Physics and the Marvel Movies

Broadly speaking, the Marvel studio movies have managed to remain largely physically credible; and by this I mean that, while there are conceits that you simply have to accept for the sake of the story, and much of what goes on is often beyond current engineering, medical science, and so on, it is at least plausible. For example, in the Iron Man movies, the suit itself is a fairly reasonable extrapolation of current and experimental military exoskeletons; the arc reactor power source, however, you're just going to have to take at face value.

By the way, I'm referring here to the interlocking movies produced by Marvel themselves, also known to fans as the MCU, for Marvel Cinematic Universe. The movies made by other studios, such as the X-Men and Fantastic Four franchises, threw credibility overboard a long time ago.

Next year (2015), the MCU is going to get seriously weird, however. With the introduction of Quicksilver and Wanda to the Avengers, and a Dr. Strange movie -- Stephen Strange was name-checked in Captain America: The Winter Soldier, so presumably this will take place in the same continuity -- it's hard to see how Marvel will explain itself without just shrugging and saying "Magic".

Before that happens, therefore, I wanted to jot down some notes on the least physical elements of the movies to date, basically because I enjoy this sort of thing. Oh, and I probably shouldn't need to say this, but obviously:

SPOILERS!

• Iron Man 1: Deceleration is the big issue here. Stark pulls some serious Gs in his flight maneuvers, especially when he opens the flaps to evade the fighter jets; but that's not the biggest problem -- let's just accept that he has invented the world's best pressure suit. No, the big issue is when he lands hard, going from full speed to a three-point landing in nothing flat. It doesn't matter how good his airbags are, his body is coming to a stop in a very short period of time. In any realistic scenario, when they open up the suit after a landing like that, they're going to find a can of Tony Stark soup. (By the way, when I first watched the movie, that wasn't the thing that made me go "Oh, c'mon!". No, that was when Tony returned from Afghanistan and he wants a burger... so he goes to Burger King. He's in California: obviously, he's going to go to In'n'Out. Let's try to keep this at least a little realistic, OK?)
• Iron Man 2: The "internal problem" in this movie is that Tony's arc reactor is poisoning him so he needs to replace the palladium that is a key component. Using instructions left to him by his father, he creates... a new element. Did anybody involved look at the Periodic Table and ask "Gee, where will this new element, which is chemically and electrically very similar to palladium, fit? I wonder why nobody else noticed that gap?". I suppose it's possible to dismiss this as one of those conceits I mentioned, but a much better solution is at hand: have Tony create a room-temperature superconductor. Not only is this a reasonable extrapolation of current science, it's an area where researchers are exploring many different approaches, so there's plenty of room for Tony to try something new and solve the challenge. Also, Tony is a genius at engineering, not basic science (notwithstanding the Avengers, where he just a generic STEM genius), so it's a better fit for the character. 
• Captain America: One could quibble about just how the Super Serum works, but the big physical problem here is simply conservation of mass: Steve Rogers bulks up by at least 100 pounds in a matter of seconds, so where did all that matter come from? Note that the naive answer "it came from the energy they drew from the electrical grid" doesn't work, because it takes an enormous amount of energy to make a very small amount of mass. To give a sense of scale, consider the Soviet Union's Tsar Bomba, the largest hydrogen bomb ever tested. That bomb yielded on the order of 50 megatonnes-equivalent, roughly 10 times all of the conventional explosives combined used in World War II. In order to create Steve Rogers' 100 pound gain, you would need to harness the energy yield of approximately twenty Tsar Bombas, and do so in just a few seconds. 
• The Avengers: This has been well addressed elsewhere, but the most obvious engineering problem is whether or not the helicarrier could fly; and the likely answer is No. At the depicted size of carrier, the rotor blades would have to be much larger. Or at the size of rotor shown, they would have to spin much faster, but then you get into problems of material science (the blades would break apart) or tip speed (what happens if the tip exceeds the speed of sound?). 
• The Hulk: One of the nicer touches in the Hulk movies (and his appearance in the Avengers) is that they take seriously what happens to the ground beneath him when the Hulk jumps and lands. But as with Captain America above, where does the extra mass of the Hulk's body come from? In the comic books, the Hulk is the result of exposure to a fictional "gamma bomb", but as noted even the largest nuclear explosions convert only a few pounds of matter to energy, so even if you could capture all that energy, turned back into matter it would still only amount to the same few pounds. The most plausible explanation I can come up with is that the Hulk, in fact, weighs the same as Banner and his huge size comes from the fact that he is inflatable -- really, they should call him The Inflatable Hulk. I do realize, however, that this theory may be difficult to reconcile with other depicted elements of the character.
• Guardians of the Galaxy: Obviously there's a lot we just have to take for granted in this movie because aliens, but my gripe is with a very Earthbound technology. Peter Quill has been playing the same cassette tape for over 25 years, and it still isn't a tangled, broken mess? He even plays it in a Sony Walkman without damaging it, which is just downright ridiculous. (On a lesser but related note, when he finally unwraps Awesome Mix 2, it's amazing that the tape hasn't degraded to the point that it is hopelessly stuck together.)

