Posts Tagged physics


In Anathem, two of the characters have a discussion about how a person can “make” facts from their observations of the universe. In the course of their discussion, one makes the point that whenever we see the world and begin predicting behavior, we are in essence creating a series of counterfactual universes and discarding them as they don’t “fit the facts”.

This reminded me of my favorite method of proof – proof by contradiction. For some reason, I sometimes found thinking about alternate math systems more interesting than solving regular problems. Proof by contradiction let me do both: I could set up the alternate system in which the rules were different somehow, and then discover the flaws with respect to the “real world” and generate the proof.

Do we set up counterfactual universes in our heads? And if we do, could we apply a more rigorous method of proof to discarding them “by contradiction” than pattern matching?

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I finished Neal Stephenson’s Anathem last night.  It was a pretty incredible book – I enjoyed it, and it covered tons of physics AND philosophy AND it was well-written and well-composited.  I would definitely recommend it to any fan of speculative fiction, or of thinking about things.  That being said, there were some oddities about the book that I wanted to write down.

One thing I found quite strange about the book was the enormous vocabulary he introduces to immerse you.  In a sense, this subtly different language is part of his theme and message, so I don’t want to spoil it, but it made the first 100 pages or so pretty sloggy.  Once I was into it, though, I really appreciated the little differences between “our” language and the language of the book.  It’s interesting, thinking about it now with the book behind me: by introducing a completely separate but intrinsically linked language that the characters use and think with, I achieved a more complete projection into their (especially the first-person narrator’s) position(s)… and so when the plot took various turns, I was much more invested.  Very clever, Stephenson… very clever.

Another thing that was odd about Anathem was the handling of science and religion simultaneously.  Most works of speculative fiction just fiat past this hurdle (“here are the G/god(s)”, or totally sidestep it and ignore it), but Anathem was up front about right away showing the in-world dichotomy amongst the learned who believed in some higher ideals, and the ones who believed in what they could see and measure.  I guess I’m a bit biased here, since his take on it is so in line with my though patterns (being/trained as a scientist), but I really liked this more concrete (if fictional) analysis of what it means to have faith – whether your faith is in a higher being, a higher plane of existence, or something else equivalent (like the Hylaean Theoric World of the book, where ideal triangles live).

Overall, I give the book a solid A.  The only reason it’s not an A+ is because the plot leaves a ton of interesting stuff uncovered, so I wanted more books to explore it.  I guess part of the book’s themes is understanding the point at which to cut loose from scholarly investigation, though, so I won’t fault it too badly.

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I really enjoy thinking about the class of technology we might call “superscience.” That includes stuff like teleportation and time travel – but it also includes some more realizeable things like broadcast power. In essence, broadcast power was imagined by Tesla and involves a power station generating a zone of power within which anyone (or maybe those with the correct technology) could tap into and utilize wirelessly. So, you could also think about it as wireless power.

I hate wires of all kinds. Being bound to a particular location to use a technology is super frustrating. The advent of laptops and wireless (even cellular) Internet have been huge steps forward, but we’re still missing two key components: holographic projection (to remove the need for visual-display cables) and broadcast power.

I heard a while ago that progress had been made in this area (I’ll see if I can find a link) that was basically a directed ramp-down field – the receiver resonated in such a way that it could pick up power from the transmitter’s field. What sort of crazy applications could this technology have? I’m imagining transport powered by such broadcasts, maybe rapid city infrastructure due to increased accessibility to power? Something else amazing that I can’t fathom?

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Quantum Suicide

A thought experiment (borrowed from wikipedia, as discussed by Todd and myself down in San Diego):

Take a modified Schroedinger’s Cat Box, which has in it a weapon set to trigger if a particular quantum particle is spin-down upon measurement (assume that the particle is equally likely to be spin-up or spin-down) – and place yourself inside.  Every ten seconds, another particle is measured; if it comes out spin-down, the weapon fires and you die.

