Why we don't live in a simulated universe

There's an oft-repeated theory that our universe is a simulation -- a computer program (or equivalent) created by some higher form of intelligence. The modern popular form of this claim is generally attributed to philosopher Nick Bostrom, although the basic idea goes back much further.

And the only problem with this idea is that it is completely wrong.

The basic "simulation argument" goes like this: imagine that an intelligent race becomes intelligent enough and powerful enough that they could simulate a universe in a computer. (We already do this ourselves, in a very crude sense, when we create computer models to simulate weather or traffic or any other aspect of the real world.) Our hypothetical aliens are able to build such rich simulations, they actually contain simulated intelligent beings of their own -- and those simulated beings would (somehow) perceive themselves to be conscious.

And here's the clever twist: according to the argument, those simulated beings could become intelligent enough to build their own simulated universes, with simulated intelligent beings of their own, who in turn... Eventually, there would be an enormously large pyramid of simulations-within-simulations. And from a simple probabilistic perspective, it's enormously unlikely that we happen to be in the topmost and only real universe (and sometime in the future will ourselves start simulating universes) rather than one of the vast number of simulations.

And this is completely mistaken.

The problem with the argument is that the universe we find ourselves in is enormously complicated from the point of view of having intelligent beings in it. For a start, you could discard the other one hundred billion galaxies in our observable universe and it wouldn't make any difference to us. So it's enormously more likely that the simulated universe we are in would be much simpler than this one. (How much more likely? Borrowing an argument from Roger Penrose, possibly something of the order of 10 to the power [10 to the power 100] -- a 1 with [10 to the power 100] zeroes after it -- more likely.)

So the simulation argument turns on itself: the exact same argument that leads to the conclusion that we live in a simulation, i.e. that there are many more simulations than real universes, also inevitably leads to the conclusion that this universe isn't simulated, because there would be hugely many more simpler simulations we would be more likely to find ourselves in.

Batman v Superman: Dawn of Just a Minute...

The internet at large has already covered a lot of what's wrong with BvS, so rather than repeat what's already been said, I'm going to restrict myself to a couple of major things not much touched upon, specifically: the Act 3 climax is a huge mis-fire; and the post-climax codicil makes no sense whatsoever.

First, the climactic battle with Doomsday. The problem here is: who really cares? Comparisons to The Avengers are inevitable, and in that movie we've had all kinds of foreshadowing and build-up: the Avengers must stop Loki from using the Cube and opening the portal, failing every step along the way, until the emotional climax of Stark laying down his life... In BvS by contrast we get a rock-monster with arbitrary powers and an equally arbitrary weakness, that appears deus ex machina (quite literally) with no motivation nor character of any kind, and that is not set up in any emotionally meaningful way by preceding events or threats. And even ignoring the disconnect from the foregoing story, there's neither a logical reason that the Kryptonian spaceship even has the ability to create a Doomsday nor a narrative reason that Lex chooses to do so (contrast Avengers, where opening a portal is Loki's motivation from the very beginning).

Consequently, here there's no sense whatsoever that we're building towards this apocalyptic battle -- a problem highlighted by the fact that Wonder Woman decides to get involved in the fight for no adequately explored reason. (More generally, Wonder Woman is woefully underdeveloped -- and not in an intriguing, "show me more backstory!" kind of way, but in a frustrating "what does she want? why is she doing that?" way.) In fact, given that Luthor's main plot is all about manipulating Superman and Batman over many months into fighting each other, the whole Doomsday plot line feels like it was left over from an entirely different draft of the script. Having made the Batman v Superman conflict the core of their movie, the writers apparently had no idea what to give them to do once they had resolved that conflict.

Second, the post-battle State funeral. Why? In the Death of Superman comic book source material, this makes perfect sense. In the comics arc, Superman is a long-established hero, known and trusted, even loved; and the world watches as he fights Doomsday all the way across the country for days on end, other heroes falling by the wayside, until finally, battered into exhaustion in full view of friends and news cameras, he sacrifices his life to save the world. Of course the world mourns. But in BvS, (i) Superman is mysterious, distrusted, and even disliked; (ii) Doomsday appears out of nowhere and spends around twenty minutes in Metropolis, hardly enough time for everybody to decide that we've tried everything and the world is going to end unless Superman can stop it (frankly, anybody that was there for Zod is probably thinking "meh, I've seen worse"); and (iii) nobody witnesses Superman's self-sacrifice and death except Batman, Wonder Woman, and Lois Lane... but their word is good enough for the US government to throw a funeral fit for a president.

