[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:00.54,Default,,0000,0000,0000,,
Dialogue: 0,0:00:00.54,0:00:05.59,Default,,0000,0000,0000,,Right now, the best estimate\Nof when the Big Bang occurred--
Dialogue: 0,0:00:05.59,0:00:08.01,Default,,0000,0000,0000,,and once again, I don't like\Nthe term that much because it
Dialogue: 0,0:00:08.01,0:00:10.26,Default,,0000,0000,0000,,kind of implies some\Ntype of explosion.
Dialogue: 0,0:00:10.26,0:00:12.13,Default,,0000,0000,0000,,But what it really is\Nis kind of an expansion
Dialogue: 0,0:00:12.13,0:00:14.54,Default,,0000,0000,0000,,of space, when space\Nstarted to really start
Dialogue: 0,0:00:14.54,0:00:16.42,Default,,0000,0000,0000,,to expand from a singularity.
Dialogue: 0,0:00:16.42,0:00:18.40,Default,,0000,0000,0000,,But our best estimate\Nof when this occurred
Dialogue: 0,0:00:18.40,0:00:24.32,Default,,0000,0000,0000,,is 13.7 billion years ago.
Dialogue: 0,0:00:24.32,0:00:26.67,Default,,0000,0000,0000,,And even though we're used\Nto dealing with numbers
Dialogue: 0,0:00:26.67,0:00:28.13,Default,,0000,0000,0000,,in the billions,\Nespecially when we
Dialogue: 0,0:00:28.13,0:00:30.54,Default,,0000,0000,0000,,talk about large amounts\Nof money and what not,
Dialogue: 0,0:00:30.54,0:00:32.75,Default,,0000,0000,0000,,this is an unbelievable\Namount of time.
Dialogue: 0,0:00:32.75,0:00:35.58,Default,,0000,0000,0000,,It seems like something that is\Ntractable, but it really isn't.
Dialogue: 0,0:00:35.58,0:00:37.83,Default,,0000,0000,0000,,And in future\Nvideos, I'm actually
Dialogue: 0,0:00:37.83,0:00:39.42,Default,,0000,0000,0000,,going to talk about\Nthe time scale.
Dialogue: 0,0:00:39.42,0:00:41.34,Default,,0000,0000,0000,,So we can really\Nappreciate how long,
Dialogue: 0,0:00:41.34,0:00:43.17,Default,,0000,0000,0000,,or even start to\Nappreciate, or appreciate
Dialogue: 0,0:00:43.17,0:00:47.82,Default,,0000,0000,0000,,that we can't appreciate how\Nlong 13.7 billion years is.
Dialogue: 0,0:00:47.82,0:00:51.51,Default,,0000,0000,0000,,And I also want to emphasize\Nthat this is the current best
Dialogue: 0,0:00:51.51,0:00:52.01,Default,,0000,0000,0000,,estimate.
Dialogue: 0,0:00:52.01,0:00:54.76,Default,,0000,0000,0000,,Even in my lifetime, even in\Nmy lifetime that I actually
Dialogue: 0,0:00:54.76,0:00:57.23,Default,,0000,0000,0000,,knew about the Big Bang and\Nthat I would pay attention
Dialogue: 0,0:00:57.23,0:00:59.36,Default,,0000,0000,0000,,to what the best estimate\Nwas, this number's
Dialogue: 0,0:00:59.36,0:01:00.26,Default,,0000,0000,0000,,been moving around.
Dialogue: 0,0:01:00.26,0:01:02.32,Default,,0000,0000,0000,,So I suspect that in\Nthe future, this number
Dialogue: 0,0:01:02.32,0:01:04.99,Default,,0000,0000,0000,,might become more accurate\Nor might move around some.
Dialogue: 0,0:01:04.99,0:01:06.35,Default,,0000,0000,0000,,But this is our best guess.
Dialogue: 0,0:01:06.35,0:01:08.85,Default,,0000,0000,0000,,Now with that said, I want to\Nthink about what this tells us
Dialogue: 0,0:01:08.85,0:01:11.74,Default,,0000,0000,0000,,about the size of the\Nobservable universe.
Dialogue: 0,0:01:11.74,0:01:17.32,Default,,0000,0000,0000,,
Dialogue: 0,0:01:17.32,0:01:22.32,Default,,0000,0000,0000,,So if all of the expansion\Nstarted 13.7 billion years ago,
Dialogue: 0,0:01:22.32,0:01:25.87,Default,,0000,0000,0000,,that 13.7 billion\Nyears ago, everything
Dialogue: 0,0:01:25.87,0:01:28.32,Default,,0000,0000,0000,,we know in our\Nthree-dimensional universe
Dialogue: 0,0:01:28.32,0:01:31.27,Default,,0000,0000,0000,,was in a single\Npoint, the longest
Dialogue: 0,0:01:31.27,0:01:34.34,Default,,0000,0000,0000,,that any photon of light could\Nbe traveling that's reaching us
Dialogue: 0,0:01:34.34,0:01:39.72,Default,,0000,0000,0000,,right now-- so let's say that\Nthat is my eye right over here.
Dialogue: 0,0:01:39.72,0:01:45.80,Default,,0000,0000,0000,,That's my eyelashes, just like\Nthat-- so some photon of light
Dialogue: 0,0:01:45.80,0:01:47.89,Default,,0000,0000,0000,,is just to getting to\Nmy eye or maybe it's
Dialogue: 0,0:01:47.89,0:01:50.84,Default,,0000,0000,0000,,just getting to the\Nlens of a telescope.
Dialogue: 0,0:01:50.84,0:01:52.80,Default,,0000,0000,0000,,The longest that that\Ncould have been traveling
Dialogue: 0,0:01:52.80,0:01:55.49,Default,,0000,0000,0000,,is 13.7 billion years.
Dialogue: 0,0:01:55.49,0:02:07.32,Default,,0000,0000,0000,,So it could be traveling\N13.7 billion years.
