00:00Ruh-roh, there might be another universe, like a dark mirror image of ours, where time flows in reverse.
00:08This flipped-over world might also be the source of dark matter, the invisible substance that's all over our universe.
00:15There might also be many more universes out there, in which an exact copy of you woke up this morning,
00:22but it chose a white t-shirt instead of a red one, sending it on a completely different life path.
00:29But let's start with this elusive dark matter.
00:32It makes up most of the universe's mass, yet we're not sure what exactly it does or where it comes from.
00:39That's because it doesn't act like regular matter.
00:42We can't see it or feel it, we just know it's there because of how it seems to bend gravity.
00:49Even though regular matter and dark matter are very different, they seem to exist in a balance.
00:55Some scientists think this must be connected somehow.
00:59A new theory suggests that, for every way regular matter moves, there's a mirror version of it in the world of dark matter,
01:07like a bridge connecting the two worlds.
01:10There's also a strange coincidence in regular matter where a neutron and a proton have almost the same weight.
01:17This allows them to stick together and make atoms stable, making everything that we can see with our eyes exist.
01:24If protons were a bit heavier, there would be no balance and atoms wouldn't form.
01:31In the dark mirror universe, maybe things happen differently.
01:35Maybe in there, the equivalent of a proton doesn't bind to other particles,
01:40leaving behind lonely neutrons, which could be the source of dark matter.
01:45This theory also suggests that dark matter might have its own chemistry,
01:49like dark atoms in a dark periodic table.
01:52For the longest time, scientists believed there was just one type of dark matter.
01:58Although these particles are similar in some ways, like being almost invisible,
02:02they may vary in their sizes, speeds, and how they affect regular matter.
02:08If this idea is right, it means there could have been interactions between our universe
02:13and the dark mirror universe in the past.
02:16Studying how elements formed in the early universe might give us clues about this.
02:22The idea of a flipped world has sparked curiosity and even some confusion in the scientific community in recent years.
02:31Astronomers use a theory called the Lambda-CDM model to explain the composition and behavior of our universe.
02:39According to Witt, most of the universe is made of two things, dark energy and dark matter.
02:45Dark energy is like the pushing force that makes the universe expand faster.
02:51Dark matter is this invisible thread that pulls things together with its gravity, acting like a universal glue.
02:58Regular objects, like stars, planets, and comets, only make up a small part of the mix.
03:05The model also tells us about the Big Bang, and how everything started from a hot, crowded beginning,
03:11and how the universe has been growing and changing ever since.
03:15While this model seems to be correct in many ways, it doesn't explain all cosmic phenomena.
03:21If you were to draw this model on a piece of paper, it would look like a series of flat pancakes stacked on top of one another.
03:31Each one of the pancakes represents a rendition of the universe at a certain point in time.
03:37Yesterday's universe would stand below that of today, but it would be a slightly smaller pancake.
03:42By the end, you'll see that the universe's history looks like this giant upside-down cone, with its minuscule tip being the Big Bang.
03:52Beyond this point, we can't see any further away in time with the tools we have.
03:58So, we don't know what's beyond.
04:00More so, we're still not even sure what happened immediately after the Big Bang.
04:05But, if we simply apply the math, the universe might go beyond this historical tipping point.
04:13Which could mean it could go in reverse, creating a similar mirrored cone where time would flow backwards, in our perspective at least.
04:23This alternative idea not only challenges our understanding of cosmic origins, but also raises questions about fundamental principles in physics.
04:33All the excitement around a mirrored universe also came from ANITA, a scientific instrument stationed in Antarctica and its discoveries.
04:43This device saw some weird high-energy particles seemingly bursting from beneath the Antarctic ice.
04:50The problem with these particles is that they didn't behave as the laws of physics dictate.
04:56Scientists think they have a type of cosmic rays.
04:59They travel from space, through the Earth, and back out again.
05:04But the particles we already know about shouldn't behave like that.
05:09That's because higher-energy particles usually collide with something inside the Earth and don't come out the other side like these do.
05:17They seem to be doing things both forward and backward.
05:21For now, there's no concrete proof of a mirrored universe.
05:25These particles could simply be ones we haven't discovered before.
05:29And scientists need to study them closely to come up with a definitive answer as to why they're behaving like this.
05:36Kind of like four-year-olds.
05:39But what if there isn't just one other universe, but many more?
05:44This multiverse concept comes from ideas like the inflation theory,
05:49which says that our world had this rapid expansion in its early stages.
05:53While inflation stopped in our neighborhood billions of years ago,
05:58it's likely that it continues in other regions of the multiverse,
06:02creating different universes with their own laws of physics and unique characteristics.
06:08Our universe is the only one that we know of that can support life.
06:12We have stable stars that can provide heat and warmth, for example,
06:17which is crucial for creatures to start moving around.
06:20We also have an abundance of elements, like carbon and hydrogen, which we also need to exist.
06:27The multiverse hypothesis gives an explanation for why our universe exhibits such life-friendly conditions.
06:34It may explain that there are countless other universes out there,
06:39with varying conditions, making the existence of life in at least one of them less likely.
06:45One fascinating implication of the multiverse theory is the idea of doppelgangers,
06:52these exact copies of individuals existing in parallel universes.
06:56This notion suggests that within the vast expanse of the multiverse,
07:01there could be infinite scenarios where identical versions of ourselves
07:06are experiencing similar events at the same time.
07:09Before we begin our travels to different universes altogether,
07:14we might need to understand our own.
07:17There's this galaxy, for instance, far from us, that might have no dark matter at all.
07:23It's about 250 million light-years away and looks normal at first glance.
07:29But if we look closer, we can't seem to find any dark matter.
07:33If it turns out that there are more galaxies like this one,
07:37it could change our ideas about how galaxies are made.
07:42Dark matter is usually thought to be necessary for this process,
07:46acting like the glue that holds the whole thing together.
07:49It is true, however, that this particular galaxy is more faint and has fewer stars than usual.
07:55When it was first discovered in 2019,
08:00scientists thought it might not have dark matter because of how fast it was spinning.
08:06The speed at which a galaxy spins tells us how much stuff there is in it.
08:11By comparing this speed with what we can see,
08:14astronomers can figure out how much extra stuff, like dark matter, must be there.
08:20And in this unique galaxy, the math says there isn't any.
08:24Among all these theories, there's also one that says dark matter might not be real at all.
08:32This new study proposes that maybe we've been looking for something that doesn't even exist.
08:38They think that our understanding of gravity might not be good enough
08:42to explain why some galaxies behave oddly.
08:45So instead of dark matter causing these weird behaviors,
08:49they say it might just be that we don't fully understand
08:53how regular matter works.
08:55They base these findings on a theory called modified Newtonian dynamics.
09:01It suggests that gravity behaves differently
09:03at very large distances or very low speeds.
