0:03 13.8 billion years
0:05 ago what we know as our universe
0:09 began with the hot big
0:13 bang the universe was extremely hot and
0:16 dense yet it was also expanding and
0:19 cooling it was made up of matter
0:22 antimatter and
0:24 radiation the volume of our observable
0:27 universe has grown to 46 billion light
0:30 years in radius by now and the limit of
0:34 what we can measure corresponds to the
0:36 light that is currently reaching our
0:40 eyes even while that distance is huge
0:43 it's not infinitely large it's merely
0:46 the limits of what we can
0:48 observe what lies beyond that what about
0:51 the unobservable
0:53 universe is it possible to determine
0:56 whether the universe we live in is
0:58 limited or infinite that is whether
1:01 there is an end to what we refer to as
1:04 the
1:05 universe or whether it is infinite
1:08 beyond our measurements and
1:11 knowledge in this documentary we embark
1:14 on a journey beyond the known delving
1:17 into Realms of theoretical physics
1:20 mindbending Concepts and the mysteries
1:23 of what might exist beyond our Cosmic
1:26 doorstep
1:39 to answer the question of what's outside
1:41 the universe we first need to understand
1:43 exactly what we mean by
1:47 Universe have you ever wondered how vast
1:50 the universe is when gazing up at the
1:53 night
1:54 sky what if I told you that it is so big
1:57 that we are unable to see it all
2:01 the observable universe is the region
2:03 that is visible to
2:05 us we are positioned exactly in the
2:08 center of what appears to be a massive
2:11 Cosmic
2:12 bubble let's dive into the fascinating
2:15 world of the observable universe and see
2:17 just how big it
2:20 is if you were to step outside right now
2:23 you'd only be able to see so far
2:26 horizontally your vision would
2:28 eventually reach the horizon Beyond
2:30 which you would be unable to see much
2:34 you're aware however that life exists
2:37 Beyond the
2:38 Horizon there is more on this planet
2:41 than what you can
2:43 see furthermore as you look
2:46 360° around you it appears as though you
2:49 are at the center of the world even
2:51 though you know that isn't actually the
2:54 case that is how it appears from any
2:57 point on
2:58 Earth in in the same manner our view of
3:01 the universe is limited to what is
3:04 visible to us on Earth and it is
3:07 probably infinite in
3:09 size we can see only as far as our
3:11 Cosmic light
3:13 Horizon because we are unable to see the
3:16 entire universe it may appear to us that
3:19 we are the center of the universe but
3:21 this is only an
3:23 illusion light which travels at a fast
3:26 but finite speed has simply not reached
3:29 us from more distant parts of the entire
3:32 universe the entire universe and the
3:35 observable universe are therefore very
3:37 different from one another all that we
3:39 have seen or been able to see up to this
3:42 point is the observable universe on the
3:45 other hand everything that exists has
3:48 existed or will exist is referred to as
3:52 the entire
3:54 universe more specifically the
3:57 observable universe is the region of
4:00 space visible to us from Earth the term
4:04 observable in this context does not mean
4:07 that there is anything to be detected
4:09 nor does it apply to the ability of
4:11 modern technology to detect light or
4:14 other information from an object it
4:17 refers to the physical boundary defined
4:21 by the speed of light there is no signal
4:25 that can move faster than light because
4:27 the signals could not have reached us
4:29 yet
4:30 there is a maximum distance known as the
4:33 particle Horizon Beyond which nothing
4:36 can be
4:38 observed
4:39 astrophysicists sometimes make a
4:41 distinction between the visible and
4:44 observable
4:45 universes the former includes signals
4:48 since the end of the inflationary Epoch
4:50 while the latter includes only signals
4:53 emitted since
4:57 recombination but how distances in space
4:59 are
5:00 measured astronomers use different
5:02 techniques to measure Cosmic
5:05 distances basic trigonometry similar to
5:08 what you studied in high school math
5:09 class can be used for measuring things
5:12 that are quite close such those in our
5:14 solar system and even in our small
5:17 neighborhood of the Milky Way within 100
5:20 light
5:21 years with the help of The Parallax
5:24 method the distance of far away objects
5:26 can be measured or estimated
5:30 when you look at your finger through
5:31 your left eye while closing the right
5:33 eye and then look at your finger through
5:35 your right eye while closing the left
5:38 eye you would notice that the position
5:40 of your finger seems to change with
5:43 respect to the point on the
5:44 wall this is called
5:47 Parallax by measuring this small change
5:50 and knowing the distance between your
5:52 eyes you can calculate the distance to
5:55 your finger that's trigonometry
5:58 [Music]
5:59 when it comes to measuring distances to
6:01 other stars there are no two eyes that
6:05 could do the trick instead the orbit of
6:08 Earth around the Sun provides the
6:10 Baseline for these
6:13 calculations simply if you take a Stars
6:16 position once a year at one point in the
6:17 sky and then again 6 months later you
6:20 will have a relative position of the
6:22 nearby object in relation to the far
6:25 more distant stars in the sky thanks to
6:28 the Pythagorean theorem you can
6:30 determine the distance if you know the
6:32 size of Earth's orbit and the angle of
6:34 light in those two
6:37 measurements nevertheless a star's shift
6:41 decreases with distance making it
6:44 difficult to measure this angle and
6:45 requiring the use of some more advanced
6:47 method for
6:50 measurement once trigonometry is no
6:52 longer a useful technique astronomers
6:55 look for seied stars which are extremely
6:58 bright and common
7:00 Stars these specific stars were first
7:02 identified in
7:04 1794 and have an ability to pulse
7:07 becoming dimmer and brighter in
7:09 predictable
7:10 Cycles surprisingly the longer a seide
7:13 takes to pulse the brighter the star is
7:16 in
7:17 reality similarly the shorter the
7:20 pulsation duration the dimmer the
7:24 seied what's more these pulsations are
7:28 directly related to their abs absolute
7:30 Luminosity which occurs within well-
7:32 defined and predictable time periods
7:35 ranging from 1 to 100
7:39 days just like if you saw candle right
7:41 in front of you and another very far
7:43 away the one closer to you would appear
7:46 much
7:47 brighter and hence the true brightness
7:50 of those Stars can be determined and
7:53 consequently their Distance by measuring
7:56 nearby seides and comparing the length
7:59 of their pulsation period to those of
8:01 those seides that are farther
8:04 away sephi variables can be seen and
8:07 measured to a distance of about 20
8:09 million light years compared to a
8:11 maximum distance of about 65 light years
8:14 for earth-based Parallax measurements
8:16 and just over 3 26 light years for the
8:20 esa's hiparco
8:23 mission they can serve as standard
8:25 distance markers constituting yet
8:27 another crucial step on the mic distance
8:30 ladder even though 20 million light
8:33 years sounds like an enormous distance
8:37 the cosmos is 1,000 times bigger thus we
8:41 need to add another step to the
8:45 ladder this is when Supernova especially
8:49 those from specific binary star systems
8:52 come in rather handy one star in these
8:55 two star systems dies and turns into a
8:58 white dwarf while the other star
9:00 continues to
9:02 exist after that the white dwarf starts
9:05 to consume the surviving star and gets
9:08 bigger until it has roughly 1.4 times
9:11 the mass of the Sun at that moment there
9:14 is a massive explosion that releases
9:16 more energy than entire galaxies and is
9:20 visible over half of the observable
