Researchers from the University of Bonn in Germany are shaking up our cosmic perspective, suggesting that our solar system might be in a sort of celestial sweet spot. They propose it's like finding ourselves in an "air bubble in a cake," a vast void where matter is significantly less dense compared to other cosmic neighborhoods. This cosmic bubble theory challenges the conventional notion of our place in the universe, hinting at a unique environment for our solar system. It's like stumbling upon a spacious, cosmic haven amidst the density of the known universe, according to these scientists. This fresh perspective invites us to ponder the mysteries of our cosmic address and rethink our understanding of the vast, interconnected cosmos.
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00:00 I don't want to spook you, but there's a chance that our entire Milky Way galaxy
00:05 is located in the so-called "space void."
00:08 It's a region where there's relatively little matter, compared to other corners of
00:12 the known universe, and it's much less dense than it is elsewhere in the universe.
00:17 In other words, we might exist in an air bubble in a cake.
00:21 If that's true, it would mean that we're even lonelier than we thought.
00:27 In our universe, all the galaxies are constantly moving away from each other.
00:31 In order to understand how far they move away, scientists use something called the Hubble
00:36 Lemaître constant.
00:37 It's like a speedometer, but for galaxies.
00:40 However, there's a cosmic mystery called the Hubble tension.
00:44 It's challenging what we know about the universe's expansion.
00:49 Scientists used to consider the Hubble Lemaître constant a reliable guide, but our recent
00:53 observations question this reliability.
00:56 The speeds we see in real life don't match up with the distances we calculated and expected.
01:01 They aren't sure why these measurements don't add up.
01:05 Researchers followed the moves of supernovas and saw that the universe seems to expand
01:09 faster around us than it does overall, as if it's actively avoiding us specifically.
01:16 After considering this, they began to assume that we might all live in a cosmic void.
01:24 Cosmic voids are vast, empty spaces between galaxies, kind of like between my ears.
01:29 They make our entire world look like a big sponge.
01:32 Now let's go back to the beginning, just a fraction of a second after the Big Bang.
01:37 Right after the beginning of everything, the universe was a hot, compressed plasma.
01:42 It only had very tiny variations in density, called quantum fluctuations.
01:47 After the Big Bang, the universe began to expand.
01:50 Those quantum fluctuations grew together with it, creating regions of varying matter density.
01:56 Because of that, the universe didn't expand everywhere uniformly.
02:00 Instead, little claps of matter began to gather together over a long period of time, creating
02:06 massive structures – galaxies.
02:09 Galaxies are arranged in huge walls and filaments, with enormous gaps in between.
02:14 And these gaps are voids, also known as dark space.
02:21 These voids aren't truly empty.
02:23 In fact, they actually hold more than 15% of the amount of matter found on average throughout
02:28 the entire universe.
02:30 They still contain gas, dust, dark matter, and even stars and galaxies.
02:34 However, they have less density than regions with galaxies – about a tenth of the average
02:40 matter density, which is why we consider them nearly empty.
02:44 Usually, they'll have a diameter ranging from about 30 to 300 million light-years.
02:50 That is an enormous distance even on a space scale.
02:53 For comparison, most planets and nebulas we've found so far have a distance of hundreds and
02:58 rarely thousands of light-years away from us.
03:01 In the case of voids, if you were in the middle of one, it would just look like seemingly
03:06 eternal darkness.
03:08 The closest stars would be so far away that they would be almost invisible to you.
03:15 Some of them are especially large.
03:17 They're known as supervoids.
03:19 The largest known one was creatively named Giant Void.
03:23 It's so big, it's impossible for us to even imagine.
03:27 1.5 billion light-years away, with a diameter of 1 to 1.3 billion light-years.
03:33 Yeah, it's basically a big dark vacuum.
03:36 But even this giant vacuum isn't entirely empty.
03:40 The Giant Void houses 17 separate galaxy clusters within its expanse.
03:45 However, it might not be the biggest emptiness in our universe.
03:49 There's this thing called the CMB cold spot.
03:52 It's this unusually large and chilly area of our universe that we saw through the microwaves.
03:58 It really stood out on the map of our universe with its unexpectedly low temperatures, and
04:02 scientists have spent many years trying to figure out what the thing is.
04:07 In 2015, scientists proposed that this place might be a supervoid, and probably the largest
04:14 one ever.
04:15 Being even more original than this one, they called it the Great Void.
