Archive for January, 2013

There is a principle in physics which says that, essentially, if two things are entirely indistinguishable, then you might as well call them the same thing.  There is even a branch of statistics (Bose-Einstein statistics) which is based on this principle.

Now, the meaning of the word “indistinguishable” has a very specific meaning in this context.  In physics, two things are indistinguishable if they cannot be distinguished no matter what anyone does.  That is, they cannot be told apart even in principle.  If there is a way to tell two things apart, then “regular” statistics holds; but if they truly are indistinguishable then they obey the much less intuitive Bose-Einstein statistics mentioned previously.

(As an aside, and entirely as a speculative exercise, one could argue that the existence of particles which clearly do obey Bose-Einstein statistics means that either (1) there is no God, or (2) there are things that even God cannot do—such as distinguish such particles—because if God could distinguish them then why do they obey Bose-Einstein statistics in the first place?  But that sounds like an idea for a later blog post…)

As an example, suppose a photon is absorbed by an atom, and the atom subsequently emits another photon of the exact same frequency and polarization.  One could say that a photon was absorbed and then the same photon was re-emitted; or one could say that a photon was absorbed (and destroyed) and then a completely different but identical photon was emitted.  The principle of identical particles says that these two cases are equivalent.  Neither one is right, or wrong.  Whichever you choose to believe is a matter of taste.  There is no experiment that even God could do that would tell you which was “right” and which was “wrong”, so why worry about it?  They represent the same thing.

Suppose two identical particles interact.  Initially they are traveling South and East, respectively, and interact at the origin:

collision 1

We can’t see what “actually” happens at the origin.  After the collision they are traveling South and East again.  If that’s all you know, and all you could know, then which of the following cases is correct?

Case 1.  They passed right through each other without actually interacting:

collision 2

Case 2.  They each turned 90° and switched roles, so to speak:

collision 3

A physicist would say that these are identical situations, as long as no one, not even God, is allowed to look under the veil.  And the distinction isn’t just semantic: if the particles are distinguishable, and these two cases really do represent two distinct physical possibilities, then the statistics of what we observe in such situations will be different.

Now, what in the world does this have to do with philosophy?

I’ve often felt that philosophy could stand to have a similar principle.  Well, fine, let’s just do it.  Let’s just make the following hypothesis:

If two things are indistinguishable even in principle, then they are the same.

Now I’d like to apply this principle to what I call the “Next morning” paradox but which is virtually identical to the Swampman paradox of Donald Davidson.  Suppose I go to sleep tonight and enter a deep sleep (so that I am not even dreaming).  And suppose that during this time of unconsciousness my body spontaneously disintegrates, and just happens to be replaced with an identical one: identical in every way, including the position of every molecule.  (Of course, you might try to cite Heisenberg here and say you could never make a body exactly like a previous one, because there’s always some uncertainty in position and/or momentum.  But, as in the original Swampman example, we assume that luck prevails: just by random chance the atoms are all found in the same way.)  This new version of “me” wakes up, lives his life, and no one (not even the new me) has any idea that anything has transpired.

Davidson and others contend that the new me is not “me” at all, even though no one could tell the difference.  They say that there is some intangible spark that can never be quantified that somehow still distinguishes yesterday’s me and today’s me.  That is, the difference between the two me’s is magic.  I find this ludicrous.

Any being that has all of your physical properties, and more importantly, all of your mental properties and memories, is you.  This may bother some, because it implies that more than one “me” can exist simultaneously; after all, we could make an exact replica of me and leave the old me intact.  Well, who cares?  As a many worlds adherent, I guess it’s not surprising I wouldn’t be bothered by such a scenario at all.

I find these ideas so obvious that it’s almost difficult for me to convey the ideas without screaming internally.  The principle has its beginnings in physics, but I find it applicable here: if x and y are indistinguishable even in principle, then x = y.  End of story.  I frankly have no idea why anyone takes Davidson’s ideas seriously anymore.

Think of it this way:  suppose you knew you were going to be killed, but that an exact replica of you would be put in your place, and have all your memories, and live your life.  On a visceral level, you’d probably be upset: “you” would live on, but it wouldn’t really be “you”.  This is the developmental stage that Davidson is stuck in.