Dialogue: 0,0:02:07.32,0:02:09.39,Default,,0000,0000,0000,,So when we looked\Nat that depiction--
Dialogue: 0,0:02:09.39,0:02:11.25,Default,,0000,0000,0000,,this I think was two\Nor three videos ago,
Dialogue: 0,0:02:11.25,0:02:14.93,Default,,0000,0000,0000,,of the observable universe--\NI drew, it was this circle.
Dialogue: 0,0:02:14.93,0:02:18.27,Default,,0000,0000,0000,,
Dialogue: 0,0:02:18.27,0:02:21.97,Default,,0000,0000,0000,,And when we see light coming\Nfrom these remote objects--
Dialogue: 0,0:02:21.97,0:02:23.59,Default,,0000,0000,0000,,that light is getting\Nto us right here.
Dialogue: 0,0:02:23.59,0:02:24.85,Default,,0000,0000,0000,,This is where we are.
Dialogue: 0,0:02:24.85,0:02:27.51,Default,,0000,0000,0000,,This is where I guess\Nin the depiction
Dialogue: 0,0:02:27.51,0:02:28.80,Default,,0000,0000,0000,,the remote object was.
Dialogue: 0,0:02:28.80,0:02:30.84,Default,,0000,0000,0000,,But the light from\Nthat remote object
Dialogue: 0,0:02:30.84,0:02:32.93,Default,,0000,0000,0000,,is just now getting to us.
Dialogue: 0,0:02:32.93,0:02:37.97,Default,,0000,0000,0000,,And that light took 13.7\Nbillion years to get to us.
Dialogue: 0,0:02:37.97,0:02:43.89,Default,,0000,0000,0000,,
Dialogue: 0,0:02:43.89,0:02:45.47,Default,,0000,0000,0000,,Now, what I'm going\Nto hesitate to do,
Dialogue: 0,0:02:45.47,0:02:48.72,Default,,0000,0000,0000,,because we're talking\Nover such large distances
Dialogue: 0,0:02:48.72,0:02:51.89,Default,,0000,0000,0000,,and we're talking on such large\Ntime scales and time scales
Dialogue: 0,0:02:51.89,0:02:55.01,Default,,0000,0000,0000,,over which space\Nitself is expanding--
Dialogue: 0,0:02:55.01,0:02:59.18,Default,,0000,0000,0000,,we're going to see in this video\Nthat you cannot say that this
Dialogue: 0,0:02:59.18,0:03:03.99,Default,,0000,0000,0000,,object over here, this is\Nnot necessarily, this is NOT,
Dialogue: 0,0:03:03.99,0:03:13.72,Default,,0000,0000,0000,,I'll put it in caps, this is NOT\N13.7 billion light years away.
Dialogue: 0,0:03:13.72,0:03:15.99,Default,,0000,0000,0000,,If we were talking about\Nsmaller time scales
Dialogue: 0,0:03:15.99,0:03:18.27,Default,,0000,0000,0000,,or I guess smaller\Ndistances, you
Dialogue: 0,0:03:18.27,0:03:20.06,Default,,0000,0000,0000,,could say approximately that.
Dialogue: 0,0:03:20.06,0:03:23.78,Default,,0000,0000,0000,,The expansion of the universe\Nitself would not make as much
Dialogue: 0,0:03:23.78,0:03:24.45,Default,,0000,0000,0000,,of a difference.
Dialogue: 0,0:03:24.45,0:03:26.87,Default,,0000,0000,0000,,And let me make it\Neven more clear.
Dialogue: 0,0:03:26.87,0:03:28.72,Default,,0000,0000,0000,,I'm talking about an\Nobject over there.
Dialogue: 0,0:03:28.72,0:03:33.06,Default,,0000,0000,0000,,But we could even talk about\Nthat coordinate in space.
Dialogue: 0,0:03:33.06,0:03:35.43,Default,,0000,0000,0000,,And actually, I should say\Nthat coordinate in space-time,
Dialogue: 0,0:03:35.43,0:03:37.95,Default,,0000,0000,0000,,because we're viewing it at\Na certain instant as well.
Dialogue: 0,0:03:37.95,0:03:43.27,Default,,0000,0000,0000,,But that coordinate is not\N13.7 billion light years away
Dialogue: 0,0:03:43.27,0:03:44.74,Default,,0000,0000,0000,,from our current coordinate.
Dialogue: 0,0:03:44.74,0:03:46.52,Default,,0000,0000,0000,,And there's a couple of\Nreasons to think about it.
Dialogue: 0,0:03:46.52,0:03:48.19,Default,,0000,0000,0000,,First of all, think\Nabout it, that light
Dialogue: 0,0:03:48.19,0:03:51.76,Default,,0000,0000,0000,,was emitted 13.7\Nbillion years ago.
Dialogue: 0,0:03:51.76,0:03:53.84,Default,,0000,0000,0000,,When that light was\Nemitted, we were
Dialogue: 0,0:03:53.84,0:03:55.75,Default,,0000,0000,0000,,much closer to that coordinate.
Dialogue: 0,0:03:55.75,0:03:57.64,Default,,0000,0000,0000,,This coordinate was\Nmuch closer to that.
Dialogue: 0,0:03:57.64,0:03:59.22,Default,,0000,0000,0000,,Where we are in the\Nuniverse right now
Dialogue: 0,0:03:59.22,0:04:01.96,Default,,0000,0000,0000,,was much closer to that\Npoint in the universe.
Dialogue: 0,0:04:01.96,0:04:04.11,Default,,0000,0000,0000,,The other thing\Nto think about is
Dialogue: 0,0:04:04.11,0:04:06.06,Default,,0000,0000,0000,,as this-- let me\Nactually draw it.
Dialogue: 0,0:04:06.06,0:04:16.17,Default,,0000,0000,0000,,So let's go 300,000 years\Nafter that initial expansion
Dialogue: 0,0:04:16.17,0:04:17.08,Default,,0000,0000,0000,,of that singularity.
Dialogue: 0,0:04:17.08,0:04:21.30,Default,,0000,0000,0000,,So we're just 300,000 years\Ninto the universe's history
Dialogue: 0,0:04:21.30,0:04:22.89,Default,,0000,0000,0000,,right now.
Dialogue: 0,0:04:22.89,0:04:30.37,Default,,0000,0000,0000,,So this is roughly 300,000\Nyears into the universe's life.