9:23 universe we refer to this as a type 1A
9:28 Supernova a astronomers can determine
9:30 the absolute brightness of the explosion
9:33 and consequently the approximate Cosmic
9:35 distance to those distant galaxies
9:38 because we know how much mass is
9:42 exploding at even greater distances into
9:45 the tens of billions of light years the
9:48 Hubble constant comes into play named
9:51 after Edwin Hubble this is the unit of
9:54 measurement for the expansion of the
9:57 universe this is where the hold
10:00 starts to get a little
10:02 complicated the universe has been
10:04 getting bigger since the Big Bang
10:06 kickstarted the growth some
10:12 [Music]
10:28 13.82% suggests that there is something
10:30 there causing the growth to slow down
10:34 this might be dark matter which is
10:36 invisible to Conventional
10:38 instruments however if the growth
10:41 increases it is possible that dark
10:43 energy is driving the expansion at a
10:45 quicker rate astronomer harlo shapley's
10:49 observation in 1929 suggested that
10:52 galaxies appear to be moving away from
10:54 the Milky
10:55 Way Hubble found that the farther these
10:58 galaxies are from Earth the faster they
11:01 appear to be moving although the
11:04 phenomena was formerly thought to be
11:06 galaxies moving apart astronomers Now
11:09 understand that what is really being
11:10 seen is the universe
11:14 expanding you would observe the same
11:16 occurrence happening at the same speed
11:19 everywhere in the
11:20 universe as better and more sensitive
11:23 telescopes have been used to conduct the
11:25 measurements Hubble's original
11:27 calculations have been finded over the
11:31 years according to observations made
11:34 recently by several telescopes the
11:36 universe is expanding at different rates
11:39 depending on where you
11:41 look the plank telescope measures the
11:44 expansion of the more distant background
11:46 Universe which is expanding at a
11:48 slightly slower rate of 41.6 m/s or 67
11:55 km/s per MEAP Parc compared to the
11:58 Hubble Space Telescope and Gia space
12:02 telescopes which measure the expansion
12:04 of the nearby Universe at 45.6
12:08 m/s 73.5 km/s per megap
12:14 Parc it may be hard to imagine but the
12:17 universe is not only expanding at an
12:19 ever increasing rate in all directions
12:22 at the same time but the space between
12:25 objects in the universe is also
12:28 expanding everything is moving away from
12:30 everything else and it is moving faster
12:33 and faster all the
12:35 time this interobject expansion and
12:39 acceleration is related to dark energy
12:42 which is beyond the topic of this
12:45 discussion therefore the further away
12:48 you look the faster the galaxies are
12:50 moving away from us galaxies that are
12:53 very far away can be measured for
12:55 Distance by measuring their red shift
12:58 which tells us how quickly they are
13:00 moving away from
13:02 us astronomers use red shifts to measure
13:05 the expansion of the universe and
13:08 consequently the distance to the oldest
13:10 and most distant objects in our
13:13 universe but what is a red
13:17 shift it is often compared to the
13:20 high-pitch sound of an approaching
13:23 ambulance siren that becomes lower as it
13:26 passes by and eventually goes away from
13:28 you
13:29 the reason behind the change in an
13:31 ambulance's sound is the phenomenon
13:34 known as the Doppler
13:36 effect it's an excellent comparison
13:39 because waves which are affected by
13:41 their motion through space and Air carry
13:45 both sound and
13:47 light sound travels through the air at a
13:51 maximum speed of 750 mph or 1,200
13:57 kmph the sound waves in front of an
14:00 ambulance get compressed as it rushes
14:02 forward and blares its siren the sound
14:05 waves behind the ambulance meanwhile
14:08 begin to
14:09 spread this means the frequency of the
14:11 sound waves is higher ahead of the
14:13 ambulance means more sound waves will
14:16 strike a listener's ear over a set
14:18 amount of time and lower behind it means
14:22 fewer sound waves will strike a
14:24 listener's ear over a set amount of
14:27 time pitch shifts are interpreted by our
14:30 brains as variations in the frequency of
14:33 sound
14:34 waves similar to sound light is a wave
14:39 that moves at a fixed speed of
14:42 186,000 m/s or 300,000
14:46 km/s or around 1 billion km/
14:50 hour thus light follows the same rules
14:54 as
14:55 sound galaxies are as We Know moving
14:59 away from us similar to how an inflated
15:02 balloon would cause a wave created on
15:04 its fabric to be stretched the wave
15:07 length of light is stretched when
15:09 galaxies move away from us through the
15:12 use of a prism or a comparable telescope
15:15 suitable instrument like defraction
15:17 gratings we can see an array of
15:19 absorption lines from elements like
15:22 sodium hydrogen and so on all those
15:26 absorption lines however experience a
15:29 Doppler shift and go toward the red
15:32 portion of the spectrum if that Galaxy
15:34 is speeding away from
15:36 us we refer to this as a red shift the
15:40 opposite occurs for Galaxies that are
15:43 moving toward us they are blue
15:46 shifted astronomers usually only use the
15:49 phrase red shift to make things simpler
15:53 if a blue shift is occurring they simply
15:55 place a negative sign in front of it
15:59 a Galaxy's red shift increases with
16:02 Galaxy distance from Earth as a result
16:05 the red shift of a Galaxy at the cosmic
16:07 light Horizon the outer end of our
16:10 observable universe is nearly infinite
16:14 this indicates that the light coming
16:16 from that distant galaxy has very little
16:18 energy which is why we can hardly see
16:21 those galaxies with the visible light
16:24 spectrum when Hubble looked at the light
16:27 from distant galaxies through a prism
16:29 he observed a red shift away from known
16:32 variable for the
16:34 color Hubble discovered that nearly all
16:37 of the galaxies he examined had this red
16:39 shift which indicates that they were
16:41 traveling away from us extremely far
16:44 Galaxy's distances could be determined
16:47 with a fair degree of accuracy by
16:49 plotting various red shifts and known
16:51 distances on a graph
16:54 [Music]
16:59 this is the last measuring tool and
17:02 serves basically as the universe's
17:04 Baseline for
17:06 distances the remaining radiation from
17:08 The Big Bang or the moment the universe
17:10 first began is known as the cosmic
17:13 microwave background according to Theory
17:17 the cosmos experienced rapid cooling
17:19 expansion and inflation during its birth
17:24 the heat left over after the big bang is
17:27 represented by the cosmic microwave
17:30 background the cosmic microwave
17:32 background is present across the cosmos
17:35 yet is invisible to the uned eye because
17:38 it is so cold just 2.72 5° above
17:42 absolute zero or -
17:46 273.15 de C it is invisible to
17:51 humans this indicates that the
17:53 electromagnetic spectrum's microwave
17:56 region is where its radiation is most
17:59 noticeable the cosmic microwave
18:01 background goes back to some 400,000
18:04 years after the big bang and as we all
18:07 know the universe started 13.8 billion
18:10 years
18:11 ago this is due to the fact that the
18:13 universe's temperature was extremely
18:15 high in its early phases when it was
18:18 just a 100 millionth of what it is
18:20 today any atoms that were there at the
18:23 moment broke rapidly into protons and
18:26 electrons which are tiny particles
18:29 the electrons scattered the CMB
18:32 radiation in the form of photons which
18:34 are particles that represent light
18:36 Quantum States or other types of
18:39 radiation in the same way as Optical
18:41 light wanders through thick fog photons
18:45 also traveled around the early
