# How much of “Doctor Who” might really be possible?

Science shows why Doctor Who is so special.

As Doctor Who’s 50th anniversary looms, time travel is everywhere – on the screen, at least. Famously, the Doctor can whizz through the years using a “dimensionally transcendental” machine, the TARDIS, and make changes to the past as and when he likes. But what is time travel – and how much of “Doctor Who” might really be possible?

A handy definition of time travel comes from philosopher David Lewis. Lewis says time travel involves a journey having different durations viewed from outside (in “external time”) or from inside (in “personal time”). Suppose you spend five minutes travelling aboard your machine, as measured by (e.g.) your watch and your memories. On arrival, you find 150 years have elapsed in the outside world. Congratulations, you have time-travelled. Five minutes of your personal time has covered 150 years of external time.

Odd as this sounds, Einstein’s theory of Special Relativity introduced such possibilities to physics in 1905. The theory says: the duration of a process varies with the relative velocity of the observer. The closer that relative velocity gets to the speed of light, the longer the travelling process takes.

Suppose you want to see the Earth a billion years hence, but worry you have only about 50 personal years left. Special Relativity specifies that if you travel very close to the speed of light relative to the Earth, your 50 personal years can cover one billion Earth years.

In backward time travel, personal and external time differ in direction, so journeys end in external time before, not after, they begin; you spend five personal minutes travelling 150 years into the external past. General Relativity suggests that the universe is essentially curved spacetime, which might allow such divergences of external and personal time.

Relativity treats space and time as aspects of a single entity: “spacetime”. One of the more remarkable features of General Relativity is that it allows time and space axes to be interchanged, so one observer’s space axis can be another observer’s time axis.

In 1949, Austrian mathematician Kurt Gödel used General Relativity to describe a universe where intrepid voyagers can go anywhere in (past or future) time without travelling faster than light. Gödel’s universe has no boundaries in space or time, and all the matter in it rotates. But our finite, non-rotating universe is not Gödel’s. Despair not though – simply spin an ultradense, very (maybe infinitely) long cylinder very fast. Spacetime should curve around the cylinder so the direction of the local future partially points into the external past. Such devices are called “Tipler Cylinders”, after physicist Frank Tipler.

Better yet, quantum theory suggests that “wormhole” connections between different spacetime points spontaneously form and break all the time. The chances are that natural wormholes are tiny - vastly smaller even than an electron, (and a billion trillion electrons can fit in a teaspoon). But you could perhaps find (or create) a wormhole big enough and durable enough to let you slip through into the past. Difficult, but theoretically possible.

## No, you can’t kill your physics teacher

So perhaps you could travel into the past. But what about paradoxes? What is to stop you assassinating your grandfather or yourself as infants? One answer says: logical consistency.

Classical logic says you cannot consistently kill in infancy someone who achieves adulthood. But, Lewis says, time travel need not involve doing the logically impossible – provided travellers’ actions in the past are consistent with the history whence they come. So you could try killing your baby grandfather, but something would foil you – you would sneeze, or your gun would jam. Lewisian time travel is therefore (classically) consistent, but might look very strange, since seemingly possible actions (like shooting an unprotected infant) would prove impossible.

Another view says that backward time travel requires many worlds – that is, many different but equally real versions of physical reality. Physicist David Deutsch and philosopher Michael Lockwood argue that time travel must involve inter-world travel. If you travel backwards in time, you must arrive in a history different from your native one and so would be quite unfettered by your past once you get there. You could even kill this other history’s counterparts of your grandfather and yourself.

Both these concepts of backwards time travel may disappoint anyone wanting to change the “one and only” past. Conventional logic says time travellers would either help make history what it was (Lewis) or create a different history (Deutsch/Lockwood). However, quantum logic might let travellers change the actual (one-and-only) past.

Suppose we hold that quantum measurements determine (or change) quantities measured, even if those quantities lie in the past. Someone could travel back and “observe” history turning out differently from how it originally was, thereby retrospectively making actuality different from what it had been. What would happen to travellers who rebooted history is not clear, but this model seems closer to the time travel familiar from “Doctor Who” and other fictions. Beware, though, because quantum theory allows no predicting, and still less controlling, of the outcomes of changing the past. There would be no way to foresee the effect you would have on the present.