If you believe in the Many Worlds Interpretation (MWI) of quantum mechanics, then entering the Box might be a way to have your consciousness “travel” into low-probability outcome universes.  MWI means each possible state is actually a parallel universe, and the observer happens to be in one of them measuring one possible state.  (This might sound crazy to you, but other possible interpretations, like the Copenhagen Interpretation, require the act of observation to force reality into a particular state, which I consider to be just as crazy, physics-ly speaking.)

I believe that I observe reality from the seat of my consciousness, my “self”, where I consider myself to be.  Even those of us (ahem) who believe in no free will still must consider the seat of their sensory centers, and can call that the “self” for the purposes of this discussion.  So the question becomes: what happens to the “self” in this experiment?  You do the experiment, and every 10 seconds, it is 50% as likely as previous that you survived.  Each time you die, you won’t make any further observations.  But each time you live, you will observe that you survived.  There will always be a smaller but nonzero number of universes in which “you” survived and made that observation.

And then the question that Todd and I posed to ourselves: is there moral value here?  By running the experiment, you “kill” the spin-down self after 10 seconds.  Even if you ended up in the spin-up universe, what is the relationship between you-up and you-down?  Should it matter?

Nobody really understands quantum mechanics, which is sometimes really disturbing.  Thinking about this idea in one sense makes things even more disturbing, but in another good way, helps me think about the high-minded issues that bother me (some not particularly related to quantum mechanics!)

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Paradox of Measurement

I got into a discussion at work about the difficulty of obtaining an opinion from an individual without changing that person’s knowledge. Imagine, for example, you had an idea and really wanted to know how a particular audience would respond to the idea – if you just ask them about it, you’ll get some interesting data, BUT (1) it won’t be the same impact on them as actually releasing the idea normally and seeing their reaction, and (2) by necessity they must br informed of the idea and thus you can’t have it kept a secret.

This peculiar character of measurement – that by taking a measurement of human opinion, you introduce information that affects their opinion – is mirrored in the physical world by measurement in quantum mechanics. Stuff at the quantum level is very small.  When you measure quantum stuff, you disturb it because the instrument you use to measure it – even just light – is about the same size as the quantum stuff.  So, it becomes impossible to perform a nondestructive measurement at the quantum level, as far as we know.

With humans, I feel like there’s definitely a way to make a “nondestructive” measurement – that is, get somebody’s honest opinion without influencing them by asking.  It’s tricky and probably differs from human to human, though.  Are there parallels here that can be applied to both quantum measurements and measurements about human psychology?  Does the same fundamental principle apply?  In order to measure human response, we have to bombard the brain with “destructive” measuring tools – in this case, the implicit transfer of information to their brain that potentially affects the results.

I need to do more research into human psychology.

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Break the Symmetry

When I lived in L.A., working on casual web games with Nate, we had a semi-regular game night with Todd and a bunch of cool people from the area (Will, Robert, Tim, Daina, others).  Often – since some board games have long turns and thus long downtimes for the nonactive players – we would have philosophical and existential conversations about random stuff.  We talked about economics, altruism, determinism, the nature of “good” and our philosophy regarding current events.  It was awesome, and I miss it. :-/

But so anyway, the following thought “puzzle” came up during one of our discussions:

Imagine that there is a universe, call it Prime, that is an exact duplicate of ours in every way.  That is, you-prime (hereafter, you’) exists in that universe, is doing exactly what you are doing now, and for every other person, object and state, the same prime-equivalent exists in the Prime universe.

Now imagine that at the same moment, in front of you and in front of you’, a portal opens to a third neutral universe.  If you and you’ both step through (we can assume that if one of you does, the other will), how do you communicate with your doppleganger?  As presented, you and you’ start talking at the same time, have the same ideas about breaking symmetry, even know that it might be difficult and can form (independently-but-together) a plan.  Can the symmetry be broken?

At its heart, this is a question about a deterministic universe.  (For my physics-y friends these days, I generally add an assumption that the third neutral universe is deterministic, so that the question is entirely about us and Prime [which is really us].) That is, given the fundamental assumption that you and you’ are identical, you will be forced as you consider the “puzzle” to conclude that symmetry can’t be broken.  But if it bothers you enough because of the implications, you will argue with the assumption and then the fundamental question is the discussion:

How exact a copy can Prime be of our universe?  If you could know the starting conditions of everything, could you reliably predict everything as it evolves?  I personally don’t believe the universe is deterministic in this way, but I think regardless, we are once again saved from our (my?) terrible need to know by quantum mechanics which says, in essence, “you don’t get to know. Neener neener.”