04:18 If it's true, this place would be an emptiness of about 1.8 billion light-years in diameter,
04:25 about a thousand times larger than typical voids.
04:28 But everyone thinks that's possible, so scientists keep arguing over this one.
04:33 There's another interesting theory going about this place.
04:36 One researcher suggested that this place might've been a trace on our collision with the parallel
04:41 world.
04:42 It's a pretty bold hypothesis, but unfortunately, there's no way for us to confirm or deny
04:48 it with our current technologies.
04:50 In any case, as the universe expands, these voids will grow, and the walls connecting
04:55 galaxy clusters will stretch and break.
04:58 Eventually, the voids will merge, leaving gravitationally bound galaxy clusters as islands
05:04 in the expanding emptiness.
05:06 In other words, sooner or later, the Great Emptiness will consume everything in our world.
05:14 So it turns out we might be a rare occasion in a supervoid, one of the 15% of matter.
05:20 This would explain why we're surrounded by relatively few galaxies.
05:24 This discovery, if true, challenges the Standard Model of Cosmology, which we created with
05:30 Albert Einstein's help.
05:32 It would mean that gravity in general behaves differently than what we expected.
05:37 According to the Standard Model, such a significant underdensity shouldn't exist.
05:42 Because of that, scientists will have to explore and consider this idea thoroughly.
05:47 It might just challenge our very basic understanding of physics.
05:51 The scientists call this the "local hole."
05:54 The discovery of the local hole may hold clues to explaining the Fermi paradise.
05:59 Maybe in this specific part of the universe, where we hang out, the chance of intelligent
06:04 life developing anywhere nearby is very low.
06:07 Perhaps all of the sentient beings hang out somewhere beyond our supervoid.
06:14 But that doesn't mean we should lose hope, or that life anywhere "nearby" is impossible.
06:19 In fact, life in the universe might be much more common than we previously thought.
06:24 We know that the inner planets, like Mercury and Venus, are inhospitable due to extreme
06:29 conditions.
06:30 However, Venus looks interesting because, even though it's a crazy toxic planet, scientists
06:36 believe that it was very Earth-like in the past.
06:39 It could've even hosted life.
06:41 Unfortunately, it was too close to the Sun, and all the nice conditions evaporated over
06:46 time.
06:47 But there's a possibility of microbial life surviving in its high-altitude clouds.
06:52 Mars, a cold desert, also might've been a friendlier place in the past with rivers
06:58 and lakes.
06:59 Though now it lacks a protective atmosphere, ancient life might've existed there.
07:04 In that case, it would leave potential fossils, and underground microbes could still survive.
07:09 We've discovered some signs of them, but are still debating whether this stuff was
07:13 truly organic or not.
07:16 The gas giants, like Jupiter and Saturn, and ice giants are not ideal for life, but their
07:21 moons offer hope.
07:23 Europa has an ocean beneath its icy surface, making it a potential hotspot.
07:28 Insetulus releases water into space, carrying complex molecules that hint at interesting
07:34 possibilities.
07:35 And Titan is especially unique.
07:38 It has liquid bodies on its surface, rivers, and lakes of hydrocarbons.
07:42 While its frigid temperatures aren't great for life, scientists ponder if it might host
07:47 life with a different kind of chemistry.
07:49 However, it will take us decades to check all these celestial bodies and study them
07:54 properly.
07:55 We haven't sent anything so far since the times of Voyager 2.
07:59 But if we're lucky, we might explore our solar system during the 21st century.
08:11 In any case, there's a lot of potential for life even in our solar system alone, not
08:16 even mentioning all the planets and galaxies we've found nearby.
08:20 Our estimates suggest that the observable universe, the one we can see, might host around
08:25 5.3 trillion habitable worlds.
08:28 One of the most likely candidates so far is Kepler-186f.
08:33 It's a potential Earth-like planet, just 10% larger than Earth.
08:37 This planet orbits a red dwarf star, which is a star a bit dimmer, colder, but more long-living
08:42 than our Sun.
08:44 And it's only about 490 light-years away, which may sound like a lot, but remember what
08:49 distances we've discussed with supervoids.
08:52 So even if we really are in a supervoid, we're still lucky to have many galaxies and planets
08:57 around.
08:58 And if one day we'll find a way to travel through the universe, leaving the local hole
09:03 probably wouldn't be a problem.