So classical logic, General Relativity and quantum theory all seem to permit time travel. Classical logic plus General Relativity suggest backward travellers face weird consistency constraints. Many-worlds travellers face no constraints, but get displaced into different histories. Quantum-logic travellers could change the (one and only) past without constraints, but they couldn’t predict or control what they would get.

So far, however, it seems only the Doctor knows how to change the past at will.

Alasdair Richmond received funding from the Arts and Humanities Research Council, to fund one semester of a two-semester leave period that covered the academic year 2008-2009.

The eleven incarnations of the Doctor. Image: BBC/Matt Burlem

Alasdair Richmond is a Senior Lecturer in Philosophy at the University of Edinburgh.

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# How Gossip Girl changed the way we talk about television

Recappers Chris Rovzar and Jessica Pressler reminisce about the Best. Show. Ever.

If you watched Gossip Girl from 2007-2012, then you’ll know it was The Greatest Show of Our Time. Silly, ridiculous, insider-y, and deeply New York, Gossip Girl was a show that lived and died on its in jokes. For so many of the show’s viewers, talking about this ridiculous Rich Kids of The Upper East Side drama was as important as watching it. But, premiering in 2007, Gossip Girl aired at a time just before social media dominated television conversations. Now, every viewer has a channel to make memes about their favourite show as soon as it hits screens. Gossip Girl was a show about bitchy teenagers mocking each other that cried out for audiences to tease them, too. They just needed a space to do it in.

Chris Rovzar and Jessica Pressler caught on to that fact early. TV recaps were still a fledgling genre when the Gossip Girl pilot emerged, but the New York Magazine writers could tell that this was a show that needed in-depth, ironic analysis, week on week. The most popular Gossip Girl recaps were born. These included the Reality Index (points awarded for, to take one episode, being “More Real Than Serena Sleeping With a Teacher After Less Than One Semester”), the cleavage rhombus (in tribute to Serena’s fashion choices), and the Most Obnoxious Real-Estate Conundrum of Our Time. If this is all second nature, you might even know what I mean when I say “No points, just saying.” It is these kinds of inside jokes that made New York Magazine’s Vulture recaps of the show so irresistible, and so influential. Each week, Rovzar and Pressler would run down the most absurd and the most spot-on New York moments of the episodes, and soon developed a cult following with a very devoted audience. Their recaps were became so popular that the creators responded to their burning questions, and the two were given a cameo on the show itself. They even also wrote recaps of the recaps, to include the best observations from hundreds of commenters.

Now the show is over, their work has spawned a thousand similarly tongue-in-cheek TV blogs: from ever-popular Game of Thrones power rankings to new versions of the Reality Index for other shows. A decade after Gossip Girl first aired, I reminisced with Rovzar and Pressler about their contributions to the Best. Show. Ever.

How did you come across Gossip Girl? Was it love at first watch?

Jessica: I had just moved to New York. Chris and I were thrown together at New York Magazine vertical Daily Intelligencer. He was much more of a seasoned New York person who knew what things were cool, and I was this yahoo from a different city. I was basically Dan Humphrey, and he was Serena. He got the pilot from a publicist, and he said there was a lot of a hype. The O.C. had been a huge show. So the fact the creators [were] coming to New York, doing all these real location shoots, and it was going to be a New York-y show was exciting, especially to us, because we were in charge of covering local New York news at that point. And it was really boring in 2007! Everything exciting happened the following year, like the Eliot Spitzer scandal, but in 2007 there was nothing going on. And Sex in the City had just ended, so there was a void in that aspirational, glamorous, TV space. So we were like, we’re going to hype this up, and then we’ll have something really fun to write about. And it was fun!

Chris: The CW needed a new hit, and it was the show that they were hoping would define the programming they would make going forward, so they really hyped it up before it aired. They sent us a screener. We watched it and realised that because they filmed it in New York, they were going to really use the city. It checked the boxes of Sex in the City and The O.C., with a young beautiful cast out in real world situations.

Jessica and I decided that this show was going to be a show that we wanted to write about, because it was so New York-y. I don’t think our bosses cared either way. Our bosses were grown-ups! They didn’t watch Gossip Girl! But from the very beginning, we called it The Greatest Show of Our Time, because we knew it was going to be a really iconic New York show. And it was very good at making these running jokes or gags, like Blair with her headbands, or Serena with her super tight dresses.

