Let me say right up front that I LOVE THIS SHOW, a Netflix orginal about a team of covert operatives, part of a small army sent back in time to prevent their own awful post-apocalyptic future. Problem is, they can't project mass backwards in time, only information, so they have to “over-write” the brains of people who were doomed to die, according to their historical records.   

[image from Netflix]

Each team typically has five members, each with a specialty, a not entirely implausible superpower. “Our” team consists of:   

Traveler 3468, “the Boss,” or team leader, inhabiting the body of Grant MacLaren, an FBI agent. He can apparently speak every human language fluently. Sitting in the front of the picture above.  You may recognize actor Eric McCormack from the hit sitcom Will & Grace, but here he is a married straight guy. Acting!    

(Also, while the photo foregrounds him both in size and clarity, the show itself is much more even, in terms of screen time and narrative importance.  Just sayin').

Traveler 3465, Carly Shannon, (on the left) is the team's Tactician. They're all way tougher than I am (just as an example), but if they need someone really expertly hurt, Carly is the go-to. Which is lucky for her, because the albatross around her host's neck is her abusive, alcoholic beat-cop baby daddy. He pretty regularly needs a knee in the 'nads to keep him in line.    

Traveler 3326, Philip Pearson, the baby-faced one immediately to the right of MacLaren, likewise got screwed by being unknowingly dropped into the body of a heroin addict. This is pretty disruptive for him, as he is the team's Historian, trained from birth (and probably genetically modified) to have perfect memory recall, better than the best current science has ever found (as in this post by @viralbear). That also means that he was not really a volunteer like the others were. He spends most of his time in their super-team hideout, “Ops,” doing hacky-type things.    

 Traveler 3569, the Medic, inhabiting the body of a brain-damaged woman named Marcy Warton. Turns out you should not base your time travel host-body decisions on a Facebook page. She does not have a superpower, exactly, but she has advanced medical knowledge from the future, and she's way better trained in hand-to-hand combat than your average doctor.  Her social worker calls her "Batgirl."

Traveler 0115, the Engineer, is an old man, one of the first subjects of the consciousness transfer program, and a veteran of multiple transfers, currently inhabiting the body of a high school quarterback named Trevor Holden. In addition to being ripped, he also has a lot of scientific and technical knowledge, so when they need some impossible futuristic gadget (which is not that often, really), he and Philip are the ones who build it. Homework is not such an issue for Trevor, but his blatant personality change (from asshole jock to stand-up physics nerd) causes him much trouble (covert operatives, remember?).    

You can see that one of the major tensions in the show is the double life, a classic trope from the super-hero comics I grew up on. It's hard to do the double-life thing in a way that is not ridiculously cheesy, which is one of the reasons that so many modern heroes don't have secret identities. Instead they have posses who do know, and only one or two intimates who need to be protected. Even Aunt May knows Peter Parker's secret these days. Travelers handles the double life more in the way that a cop show or a spy show would handle it, with compartentalization and security clearance technobabble more than lame spur-of-the-moment excuses.   

The show handles most things in a similarly practical way. These people are enduring extraordinary circumstances, sure, but they are also highly competent professionals (most of the time). They get the job done with a minimum of infighting and snarky comments. On the other hand, the quality of the writing guarantees that those few snarky comments will be really good ones. And in those moments where they can relax and banter with one another or their 21st century loved ones, that stuff is good too. They shoot it to look like a drama, not a cheesecake tropical detective show with random cut scenes of bikini girls. The soundtrack is equally understated.   

It's just a good show, overall. 

I really like the way the future is referred to obliquely, in side comments and diagrams scrawled in chalk on sidewalks, but at least in the first two seasons, we never go there. That ambiguity, in a sense, heightens the realism of the show, because there's nothing concrete to critique. You can't complain about the lameness of the CGI Attilan if they never show it to you (Inhumans has a lot of other problems, as well; don't get me started).   

My geekish delight in Travelers, and the care they take in getting modern science and tech right, from organ donation to PTSD treatment, mean that I do not feel bad for pointing out a couple of glaring scientific issues that go right to the heart of the time travel conceit. One of those I am competent to talk about, and one of them I am not (but I will anyway).   