On reflection, the two best sequences in Dawn of Justice are (i) Batman rescuing Martha Kent, and (ii) Wonder Woman fighting Doomsday. The former is the one fight scene that is most true to the Batman character (I wouldn't be at all surprised to learn it was done entirely by the Second Unit); and the latter the only part of the movie where anybody seems to be having fun. Like Doomsday, Wonder Woman seems to have wandered in from the theater next door where she had been starring in a movie that was a lot more fun than the one I was sitting through.

And so it struck me: DC could in fact have made a far more interesting movie if Superman never appeared at all. Sure, he's out there in the world somewhere, motivating Lex and the others to their actions, but never actually seen. Edit out every scene with Kent or Superman (except maybe Bruce's nightmare sequences), give Wonder Woman some proper background and motivation, and you've probably got a pretty decent movie about how the rest of the world feels about Superman, and how it copes when he doesn't come flying to the rescue.

Quantum entanglement does not work like that

Whenever the topic of quantum entanglement -- which Einstein decried as "spooky action at a distance" -- comes up in online conversation, somebody will always ask whether this phenomenon can be used for instantaneous communication. And this is a very reasonable question because although the answer is definitively No, it's far from intuitively obvious why this is so, not least because it depends on details of quantum behavior usually omitted from non-technical explanations -- details that are critical to understanding the phenomenon.

I originally wrote the explanation below in response to a post on Gizmodo. Several people said it was helpful, so I decided to preserve it online for when the question inevitably comes up again.

The Very, Very Short Version

Entanglement allows you to infer what result somebody else's experiment will get; but it doesn't allow you to influence what result they will get.

The long version:

First, entangle your electrons

Suppose you “entangle” two electrons (there are lots of ways to do this; we'll take it as given). What this means is that they are paired in such a way that certain of their properties are reflections of each other. (In technical language we would say they have a "shared state".) In particular, we are interested in the so-called "spin". So you send me one electron and keep the other. Now you measure yours to see if it's spin is pointed up or down; if you find yours is up, you’ll know that if I do the same experiment, mine is pointed down; and vice versa. (The entangled electrons are always opposite, like two sides of a coin). 

Importantly, you won’t know whether you’ll get up or down until you do the experiment -- it’s a coin toss. The only way to tell which is the Up electron and which is the Down, by definition, is to do the measurement. 

Anyway: so far, so normal. Up to this point, it's really no more surprising than if you had split a coin down the middle and sent one half to me. It's no surprise that if you kept the heads side, I got the tails side.

But note the really important part here: I can't use this to send you a signal. The typical misunderstanding at this point is to think that since the electrons are always opposite, if I somehow force my electron into the Up position before measuring, yours will instantaneously be in the Down position, and from there with enough entangled electrons I can easily construct a binary code. And the simple fact is, entanglement does not work like that. Although the electrons are opposite to begin with, anything I do to change the state of my electron does not change the state of yours; instead it just breaks the entanglement. I can no more flip your electron by flipping mine than I can turn your half of the coin from heads to tails.

Let's get spooky

But now it gets quantum. Unlike a coin, there are lots of ways you can measure spin: in fact you can choose any axis you want to measure it along. You don’t have to measure whether your electron is pointing up or down like this: |. You could measure whether it is pointing left or right, like this --. Or along any in-between axis, like / or \. 

Now here's the critical part: electron spin is quantized. This means that whatever axis you measure spin on, the answer will always be precisely "+1" or "-1" units of spin (using the units that physicists typically choose), regardless of what state you thought the electron was previously in; in other words, either clockwise or counterclockwise. Yes, even if you think your equipment only generates up and down electrons, if you choose to measure it on the left-right axis, its spin will definitely be measured as either one unit of left or right spin. Oh, and of course if I measure mine on the same axis, it is pointing the other way. Or you could measure it on any orientation in between, and if I measure it on the same orientation, I get the opposite.