Dialogue: 0,0:04:30.37,0:04:33.66,Default,,0000,0000,0000,,I guess we could\Nview it that way.
Dialogue: 0,0:04:33.66,0:04:37.40,Default,,0000,0000,0000,,And first of all, at that point\Nthings haven't differentiated
Dialogue: 0,0:04:37.40,0:04:39.13,Default,,0000,0000,0000,,in a meaningful\Nway yet right now.
Dialogue: 0,0:04:39.13,0:04:40.86,Default,,0000,0000,0000,,And we'll talk more\Nabout this when
Dialogue: 0,0:04:40.86,0:04:43.58,Default,,0000,0000,0000,,we talk about the cosmic\Nmicrowave background radiation.
Dialogue: 0,0:04:43.58,0:04:45.65,Default,,0000,0000,0000,,But at this point\Nin the universe,
Dialogue: 0,0:04:45.65,0:04:49.90,Default,,0000,0000,0000,,it was kind of this almost\Nuniform white-hot plasma
Dialogue: 0,0:04:49.90,0:04:50.40,Default,,0000,0000,0000,,of hydrogen.
Dialogue: 0,0:04:50.40,0:04:51.98,Default,,0000,0000,0000,,And then we're going\Nto talk about it.
Dialogue: 0,0:04:51.98,0:04:53.87,Default,,0000,0000,0000,,It was emitting\Nmicrowave radiation.
Dialogue: 0,0:04:53.87,0:04:55.91,Default,,0000,0000,0000,,And we'll talk more about\Nthat in a future video.
Dialogue: 0,0:04:55.91,0:05:01.09,Default,,0000,0000,0000,,But let's just think about two\Npoints in this early universe.
Dialogue: 0,0:05:01.09,0:05:03.60,Default,,0000,0000,0000,,So in this early universe,\Nlet's say you have that point.
Dialogue: 0,0:05:03.60,0:05:05.93,Default,,0000,0000,0000,,And let's say you have the\Ncoordinate where we are right
Dialogue: 0,0:05:05.93,0:05:06.89,Default,,0000,0000,0000,,now.
Dialogue: 0,0:05:06.89,0:05:10.21,Default,,0000,0000,0000,,You have the coordinate\Nwhere we are right now.
Dialogue: 0,0:05:10.21,0:05:12.63,Default,,0000,0000,0000,,And in fact, I'll just make\Nthat roughly-- I won't make it
Dialogue: 0,0:05:12.63,0:05:14.34,Default,,0000,0000,0000,,the center just because I\Nthink it makes it easier
Dialogue: 0,0:05:14.34,0:05:15.95,Default,,0000,0000,0000,,to visualize if\Nit's not the center.
Dialogue: 0,0:05:15.95,0:05:19.08,Default,,0000,0000,0000,,And let's say at that very\Nearly stage in the universe,
Dialogue: 0,0:05:19.08,0:05:22.09,Default,,0000,0000,0000,,if you were able to just take\Nsome rulers instantaneously
Dialogue: 0,0:05:22.09,0:05:26.82,Default,,0000,0000,0000,,and measure that, you\Nwould measure this distance
Dialogue: 0,0:05:26.82,0:05:36.15,Default,,0000,0000,0000,,to be 30 million light years.
Dialogue: 0,0:05:36.15,0:05:38.05,Default,,0000,0000,0000,,And let's just say\Nright at that point,
Dialogue: 0,0:05:38.05,0:05:40.14,Default,,0000,0000,0000,,this object over here--\NI'll do it in magenta--
Dialogue: 0,0:05:40.14,0:05:43.07,Default,,0000,0000,0000,,this object over here\Nemits a photon, maybe
Dialogue: 0,0:05:43.07,0:05:45.79,Default,,0000,0000,0000,,in the microwave\Nfrequency range.
Dialogue: 0,0:05:45.79,0:05:48.37,Default,,0000,0000,0000,,And we'll see that that was the\Nrange that it was emitting in.
Dialogue: 0,0:05:48.37,0:05:50.22,Default,,0000,0000,0000,,But it emits a photon.
Dialogue: 0,0:05:50.22,0:05:52.34,Default,,0000,0000,0000,,And that photon is traveling\Nat the speed of light.
Dialogue: 0,0:05:52.34,0:05:53.18,Default,,0000,0000,0000,,It is light.
Dialogue: 0,0:05:53.18,0:05:55.14,Default,,0000,0000,0000,,And so that photon, says,\Nyou know what, I only
Dialogue: 0,0:05:55.14,0:05:56.99,Default,,0000,0000,0000,,got 30 million light\Nyears to travel.
Dialogue: 0,0:05:56.99,0:05:57.79,Default,,0000,0000,0000,,That's not too bad.
Dialogue: 0,0:05:57.79,0:06:00.65,Default,,0000,0000,0000,,I'm going to get there\Nin 30 million years.
Dialogue: 0,0:06:00.65,0:06:01.98,Default,,0000,0000,0000,,And I'm going to do it discrete.
Dialogue: 0,0:06:01.98,0:06:04.38,Default,,0000,0000,0000,,The math is more complicated\Nthan what I'm doing here.
Dialogue: 0,0:06:04.38,0:06:05.80,Default,,0000,0000,0000,,But I really just\Nwant to give you
Dialogue: 0,0:06:05.80,0:06:07.32,Default,,0000,0000,0000,,the idea of what's\Ngoing on here.
Dialogue: 0,0:06:07.32,0:06:09.84,Default,,0000,0000,0000,,So let's just say,\Nwell, that photon
Dialogue: 0,0:06:09.84,0:06:13.87,Default,,0000,0000,0000,,says in about 10 million years,\Nin roughly 10 million years,
Dialogue: 0,0:06:13.87,0:06:18.08,Default,,0000,0000,0000,,I should be right about\Nat that coordinate.
Dialogue: 0,0:06:18.08,0:06:20.96,Default,,0000,0000,0000,,I should be about one\Nthird of the distance.
Dialogue: 0,0:06:20.96,0:06:26.08,Default,,0000,0000,0000,,But what happens over the course\Nof those 10 million years?