I'm sure there's more to be found in the movies not mentioned above, but that's all for now. Comments welcome.

Quantum Leap: the Movie

Like many people, I found the ending of Quantum Leap unsatisfactory. I've long had an idea for a story that would wrap it up both more neatly and provocatively.

And by the way, if anybody from the copyright holder (or anybody who knows somebody...) happens to be reading: I disclaim all rights in this idea. Use if freely. I'd far rather see this made than get paid (although a "from an idea by..." credit would be nice.)


[fade to black]
Open on: the same set and title card that closed out the original TV series.

 Burn in: Dr. Sam Beckett never returned home.
[crossfade to]
Burn in: ...Until today

Open on Sam, emerging from a leap. He is in an anonymous office bathroom, could be anywhere in America, any time from the 1980s to the present day. POV over his shoulder, he looks into a wall mirror and sees...

…himself, as young as he looked at the beginning of the project.

Sam: Oh boy!

[Titles]

The story then unfolds: after many years of leaping, Sam has somehow leaped into his own body. It is 1999 [the "present day" of the project in the original series], just a few days before the experiment that launched his first leap. And Sam has just days to decide: knowing what he knows now, does he take the leap or not? If he does leap, he knows he may never get home again. This may be his one and only chance to break out. But if he doesn't leap, does he change history and erase all the good he has ever done? He has no idea... and no help (at first).

Back in his own timeline [our present day], a long-retired Al dozes in a chair. The QL project was shut down years ago. They had lost contact with Sam, and after months with no sign of him, everybody had assumed he was lost in time. The one exception: Al never gave up hope, and even though the project is mothballed, he still has the comm device gathering dust in a drawer of his desk.

And after all these years it blinks into life, and starts bleeping, waking Al.

So now Al, with the help of a grown-up Sammy Jo, tries to reboot Ziggy, contact Sam in 1999, and figure out the consequences of his decision. But the closer they get to the choice to leap or not, the more erratic and unhelpful Ziggy becomes: instead of converging, her predictions and probabilities are bouncing wildly, as every choice Sam makes seems to involve terrible paradoxes and instabilities. Whatever Sam chooses seems to be wrong...

On the fallibility of autobiographical memories

I suspect that most people who have not actively studied the subject have a fairly naive view of how autobiographical memories work. They imagine our memories of events in our lives to be little home movies, tucked away in slots in our brains, ready to be recalled when prompted by circumstance or demanded by our conscious selves.

That this model is entirely inadequate was brought home to me the other day when I was recalling a particular drive I used to take on a weekly routine in my early 20s, when I lived in England. The memory was crisp and detailed, including the undulations of the road, signposts to various villages along the route, and the appearance of the landscape at different times of year. Just one detail was wrong: in my memory, I was driving on the right and sitting in the left-hand seat, as one would in America or Europe; of course, since these events took place in England, the reverse would have been how it actually took place.

As I thought about it more, I realized that the same was true for (almost) all of my memories of England involving cars. In my mind's eye I am opening the wrong door, getting in or out of the wrong side of the car, driving on the wrong side of the road. Only by a conscious effort of will can I restore the image in my head to how reason tells me it actually must have happened.

What this tells us is that autobiographical memories are not really like a movie, but more like the script of a movie. Somewhere in my memory is stored a script about that familiar drive, perhaps associated with a high-fidelity description or image of the landscape, and a slug line such as:

EXT. DAY: CARL drives a late-model compact through winding country roads.

...and from that, like a movie director, my brain constructs the movie, using its library of backdrops and knowledge of what driving involves. Only now that I have spent more years driving on the right than I ever did on the left, it defaults to the more habitual perspective, like an American movie director setting a scene in England and forgetting that they drive on the other side there.

I said "almost" above, for good reason. A few of my English driving memories are correctly oriented, invariably ones involving some amount of drama. For example, once while driving on the M25 I was witness to a multiple-car pile-up that caused a huge back-up on both sides of the motorway. In my memory of that event, I remember every moment with great precision, including which lane I was in and how I avoided being part of the accident myself.

