150:
146:
136:
115:
79:
64:Frank Tipler
57:
44:Solar System
31:
29:
2647:Exotheology
2459:Grey aliens
2312:Active SETI
2240:Opportunity
2120:BioSentinel
1938:Wow! signal
1887:KIC 8462852
1836:CI1 fossils
1701:Prix Guzman
1623:Jon Lomberg
1598:Frank Drake
1557:Cosmic Call
1489:Active SETI
1260:undeveloped
1110:BioSentinel
1000:Fobos-Grunt
897:Earth orbit
719:Biomolecule
709:Abiogenesis
702:Main topics
636:Disciplines
530:: 277–281.
90:intelligent
2746:Hypotheses
2735:Categories
2682:Noogenesis
2662:Hemolithin
2540:Panspermia
2488:Hypotheses
2464:Insectoids
2429:Water hole
1930:SHGb02+14a
1903:VVV-WIT-07
1628:Carl Sagan
1603:Ann Druyan
1307:Red Dragon
1087:OSIRIS-REx
1071:Comets and
774:Panspermia
586:18 October
560:18 October
481:27 October
455:27 October
429:18 October
403:18 October
377:18 October
348:18 October
297:2024-02-23
271:18 October
202:1605.09187
172:18 October
128:References
70:Background
2552:solutions
2419:setiQuest
2414:SETI@home
2229:Mars 2020
2204:Laplace-P
2141:Dragonfly
2126:Curiosity
2007:Planetary
1224:Laplace-P
1127:Dragonfly
1081:Hayabusa2
1073:asteroids
1042:Tianwen-1
1020:Mars 2020
1011:Curiosity
944:Eu:CROPIS
799:Planetary
343:219414685
266:0035-8738
167:253014320
2404:SERENDIP
2379:NIROSETI
2291:Viking 2
2284:Viking 1
2189:Foton-M3
2179:ExoLance
2110:Beagle 2
1725:Category
1562:CosmicOS
1525:Messages
1482:Programs
1420:Category
1282:Kazachok
1272:Beagle 3
1204:ExoLance
1157:Proposed
995:Beagle 2
969:OREOcube
949:EXOSTACK
890:missions
227:25719510
102:Universe
2268:Tanpopo
2164:ExoMars
1868:CTA-102
1860:CP 1919
1432:Commons
1249:Trident
1239:Oceanus
1138:ExoMars
1119:Planned
1093:Rosetta
1048:Zhurong
1036:Phoenix
974:Tanpopo
964:O/OREOS
909:BIOCORE
532:Bibcode
254:Bibcode
252:: 128.
207:Bibcode
100:in the
2672:MERMOZ
2261:Spirit
2184:EXPOSE
2134:Darwin
2092:Tholin
1838:(2011)
1832:(2000)
1826:(1984)
1820:(1977)
1814:(1976)
1808:(1969)
1802:(1911)
1796:(1865)
1691:Lincos
1591:People
1381:MERMOZ
1174:CAESAR
1062:Viking
979:VEGGIE
954:EXPOSE
934:E-MIST
924:BIOPAN
914:Biolab
874:Tholin
503:25 May
341:
331:
264:
225:
165:
82:aliens
2263:rover
2250:rover
2242:rover
2172:rover
2128:rover
1923:Other
1880:Stars
1652:Other
1297:MELOS
1169:BRUIE
1146:rover
1050:rover
1028:rover
1013:rover
888:Space
368:(PDF)
339:S2CID
197:arXiv
163:S2CID
98:Earth
86:Earth
1954:BLC1
1244:THEO
988:Mars
919:Bion
588:2022
562:2022
505:2023
483:2022
457:2022
431:2022
405:2022
379:2022
350:2022
329:ISBN
273:2022
262:ISSN
223:PMID
174:2022
116:The
30:The
939:ERA
904:BIO
321:doi
215:doi
155:doi
38:is
2737::
579:.
553:.
528:19
526:.
522:.
474:.
448:.
422:.
396:.
370:.
337:.
327:.
315:.
290:.
260:.
250:16
248:.
244:.
221:.
213:.
205:.
193:15
191:.
161:.
151:22
149:.
145:.
66:.
1772:e
1765:t
1758:v
1467:e
1460:t
1453:v
621:e
614:t
607:v
590:.
564:.
538:.
534::
507:.
485:.
459:.
433:.
407:.
381:.
352:.
323::
300:.
275:.
256::
229:.
217::
209::
199::
176:.
157::
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.