Dialogue: 0,0:06:26.08,0:06:28.08,Default,,0000,0000,0000,,Well, over the course of\Nthose 10 million years,
Dialogue: 0,0:06:28.08,0:06:30.24,Default,,0000,0000,0000,,the universe has expanded some.
Dialogue: 0,0:06:30.24,0:06:32.73,Default,,0000,0000,0000,,The universe has expanded\Nmaybe a good deal.
Dialogue: 0,0:06:32.73,0:06:35.69,Default,,0000,0000,0000,,So let me draw the\Nexpanded universe.
Dialogue: 0,0:06:35.69,0:06:40.92,Default,,0000,0000,0000,,So after 10 million years, the\Nuniverse might look like this.
Dialogue: 0,0:06:40.92,0:06:42.71,Default,,0000,0000,0000,,Actually it might even\Nbe bigger than that.
Dialogue: 0,0:06:42.71,0:06:44.76,Default,,0000,0000,0000,,Let me draw it like this.
Dialogue: 0,0:06:44.76,0:06:47.57,Default,,0000,0000,0000,,After 10 million\Nyears, the universe
Dialogue: 0,0:06:47.57,0:06:49.51,Default,,0000,0000,0000,,might have expanded a good bit.
Dialogue: 0,0:06:49.51,0:06:53.47,Default,,0000,0000,0000,,So this is 10 million\Nyears into the future.
Dialogue: 0,0:06:53.47,0:06:58.20,Default,,0000,0000,0000,,Still on a cosmological time\Nscale, still almost at kind
Dialogue: 0,0:06:58.20,0:07:00.37,Default,,0000,0000,0000,,of the infancy of the\Nuniverse because we're
Dialogue: 0,0:07:00.37,0:07:02.36,Default,,0000,0000,0000,,talking about 13.7\Nbillion years.
Dialogue: 0,0:07:02.36,0:07:04.31,Default,,0000,0000,0000,,So let's say 10 million years.
Dialogue: 0,0:07:04.31,0:07:07.51,Default,,0000,0000,0000,,10 million years go by.
Dialogue: 0,0:07:07.51,0:07:09.10,Default,,0000,0000,0000,,The universe has expanded.
Dialogue: 0,0:07:09.10,0:07:10.98,Default,,0000,0000,0000,,This coordinate, where\Nwe're sitting today
Dialogue: 0,0:07:10.98,0:07:15.35,Default,,0000,0000,0000,,at the present time, is\Nnow all the way over here.
Dialogue: 0,0:07:15.35,0:07:19.35,Default,,0000,0000,0000,,That coordinate where the\Nphoton was originally emitted
Dialogue: 0,0:07:19.35,0:07:24.30,Default,,0000,0000,0000,,is now going to be\Nsitting right over here.
Dialogue: 0,0:07:24.30,0:07:26.76,Default,,0000,0000,0000,,And that photon, it said, OK,\Nafter 10 million light years,
Dialogue: 0,0:07:26.76,0:07:28.10,Default,,0000,0000,0000,,I'm going to get over there.
Dialogue: 0,0:07:28.10,0:07:29.30,Default,,0000,0000,0000,,And I'm approximating.
Dialogue: 0,0:07:29.30,0:07:30.80,Default,,0000,0000,0000,,I'm doing it in a\Nvery discrete way.
Dialogue: 0,0:07:30.80,0:07:32.89,Default,,0000,0000,0000,,But I really just want\Nto give you the idea.
Dialogue: 0,0:07:32.89,0:07:35.28,Default,,0000,0000,0000,,So that coordinate,\Nwhere the photon roughly
Dialogue: 0,0:07:35.28,0:07:38.34,Default,,0000,0000,0000,,gets in 10 million light years,\Nis about right over here.
Dialogue: 0,0:07:38.34,0:07:39.76,Default,,0000,0000,0000,,The whole universe has expanded.
Dialogue: 0,0:07:39.76,0:07:42.86,Default,,0000,0000,0000,,All the coordinates have gotten\Nfurther away from each other.
Dialogue: 0,0:07:42.86,0:07:44.18,Default,,0000,0000,0000,,Now, what just happened here?
Dialogue: 0,0:07:44.18,0:07:45.42,Default,,0000,0000,0000,,The universe has expanded.
Dialogue: 0,0:07:45.42,0:07:49.24,Default,,0000,0000,0000,,This distance that was 30\Nmillion light years now--
Dialogue: 0,0:07:49.24,0:07:52.00,Default,,0000,0000,0000,,and I'm just making\Nrough numbers here.
Dialogue: 0,0:07:52.00,0:07:53.64,Default,,0000,0000,0000,,I don't know the\Nactual numbers here.
Dialogue: 0,0:07:53.64,0:07:55.69,Default,,0000,0000,0000,,Now, it is actually--\Nthis is really just
Dialogue: 0,0:07:55.69,0:08:01.13,Default,,0000,0000,0000,,for the sake of giving you the\Nidea of why-- well, giving you
Dialogue: 0,0:08:01.13,0:08:03.10,Default,,0000,0000,0000,,the intuition of\Nwhat's going on.
Dialogue: 0,0:08:03.10,0:08:08.18,Default,,0000,0000,0000,,This distance now is no\Nlonger 30 million light years.
Dialogue: 0,0:08:08.18,0:08:10.24,Default,,0000,0000,0000,,Maybe it's 100 million.
Dialogue: 0,0:08:10.24,0:08:16.17,Default,,0000,0000,0000,,So this is now 100 million light\Nyears away from each other.
Dialogue: 0,0:08:16.17,0:08:17.25,Default,,0000,0000,0000,,The universe is expanding.
Dialogue: 0,0:08:17.25,0:08:20.91,Default,,0000,0000,0000,,These coordinates, the space\Nis actually spreading out.
Dialogue: 0,0:08:20.91,0:08:22.70,Default,,0000,0000,0000,,You could imagine it's\Nkind of a trampoline
Dialogue: 0,0:08:22.70,0:08:23.87,Default,,0000,0000,0000,,or the surface of a balloon.