And the cleavage rhombus?

Chris: And the cleavage rhombus! We eventually got to know the costume designer and the producers and the writers. Once they recognised the things that we were writing about in the show, they would adopt them. The cleavage rhombus came up a few more times because they knew the audience knew about the cleavage rhombus.

Do you have an all-time favourite character or plot line or episode?

Chris: Our favourite character was Dorota. She was very funny and the actress, Zuzanna Szadkowski, was very well used. I think we were all rooting for Chuck and Blair. Sometimes with shows like Friends, by the end, when Ross and Rachel finally get together, you think, “Hm, I’m not sure I wanted Ross and Rachel to get together.” But the show was good at making Chuck and Blair the central romance, and you were psyched about how that ended up.

Jessica: Well, now, of course you look back and the Jared [Kushner] and Ivanka [Trump] cameo was, like, the best thing ever. It’s so nice to remember a time when those two were extras in our lives, instead of central characters. And then Nate, of course, went and bought that newspaper, which I believe was called The Spectator, which was a thinly veiled Observer. There was this succession of blonde temptresses brought in to tempt Nate. I don’t even know what he was supposed to be doing! I don’t know why they were there, or what their purpose was! But that was an ongoing theme, and that was kind of amazing. One was a schoolgirl, one was a mom. Catherine, and Juliet – and yes, I do remember all their names.

But for us, it was the real stuff that was really fun. They put in cameos of people only we would know – like Jonathan Karp, the publisher at Simon & Schuster. Or the couple who run The Oracle Club [a members’ club in New York] – I saw them recently and we talked about how we still receive \$45 royalty cheques from our cameos because an episode aired in Malaysia. And Armie Hammer! They really went out of their way to involve real New Yorkers.

How did it work each week? Did you have screeners and write it leisurely in advance?

Jessica: No, no, we had to do it live! We had a screener for the pilot. We got them probably three times in the whole course of the show. We would normally be up till three in the morning.

Chris: My husband eventually stopped watching it with me because I was constantly pausing and rewinding it, asking: “What did they say? What was that? Did you see that street sign? Do you think that dress is Balenciaga?” It becomes very annoying to watch the show with someone who’s doing that. Each of us would do our own points and we would email them to each other and mix them up. That way you could cover a lot more stuff.

What made you decide to do the Reality Index? Did you ever really disagree on points?

Chris: It always more about wanting to say something funny than about the actual points. Very occasionally we would disagree over whether something was realistic or not. We were both adults, and there was a lot of trying to figure out what kids would do. Like in the first episode, they sent out paper invites for a party, and we said, “Oh, no, kids would use Evite!” And then a lot of readers were like “Are you kidding me? Kids would use Facebook cause this is 2007.” And we were like, “Oh yes, we’re not actually kids. We don’t know.”

Jessica: We came from different places of expertise. He had been in New York so much longer than me. In a cotillion scene, he knew the name of the band that was playing, because he knew which bands people had come to play at cotillion. I was more like, “This is realisitic in terms of the emotional lives of teenagers.” But the Reality Index stopped being about reality early on, and we had to just had to comment on the cleavage rhombus instead.

The comments were really important – how did you feel about all these people who seemed to have as intense feelings about the minute details of this show as you did?

Chris: We definitely weren’t expecting it, more so because internet commenters on the whole are awful. They’re mean and they’re angry and they have an axe to grind. Our commenters were very funny and wanted to impress each other and wanted to make each other laugh. They were really talking to each other more than they were talking to us. We decided, a couple of years in, to start rounding up their comments and do a recap of the recap. This was one of the most rewarding parts about it, because they were just so smart and on top of it. And they definitely disagreed with us. A lot!

Jessica: It did feel like people liked the Reality Index because of the participatory aspect of it. We became more like the moderators of this little world within a world. We couldn’t believe it - we thought it was amazing and bizarre. There would be hundreds of comments as soon as you put it up, it was like people were waiting. And sometimes people would email us, if one of us had overslept or been out to dinner the night before so couldn’t watch the show until the morning. And you got to know people through that – actual humans. I know some of the commenters now!