18:47 Universe the universe was cool enough
18:49 for hydrogen to form some
18:52 38,000 years after the big bang the CMB
18:57 photons move move in straight lines
19:00 because collisions with hydrogen hardly
19:02 affect them the point at which CMB
19:06 photons last collided with matter is
19:08 known as the surface of last
19:11 scattering beyond that point the
19:14 universe was too
19:16 big this means that when we map The
19:19 Cosmic microwave background we are
19:21 gazing back in time to 380,000 years
19:25 following the Big Bang right after the
19:28 the radiation opaque
19:30 Universe in 1948 American cosmologist
19:34 Ralph aper made the first prediction
19:37 about the CMB while collaborating with
19:40 Robert Herman and George gamoo the group
19:43 study focused on Big Bang
19:46 nucleosynthesis or the synthesis of
19:48 elements other than the lightest
19:50 hydrogen isotope type in the
19:53 universe this kind of hydrogen was
19:56 produced very early in the history of
19:57 the universe
19:59 but the discovery of the CMB was
20:02 accidental Aro penus and Robert Wilson
20:05 two Bell Telephone Laboratories
20:07 researchers were developing a radio
20:09 receiver in
20:11 1965 and were perplexed by the noise it
20:13 was taking up they quickly discovered
20:17 that the noise originated from every
20:19 direction in the sky in the empty space
20:22 between Stars this radiation is the
20:25 oldest and furthest radiation yet found
20:29 this essentially means that the furthest
20:32 back in time we can see is 13.8 billion
20:36 years because it has taken 13.8 billion
20:40 years for light while moving at the
20:42 speed of light to reach
20:44 us therefore the observable universe has
20:48 a radius of 13.8 billion light
20:52 years furthermore no matter which way we
20:55 look the light we see has only been
20:57 traveling for a maxim maximum of 13.8
21:00 billion years because the universe is
21:03 only around 13.8 billion years old and
21:07 light takes time to travel through
21:11 space given this one would naturally
21:14 assume that the observable universe
21:17 would be 2 * 13.8 light years
21:21 across however this is not
21:23 correct that's because space has been
21:26 expanding over time pushing the far off
21:29 objects that released that light 13.8
21:33 billion years ago even further away from
21:37 us recall the Hubble constant and how it
21:41 was used to measure the universe's
21:44 expansion the universe has been
21:46 expanding over the 13.8 billion years
21:50 that the light from the CMB has been
21:52 moving toward our eyes pushing the edge
21:55 of the known universe farther out even
21:58 though humans aren't technically able to
22:00 see that
22:01 far the current location of the photon's
22:04 origin as determined by the Hubble
22:06 constant is an astounding 46 billion
22:09 light years away thus the observable
22:13 universe's diameter calculated by
22:15 multiplying by two is thus 93 billion
22:19 light
22:21 years clearly calculating distances of
22:24 this magnitude can bend the brain Beyond
22:28 The Realm of human
22:30 comprehension fortunately with the
22:32 cosmic distance ladder in place and
22:35 plenty of astronomers well vered in
22:36 these types of measurements we're able
22:39 to keep tabs on how the universe is
22:41 moving as well as our place within
22:47 it upon totaling all the galaxies in
22:50 this region of space we would discover
22:53 that our observable universe contains an
22:56 astounding two trillion of them
23:00 you may think that there would be no
23:02 upper limit to the amount of the
23:04 universe that could be seen if we waited
23:06 an arbitrarily long amount of time and
23:09 that we could see an arbitrarily vast
23:13 distance but in a universe with dark
23:15 energy that simply isn't the
23:19 case dark energy is expanding the fabric
23:22 of space at such a rate that gnz11 the
23:26 high redshift Galaxy is moving away from
23:29 us at an estimated speed of
23:37 426,000
23:39 km/s over twice the speed of
23:42 light further off objects will appear to
23:45 gradually disappear from our perspective
23:47 as time passes in a universe powered by
23:50 dark energy there's always more to
23:53 discover in the universe but the amount
23:55 that can ever be observed by humans is
23:59 finite we can determine what we refer to
24:02 as the future visibility limit or the
24:05 farthest distance humans will ever be
24:07 able to observe based on the rate of
24:10 expansion the amount of dark energy we
24:13 have and the current cosmological
24:15 parameters of the
24:18 universe our current Vision limit is 46
24:21 billion light years in a universe that
24:23 is 13.8 billion years old our maximum
24:27 visibility in the future will be around
24:29 33% larger at 61 billion light
24:34 years there are currently galaxies out
24:37 there whose light is headed toward our
24:39 eyes but hasn't had a chance to reach us
24:41 yet there are more galaxies yet to be
24:44 discovered than there are in the visible
24:47 Universe which might surprise us if we
24:50 were to add up all the galaxies in the
24:52 regions of the universe that we will one
24:54 day see but are not able to access now
24:58 [Music]
25:00 in addition to the two trillion galaxies
25:02 that are currently visible to us there
25:04 are an additional 2.7 trillion galaxies
25:08 just waiting for us to
25:10 see our measurements of these
25:12 occurrences would indicate if the
25:13 universe had a finite size and Edge or
25:17 if its properties started to change as
25:19 we peered to higher
25:22 distances the unobservable universe is
25:25 at least 250 times as as large as the
25:29 presently visible
25:31 part we'll never be able to observe
25:34 anything approaching those great
25:36 distances we will be able to see objects
25:38 up to 61 billion light years away from
25:41 us in the future but no
25:44 further it will reveal slightly over
25:47 twice the amount of the universe that is
25:50 currently visible to us in contrast the
25:54 unobservable universe has to have a
25:56 diameter of at least 23 trillion light
26:00 years and include a volume of space that
26:03 is more than 15 million times larger
26:06 than what is visible to people here on
26:10 Earth but when we consider the universe
26:13 beyond our current limit for observation
26:16 it's important to keep in mind just how
26:19 little of that Universe we can truly
26:21 reach or
26:23 explore everything we can't wait to see
26:25 depends on light that was already
26:27 released billions of years ago precisely
26:30 at the time of the Big
26:33 Bang as things stand right now humans
26:36 could not possibly reach almost all of
26:38 the galaxies in space even if we fled at
26:41 the speed of light not only is the
26:44 universe expanding but distant galaxies
26:47 appear to be moving from us faster due
26:50 to Dark
26:51 Energy the limit of what we can observe
26:54 today is far smaller than the 4.7
26:57 trillion galaxies that we will
26:59 eventually be able to observe out to a
27:01 distance of 61 billion light
27:05 years to put it another way there will
27:08 be 4.7 trillion Galaxies for us to view
27:11 in the
27:12 future not many of them will ever see us
27:15 as we are now and most of them will only
27:17 ever see us as they were in the very
27:20 distant
27:22 past of all those galaxies we'll someday
27:24 see 4.63 4 trillion of the galaxies are
27:29 currently unreachable even traveling at
27:32 the speed of
27:34 light someday far in the future it will
27:38 arrive at our
27:39 eyes as time passes and the light from
27:42 the final Galactic holdouts continues on
27:44 its inevitable Journey towards us in the
27:47 expanding Universe we get closer and
27:50 closer to our ultimate Cosmic
27:54 Viewpoint all of that contributes to our
27:56 understanding of the night sky
27:59 Darkness the expanding universe theory