There is no analogy in the macroscopic world for this behavior that I can think of. If you had, say, a spinning basketball and you measured it's spin as "+1" in the up/down axis, it's spin on the left/right axis would be 0, and its spin in the / or \ directions would be somewhere between 0 and 1. This is a crucial difference between the quantum world and the familiar classical world.

One of the things this tells us is that, unlike basketballs and other classical objects, electrons don't have a definite spin until you measure it (and even then, that spin is only good until you measure it again on a different axis).

It gets worse (or maybe better)

Now, we’re not done. Up to now we've always measured our electrons on the same axis. It gets even spookier if you and I choose to measure our electrons along different orientations. 

Suppose you measure on the | axis and, say, get Up; but I choose to measure on the -- axis. Now two things I said above seem to be in conflict: 

• entangled spins are always opposite, so mine must be Down; but 
• if I measure left/right I must get precisely left or right. 

So what happens? Well, in fact I get left or right, and with an equal chance of each. It’s as if my electron was pointing Down after your experiment, and randomly chose which of left or right to flip to when I measured it.

Notice, by the way, that when I do my measurement, nothing now happens to your electron. If you were to subsequently measure your electron on the -- axis, your result would be completely random. The moment you measured your electron the first time, the entanglement was over. So no amount of cleverness with repeated measurements will let me send a signal either.

The really hard part

Now I do something even more interesting: instead of measuring --, I set my equipment at an angle to yours, lets say at /. If we think of a clock face with Up/Down at 12 o’clock / 6 o’clock, I set mine at 1 o’clock / 7 o’clock. Now what happens? 

What I find is that when your result is Up (12), I’ll get 7 most of the time and 1 some of the time (the exact proportions can be predicted, and have been demonstrated experimentally literally billions of times). And if your result was Down (6), I get the opposite results; mostly 1, some 7. Somehow, my electron “knows” what axis you measured along and what result you got -- even though the orientation was not fixed at the beginning before the electrons separated. In fact, even the orientations of our measurements can be chosen long after the electrons have separated, yet the entanglement still occurs. 

So maybe there's something here that can be used to communicate? Maybe you can send a signal with the way you choose the axis you measure on, since that influences the distribution of my measurements on a different axis? 

Unfortunately, no. And the reason is this:

Remember that when you measure on your end, you always get a random result, either up or down. You can’t force your electron to Up, and thereby influence my distribution; you can only discover whether it is Up or Down (and then infer what I am seeing). You can choose the axis you measure on, but not the outcome you get. (You can't even "separate out" the Up electrons from the Down: the only way to know which is which is to measure them, which destroys the entanglement.) And since you are getting 12 or 6 at random, to me it looks like I'm getting 7 or 1 at random too.

One last throw of the dice?

So perhaps there is one last loophole. If being entangled affects the measurements I get, maybe there is some way I can tell whether our electrons are still entangled? Since entanglement breaking is also instantaneous, maybe that in itself can be used to send a message? But no. Even while our electrons are still entangled, your stream of results looks completely random to you. Similarly on the other end, whatever I measure looks completely random to me: 1 or 7, 7 or 1, with no pattern. It’s only when we bring our results together that we see that whenever you got 12 I was more likely to get 7, and whenever you got 6 I was more likely to get 1, thereby proving that our electrons were entangled.

This is what physicists mean when they say our results are correlated, and the degree of correlation (as mentioned above) is precisely predictable, and has been tested in the lab. But it's only by bringing our results together that we see the correlation -- in isolation, each of us appears to get a random series of results. And bringing our results together to compare requires conventional slower than light communication.

(By the way, this is the basis of quantum cryptography, but that's a long story for another time.)

So in summary...

A lot of the confusion here comes from non-technical explanations being loose in their language when they say that one electron "influences" the other. This is true in the sense explained above -- the result I measure is linked at a distance (yes OK, Albert, "spookily") to the result you measure. But it's not true in the sense that you could change your electron and instantaneously cause a change in my electron. Any change you make to your electron in an attempt to change mine simply breaks the entanglement, and our results are no longer connected in any way.

Experimental theology: religious football

Somewhere between one third and one half of Americans believe that God / Jesus cares enough about the outcome of sports contests to intervene, typically in favor of those who pray most fervently. I propose to put this belief to the test with the new game of Religious Football.