You wrote the “Best Show Ever” cover story on Gossip Girl for New York Magazine, which reads like it was incredible fun to write, and is now immortalised as a key moment in the show’s history. Every fan of the show remembers that cover image. What’s your favourite memory from working on that piece?

Jessica: Oh my God! It was so fun! We split them up – I interviewed Chace Crawford and Jessica Szohr and Blake Lively. Those kids were in New York living this vaguely Gossip Girl-esque lifestyle at the same time as the show was on, being photographed as themselves, but often in character during filming. So the overlap was fun. Ed Westwick and Chace Crawford lived together in a dude apartment! I think Sebastian Stan moved in. And Penn Badgley would hate me saying this, but he was and is Dan. He just never wasn’t Dan. He lived in Brooklyn and dated Blake Lively and girls who looked like Vanessa. It was so fun to have this show within a show going on in New York.

Chris: The fun thing about the kids, is that they were all really excited. For almost all of them, it was their first brush with fame. Blake Lively was the only one who had an acting background. So they were really excited to be in the city. It was very fun to hang out with them, and they all liked each other. It was fun to be out in the world with them. Leighton Meester is very funny, and a really fun person to be around, and after we did the story someone sent in a sighting to Page Six of us, where we had lunch. And when I went out for lunch with Chace Crawford, who’s also very nice, it was the first time I’d been in a situation where somebody tries to subtly take a cellphone photo of you. I was like: “Wow, I have done this, as a New Yorker, and it is so obvious.” You think you’re being slick and it’s very, very plain to see. And Chace was very gracious with everybody. I wasn’t there for the photoshoot but Taylor Momsen’s mom had to be there, because I think she was 16. And I remember when the photos came back, thinking, “Errr... we have some very young people in underwear on the cover!” But I guess everyone was OK with it! It was a really striking cover, and a really great choice with the white virginal clothes and the implication of the opposite. I love how it came out.

Can you talk about your cameo on the show? How did that work, what was it like?

Chris: That was really fun. I don’t know what I expected, but I didn’t expect it to be so interesting and fun. They wanted someone from New York [Magazine], they wanted someone from Vanity Fair, and they wanted someone from another magazine, and I think they’d asked a lot of magazines if they would send an editor. I was at Vanity Fair, and they asked Graydon Carter, the editor-in-chief, if he would do it – and he said no. One of my friends from college was by that point a writer on the show, and she said to the producer: “You know, if you want a Vanity Fair editor, I know one guy who will definitely do it!” And then they asked me and I had to ask the publicist for Vanity Fair if I could do it. And she laughed! And I said, “No, I’m serious, can I do this?” And she said “Oh! Uhh… Yeah, OK.”

It was me, Jessica, and Katrina vanden Heuvel from The Nation. Katrina was the only one working the whole time: tweeting and writing stuff. Jessica and I were like kids in a candy store. We were running around checking out the set, opening drawers! They had us wear our own clothes, which was stressful.

Jessica: They put fun clothes on me! It was so nice, I got to wear a really good outfit! Which I wish I had stolen, actually. But we got to the set and they had made up our offices. We sent them pictures of what they looked like and they recreated it.

Chris: They completely recreated it, right down to the Post-It notes that I had all along my bookshelves. Some of the books that I had on my desk were there. It was really surreal. Sitting there with Michelle Trachtenberg and Penn Badgley was completely surreal. They were funny, we joked around, it took probably 15 minutes.

Jessica: My scene was with Penn, and I had a line that made absolutely no sense. And we were all like, “That line makes no sense!” And they were like, “Oh it’s fine, just say it anyway.” And I thought: “Ok, well they’ll cut it out later.” But no, it just… went in.

Chris: But so many cool people had done cameos already, like Jared and Ivanka and Tory Burch, and just a million New Yorkers you’d heard of. So it was cool to join that crew.

You had this cameo, and plenty of people who worked on and starred in the show confessed to having read your recaps religiously. Stephanie Savage even emailed in over the exact location of Dan’s loft – whether it was Dumbo or Williamsburg. What was it about these recaps that allowed them to enter the world of the show in a way that TV writing normally doesn’t?