Time Travel Does Not Work Like That

Whenever a discussion thread turns to time travel, somebody will always raise the challenging question: If you jump forward in time, say by a week, shouldn't you reappear in outer space because the Earth has continued to move and is now seven days further along in its orbit?

And I always feel obliged to answer: Time travel does not work like that.

This conception of time travel typically imagines a time machine as a box of some kind that jumps in time but stays in the same place. And written into that conception are some assumptions that mislead. One is the assumption that you can "jump" discontinuously from one point in time to another. A second is the assumption that movement in time can be considered separately from movement in space. And a third is the implication that the expression "in the same place" is well-defined: as Relativity taught us, we have to ask "the same place relative to what? The Earth? The sun? The center of the galaxy?" (and once we answer that question, we realize that we have pretty much answered our own conundrum.) To properly understand what should happen in time travel, we need to overturn each of those assumptions.

So as far as we know* there is no possibility of "a box that travels through time but doesn't travel through space". It's not just hard, it's an oxymoron -- although in order to understand why, you have to teach yourself to think about spacetime properly, instead of thinking of space and time as separable.

So we have to take a few steps back, discard the presumption that such a box exists, and ask what an actual time machine could be like. And it turns out that (realistic) time travel is a characteristic of a region of spacetime, not a characteristic of a particular machine.

The first thing to understand is that nothing ever moves through space alone or through time alone**. Everything is moving through spacetime, all the time (so to speak). And that movement is always continuous. It simply doesn't make sense to say that a particle X moved from time t1 to time t2 without specifying space coordinates too. The only thing that makes sense is to say that X moved from spacetime position (x1, y1, z1, t1) to (x2, y2, z2, t2). This is so basic that, Relativity shows, even basic concepts like "before", "after", and "simultaneous" are not well defined if you don't specific both time and space coordinates.

The second thing to understand is that physicists have dreamed up lots of ways that time travel might be possible, and all of them involve a continuous path through spacetime, not a mysterious jump. The trick is, the spacetime curves in such a way that when you return to the same coordinates in space, you arrive at a different time from, say, an identical twin who stayed home. However, at no point do you perceive anything "weird" or discontinuous happening. Think of it as being like an extreme version of the famous Twins Paradox from Relativity. In that "paradox" you leave home with a clock that reads 2pm, travel in a big loop at almost the speed of light, come home, and your clock now reads 3pm while an identical clock that stayed home reads 4pm. (This happens all the time, on a smaller scale, right here on Earth: the GPS satellites you rely on for satnav have to correct for the fact that their atomic clocks drift slightly from identical clocks on the surface of the Earth). If the spacetime path you follow is sufficiently warped, when you get home your clock might read 3pm while the one on Earth reads 1pm -- congratulations, you've traveled an hour into your own past!

Of course, we should also note that when you return from your big loop you might be a little surprised to discover that the Earth isn't where you expected it to be, it's actually a little earlier in its orbit from where you would calculate according to the clock that traveled with you, so you have to adjust your path in spacetime a little to navigate back to it. But notice there was still no "jump" involved: you traveled away from Earth, you traveled back to Earth, and found something unexpected, because the paths you and Earth followed through spacetime put your clocks out of sync.

Note also that I pulled a little sleight of hand in that paragraph. When I said "where you expected the Earth to be", I should really specify relative to what for the sentence to have any meaning. And what I really mean is "relative to where you would expect it to be if you had traveled at low speed through flat spacetime and your clock had kept time with Earth clocks". This is kind of a subtle point, but it is at the heart of what's going on here. Your clock tells you where Earth "should" be, and relative to your clock Earth has moved "out from under you" -- but that is only because you assume that you and your clock traveled in flat spacetime. If you could look back with a telescope and watch the Earth the whole time you were on your trip you would see nothing odd happen, other than that it's position drifts slowly more and more backwards from where your clock says it should be. But at no point does Earth blink out of view and reappear further back in its orbit, the way a "time jump" is typically depicted in sci-fi.

So really, when I say "return to the same coordinates", I need to specify relative to what. If I "return to the same coordinates" relative to the Earth, it's right where I expect. If I choose some other point of reference relative to which the Earth is moving, it's not.

By the way, one of the first people to demonstrate rigorously that this kind of thing could happen in General Relativity was Einstein's good friend Kurt Godel. He showed that if the universe is rotating and sufficiently large, you could follow a very long loop around the universe and return to your starting point at an earlier time. Reportedly, Einstein was quite upset by this.