You Can't Over-Write a Brain (and if you could, it wouldn't hurt!)   

One of the tropes of the show is the screaming and nosebleeds that accompany the transfer of consciousness from the future to here. That makes no sense, because there are no pain receptors in brain tissue. That's how neurosurgeons like Henry Marsh can operate on patients while they are awake and undrugged beyond the local anesthetic they need to get through the skin, bone, and meninges. That's a simple one, one you can't get around with technobabble. It's purely for dramatic effect.   

More serious, and more controversial in our current culture, is this ever-present metaphor of the brain as a computer. It's useful in certain ways and hugely misleading in others (I wrote here about the use of near and distant analogies in research). In Travelers, we hear about the consciousness transfer machine, but we don't get to see it until the last episode of Season 2. It's a big glowy thing pointed at the subject's head, just as you might intuitively expect.       

[image from Netflix]

Problem is, in the brain there's no separation between the silicon-based semiconductor hardware and the software, made up of electrons that zip around through the hardware. The brain doesn't compute only with electricity; most of the work is done at chemical synapses. Memory is a chemical process that requires protein synthesis, dependent on gene expression in the nucleus. The electrical aspects of neurons are mostly just to speed up the transmission of signals along the “wires” between those synapses, and it is not necessary. Trees are bigger than we are, and they communicate chemically. It's really slow, but because they don't need to move around, they don't care.   

We're making good progress with brain/machine interfaces, helping amputees and bypassing spinal cord damage and such, but let's be clear – that's about broken wires. Consciousness is not a computer program, any more than it is a fluid that you can suck up into a syringe and transfer to another person. Even if we could copy a mind, or simulate the functions of a mind on a computer with enough fidelity to fool ourselves (which is a real but distant possibility), it wouldn't remove anything from the source brain. My very first column for IGMS says more about the historical development of these persistently wrong ideas, in science and in SF.   

Time Travel is Also Space Travel    

[image credit Chris Setter/Phil Plait]

My other, more general gripe is with the concept of time travel. Except maybe for Doctor Who, nobody ever seems to take into account that we are moving. It doesn't matter if you're standing still on the surface of the planet. The continents themselves are moving. Our planet, and the star it circles, are not in the same place they were a hundred years ago. Moving backwards in time would require moving “backwards” along our orbits through space as well. The Travelers say they are only sending information, not mass, and they are very concerned about location (in the form of GPS coordinates), because they want to hit that human head with their stream of information. Still, that information has to be encoded as some physical thing, either electromagnetic or gravitic or a stream of tachyons or something, but for the sake of my own ignorance I'll say that's a technical issue, not a conceptual one.   

The deeper conceptual problem has a history. Ever since HG Wells conceived of time as a fourth dimension, separable from the three dimensions of space and mathematically orthogonal to them, we've had people moving back and forth along those time-lines. Mathematically, this is perfectly OK. Any arbitrary number of dimensions can be mathematically orthogonal to one another. But Einstein showed that time and space are not physically separable. At least, as a relativistic layman, that's what I get out of it. I'd be happy to be corrected by an actual physicist, although physicists are not unanimous on these issues. 

Now: The Physics of Time suggests that the universe is constantly creating new spacetime in the process of expansion. Not that the matter is expanding into previously existing empty space – what he calls “the theater in which the laws of physics were performed” – but that new space time is added between the bits of older spacetime, forcing the old stuff apart.    This blog post about the book also mentions “Feynman's fantastic conclusion that antimatter is just ordinary matter moving backward in time,” which kind of freaked me out a little bit. But, like I said, physicists have different opinions about the importance of such pithy attention-getting statements.   

http://www.askamathematician.com/2016/11/q-does-anti-matter-really-move-backward-through-time/   

(By the way, how about a Steemit version of this project? “Ask a neuroscientist”?)    

Thanks for reading!

REFERENCES (many spoilers)

https://en.wikipedia.org/wiki/Travelers_(TV_series)

https://www.reddit.com/r/TravelersTV/comments/5n2tsq/spoilers_all_question_about_the_travelers_numbers/

http://www.slate.com/blogs/bad_astronomy/2013/03/04/vortex_motion_viral_video_showing_sun_s_motion_through_galaxy_is_wrong.html