Dialogue: 0,0:08:23.87,0:08:25.49,Default,,0000,0000,0000,,It's getting stretched thin.
Dialogue: 0,0:08:25.49,0:08:27.64,Default,,0000,0000,0000,,And so this coordinate\Nwhere the light happens
Dialogue: 0,0:08:27.64,0:08:29.94,Default,,0000,0000,0000,,to be after 10\Nmillion years, it has
Dialogue: 0,0:08:29.94,0:08:32.18,Default,,0000,0000,0000,,been traveling for\N10 million years,
Dialogue: 0,0:08:32.18,0:08:33.82,Default,,0000,0000,0000,,but it's gone a much\Nlarger distance.
Dialogue: 0,0:08:33.82,0:08:37.54,Default,,0000,0000,0000,,
Dialogue: 0,0:08:37.54,0:08:40.44,Default,,0000,0000,0000,,That distance now might\Nbe on the order of-- maybe
Dialogue: 0,0:08:40.44,0:08:42.51,Default,,0000,0000,0000,,it's on the order of\N30 million light years.
Dialogue: 0,0:08:42.51,0:08:44.10,Default,,0000,0000,0000,,And the math isn't exact here.
Dialogue: 0,0:08:44.10,0:08:47.62,Default,,0000,0000,0000,,I haven't done the\Nmath to figure it out.
Dialogue: 0,0:08:47.62,0:08:50.36,Default,,0000,0000,0000,,So it's done 30\Nmillion light years.
Dialogue: 0,0:08:50.36,0:08:53.90,Default,,0000,0000,0000,,And actually I shouldn't even\Nmake it the same proportion.
Dialogue: 0,0:08:53.90,0:08:56.59,Default,,0000,0000,0000,,Because the distance it's gone\Nand the distance it has to go,
Dialogue: 0,0:08:56.59,0:08:58.05,Default,,0000,0000,0000,,because of the\Nstretching, it's not
Dialogue: 0,0:08:58.05,0:08:59.71,Default,,0000,0000,0000,,going to be completely linear.
Dialogue: 0,0:08:59.71,0:09:02.38,Default,,0000,0000,0000,,At least when I'm thinking about\Nit in my head, it shouldn't be,
Dialogue: 0,0:09:02.38,0:09:02.96,Default,,0000,0000,0000,,I think.
Dialogue: 0,0:09:02.96,0:09:06.34,Default,,0000,0000,0000,,But I'm going to make a\Nhard statement about that.
Dialogue: 0,0:09:06.34,0:09:10.50,Default,,0000,0000,0000,,But the distance that it\Nreversed, maybe this distance
Dialogue: 0,0:09:10.50,0:09:15.79,Default,,0000,0000,0000,,right here is now 20\Nmillion light years
Dialogue: 0,0:09:15.79,0:09:16.92,Default,,0000,0000,0000,,because it got there.
Dialogue: 0,0:09:16.92,0:09:20.96,Default,,0000,0000,0000,,Every time it moved some\Ndistance, the space that it
Dialogue: 0,0:09:20.96,0:09:23.02,Default,,0000,0000,0000,,had traversed is now stretched.
Dialogue: 0,0:09:23.02,0:09:27.66,Default,,0000,0000,0000,,So even though its traveled\Nfor 10 million years,
Dialogue: 0,0:09:27.66,0:09:29.64,Default,,0000,0000,0000,,the space that it\Ntraversed is no longer
Dialogue: 0,0:09:29.64,0:09:31.36,Default,,0000,0000,0000,,just 10 million light years.
Dialogue: 0,0:09:31.36,0:09:34.13,Default,,0000,0000,0000,,It's now stretched to\N20 million light years.
Dialogue: 0,0:09:34.13,0:09:35.89,Default,,0000,0000,0000,,And the space that it\Nhas left to traverse
Dialogue: 0,0:09:35.89,0:09:38.57,Default,,0000,0000,0000,,is no longer only 20\Nmillion light years.
Dialogue: 0,0:09:38.57,0:09:41.42,Default,,0000,0000,0000,,It might now be 80\Nmillion light years.
Dialogue: 0,0:09:41.42,0:09:44.41,Default,,0000,0000,0000,,It is now 80\Nmillion light years.
Dialogue: 0,0:09:44.41,0:09:47.06,Default,,0000,0000,0000,,And so this photon might\Nbe getting frustrated.
Dialogue: 0,0:09:47.06,0:09:48.88,Default,,0000,0000,0000,,There's an optimistic\Nway of viewing it.
Dialogue: 0,0:09:48.88,0:09:50.67,Default,,0000,0000,0000,,It is like, wow, I\Nwas able to cover
Dialogue: 0,0:09:50.67,0:09:53.39,Default,,0000,0000,0000,,20 million light years\Nin only 10 million years.
Dialogue: 0,0:09:53.39,0:09:55.72,Default,,0000,0000,0000,,It looks like I'm moving\Nfaster than the speed of light.
Dialogue: 0,0:09:55.72,0:09:58.27,Default,,0000,0000,0000,,The reality is it's not\Nbecause the space coordinates
Dialogue: 0,0:09:58.27,0:10:00.61,Default,,0000,0000,0000,,themselves are spreading out.
Dialogue: 0,0:10:00.61,0:10:01.63,Default,,0000,0000,0000,,Those are getting thin.
Dialogue: 0,0:10:01.63,0:10:04.50,Default,,0000,0000,0000,,So the photon is just moving\Nat the speed of light.
Dialogue: 0,0:10:04.50,0:10:05.87,Default,,0000,0000,0000,,But the distance\Nthat it actually
Dialogue: 0,0:10:05.87,0:10:10.09,Default,,0000,0000,0000,,traversed in 10 million\Nyears is more than 10 million
Dialogue: 0,0:10:10.09,0:10:10.59,Default,,0000,0000,0000,,light years.
Dialogue: 0,0:10:10.59,0:10:12.09,Default,,0000,0000,0000,,It's 20 million light years.