Now, when we see time travel in TV or movies, one way to think about it is to assume that the device is creating its own region of curved spacetime that is extremely small and very severely curved. I like  to pretend that the time travel in 7 Days works this way: the device creates a highly distorted region of spacetime around the capsule. The capsule travels in that highly distorted region which takes it both into space (relative to the Earth) and back in time (again, relative to the Earth). It then emerges from that distorted region and navigates back to Earth traveling in our (relatively) flat spacetime. But rather than "jumping 7 days into the past", I think of it as "traveling 7 days into the past and elsewhere in space".

Another way to  think about it is this: the most consistently realistic depiction of time travel in fiction is wormholes: a wormhole connects two different points in both space and time. If you had a pair of wormholes -- or a single wormhole that connects two points close to each other in space but distant in time -- you would effectively have the classic time machine. And in fact, the wormhole is simply an extreme*** example of curved spacetime. 

I have an even longer answer than this that also explains why we haven't met time travelers from the future yet, but it runs to several pages, and I'm saving it for the book I'm never going to write, "Physics for Smarties: an essential math-free guide for curious arts and humanities students".

Anyway, I hope that helps a little bit, and if you take away nothing else, remember "continuous path through spacetime" and "doesn't travel in space -- relative to what?"


Footnotes


*And yes, I readily concede that "as far as we know" is not very far, but the fundamental character of General Relativity is very, very suggestive on this point.

**OK, you could imagine such a thing if you wanted to, but we have no idea what physics would describe it, so basically you could decide how it behaves completely arbitrarily. It does whatever you want it to do. You just have to bear in mind that there are no absolute coordinates in spacetime, so if you define that your box "doesn't travel through space", it's up to you define what you mean by that: doesn't travel relative to what frame of reference? In short, your time box does whatever you choose it to do, because you are making it up.

***Insert your own Wormhole Extreme! reference here.

Fulfilling work

I've been struggling for a while to figure out what makes, for me at least, a fulfilling or satisfying job. Yesterday it struck me that the answer was more or less at my fingertips in the form of a book by my friend Tharon Howard called Design to Thrive. In that book, Tharon lays out a model for how to think about a successful online community around the handy mnemonic RIBS: Remuneration, Influence, Belonging, and Significance. It occurred to me that a tweak on that model would equally well describe what I would want from the ideal job:

Remuneration: Obviously this includes salary and benefits, but beyond a certain point salary doesn't make much difference (until you are talking about start up IPO levels of Walk Away money). But remuneration also comes in other form such as respect of colleagues and industry peers, thanks for a job well done, or the knowledge that you've made a difference. In fact, the R in RIBS could stand for a whole collection of Rewards including Respect and Recognition.

Influence: It's well established that people are happier in their work when they have more control over their environment rather than feeling like helpless drones working on one assignment after another. That can mean little things like personalizing your workspace, more substantive things like flex time, and ultimately having a significant say in what assignments you are working on. This concept can be seen in so-called self-managed teams, and in the development world it's a significant (if often overlooked) element of the Agile movement. Even something as simple as believing that your opinion is taken into consideration in your manager's decisions makes a difference.

Belonging: This is a huge element of the success of online communities, and includes the rituals and stories that people tell each other to reinforce their sense of belonging to something greater than themselves. Many companies have a "founding myth" that, factual or not, helps new employees adapt to the culture. The team I'm in right now has been fairly good at this kind of thing: we have ritualized expressions ("Yes, and..." instead of "Yes, but..." is one) and running jokes that we initiate new team members into.

Significance: This one is probably the hardest to achieve when you're in the depths of a large company. I've left jobs before even when the day to day work was interesting and satisfying ("remuneration") because it felt like what I produced made no more difference than throwing stones into the ocean, that nothing I did or said or wrote would matter to anybody a month from now. 

Everybody will weight these four elements differently, but for me significance is the biggest one. I get very restless when I feel that my job amounts to no more than shuffling paper, reviewing other people's proposals to evaluate considering investigating something, or spreadsheet engineering. To be satisfying to me, my work has to at least appear to matter to somebody's real life.

Flash Fiction: Of All Possible Worlds

[Note: this story was written for the New Scientist 2010 competition Forgotten Futures, which asked entrants to write a very short story -- 350 words or fewer -- about how things might have worked out if some scientific event or discovery had turned out differently. My entry wasn't shortlisted, so I'm sharing it here.]