28:02 also contributes to the understanding of
28:04 why our night sky is dark and how it
28:07 relates to the observable
28:13 universe now what about the center of
28:15 the
28:17 universe we are the center of the
28:20 observable universe after all since the
28:23 observable universe is limited to the
28:25 space that is visible from Earth we are
28:29 in the center of it and kind of like how
28:31 the view from a very tall tower is a
28:34 circle centered on the tower the piece
28:36 of space we can see from here is
28:38 naturally centered here to be more exact
28:42 each of us is the center of our own
28:45 observable universe but that does not
28:47 imply that we are the center of the
28:49 universe as a whole just as the tower is
28:52 not the center of the earth up to the
28:54 Horizon it is the center of the portion
28:57 of the world that it can view that
28:59 doesn't mean there isn't anything there
29:01 though simply because you can't see past
29:03 the
29:04 Horizon similarly the observable Cosmos
29:08 is no
29:09 different gazing up at the sky we
29:12 observe light coming from matter that is
29:15 currently 46 billion light years away
29:19 and with a maximum age of 13.8 billion
29:23 years but beyond that there ought to be
29:25 much more universe beyond the limits of
29:28 what we can presently see the
29:30 unobservable universe our field of view
29:34 into the universe is expanding
29:36 exponentially all we need to do is watch
29:39 and wait for the universe to age and
29:42 light from farther away to reach
29:46 us despite all of the techniques of
29:48 measurement the universe's true size
29:51 remains
29:52 uncertain it might be infinite and
29:55 portions of it remain outside the
29:56 observable universe because they are too
29:59 far away for Earth or our equipment to
30:02 have received any of the light emitted
30:04 since the Big
30:06 Bang although detailed maps of the
30:08 universe's oldest light have been made
30:10 possible by the European space agency's
30:13 plank Space Project the size of the
30:16 cosmos is still far beyond our
30:20 understanding according to inflation
30:22 Theory the universe may be infinite and
30:25 the visible universe is only a small
30:27 portion of it the size of the universe
30:30 is also determined by its shape which
30:33 can be anything from a closed sphere to
30:36 an endless flat
30:39 surface the theory of general relativity
30:42 under which space itself can curve
30:45 allows for the universe to take one of
30:47 three forms flat like a sheet of paper
30:51 closed like a sphere or open like a
30:55 saddle the fate of the universe dep
30:58 depends on this Cosmic
30:59 geometry the universe's shape provides
31:03 information about both its past and
31:06 future for example it can reveal whether
31:09 the universe is infinite or finite and
31:12 whether it will continue to expand
31:14 indefinitely Or finally
31:17 collapse for a matter that bears on such
31:19 Grand questions its components are
31:22 remarkably simple the density and the
31:25 rate of expansion of the universe are
31:28 the only two parameters that determine
31:30 its final
31:32 structure Dark Energy makes up about 68%
31:36 of the universe whereas Dark Matter
31:39 makes up
31:41 27% planets stars and other bodies are
31:45 comprised of normal matter which makes
31:47 up the remaining
31:50 portion the amount of matter contained
31:52 in a specific volume of space is
31:55 referred to as the universe's density
31:58 the universe can curl into a ball if its
32:01 density is high enough to overcome the
32:04 force of expansion through
32:07 gravity this is referred to as the
32:10 closed model because of its sphere-like
32:12 positive
32:14 curvature a mindboggling property of
32:17 this universe is that it is finite yet
32:20 it has no
32:22 bounds however space will warp in the
32:24 opposite direction if the universe has a
32:27 low it and is unable to stop
32:30 expanding this would create an open
32:33 Universe with a saddle like negative
32:36 curvature the most likely possibility
32:39 for the universe according to scientists
32:41 is the goldilock
32:43 scenario the majority of cosmological
32:45 data suggests that the Universe extends
32:48 in all directions without curving
32:51 positively or negatively and that its
32:54 density is around six protons per 1 3
32:58 cubic
32:59 yards to put it another way the universe
33:02 is flat perhaps this will come as some
33:06 consolation to anyone disappointed by
33:09 our planet's
33:10 roundness current observations and
33:12 measurements of the curvature of the
33:14 universe also indicate that it is almost
33:17 perfectly
33:18 flat this may lead one to believe that
33:21 the cosmos is infinite however it's not
33:24 that easy it is not necessary for the
33:27 Universe to be infinitely big even in
33:30 the scenario where it is
33:32 flat consider the surface of a cylinder
33:35 for example it is geometrically flat
33:38 because parallel lines drawn on the
33:40 surface remain parallel that's one of
33:43 the definitions of
33:44 flatness and yet it has a finite
33:49 size the same could be true of the
33:51 universe it could be completely flat yet
33:55 closed in on itself
33:59 still what does a flat universe mean
34:02 although this flatness isn't the typical
34:04 two-dimensional kind we see in daily
34:06 life there are a few examples that can
34:08 help you picture
34:10 it imagine yourself in a square room
34:13 standing at one corner turn 90° after
34:17 moving 10 ft along the wall to the next
34:19 Corner take 10 more steps and make
34:22 another 90° rotation once you finish two
34:25 more of these you will find yourself
34:27 self back at the beginning of the
34:30 square we all studied ordinary ukian
34:33 geometry in high school and adding one
34:36 additional Dimension results in a flat
34:39 universe however the results would be
34:42 different if this experiment were
34:44 carried out on a positively curved space
34:47 which is a representation of a closed
34:50 Universe in the closed World example
34:53 returning to the starting point required
34:55 only three turns however in the flat
34:58 universe example it required four in
35:02 case you're still not clear here's
35:03 another illustration two rockets
35:06 traveling close to one another in a flat
35:08 universe will always remain parallel
35:12 this is unlike a closed Universe in
35:14 which the paths of these two rockets
35:16 will diverge Trek along the curvature of
35:19 space and eventually loop around to meet
35:22 where they started in an open Universe
35:25 with a negative curvature the Rockets
35:28 will separate and never cross paths
35:32 again the cosmic microwave background or
35:36 the Afterglow of the big bang that
35:38 radiates toward us from all directions
35:41 contains the best hints about the
35:43 structure of the
35:45 universe scientists have been measuring
35:47 temperature variations in the CMB for
35:50 several decades effectively doing
35:53 trigonometry at the greatest scale
35:55 imaginable and have found nearly no
35:57 curve curvature at all a flat universe
36:00 is a key piece of the standard
36:02 cosmological model also known as the
36:04 Lambda cold Dark Matter lcdm model
36:09 Lambda is the Greek letter for Lambda
36:12 denoting Dark Energy additional evidence
36:15 for flatness comes from Barian acoustic
36:18 oscillations which are the traces of
36:20 primordial sound waves left on Galaxies
36:24 after the big
36:26 bang as we continue to explore and map
36:29 the cosmos the universe's immensity
36:31 serves as a humbling reminder of our
36:33 place within it the actual size of the
36:37 universe may remain one of science's
36:39 greatest Mysteries even though we may
36:41 get closer to making more prise
36:46 measurements let's make a comparison
36:49 between the observable universe's size