Dialogue: 0,0:10:12.09,0:10:15.48,Default,,0000,0000,0000,,So you can't just\Nmultiply a rate times time
Dialogue: 0,0:10:15.48,0:10:19.09,Default,,0000,0000,0000,,on these cosmological scales,\Nespecially when the coordinates
Dialogue: 0,0:10:19.09,0:10:23.10,Default,,0000,0000,0000,,themselves, the distance\Ncoordinates are actually
Dialogue: 0,0:10:23.10,0:10:24.69,Default,,0000,0000,0000,,moving away from each other.
Dialogue: 0,0:10:24.69,0:10:27.43,Default,,0000,0000,0000,,But I think you see,\Nor maybe you might see,
Dialogue: 0,0:10:27.43,0:10:29.52,Default,,0000,0000,0000,,where this is going.
Dialogue: 0,0:10:29.52,0:10:33.15,Default,,0000,0000,0000,,OK, this photon says, oh, in\Nanother-- let me write this.
Dialogue: 0,0:10:33.15,0:10:35.43,Default,,0000,0000,0000,,This is 80 million light\Nyears-- in another 40 million
Dialogue: 0,0:10:35.43,0:10:40.19,Default,,0000,0000,0000,,light years, maybe I'm\Ngoing to get over here.
Dialogue: 0,0:10:40.19,0:10:43.11,Default,,0000,0000,0000,,But the reality is over that\Nnext 40 million light years--
Dialogue: 0,0:10:43.11,0:10:47.44,Default,,0000,0000,0000,,sorry, in 40 million years,\NI might get right over here,
Dialogue: 0,0:10:47.44,0:10:49.65,Default,,0000,0000,0000,,because this is 80\Nmillion light years.
Dialogue: 0,0:10:49.65,0:10:52.42,Default,,0000,0000,0000,,But the reality is\Nafter 40 million years--
Dialogue: 0,0:10:52.42,0:10:56.03,Default,,0000,0000,0000,,so another 40 million years\Ngo by-- now, all of a sudden,
Dialogue: 0,0:10:56.03,0:10:59.75,Default,,0000,0000,0000,,the universe has\Nexpanded even more.
Dialogue: 0,0:10:59.75,0:11:01.71,Default,,0000,0000,0000,,I won't even draw\Nthe whole bubble.
Dialogue: 0,0:11:01.71,0:11:04.68,Default,,0000,0000,0000,,But the place where the\Nphoton was emitted from
Dialogue: 0,0:11:04.68,0:11:07.63,Default,,0000,0000,0000,,might be over here.
Dialogue: 0,0:11:07.63,0:11:11.85,Default,,0000,0000,0000,,And now our current\Nposition is over here.
Dialogue: 0,0:11:11.85,0:11:18.25,Default,,0000,0000,0000,,Where the light got after 10\Nmillion years is now over here.
Dialogue: 0,0:11:18.25,0:11:24.07,Default,,0000,0000,0000,,And now, where the light\Nis after 40 million years,
Dialogue: 0,0:11:24.07,0:11:27.50,Default,,0000,0000,0000,,maybe it's over here.
Dialogue: 0,0:11:27.50,0:11:29.52,Default,,0000,0000,0000,,So now this distance,\Nthe distance
Dialogue: 0,0:11:29.52,0:11:32.24,Default,,0000,0000,0000,,between these two\Npoints, when we started,
Dialogue: 0,0:11:32.24,0:11:33.59,Default,,0000,0000,0000,,it was 10 million light years.
Dialogue: 0,0:11:33.59,0:11:36.38,Default,,0000,0000,0000,,Then it became 20\Nmillion light years.
Dialogue: 0,0:11:36.38,0:11:39.10,Default,,0000,0000,0000,,Maybe now, it's on the order\Nof-- I don't know-- maybe it's
Dialogue: 0,0:11:39.10,0:11:41.14,Default,,0000,0000,0000,,a billion light years.
Dialogue: 0,0:11:41.14,0:11:43.24,Default,,0000,0000,0000,,Maybe now it's a\Nbillion light years.
Dialogue: 0,0:11:43.24,0:11:45.51,Default,,0000,0000,0000,,And maybe this distance\Nover here-- and I'm
Dialogue: 0,0:11:45.51,0:11:46.72,Default,,0000,0000,0000,,just making up these numbers.
Dialogue: 0,0:11:46.72,0:11:49.45,Default,,0000,0000,0000,,In fact, that's probably be too\Nbig for that point-- maybe this
Dialogue: 0,0:11:49.45,0:11:52.01,Default,,0000,0000,0000,,is now 100 million light years.
Dialogue: 0,0:11:52.01,0:11:55.39,Default,,0000,0000,0000,,This is now 100\Nmillion light years.
Dialogue: 0,0:11:55.39,0:11:59.05,Default,,0000,0000,0000,,And now, maybe\Nthis distance right
Dialogue: 0,0:11:59.05,0:12:01.73,Default,,0000,0000,0000,,here is-- I don't know--\N500 million light years.
Dialogue: 0,0:12:01.73,0:12:04.08,Default,,0000,0000,0000,,And maybe now the total\Ndistance between the two points
Dialogue: 0,0:12:04.08,0:12:05.95,Default,,0000,0000,0000,,is a billion light years.
Dialogue: 0,0:12:05.95,0:12:08.73,Default,,0000,0000,0000,,So as you can see, the photon\Nmight getting frustrated.
Dialogue: 0,0:12:08.73,0:12:10.23,Default,,0000,0000,0000,,As it covers more\Nand more distance,
Dialogue: 0,0:12:10.23,0:12:13.20,Default,,0000,0000,0000,,it looks back and says, wow,\Nin only 50 million years,
Dialogue: 0,0:12:13.20,0:12:16.02,Default,,0000,0000,0000,,I've been able to cover\N600 million light years.
Dialogue: 0,0:12:16.02,0:12:16.91,Default,,0000,0000,0000,,That's pretty good.
Dialogue: 0,0:12:16.91,0:12:18.70,Default,,0000,0000,0000,,But it's frustrated\Nbecause what it thought
Dialogue: 0,0:12:18.70,0:12:22.51,Default,,0000,0000,0000,,was it only had to cover\N30 million light years
Dialogue: 0,0:12:22.51,0:12:23.05,Default,,0000,0000,0000,,in distance.