Hugh Everett III eased himself into the oversized leather chair, taking care not to spill his cognac. Outside, he could hear the laughter of his children, grandchildren, and great-grandchildren, still loudly celebrating the 80^th birthday of the Grand Old Man of Physics, as he had become known. The door opened quietly and his son Mark slipped inside, cradling the glass display case that held Hugh’s Nobel Prize medal. Mark reverently returned the medal, the centerpiece of the party, to its accustomed place on the bookcase.

Hugh gestured to the chair next to him where another glass of cognac waited, and Mark settled in next to his worlds-famous father.

“It’s ironic,” said Hugh, toasting the medal with his glass. “The press called me ‘the new Einstein’, and just like him, they gave me the Prize for my second-best work.” Few people outside the physics community realized that Everett’s Prize had been awarded for his audacious doctoral thesis that introduced the Many Worlds interpretation of quantum mechanics, not his later quantum gravity insights that had led to the exploitation of Dark Energy, the basis of the peace and prosperity enjoyed by everybody on Earth, not to mention it’s colonies on Mars and Ganymede.

“I’ll tell you what else is ironic,” replied Mark with a mischievous smile. “If everything possible happens in some universe, then somewhere out there is a world where everything went as wrong as it possibly could. Imagine if nobody had paid attention to your thesis and you had abandoned physics. In that world you became bitter and disillusioned, turned to cigarettes and drink, and died long before your time, leaving a world still suffocating and sweltering in its own pollution.”

Hugh laughed warmly. “Mark, that story gets worse every time you tell it. Many Worlds requires everything possible to happen, but it doesn’t allow for the impossible.” He took another sip of cognac and pushed away the thought of a life and a world gone to ruin. What ever might be might be, he mused to himself, but whatever must be must be.

The worst romantic comedy in recent movie history

Somebody recently referred to "Something's gotta give" in my hearing as "charming". Hence this rant...

The essence of any rom-com is an ill-matched couple, kept apart by some apparently insurmountable barrier, destined to somehow be together by the end of the movie. "Sleepless in Seattle": they live on opposite coasts. "You've got mail": opposing political beliefs. etc. Age, culture, distance, class, political beliefs, disapproving families: something has to keep the couple apart for ninety minutes before we can all go home happy.

"Something's gotta give" offers us the unique sight of a romantic comedy about a couple who are kept apart by... absolutely nothing.

Harry and Erica are two independent, financially stable people of similar age, both well-established in life and successful in their careers. Both are single and unencumbered. Circumstances force them to live in the same house. Erica has no obligations as her adult daughter is self-sufficient. Everybody approves of their relationship, including Erica's daughter (who might have been expected to object since she had previously dated Harry) and Erica's ex-husband, with whom she has such a comfortable relationship that he drops by for coffee. Even Harry's rival in love, Julian, simply smiles and gracefully steps aside when the moment comes, accepting that Harry and Erica should be together. There's not a shred of conflict or difficulty or incompatibility in this entire setup.

The only reason they're not a couple after the first five minutes? "He only dates younger women", the other characters repeatedly tell us, although this essential fact is something that the movie completely fails to show. We don't even get to see all of these alleged younger girlfriends until almost the end of the movie, and none of them is dignified with a name, let alone a personality, a story, or a motivation for dating him. We have to take the word of the other characters, sitting around a dinner table, that he is a desirable, eligible, notorious bachelor who was featured as such on the cover of a New York magazine. (I believe that "featured on a magazine cover" is what movies go for to illustrate that somebody or something is well-known when they can't afford the obligatory scene of Jay Leno telling jokes about their movie's subject: "How about that Harry Sanborn? His latest girlfriend is so young, he has to leave her outside when he goes into a bar!". Or perhaps there are some things that even Jay Leno won't do?) Oh, and there's also some business about her being too busy/vulnerable for a relationship, although again there's no reason offered for why.

And since the movie provides no coherent explanation for why Harry collects notches in his headboard, we also get no explanation for what resistance he is trying to overcome nor why he chooses to change. At the start of the movie, he doesn't date women his own age; at the end of the movie, he does.

Even the title of the movie falls flat. "Something's gotta give" implies that both of them have deeply-held positions that are incompatible and that one of them will have to "give". Harry could accept that he should date women closer to his own age; or Erica could... I don't know, become a younger woman?

Once Erica and Harry have met, the rest of the movie is just marking time until it delivers its unearned and emotionally flat payoff and pairs them off. There's not a single moment in the entire film that rings true, emotionally or dramatically.