36:52 and some more recognizable things the
36:55 observable universe is so big
36:58 that it could fit around one septian
37:00 Earths a one followed by 24 zeros inside
37:03 of it that is equivalent to more Earths
37:07 than there are sand grains on all of the
37:09 world's
37:10 beaches one would assume that the
37:12 observable universe must be densely
37:14 packed with matter given its vast size
37:19 well and it
37:20 isn't the observable universe is thought
37:23 to contain several hundred billion
37:25 galaxies
37:27 there are billions or possibly trillions
37:29 of stars in each of these
37:32 galaxies in reality however the majority
37:35 of the observable universe is empty
37:38 space the likelihood is that if you
37:41 choose a random location in the
37:43 observable universe you will end up in
37:45 empty space rather than close to a star
37:48 or
37:50 Galaxy we are actually looking back in
37:52 time when we gaze far into the
37:55 observable universe because light takes
37:58 time to
38:00 travel the length of time it takes for
38:02 light from a star or Galaxy to reach us
38:06 increases with its distance from us
38:10 therefore the observable universe is not
38:12 only a location but also a cosmic
38:15 history
38:18 book just because we can't see things
38:21 beyond our fiery Horizon it doesn't mean
38:24 that there's nothing there
38:32 as if the mysteries of dark matter and
38:34 dark energy weren't vexing enough
38:37 another baffling Cosmic puzzle has been
38:40 discovered whole galaxy clusters have
38:42 been observed to be traveling in sync
38:45 toward a single Sky Point by
38:48 astronomers the researchers even
38:50 speculate that a force beyond the
38:52 observable world may be to blame for
38:56 this unexpected motion
38:58 which doesn't seem to be related to the
39:00 universe's
39:02 expansion the finding has been named
39:05 dark
39:06 flow according to astronomers there may
39:09 be dark flow or unobservable external
39:12 forces originating from vast structures
39:15 outside of our universe that we are now
39:18 unable to fully understand studying
39:21 massive clusters of galaxies among of
39:23 the biggest structures in the universe
39:26 scientists found the flow these clusters
39:29 are made up of thousands of galaxies
39:31 grouped together with extremely hot gas
39:34 that produces
39:36 x-rays scientists investigated the
39:39 motion of clusters by analyzing how
39:41 x-rays interact with the cosmic
39:43 microwave background which is leftover
39:46 radiation from The Big
39:49 Bang the cnb's temperature is changed by
39:52 the x-rays scattering photons a
39:54 phenomenon called sunv Zelda
39:57 effect a team of scientists led by
40:01 astrophysicist Alexander kashlinsky of
40:03 NASA's Godard space flight center in
40:06 greenb Belt Maryland discovered this
40:08 effect after studying a massive catalog
40:12 of 700 clusters that were as far apart
40:16 as 6 billion light years or half of the
40:21 universe this effect had not previously
40:23 been observed as a result of Galaxy
40:26 clusters they compared this list with
40:29 the Wilkinson microwave anisotropy probe
40:31 satellite map of the CMB from NASA they
40:35 found that the Clusters were traveling
40:37 in the direction of an area in the sky
40:40 between the constellations of v and
40:42 Centaurus at around 2 million mph or 3.2
40:47 million km hour this velocity is not the
40:50 same as the universe's outer expansion
40:54 which is accelerated by a force known as
40:57 Dark
40:58 Energy scientists discovered a very
41:00 significant velocity and this velocity
41:03 does not decrease with distance the flow
41:06 that astronomers detect simply cannot be
41:09 produced by matter in the observable
41:12 universe scientists concluded that
41:14 whatever is causing the Clusters to move
41:17 around must exist outside of our
41:20 observable
41:22 universe while inflation theory predicts
41:24 many strange aspects of the far off
41:26 universe few scientists were able to
41:29 predict the dark
41:31 flow dark flow structures might be a
41:34 component of an unknown higher
41:36 dimensional
41:42 creation surely you're wondering whether
41:45 things can get any stranger at this
41:47 point well the next potential theory is
41:50 based on the physics of the very very
41:53 early Universe right back during the Big
41:55 Bang
41:58 our universe resembles a bubble Beyond
42:01 it other bubble universes can be found
42:04 all submerged in the
42:07 Multiverse an endlessly energizing
42:11 sea the concept of a Multiverse which
42:14 consists of Worlds similar to our own
42:17 but with some subtle differences
42:19 originates from two places in
42:22 theoretical
42:24 physics one comes from our understanding
42:26 of many branching possibilities in
42:29 subatomic experiments through the lens
42:32 of quantum mechanics the other is a
42:35 little more concrete coming from our
42:37 theories of the extremely early
42:41 Universe however we must begin with the
42:44 universe in order to reach the
42:46 Multiverse the universe is all the
42:49 things by definition it is the whole of
42:53 all physical reality if it's a thing
42:56 it's in the
42:58 universe however we can begin to open
43:01 the door to other worlds even with that
43:04 definition realizing that light can only
43:07 move at a finite pace and that the
43:09 universe is only a certain age is one
43:12 approach to do
43:14 that as we've already covered our
43:17 ability to witness the universe is
43:18 limited but that explanation gives you a
43:21 very weak understanding of the
43:24 Multiverse actually there's more to the
43:26 universe than what we can observe so
43:28 there's more stuff out there more stars
43:32 more galaxies maybe even more
43:34 intelligent creatures than we could ever
43:37 make contact with all of these things
43:40 are in the universe but are definitely
43:42 not a part of our own world those
43:45 regions outside our observable bubble of
43:47 the universe still look and act the same
43:50 as inside it it's all the same physics
43:53 at play just with various other
43:55 combinations but but that's not where
43:57 the story has to
43:58 [Music]
44:06 end as of right now our knowledge of the
44:09 big Bang's earliest moments is
44:12 limited we are aware of the basic
44:15 picture our universe used to be much
44:18 smaller and hotter today it is
44:21 considerably
44:23 colder we've also put this fundamental
44:26 Theory to the test using a range of
44:29 studies however when we go all the way
44:32 back to the Big Bang we get to a point
44:35 when our understanding of physics
44:37 fails the conditions in the universe
44:40 when it was younger than a second old
44:42 were so extreme that there isn't a
44:44 single physics theory that can help
44:47 us nevertheless we believe that the
44:50 cosmos experienced inflation an extreme
44:54 transformation in its early stages
44:57 it appears from all available evidence
45:00 that when our Cosmos was only a fraction
45:02 of a second old it rapidly expanded to
45:05 enormous proportions growing by at least
45:07 a factor of 10 to the
45:10 60 the rest of the big bang when our
45:13 universe was saturated with particles
45:15 and radiation and gave rise to stars
45:18 planets and galaxies was set in motion
45:22 by this inflationary event this is where
45:25 the Multiverse comes into play
45:28 perhaps inflation never
45:30 stopped perhaps the universe is
45:33 expanding at an uncontrollably fast rate
45:35 all the time but some of it splits off
45:39 and becomes calmer th what we call the
45:42 universe is just a tiny bubble of the
45:45 true ever inflating ever expanding huge
45:51 universe according to this theory of
45:53 inflation the universe is always
45:56 expanding it just never stops expanding
45:58 at a rate that is faster than the speed
