logo

English
                 

Our Unbounded Finite Universe

posted by Jason Kottke   Jan 08, 2019

I’ve always had a hard time wrapping my head around the idea that the universe could be both finite and infinite at the same time (or something like that *takes bong rip*), but this passage from Coming of Age in the Milky Way by Timothy Ferris succinctly explains what’s going on:

General relativity resolved the matter by establishing that the universe could be both finite — i.e., could contain a finite number of stars in a finite volume of space — and unbounded. The key to this realization lay in Einstein’s demonstration that, since matter warps space, the sum total of the mass in all the galaxies might be sufficient to wrap space around themselves. The result would be a closed, four-dimensionally spherical cosmos, in which any observer, anywhere in the universe, would see galaxies stretching deep into space in every direction, and would conclude, correctly, that there is no end to space. Yet the amount of space in a closed universe would nonetheless be finite: An adventurer with time to spare could eventually visit every galaxy, yet would never reach an edge of space. Just as the surface of the earth is finite but unbounded in two dimensions (we can wander wherever we like, and will not fall off the edge of the earth) so a closed four-dimensional universe is finite but unbounded to us who observe it in three dimensions.

In the terms of Edwin Abbott Abbott’s Flatland: A Romance of Many Dimensions, we are Flatlanders living in a Lineland world who, with the aid of mathematics, have been able to peer into Spaceland.

No. Subject Date Author Last Update Views
Notice How to write your comments onto a webpage [2] 2016.07.06 운영자 2016.11.20 18175
Notice How to Upload Pictures in webpages 2016.07.06 운영자 2018.10.19 32325
Notice How to use Rich Text Editor [3] 2016.06.28 운영자 2018.10.19 5904
Notice How to Write a Webpage 2016.06.28 운영자 2020.12.23 43822
2662 참말같은 거짓말 2019.03.12 온기철*71 2019.03.13 52
2661 [LPGA] Park Leaves No Anxious Moments In Win In singapore [8] 2019.03.03 황규정*65 2019.03.13 156
2660 50 Charged for College Admission Bribery in U.S. [3] 2019.03.12 온기철*71 2019.03.14 153
2659 Painted Lady Butterfly Migration [2] 2019.03.15 이한중*65 2019.03.15 380
» Our Infinite Finite Universe [3] 2019.03.14 이한중*65 2019.03.16 170
2657 This Video Will Make Any Golfer Laugh [3] 2019.03.16 이한중*65 2019.03.17 77
2656 [Medical] Elderberry and URI [2] 2019.03.17 이한중*65 2019.03.17 128
2655 Nella Fantasia [2] 2017.06.12 운영자 2019.03.17 17828
2654 내맘의 강물 [4] 2019.03.16 운영자 2019.03.17 139
2653 이강인ㆍ백승호, 벤투호 합류 [1] 2019.03.18 황규정*65 2019.03.19 32
2652 The New Koreans; The Story of A Nation [2] 2019.03.18 온기철*71 2019.03.19 98
2651 대입비리; 한국과 닮아가는 미국 2019.03.20 온기철*71 2019.03.20 42
2650 Swallows Legend, San Juan Capistrano, CA [4] 2019.03.18 이한중*65 2019.03.20 102
2649 Why space is so dark? [1] 2019.03.20 이한중*65 2019.03.20 61
2648 차범근-박지성-손흥민, 누가 최고인가 [1] 2019.03.20 황규정*65 2019.03.20 60
2647 여순사건; 제임스 하우스만, 김창룡, 박정희 2019.03.21 온기철*71 2019.03.21 193
2646 Finland, World's Happiest Country Again 2019.03.21 이한중*65 2019.03.21 42
2645 The Cause of Pohang Earthquake Revealed [1] 2019.03.22 이한중*65 2019.03.22 48
2644 '이청용 결승골' 한국, 볼리비아에 1:0 승리 [2] 2019.03.22 황규정*65 2019.03.22 46
2643 [Medical] Safety Comparison, Apixaban vs Rivaroxaban [1] 2019.03.24 이한중*65 2019.03.24 52