Dialogue: 0,0:12:23.05,0:12:25.07,Default,,0000,0000,0000,,That keeps stretching\Nout because space
Dialogue: 0,0:12:25.07,0:12:26.56,Default,,0000,0000,0000,,itself is stretching.
Dialogue: 0,0:12:26.56,0:12:32.19,Default,,0000,0000,0000,,So the reality, just going\Nto the original idea,
Dialogue: 0,0:12:32.19,0:12:36.05,Default,,0000,0000,0000,,this photon that is\Njust reaching us,
Dialogue: 0,0:12:36.05,0:12:38.87,Default,,0000,0000,0000,,that's been traveling\Nfor-- let's say
Dialogue: 0,0:12:38.87,0:12:41.69,Default,,0000,0000,0000,,it's been traveling\Nfor 13.4 billion years.
Dialogue: 0,0:12:41.69,0:12:43.18,Default,,0000,0000,0000,,So it's reaching us is just now.
Dialogue: 0,0:12:43.18,0:12:46.69,Default,,0000,0000,0000,,So let me just fast\Nforward 13.4 billion years
Dialogue: 0,0:12:46.69,0:12:49.62,Default,,0000,0000,0000,,from this point now to\Nget to the present day.
Dialogue: 0,0:12:49.62,0:12:54.84,Default,,0000,0000,0000,,So if I draw the whole visible\Nuniverse right over here,
Dialogue: 0,0:12:54.84,0:12:56.30,Default,,0000,0000,0000,,this point right\Nover here is going
Dialogue: 0,0:12:56.30,0:13:00.34,Default,,0000,0000,0000,,to be-- where it was emitted\Nfrom is right over there.
Dialogue: 0,0:13:00.34,0:13:04.89,Default,,0000,0000,0000,,We are sitting right over there.
Dialogue: 0,0:13:04.89,0:13:06.64,Default,,0000,0000,0000,,And actually, let me\Nmake something clear.
Dialogue: 0,0:13:06.64,0:13:08.77,Default,,0000,0000,0000,,If I'm drawing the whole\Nobservable universe,
Dialogue: 0,0:13:08.77,0:13:10.92,Default,,0000,0000,0000,,the center actually\Nshould be where we are.
Dialogue: 0,0:13:10.92,0:13:12.63,Default,,0000,0000,0000,,Because we can observe\Nan equal distance.
Dialogue: 0,0:13:12.63,0:13:14.64,Default,,0000,0000,0000,,If things aren't\Nreally strange, we
Dialogue: 0,0:13:14.64,0:13:16.62,Default,,0000,0000,0000,,can observe an equal\Ndistance in any direction.
Dialogue: 0,0:13:16.62,0:13:19.21,Default,,0000,0000,0000,,So actually maybe we should\Nput us at the center.
Dialogue: 0,0:13:19.21,0:13:21.65,Default,,0000,0000,0000,,So if this was the entire\Nobservable universe,
Dialogue: 0,0:13:21.65,0:13:26.18,Default,,0000,0000,0000,,and the photon was emitted from\Nhere 13.4 billion years ago--
Dialogue: 0,0:13:26.18,0:13:29.80,Default,,0000,0000,0000,,so 300,000 years after\Nthat initial Big Bang,
Dialogue: 0,0:13:29.80,0:13:35.62,Default,,0000,0000,0000,,and it's just getting\Nto us, it is true
Dialogue: 0,0:13:35.62,0:13:41.15,Default,,0000,0000,0000,,that the photon\Nhas been traveling
Dialogue: 0,0:13:41.15,0:13:47.05,Default,,0000,0000,0000,,for 13.7 billion years.
Dialogue: 0,0:13:47.05,0:13:50.90,Default,,0000,0000,0000,,But what's kind of nutty about\Nit is this object, since we've
Dialogue: 0,0:13:50.90,0:13:53.97,Default,,0000,0000,0000,,been expanding away from each\Nother, this object is now,
Dialogue: 0,0:13:53.97,0:13:56.18,Default,,0000,0000,0000,,in our best\Nestimates, this object
Dialogue: 0,0:13:56.18,0:14:06.42,Default,,0000,0000,0000,,is going to be about 46 billion\Nlight years away from us.
Dialogue: 0,0:14:06.42,0:14:08.78,Default,,0000,0000,0000,,
Dialogue: 0,0:14:08.78,0:14:10.16,Default,,0000,0000,0000,,And I want to make\Nit very clear.
Dialogue: 0,0:14:10.16,0:14:13.22,Default,,0000,0000,0000,,This object is now 46 billion\Nlight years away from us.
Dialogue: 0,0:14:13.22,0:14:16.78,Default,,0000,0000,0000,,When we just use light to\Nobserve it, it looks like,
Dialogue: 0,0:14:16.78,0:14:18.53,Default,,0000,0000,0000,,just based on light\Nyears, hey, this light
Dialogue: 0,0:14:18.53,0:14:21.28,Default,,0000,0000,0000,,has been traveling 13.7\Nbillion years to reach us.
Dialogue: 0,0:14:21.28,0:14:22.98,Default,,0000,0000,0000,,That's our only way\Nof kind with light
Dialogue: 0,0:14:22.98,0:14:24.48,Default,,0000,0000,0000,,to kind of think\Nabout the distance.
Dialogue: 0,0:14:24.48,0:14:27.74,Default,,0000,0000,0000,,So maybe it's 13.4\Nor whatever-- I
Dialogue: 0,0:14:27.74,0:14:31.34,Default,,0000,0000,0000,,keep changing the decimal-- but\N13.4 billion light years away.
Dialogue: 0,0:14:31.34,0:14:36.60,Default,,0000,0000,0000,,But the reality is if you had a\Nruler today, light year rulers,
Dialogue: 0,0:14:36.60,0:14:38.57,Default,,0000,0000,0000,,this space here has\Nstretched so much
Dialogue: 0,0:14:38.57,0:14:41.70,Default,,0000,0000,0000,,that this is now 46\Nbillion light years.