46:01 of light a region simply slows down and
46:05 pinches off due to a random Quantum
46:09 fluctuation the rest of the world
46:10 outside of our bubble keeps doing what
46:13 it normally does and just so happens to
46:16 have stopped randomly while our patch or
46:19 bubble of the universe has simply
46:21 happened to stop expanding compared to
46:23 the larger
46:25 universe our patch is not alone
46:28 different patches can also randomly
46:31 settle down and become a normal calmly
46:34 expanding
46:35 Universe to observers in any of those
46:38 patches the universe will appear to them
46:40 as having a big bang in the past a
46:43 universe full of matter and radiation
46:46 and an observation limit just like it
46:48 does to
46:50 us these patches or bubbles appear to be
46:54 individual universes in this scenario of
46:57 endless inflation divided from one
46:59 another by a continuously growing
47:02 expanse of absolutely
47:07 nothing this Multiverse a collection of
47:10 independent distinct universes full of
47:12 creatures stars planets people each
47:16 doing their own thing is physically
47:18 driven and potentially very real in the
47:22 Multiverse our universe is not the first
47:25 bubble to arise but merely one of an
47:27 infinite chain of
47:29 universes picture a massive foam like to
47:32 the surface of a bubble bath the
47:35 Multiverse is the foam itself always
47:37 expanding and forming new bubbles Each
47:40 of which functions as a separate
47:42 Universe unto
47:44 itself each of these bubble universes
47:47 exists inside the same SpaceTime
47:50 structure if you point your finger in
47:52 any random way there is another world
47:55 out there past some unfathomably great
47:58 distance and beyond that another and
48:01 still
48:03 another there are an endless number of
48:05 worlds in the Multiverse if this type of
48:07 inflation really never
48:10 ends while it is possible that all of
48:12 those universes ended their local
48:14 inflation in the same way it is also
48:17 plausible that as each Universe pinched
48:19 off it got a brand new set of physics to
48:23 go along with it with different
48:25 collections of forces and
48:28 particles some of those universes would
48:30 look incredibly similar to our own
48:34 others may have failed full of nothing
48:37 but
48:38 void some may be far stranger than we
48:41 can possibly imagine and some might be
48:44 our exact
48:45 clones if and this is a big if there are
48:49 only a finite number of ways to arrange
48:52 all the particles in a given Universe
48:54 then with an infinite number of
48:56 universes you're bound to get repeated
48:59 copies this implies that not only is
49:02 there another Universe out there in a
49:04 random Direction but if you travel far
49:06 enough along that line you will run into
49:09 a duplicate of yourself doing exactly
49:12 the same thing that you are doing at
49:14 this very moment this is all pretty wild
49:17 but difficult to test the issue is that
49:21 there is no way for any of the
49:23 multiverses bubbles to interact with one
49:26 another although they are unrelated they
49:29 do exist therefore we are unable to
49:32 Simply hop in a rocket and travel to our
49:35 closest
49:36 neighbor however there might have been a
49:39 few Cosmic mishaps in our ancient past
49:42 our universe had recently separated from
49:45 the greater inflation driven flow when
49:47 it was
49:48 younger a small possibility exists that
49:51 our universes momentarily overlapped
49:54 before being irreversibly forced apart
49:57 if another bubble Universe just happened
50:00 to form close to ours that offers a way
50:03 of testing the Multiverse because the
50:05 likelihood of it occurring is extremely
50:08 low yet not zero sadly there are yet no
50:12 signs from observations of The Wider
50:15 Universe suggesting that we have been
50:17 involved in a collision of this kind
50:20 those experiments don't exactly support
50:22 the Multiverse Theory but they also
50:25 don't rule it out either NE all we have
50:28 left is our theoretical understanding of
50:30 the early Universe which is based on
50:33 theories rather than actual
50:35 knowledge our understanding of inflation
50:38 is quite limited we do not know what
50:40 caused it why it had the energy it did
50:44 or why it ended in our
50:46 universe we're not even sure if
50:48 inflation inevitably results in a
50:51 Multiverse or if our own calculations
50:53 are incorrect
50:57 [Music]
51:00 another such enduring Enigma is the
51:02 concept of the Eternal recurrence or the
51:05 cosmic
51:06 cycle the idea that the Universe has
51:09 been and will continue to be reborn in a
51:12 NeverEnding
51:14 cycle although this idea has its origins
51:17 in ancient religions and ideologies it
51:19 is also present in modern
51:22 cosmology it dates back thousands of
51:24 years to the time of ancient Egyptian
51:27 Greek and Indian
51:29 civilizations the cosmic cycle was a
51:32 deeply religious and philosophical idea
51:35 among many cultures in addition to being
51:38 a cosmological concept the concept that
51:41 the universe is cyclical was frequently
51:44 used to explain how life and death
51:47 growth and Decay and other natural
51:50 cycles affect life on Earth for example
51:54 the universe was thought to go through
51:56 recur during cycles of creation and
51:58 destruction in ancient Egyptian
52:00 mythology each lasting a certain amount
52:03 of
52:04 time similar cycles of creation
52:07 preservation and dissolution known as
52:10 the kalpa are seen in Hindu cosmology it
52:14 is thought that this cycle never ends
52:16 and that a kalpa lasts billions of
52:19 years among the most interesting
52:21 features of cosmic Cycles is the
52:24 possibility that a recurring pattern
52:27 exists in universe
52:29 itself over time a number of cyclic
52:33 models have been developed including the
52:35 oscillating universe
52:37 theory a cosmological concept known as
52:40 the oscillating universe theory combines
52:43 the big bang and the Big Crunch into a
52:46 single cyclical event that is if this
52:49 Theory holds true then the universe in
52:51 which we live in exists between a big
52:54 bang and a big crunch
52:57 according to the Big Crunch Theory the
52:59 universe will eventually stop expanding
53:02 it will then start to shrink the
53:04 universe will get hotter as it gets
53:07 smaller this can be viewed as the
53:09 opposite of the Big Bang the universe
53:11 will contract and get hotter rather than
53:14 expanding and cooling everything in the
53:17 universe will eventually collapse into a
53:20 single small spot where it all
53:24 started the idea was that each big
53:27 crunch would be followed by a new Big
53:29 Bang tracing an endless accordion of
53:32 expansions and
53:35 contractions this description would only
53:37 mean one thing all the laws of physics
53:40 will be thrown out of the window for
53:43 physicists this is simply
53:46 unacceptable to worsen the situation
53:49 some cosmologists even hold that the
53:51 universe will eventually collapse in on
53:53 itself after reaching its greatest peak
53:56 of
53:57 expansion this will essentially lead to
54:00 the same conditions as when we
54:02 extrapolate back to the moment of the
54:04 Big
54:05 Bang in order to solve this mystery some
54:08 scientists are suggesting that maybe the
54:11 universe won't reach the singularity
54:13 after
54:15 all the universe will instead return to
54:18 an expanding State due to repulsive
54:21 forces brought about by the quantum
54:24 effects of gravity
54:27 an expansion or big bang following a
54:30 collapse or big crunch such as this is
54:33 aptly called a big bounce the bounce
54:37 signals the end of one universe and the
54:39 start of another the probability of a
54:42 big bounce or even a big crunch for that
54:44 matter is however becoming
