1 00:00:00,560 --> 00:00:03,600 Speaker 1: Welcome to brain Stuff from how Stuff works dot com 2 00:00:03,640 --> 00:00:07,280 Speaker 1: where smart happens. This podcast is brought to you by 3 00:00:07,320 --> 00:00:11,840 Speaker 1: Audible dot com, the Internet's leading provider of spoken word entertainment. 4 00:00:12,119 --> 00:00:14,920 Speaker 1: Get a free audio book download of your choice when 5 00:00:14,920 --> 00:00:18,239 Speaker 1: you sign up today. Log on to audible podcast dot 6 00:00:18,280 --> 00:00:24,680 Speaker 1: com slash brain Stuff today for details. I am Marshall 7 00:00:24,720 --> 00:00:27,840 Speaker 1: brain with today's question. If we were to move all 8 00:00:27,880 --> 00:00:30,880 Speaker 1: of the matter in the universe into one corner, how 9 00:00:30,960 --> 00:00:33,920 Speaker 1: much space would it take up. It's hard to answer 10 00:00:33,960 --> 00:00:37,040 Speaker 1: this question exactly because there are some unknowns, but if 11 00:00:37,040 --> 00:00:40,159 Speaker 1: you're willing to accept three assumptions, we can come up 12 00:00:40,200 --> 00:00:43,360 Speaker 1: with an answer that at least sounds reasonable. The first 13 00:00:43,440 --> 00:00:47,040 Speaker 1: question is how big is the universe. No one knows, 14 00:00:47,159 --> 00:00:50,080 Speaker 1: but based on observations, we might guess that it's a 15 00:00:50,200 --> 00:00:53,960 Speaker 1: sphere that's thirty billion light years across. That means that 16 00:00:54,040 --> 00:00:57,880 Speaker 1: the whole universe contains about ten to the thirty second 17 00:00:58,000 --> 00:01:03,080 Speaker 1: power cubic light years. It's incredibly big. The next question 18 00:01:03,160 --> 00:01:07,000 Speaker 1: is how much matter does the universe contain. The mass 19 00:01:07,000 --> 00:01:09,399 Speaker 1: of the universe is a source of debate right now, 20 00:01:09,440 --> 00:01:11,720 Speaker 1: because there's no easy way to put the universe on 21 00:01:11,800 --> 00:01:15,600 Speaker 1: a scale NASA estimates that it's about ten to the 22 00:01:15,760 --> 00:01:20,640 Speaker 1: sixtims for the whole thing. Other estimates give other numbers, 23 00:01:20,640 --> 00:01:23,720 Speaker 1: but they're all in that same ballpark. The next question 24 00:01:23,800 --> 00:01:26,679 Speaker 1: is what density do you want to assume that the 25 00:01:26,720 --> 00:01:29,520 Speaker 1: mass will have once you push it all into one corner. 26 00:01:29,959 --> 00:01:32,640 Speaker 1: If you were to really do this, if you actually 27 00:01:32,680 --> 00:01:35,040 Speaker 1: didn't move all of the mass of the universe into 28 00:01:35,040 --> 00:01:38,440 Speaker 1: one corner, it would condense into a black hole. But 29 00:01:38,560 --> 00:01:40,679 Speaker 1: let's say that you could keep it from doing that, 30 00:01:40,760 --> 00:01:43,160 Speaker 1: and you were somehow able to keep all the mass 31 00:01:43,520 --> 00:01:47,600 Speaker 1: evenly distributed at a density of the sun. If you 32 00:01:47,640 --> 00:01:51,160 Speaker 1: are willing to accept these three assumptions, then all of 33 00:01:51,160 --> 00:01:53,920 Speaker 1: the matter in the universe would fit into about one 34 00:01:54,040 --> 00:01:58,040 Speaker 1: billion cubic light years, or a cube that's approximately a 35 00:01:58,120 --> 00:02:01,440 Speaker 1: thousand light years on each side. Compared to the size 36 00:02:01,440 --> 00:02:05,600 Speaker 1: of the universe, that's tiny. Imagine a despec Compared to 37 00:02:05,640 --> 00:02:10,760 Speaker 1: Planet Earth. The universe is an incredibly empty place. Do 38 00:02:10,800 --> 00:02:14,280 Speaker 1: you have any ideas or suggestions for this podcast? If so, 39 00:02:14,440 --> 00:02:17,160 Speaker 1: please send me an email at podcast at how stuff 40 00:02:17,160 --> 00:02:19,920 Speaker 1: works dot com. For more on this and thousands of 41 00:02:19,919 --> 00:02:24,520 Speaker 1: other topics, go to how stuff works dot com.