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I had an idea last night before going to bed, that was still in my head on the way to work (usually a good sign!), for a possible science fiction novel.  What if there was a pseudo-humanoid race that “saw” using gravitons (i.e. gravity) instead of light (i.e. electromagnetism)?

Small physics lesson, for background: there are four fundamental forces – in order from weakest to strongest, they are Gravitational, Weak, Electromagnetic, Strong.  All of them except gravity have to do with interactions at the atomic scale; gravity is the only one that, due to some of its special properties, has major effects at the macroscopic level.  If electricity and magnetism didn’t have opposites (like positive and negative charge) it would have a far greater effect macroscopically — gravity only attracts, and has infinite range, and can’t be shielded against, so it has the largest impact at the macro level.

We interact with the world using our eyes primarily, and then less so through our other senses.  But our eyes, as amazing and complex as they are, are really only capable of observing a small portion of the electromagnetic spectrum.  I’m no expert on how eyes work, but essentially photons (the carrier of EM) are reflected off of objects and then absorbed by our retinas.  In this way, we form a picture of our surroundings – quite a detailed picture!

So what about a story in which this hypothetical g-human race had “eyes” that sensed gravitational force?  I imagine the beings form sort of a 3-d “sonar” map of their surroundings, based on the raw attractive power of objects near them.  They’d have to be hypersensitve (gravity is a literal hojillion times weaker than EM), and they’d probably develop “microgravity” to differentiate themselves from each other — like plumage, but due to very dense spots in their physical makeup.

One of the major challenges with writing this story will be how hard it is to SHOW things – it would take a great deal of effort to immerse a human reader in the g-human world.  Also, what would the story be about?  I don’t think it’s a good idea to have a human meet a g-human; I think the story is more interesting if it is entirely within the context of this gravity-sense world.  Maybe there’s a fundamental problem that this species had “solved for them” by happenstance – think of their “sun” as a black hole, and that their planet is somehow in a stable orbit around it due to (some reason), that they took for granted for a loooong time.  And now, it’s becoming undone and they have to figure out why their planet is sliding into the “sun” and how to stop it!

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Entropy and People

Entropy, my nemesis, is actually sort of a confusing concept.  My favorite re-statement of the three (four) laws of thermodynamics is:

0. Everyone must play. (Systems that interact reach thermal equilibrium.)
1. You can’t win. (Energy cannot be created or destroyed.)
2. You can’t break even. (Work done increases heat and heat cannot be converted completely into work.)
3. You can’t leave the game. (Entropy goes to zero as you approach absolute zero, but you can’t reach absolute zero.)

Entropy is a measure of the number of ways a system can be arranged.  The higher it is, the more “disorder” a system has.  You can’t reduce this disorder, because forcing the system back into a smaller number of possible arrangements takes work, and work produces heat (which is itself increasing entropy).

Entropy tending to increase has two major physical consequences: it prevents perpetual motion (no work-creation process is totally reversible) and it indicates a direction for time (time is the direction in which entropy increases).

Alright, with those definitions out of the way, I had an intriguing thought: over time, relationships between people become more complicated.  Logic tells me that this is because of shared history – as the number of experiences you have with a person increases, your expectations and internal analysis of their behavior become more refined.  When I first meet a person, the number of things we have to talk about is small.  When I have known a person for years, the number is much larger.

Is the number of potential (plausible, likely?) interactions between people in some sense related to entropy of a nonliving system?  That is, are the number of “possible person-to-person interactions” the same as the number of “possible arrangements of a system”?  And if so, can we formulate Laws of Human Dynamics that are extensions of the Laws of Thermodynamics?

I expect that a more formal revisit of this topic (by which I mean, more logically structured rather than stream of consciousness) is necessary.

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