Dialogue: 0,0:14:41.70,0:14:43.16,Default,,0000,0000,0000,,And just to give\Nyou a hint of when
Dialogue: 0,0:14:43.16,0:14:45.10,Default,,0000,0000,0000,,we talk about the cosmic\Nmicrowave background
Dialogue: 0,0:14:45.10,0:14:47.96,Default,,0000,0000,0000,,radiation, what will\Nthis point in space
Dialogue: 0,0:14:47.96,0:14:49.50,Default,,0000,0000,0000,,look like, this\Nthing that's actually
Dialogue: 0,0:14:49.50,0:14:52.01,Default,,0000,0000,0000,,46 billion light years\Naway, but the photon only
Dialogue: 0,0:14:52.01,0:14:54.54,Default,,0000,0000,0000,,took 13.7 billion\Nyears to reach us?
Dialogue: 0,0:14:54.54,0:14:56.12,Default,,0000,0000,0000,,What will this look like?
Dialogue: 0,0:14:56.12,0:14:59.61,Default,,0000,0000,0000,,Well, when we say\Nlook like, it's
Dialogue: 0,0:14:59.61,0:15:02.34,Default,,0000,0000,0000,,based on the photons that\Nare reaching us right now.
Dialogue: 0,0:15:02.34,0:15:05.35,Default,,0000,0000,0000,,Those photons left\N13.4 billion years ago.
Dialogue: 0,0:15:05.35,0:15:07.09,Default,,0000,0000,0000,,So those photons are\Nthe photons being
Dialogue: 0,0:15:07.09,0:15:10.04,Default,,0000,0000,0000,,emitted from this\Nprimitive structure,
Dialogue: 0,0:15:10.04,0:15:16.46,Default,,0000,0000,0000,,from this white-hot\Nhaze of hydrogen plasma.
Dialogue: 0,0:15:16.46,0:15:19.24,Default,,0000,0000,0000,,So what we're going to see\Nis this white-hot haze.
Dialogue: 0,0:15:19.24,0:15:26.93,Default,,0000,0000,0000,,So we're going to see this kind\Nof white-hot plasma, white hot,
Dialogue: 0,0:15:26.93,0:15:28.79,Default,,0000,0000,0000,,undifferentiated\Nnot differentiated
Dialogue: 0,0:15:28.79,0:15:32.55,Default,,0000,0000,0000,,into proper stable atoms,\Nmuch less stars and galaxies,
Dialogue: 0,0:15:32.55,0:15:33.71,Default,,0000,0000,0000,,but white hot.
Dialogue: 0,0:15:33.71,0:15:36.22,Default,,0000,0000,0000,,We're going to see\Nthis white-hot plasma.
Dialogue: 0,0:15:36.22,0:15:38.64,Default,,0000,0000,0000,,The reality today is\Nthat point in space
Dialogue: 0,0:15:38.64,0:15:40.19,Default,,0000,0000,0000,,that's 46 billion\Nyears from now,
Dialogue: 0,0:15:40.19,0:15:45.16,Default,,0000,0000,0000,,it's probably differentiated\Ninto stable atoms, and stars,
Dialogue: 0,0:15:45.16,0:15:46.78,Default,,0000,0000,0000,,and planets, and galaxies.
Dialogue: 0,0:15:46.78,0:15:49.02,Default,,0000,0000,0000,,And frankly, if that\Nperson, that person,
Dialogue: 0,0:15:49.02,0:15:51.21,Default,,0000,0000,0000,,if there is a civilization\Nthere right now
Dialogue: 0,0:15:51.21,0:15:52.70,Default,,0000,0000,0000,,and if they're sitting right\Nthere, and they're observing
Dialogue: 0,0:15:52.70,0:15:54.61,Default,,0000,0000,0000,,photons being emitted\Nfrom our coordinate,
Dialogue: 0,0:15:54.61,0:15:56.53,Default,,0000,0000,0000,,from our point in\Nspace right now,
Dialogue: 0,0:15:56.53,0:15:57.92,Default,,0000,0000,0000,,they're not going to see us.
Dialogue: 0,0:15:57.92,0:16:01.81,Default,,0000,0000,0000,,They're going to see us\N13.4 billion years ago.
Dialogue: 0,0:16:01.81,0:16:05.14,Default,,0000,0000,0000,,They're going to see the\Nsuper primitive state
Dialogue: 0,0:16:05.14,0:16:07.31,Default,,0000,0000,0000,,of our region of\Nspace when it really
Dialogue: 0,0:16:07.31,0:16:09.16,Default,,0000,0000,0000,,was just a white-hot plasma.
Dialogue: 0,0:16:09.16,0:16:11.58,Default,,0000,0000,0000,,And we're going to talk more\Nabout this in the next video.
Dialogue: 0,0:16:11.58,0:16:12.70,Default,,0000,0000,0000,,But think about it.
Dialogue: 0,0:16:12.70,0:16:15.51,Default,,0000,0000,0000,,Any photon that's coming\Nfrom that period in time,
Dialogue: 0,0:16:15.51,0:16:17.67,Default,,0000,0000,0000,,so from any direction,\Nthat's been traveling
Dialogue: 0,0:16:17.67,0:16:21.17,Default,,0000,0000,0000,,for 13.4 billion years\Nfrom any direction,
Dialogue: 0,0:16:21.17,0:16:23.72,Default,,0000,0000,0000,,it's going to come from\Nthat primitive state
Dialogue: 0,0:16:23.72,0:16:27.39,Default,,0000,0000,0000,,or it would have been\Nemitted when the universe was
Dialogue: 0,0:16:27.39,0:16:29.58,Default,,0000,0000,0000,,in that primitive\Nstate, when it was just
Dialogue: 0,0:16:29.58,0:16:32.20,Default,,0000,0000,0000,,that white-hot plasma,\Nthis undifferentiated mass.
Dialogue: 0,0:16:32.20,0:16:33.57,Default,,0000,0000,0000,,And hopefully,\Nthat will give you
Dialogue: 0,0:16:33.57,0:16:36.48,Default,,0000,0000,0000,,a sense of where the\Ncosmic microwave background
Dialogue: 0,0:16:36.48,0:16:38.92,Default,,0000,0000,0000,,radiation comes from.