Chris: It was a very early recap. There wasn’t the endless recapping that there is now, of every show. It was kind of a silly show to recap – it wasn’t like Game of Thrones, where there’s all this politics to analyse. So it was an unusually devoted account of the show, with a ton of attention to detail – and then all the commenters also had a ton of attention to detail. So it was a great way for the show to get a sense of what the audience was thinking. And I think it was just funny for them. When they made a joke, we would catch the joke and laugh at it and make a joke back. It became a fun game for them too.

Jessica: The creators were definitely trying to foster the same atmosphere that we picked up on. They said early on that their goal for the show was “cultural permeation”. So they did what they could to encourage us, in some ways, and responded to us when we had questions.

Do you think your recaps changed television writing? Have you seen anything by other writers in recent years that has made you think, “Oh, we influenced that!”? For me, the Reality Index was very influential, and I feel like it was instrumental in this tone that was, yes, snarky and mocking, but the kind of mocking that can only come out of genuinely, truly loving something – now, that’s how most TV writing sounds.

Chris: I think we definitely were early on the trend of having the audience feel like they had the right to have their opinion on the show known, that they could voice an opinion – and maybe at some point the creators of the show would hear it. I think also having a very specific structure to a recap was new. Over the past ten years you’ve seen a lot of people do Power Rankings or try different ways of doing recaps other than just repeating what happened. I’d like to think that the recaps helped break the mould and create a new format.

Jessica: I definitely see things that are called Reality Indexes, and I’m pretty sure that wasn’t a thing before us, because it doesn’t even totally make sense as a concept. As far as tone, I think that came both from the combination of Chris’s and my personalities – Chris was more of the fan, and I was more of the snark. But also that was Vulture’s thing – I think the site’s tagline was “heart of a fan, mind of a critic”. It came after the early 2000s era of pure snark and sarcasm. But I just met Rebecca Serle, who wrote the series Famous in Love, and she said the Gossip Girl recaps helped inspire her career. I was like: “That’s amazing!”

Looking back, why do you think Gossip Girl and the conversation around captured the zeitgeist?

Chris: It had a lot of elements of the great shows. It had a core ensemble cast like Friends. It had a very soapy way of running the plots, that just meant that a lot happened in every episode, and not all of it was believable! And that’s really fun to watch. But unlike Ugly Betty, which was making fun of telenovelas, it took itself seriously, which let the audience take it seriously too, while at the same time laughing about it and appreciating how over the top it was. And I also think the cast was very key to it. They were so young and attractive and good, and you could tell they were all going to go on to bigger and better things. You were watching them at the very start of their careers. And they all stayed through the whole thing, and that was great. You knew the show was going to end the way the creators wanted, which made it feel like a great, rare moment in TV.

Jessica: That show captures that era of socialites in New York City, when it was like Olivia Palermo and Tinsley Mortimer and everyone was running around going to parties and being photographed. It was like an education about New York as I was arriving there. And they did an amazing job, especially now, when you look back at it. All those location shots! I don’t think people can afford those any more, they just aren’t happening. And the costumes! All of that was so enjoyable and fun. I’m not sure I fully appreciated how fun it was, like I do now, when everything is much more drab and Brooklyn-centric. But I felt a real kinship with Penn Badgley because we talked a lot over the course of things, occasionally about how we didn’t expect the show to go on this long! He wanted to go and play other roles and I wanted to do… other things, and we were both stuck with Gossip Girl.

And finally: looking back, how do you feel about Dan being Gossip Girl?

Chris: I was talking to someone about this the other day! I still don’t know if in the books, Dan was Gossip Girl. At the time, we didn’t really devote a lot of time to thinking about who Gossip Girl would be. It felt like they were just going to pick somebody in the last season – which they did. But I thought they did a good job of backing up that decision.

Jessica: Oh my God, I was just talking about this! I feel like, you know… It’s just a total disappointment, there’s no getting around it. They tried to play it like they had been planning for it to be Dan all along, and that was clearly false. So it was annoying that they postured in that way. But I remember maybe even just the season before, a character said “Gossip Girl is all of you! Look at you all, on your phones!” That should have been the ending, that Gossip Girl was everyone. That would have been the cleverer ending, in a way. But Dan as Gossip Girl gets a minus from me in the Reality Index. -100

Anna Leszkiewicz is a pop culture writer at the New Statesman.