54:47 negligible according to the most recent
54:49 observations of the cosmic microwave
54:51 background radiation the universe will
54:53 probably continue to expand until it
54:56 comes to an end in a big freeze or heat
54:59 death currently cmbr measurements are
55:03 collected using the highly precise
55:05 Wilkinson microwave anisotropy
55:08 probe the age of our universe has been
55:10 determined with extreme Precision using
55:13 the same equipment therefore it is
55:16 extremely unlikely that discoveries
55:18 about the expansion of the universe in
55:20 the future will significantly differ
55:22 from current
55:24 understanding nevertheless a more
55:27 thorough comprehension of one mysterious
55:29 entity might change the odds like the
55:32 dark
55:33 energy we may have to put the
55:35 oscillating universe theory on hold
55:37 unless its true properties are
55:39 drastically different from what it is
55:41 now
55:48 showing in the conformal cyclic
55:50 cosmology model proposed by Sir Roger
55:53 Penrose each Eon begins with with a big
55:57 bang event followed by an expansion
55:59 phase where matter and radiation dilute
56:03 and
56:04 cool eventually the cosmic microwave
56:07 background Fades and galaxies drift away
56:11 as the universe enters a phase dominated
56:14 by dark
56:15 energy time becomes meaningless and
56:18 conformal rescaling takes place as the
56:21 cosmos gets closer to its final state of
56:24 cold disordered nothingness
56:27 the result is a smooth cold empty
56:31 universe that serves as the beginning of
56:33 the
56:35 nexton a conformal rescaling is a
56:38 stretching or shrinking that maintains
56:40 all relative
56:42 angles Penrose uses that because you can
56:46 use a conformal rescaling to make
56:48 something that has infinite size into
56:50 something that has finite
56:52 size the infinite thing that you rescale
56:56 is is not just space but space time you
56:59 rescale them both and then you glue the
57:02 end of our universe to A New Beginning
57:06 mathematically you can totally do
57:09 that most importantly this cyclical
57:12 process suggests that there is no
57:14 beginning or end to the universe and
57:17 that the large scale structure that has
57:19 been observed is an ordinary consequence
57:22 of this ongoing Cosmic Evolution the
57:26 possibility of observational evidence is
57:28 one of the most interesting features of
57:30 the this model Penrose has proposed that
57:33 the cosmic microwave background
57:35 radiation may have round patterns called
57:38 Hawking points that represent remnants
57:41 of earlier ages these spots which carry
57:44 the name of the physicist Steven Hawking
57:47 are locations where previously existing
57:49 black holes have vanished and left
57:52 behind traces in the cosmic microwave
57:55 background radiation
57:57 there is still disagreement in the
57:58 scientific community on the accuracy of
58:01 certain studies that suggest they have
58:04 found potential Hawking points in the
58:06 CMB data others argue that more research
58:10 is required to support or disprove the
58:13 presence of Hawking points as proof for
58:16 conformal cyclic cosmology as The
58:18 observed patterns may be the result of
58:21 chance or instrumental
58:23 effects the conformal Cy cosmology model
58:27 would significantly change our knowledge
58:29 of the universe if it turns out to be
58:32 accurate the model provides a fresh
58:34 viewpoint on the nature of time the
58:38 development of cosmic structure and the
58:40 destiny of the universe by putting forth
58:42 a cyclical structure rather than a
58:45 single origin it also raises interesting
58:49 queries concerning the function of
58:50 information causation and entropy over
58:54 eons
58:56 following research in this field are
58:58 likely to focus on improving this model
59:00 and looking for stronger observational
59:03 support the James web Space Telescope is
59:07 also providing useful information for
59:10 testing the predictions of the conformal
59:12 cyclic cosmology model further
59:15 developments in theoretical physics
59:17 including the creation of a quantum
59:19 theory of gravity could Aid in the
59:22 reconciliation of the model with
59:24 alternative cosmological
59:26 models penrose's conformal cyclic
59:29 cosmology Theory differs from the Big
59:31 Bounce theory in that the expansion in
59:34 conformal cyclic cosmology never
59:37 reverses in the Big Bounce Theory the
59:40 universe slows down and eventually
59:42 reverses into contraction then reaches a
59:45 high enough density to begin expanding
59:48 again in a new Big
59:51 Bang recent discoveries in various
59:54 fields of physics and cosmology ology
59:56 have provided potential evidence for
59:58 Cosmic Cycles like in the cosmic
60:01 microwave background which serves as a
60:04 valuable tool in understanding the early
60:08 Universe researchers have found
60:10 potential evidence for this model in the
60:12 cm's patterns which may indicate the
60:16 presence of events from previous
60:18 eons the other enigmatic elements of the
60:21 universe dark energy and dark matter
60:25 have baffled scientists for decades but
60:28 according to some theories they might be
60:31 quite important in Cosmic Cycles with
60:33 dark matter possibly triggering the
60:35 universe's final contraction and dark
60:38 energy causing its accelerated
60:41 expansion also the detection of
60:44 gravitational waves from colliding black
60:46 holes and neutron stars has opened up a
60:49 new window into the universe some
60:52 researchers believe that studying these
60:54 waves May reveal clues about the
60:57 universe's cyclic nature and help test
61:00 various cyclic models whether it comes
61:03 from Modern cosmology or ancient
61:05 philosophy the concept of the cosmic
61:07 cycle has a significant impact on how we
61:10 see the nature of the universe and our
61:13 place in
61:14 it if the universe truly follows an
61:17 eternal cycle it challenges our Notions
61:20 of linear time and the uniqueness of our
61:23 own
61:24 existence it raises questions on the
61:26 nature of time and life's greater
61:29 purpose furthermore Research into the
61:33 cosmic cycle and its potential
61:35 implications to Modern cosmology Can
61:37 Shed light on the fundamental laws
61:40 governing the
61:42 universe the ancient idea of the cosmic
61:44 cycle May hold the key to solving some
61:47 of the universe's greatest riddles as
61:50 our understanding of the cosmos
61:52 increases philosophers theologians and
61:56 physicists have all been fascinated with
61:58 the idea of the cosmic cycle the concept
62:02 of a constantly repeating universe may
62:05 provide important new insights into the
62:08 nature of existence as we continue to
62:11 investigate the secrets of the
62:22 universe higher dimensions of space are
62:24 also a requirement for string theory
62:27 which postulates that what we see as
62:29 Elementary particles are actually
62:31 strings of energy vibrating in several
62:34 more Dimensions than we can
62:36 see according to those theories the
62:39 other dimensions are compactified or
62:42 curled up on themselves so even if you
62:45 were to find one of those New Dimensions
62:47 and embark on a voyage you wouldn't be
62:49 able to travel very far before returning
62:52 to your starting point but what if an
62:54 extra dimension can hide an entire
63:00 universe a theory regarding the
63:02 structure of the universe formulated in
63:04 the early 2000s proposes that humans
63:07 could reside in a three-dimensional
63:10 brain surrounding a more larger space
63:13 with four spatial Dimensions plus
63:17 time there may be another 3D brain
63:21 holding another Universe inside that
63:23 higher dimensional bulk that
63:25 occasionally might collide with our own
63:28 this Theory's Originators called it the
