This week's episode of Cosmos: A Spacetime Odyssey really honored the "spacetime" component of the series' title. Veering away from the science history vignettes of recent episodes — but not their anti-creationist campaign — the fourth episode in the rebooted series was all about the laws of physics, and what happens when they're broken. 

What if everything that is happening has already happened?

Danielle: I have to say that I think this week’s episode was the most informative so far. Neil deGrasse Tyson is clearly a very gifted teacher, and his explanation of Einstein’s principles of relativity was illuminating. And the approach looking at how time travel works in the context of the space-time continuum, and the types of illusions we confront each day was captivating. This was also the first time he threw some hard math our way, which I enjoyed. Plus black holes are cool, and imagining what happens within a black hole is also cool.

Abby: So first of all, I'm pretty sure this week's episode means that Neil deGrasse Tyson is a Time Lord. The science fiction portion of the show — where Tyson slides from what we know about black holes to the coolest things we can plausibly imagine about them — was a much-needed demonstration of educated fantasy. 

Danielle: I don’t actually know anything about string theory, but this is a broad strokes explanation of string theory, right? Black holes could potentially break the laws of physics, and possibly act as a portal to other universes, or times, or dimensions? Okay I’m going to go reread Flatland and then A Wrinkle In Time, brb.

Abby: Yes, good, me too. I think you're correct, although I too have a giant string theory blind spot. I know commenters on the internet are really reluctant to tell someone they're wrong about something, now might be a good opportunity to try that out, people. 

Danielle: Speaking of fantasy and fiction, Tyson again threw some shade at anti-evolutionists, saying that to believe that the universe is between 6,000 and 7,000 years old “is to extinguish the light from most of the galaxy.” He’s targeting young-earth creationists here, who believe that the world is 6,500 years old  but this would, logically, mean that we would only be able to see stars that were formed 6,500 years ago, which isn’t the case. It’s a standard argument, but Tyson delivers it with flair, and the earlier part of the episode really sets him up to authoritatively rule out any possibility of a young earth.

Abby: He's also setting up a really interesting comparison: viewers, which universe do you want? The disproven, small universe of the young-earth creationists that could only extend to the crab nebula and back (a tiny portion of the milky way galaxy) or the one with galaxies billions of years older than the earth itself, with black holes leading to an extraordinary unknown? 

Danielle: Exactly. Tyson still presents science as a nearly-mystical pursuit. The show opens with cartoon William Herschel (who discovered Uranus and apparently was also a musician) talking about ghosts -- planet ghosts, it turns out. Which takes us into time travel, which takes into spacetime, etc. The idea of science as belief in the extraordinary is highlighted, once again. Four episodes in, I think it’s safe to say that this is a Theme of Cosmos.

Abby: Yes, for sure. Tyson is asking mystical question and providing scientific — or at least science-based — answers. Not to get too academic, but this episode actually reminded me a little of St. Augustine's theories of time and memory. He divided time up into memory, experience, and expectation, or "a time present of things past; a time present of things present; and a time present of things future." He does this to bracket out our understanding of "time" from what Augustine, who was after all a Bishop, believed to be a defining characteristic of God: an eternalness. For Augustine, there was no literal act of "creation" of the universe — it is a unified act with the rest of the universe. Although obviously science leads to somewhat different conclusions and priorities than those of Augustine's, it felt like Tyson was answering or wondering about the same questions. 

Danielle: That's an interesting point, and is in keeping with the show's openness to different approaches to science and learning. I don't think that the show is anti-religion at all, I think it's anti-bias and anti-closed-mindedness, and I wonder if an allusion to religious texts is intentional.

On an unrelated note, the graphics in this episode are amazing -- especially when it came to the black hole stuff. But also the more mundane things were pretty cool, like New York City in zero gravity and hyper-gravity, and that girl riding her motorbike at super-high speed. That scene was especially cool because of all the music.

Abby: ... 

Danielle: Okay no, the music was pretty silly. And I wasn’t crazy about the live-action science scenes. The cartoons can be a bit awkward but the “scientist-writing-science-things-with-a-quill” thing is definitely hackneyed and worse. I am happy, however, that the show seems to take great care to note when there’s no historical record of what someone actually looked like -- as with John Marshall, except for a description of him as “a short little man of black complexion and fat,” which is a pretty good detail.

Abby: Given our discussion last week about the show's limitations when it comes to the history of science, their adherence to not imagining the faces of those who left no record of them is kind of amusing to me. But at least Marshall was not, a la last week's Hooke, turned into a hunchbacked villain.  

Danielle: Poor Hooke, that was unfair. Should we talk about Tyson on the bicycle? It’s this episode’s Tyson-with-a-baby, except I think it might be better because it’s in Italy and ends with a picnic and an old book. Clearly this show knows what it’s audience wants.

Abby: Yes. I would like a picnic with Tyson, and then he can explain to me how I go back in time to meet Carl Sagan. Good idea. 

Danielle: That was basically the implication, right? Tyson ends the episode talking about our possible ability to travel back into time, which I assumed would mean more picnics with scientists like Tyson and Sagan.

But what does the Internet think?

Danielle: I really appreciated the academic tone of this episode, and I wasn’t the only one:

 Everyone was very sensitive to the creationist jab:

And, as always, @NASA and @COSMOSonTV had some pretty great complementary info: 

What we learned: 

Danielle: This was a major connecting-the-dots episode for me. I knew what light-years are and what gravity is and how black holes work, mostly, but I couldn’t have explained to you how and why those are all connected. I probably couldn’t explain it now, either, but this episode presented the information in a way that really made it click for me. It was satisfying in the way that solving algebra problems is satisfying, you know?

Also, I did not know that Patrick Stewart was apparently a guest on this episode. I somehow totally missed that. 

Abby: I knew I recognized that voice! He played William Herschel, in what I thought was the best use of animation so far in the Cosmos reboot. 

Click through for our thoughts on episodes one, two, and three