The game is very simple. It is played on a conventional American football field with a standard ball. The game begins with the ball at midfield on a tee, and two teams of eleven prayers line up on opposite sides of the field, five yards from the 50 yard line. Each team prays as hard as it can for the ball to move towards the opponents' end zone. Prayers can be spoken or silent, according to each team's ecclesiastical tradition.

If a team manages to pray the ball across the line, they score a point, the ball is re-centered, and the process begins again. After 60 minutes, the game ends and the team with the most points win.

This is a game where the "twelfth man" is exceptionally important. Supporters are allowed, even encouraged, to pray along with their team to help move the ball. (Conversely, the 13th man will be hung from the goalposts at half time).

There are a few other rules and penalties, to maintain order. The major ones include:

• Offsides: The players must maintain five yards from the ball at all times, so if one team's prayers cause the ball to move, it can advance and the other team must retreat. Approaching closer than that incurs a five yard penalty.
• Illegal touching: touching the ball in any way, or causing it to move with anything other than the power of prayer, is a ten yard penalty. 
• Out of bounds: any reference to an opponent's mother, sister, or other female relative is completely out of bounds and will be penalized ten yards.
• Roughing the pastor: any contact with the opponent's spiritual leader on the sidelines results in a 15 yard penalty. 

 I propose that we launch this game in Texas where, I'm told, both Jesus and football are popular.

I Hate Birthdays

The thing I hate most about birthdays in the Web era is the absurdly insincere birthday greetings in email and on FB from corporations that happen to have my birthday in their database. What am I supposed to think about "good wishes" that don't emanate from any actual person? At best, it's an attempt to co-opt the natural human reaction of reciprocity; at worst, it's a crude sales pitch (who doesn't want a new weed trimmer on their birthday, right?).

If I wanted to read meaningless, empty, formulaic wishes that don't genuinely emanate from any real person with real feelings, I would go stand and stare in front of the birthday card rack at Hallmark for an hour.

 At least, that's what I used to do before the restraining order.

Some Thoughts On Jurassic World

Oh, and SPOILERS, obviously.

Here's a couple of thoughts about Jurassic World that I haven't seen mentioned elsewhere.

1. Owen (Chris Pratt) is actually responsible for hundreds of deaths. If instead of trying to escape from the Indominus Rex compound he had heroically accepted his fate and sacrificed his own life so that the others could escape without releasing the dinosaur, nobody else would have died. Also, the movie would have been over much more quickly.

2. Everybody online is complaining about Claire (Bryce Dallas Howard) running around the woods in her high heels and never once sinking in, losing a shoe, or breaking a heel. I think the director missed a great opportunity to capitalize on that. When Owen is pinned down by a pterosaur and Claire saves him, instead of shooting the pterosaur she should have spiked it in the head with her heel.

And then she and Chris could have exchanged some witty banter about how he's sorry for mocking her footwear, while all around them people continue to be dragged to their horrible deaths, all because Owen didn't sacrifice himself in the first act (see point 1 above).

3. As an aside, Claire is obviously not from New York or she would have a pair of sneakers in her purse that she changes into when it's time to run for the train.

4. I don't think I've ever seen such gratuitous product placement in a movie ostensibly about the evils of over-commercialization. Even in actual Mercedes commercials the camera doesn't caress the bodywork so lovingly before coming to rest on such a prominent shot of the emblem. The director of this movie either has the most profound sense of irony on the planet, or none at all. I'm not sure which.

How to win bar bets with Wikipedia

Step 1: Edit Wikipedia to insert a fake "fact". Choose your fact carefully: it needs to be unlikely enough that your mark will bet against it, but not so crazy that it will provoke obvious incredulity ("Prince Philip, the Duke of Edinburgh, is a Furry"), causing the mark to doubt the veracity of Wikipedia. You also need to be sure that your edit won't get quickly reverted, so stay away from entries that are closely watched, controversial, or recently in the news ("in 2014, more goats were killed in rail accidents in the US than people").

Step 2: Choose your mark and place your bet.

Step 3: "Prove" your claim by looking it up on Wikipedia. Collect your winnings and leave before the mark checks other sources or your Wikipedia edit gets reverted.