63:30 eerotic model of the
63:33 cosmos after a Greek term for
63:35 conflagration a nod to the fact that
63:39 each Cosmic Collision would result in
63:42 the fiery conditions of the big bang and
63:45 could explain the origin and eventual
63:48 fate of our
63:50 universe in this model the brains
63:53 alternately move toward each other coll
63:55 hide and then move apart again in an
63:58 endless cycle going from big bang to
64:01 expansion to Big Crunch and back to Big
64:05 Bang the patterns of structure we see in
64:07 the cosmos today in distributions of
64:09 galaxies and clusters are in this model
64:13 seeded by the interaction between the
64:15 two brains in the slow collapse phase
64:18 before the bang although the idea of
64:21 proposing new universes and higher
64:24 Dimensions to explain the big Big Bang
64:26 may appear extravagant at first there
64:29 are good reasons why physicists take
64:31 these ideas seriously you've probably
64:34 been misled into thinking that the
64:37 standard view of the early Cosmos is
64:40 simpler than it actually
64:42 is when you think of the Big Bang the
64:45 first thing to come to mind is likely to
64:47 be a singularity an infinitesimal point
64:50 of infinite density containing all of
64:53 space and time that suddenly explodes
64:56 out to create the entire
65:00 Cosmos that idea became popular because
65:03 Einstein's equations of gravity can
65:06 describe a cosmos that begins that way
65:08 and perhaps wraps itself up with a big
65:10 crunch Singularity at the
65:13 end but it doesn't work with what we see
65:16 in our observations we can see the
65:18 Afterglow of the big bang and background
65:21 light just at the cosmic Horizon which
65:24 indicates that a simple Evolution from a
65:28 singularity to the big amazing Universe
65:32 we live in today now just doesn't make
65:35 sense the problem is that the cosmic
65:38 microwave background the remnants of the
65:40 Big Bang is too perfect it is identical
65:44 to an incredible degree of precision one
65:47 part in 100,000 in all
65:51 directions same Spectrum same intensity
65:55 same color
65:56 or given its microwave light
65:58 frequency that's Troublesome since there
66:01 is no justification for two locations on
66:03 different sides of the sky to match up
66:06 that
66:07 way even if everything started together
66:10 wrapped up in a
66:11 singularity the way it expanded outward
66:14 should have introduced extreme
66:16 differences in different parts of the
66:18 early
66:19 Cosmos in the expanding stage of cosmic
66:22 Evolution regions that are currently
66:25 separated from one another never had a
66:27 chance to get on a common
66:29 temperature on one side of the sky the
66:32 cosmic microwave background should
66:35 differ significantly from the
66:37 other from what we've seen so far
66:40 inflation seems to work well with our
66:42 current Paradigm and even nicely
66:45 explains the little one part in 100,000
66:48 fluctuations observed in the cosmic
66:50 microwave background light but we don't
66:53 have what anyone would call Sol proof
66:56 that it happened nor can we say how or
66:58 why it started or what drove it and
67:02 likewise it's not entirely possible to
67:05 get hit by another Universe even in the
67:07 inflationary
67:09 scenario two bubble universes might at
67:12 some point Collide leaving imprints like
67:14 bruises on each other's background light
67:17 if inflation did happen the sequence of
67:20 events that created our observable
67:22 universe could have occurred time and
67:25 time again in different parts of a much
67:28 larger space in a process called Eternal
67:33 inflation the theory states that while
67:35 the larger background space is always
67:37 expanding inflation sometimes stops in a
67:41 small portion of it which causes that
67:44 region of the universe to heat up and
67:47 give way to normal Cosmic
67:50 expansion as a result little bubble
67:53 universes identified by their distinct
67:57 [Music]
67:59 post-inflationary background giving rise
68:02 to a kind of
68:04 Multiverse astronomers have searched for
68:06 such bruises though none have shown up
68:09 yet they'll keep
68:11 searching the eerotic model has been
68:14 revised several times over the years and
68:17 the most recent iteration does not
68:19 suggest Cosmic collisions or higher
68:22 Dimensions it looks similar to inflation
68:24 in certain aspects
68:26 instead of being pushed by brain motion
68:28 it is driven by the evolution of a Scala
68:31 field a type of space filling energy
68:35 field like to the one that most
68:37 physicists believe drove Cosmic
68:41 inflation despite no longer requiring
68:43 Grand Cosmic collisions the ecopy rotic
68:46 model still includes a transition
68:49 between a collapsing universe and a big
68:52 bang the cosmic Horizon defining our
68:55 observable universe is a hard limit we
68:59 can't see beyond it and unless our
69:02 understanding of the structure of
69:03 reality changes drastically we can be
69:06 confident we never
69:10 will the expansion of the cosmos is
69:13 speeding up anything beyond our Horizon
69:16 now will be carried away from us faster
69:19 and faster and its light will never be
69:22 able to catch
69:23 up while we might never be able to say
69:26 with certainty what lies beyond that
69:28 border what all the theories have in
69:31 common is that our observable universe
69:34 is part of a much much larger
69:38 space whether that space contains a
69:41 Multiverse of bubbles each with
69:43 different physical
69:45 laws whether it's part of an everwing
69:47 Cosmos of which we are only one part in
69:51 one cycle or whether space extends
69:54 outward into directions we can't
69:56 conceive we currently just don't
70:01 know but we're seeking Clues the
70:05 patterns in the cosmic microwave
70:06 background light the distribution of
70:09 galaxies and even experiments testing
70:11 gravity and the behavior of particle
70:14 physics are giving us insight into the
70:17 fundamental structure of the universe
70:19 and into its evolution in its earliest
70:24 moments we are getting closer and closer
70:27 to being able to tell our whole Cosmic
70:30 story we can already see directly the
70:33 fire in which our universe was forged
70:36 the moments just after its
70:38 beginning with the clues we are
70:40 gathering now we might someday follow
70:44 the story all the way to its
70:48 end our understanding of the universe
70:51 has massively evolved over the course of
70:53 our own evolution
70:56 actually the beauty of science lies in
70:58 how little we yet
71:00 know currently some of the world's best
71:03 minds are delving into the questions of
71:05 what the universe really is and what if
71:09 anything is
71:11 beyond like many Mysteries like Pluto
71:15 the truth is that it all depends on how
71:17 we Define it is the universe everything
71:20 that
71:21 exists or is it something more limited
71:25 just another aspect of all that
71:27 exists and is there another one like it
71:29 out there there are an infinite number
71:33 of possibilities ranging from Worlds
71:35 inside black holes to universes other
71:38 than our
71:41 own one of the most intrinsic human
71:44 parts about us is our ability to wonder
71:48 to dream and to
71:51 imagine thanks to this we have several
71:54 theories about what lies Beyond or is
71:57 bigger than our
71:58 universe that line up with at least
72:00 certain current observations physics and
72:05 math the possibilities are
72:09 endless as we gaze at the stars let's
72:13 remember that our curiosity transcends
72:16 boundaries the universe where the finite
72:19 or infinite beckons us to explore to
72:23 seek answers to dream and to
72:29 wonder perhaps the greatest discoveries
72:32 await us Beyond The Cosmic Veil
72:37 [Music]
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