My response: that scenario might have happened last night.  You might actually have died, and been replaced.  No big deal, right?  In fact, it might be true that everyone dies, every single night, and is always replaced by a perfect simulacrum.  The important point is that you could never know.  No one would know.  The universe would appear exactly the same.  We might as well take these two cases (that we are replaced, or that we are not) as being operationally identical.  For all intents and purposes, you can assume that every night you die, and that in the morning a different version of you is created with the same memories, that will act exactly as you would have acted.  Because this way of looking at things is really identical to the way we normally perceive reality, there can be no harm in thinking this way.  In fact, thinking this way may very well lead to insights and attitudes that you wouldn’t have had before.


I find this idea strangely liberating.  Each “me”, every day, can be thought of as a different person, related to me, and sharing some of my qualities, but separated both by time and space.  And we’ve come now to the final point of this post: how I learned to stop procrastinating.  For when you think of future selves as being entirely different people (which, in some sense, they are) then you can start thinking about doing favors for your future selves.

I don’t want to clean the kitchen now.  I could procrastinate.  However, to do so would be doing a disservice to “future me.”  Why not clean the kitchen today, and do a favor to my future self?  It’s no different than doing the dishes as a favor to your spouse, or mowing a lawn as a favor to a friend.  Your future self will appreciate it, and be grateful for your thoughtfulness.

For, if you’re a nice person, and enjoy helping others, why not put your future self in that category?  Treat your future self as a fully formed, thinking, rational person, with thoughts and feelings and aspirations and concerns.  It’s easier to do this if you actually think of a future self as a different person entirely.  Then, it will be easier to do a favor for this person, be nice to them, care for them, sacrifice for them.  When seen in this light, procrastination is just a form of selfishness.  Would you get drunk if you knew someone else, a random person somewhere, would have a terrible hangover because of your actions?  I’d hope that most people would not.  And yet, “Saturday morning you” is a person, just like “Friday night you” is.  So why be so selfish?  Why have that tequila?

I am not trained as a philosopher, although I have published works on the philosophy of quantum mechanics.  Nevertheless, I don’t think philosophy is the exclusive playground of those with philosophy PhD’s.  As this example shows, something as abstract as Bose-Einstein statistics can inform “traditional” philosophical questions such as the existence of God, the mind/brain problem, and philosophical zombies.  My intent here is to get people thinking, discussing, evaluating.  Science and philosophy are not enemies.  They’re frenemies.  Let’s hope they continue to play together in the sandbox.


Read Full Post »


I don’t want this shirt for my birthday.

What do the colors pink, gray, and beige have in common?

For one thing, they’re all annoying.  I mean, come on…this isn’t rocket science.

But why are they annoying?  Why is lilac (RGB = [220, 208, 255]) so insipid?  Why does jasmine (RGB = [248, 222, 126]) make one vaguely nauseated?  Why is Crayola fuchsia (RGB = [193, 84, 193]) worse than a bout of the common cold?  (Use this applet to investigate these combinations.)

My thesis is this: that these colors are so annoying because they’re extra spectral colors.  And on some primal, instinctual level, humans don’t like extra spectral colors very much.

In a previous post, I talked about how humans have 3 kinds of cones in their retinas.  Roughly speaking, these cones react most strongly with light in the red, green, and blue parts of the visible spectrum.  Now, as I mentioned, “color” is a word we give to the sensations that we perceive.  Light that has a wavelength of 570 nm, for example, stimulates “red” and “green” cones about equally, and we “see” yellow.  That’s why we say that R+G=Y.  That’s why we also say that 570 nm light is “yellow” light.

Extra spectral colors are colors that don’t correspond to any one single wavelength of light.  They are “real” colors, in the sense that retinal cones get stimulated and our brains perceive something.  However, extra spectral colors don’t appear in any rainbow.  To make an extra spectral color, more than one wavelength of light must hit our retinas.  Our brains then take this data and “create” the color we perceive.

In terms of the RGB color code, extra spectral colors are those in which both R and B (corresponding to the cones at either end of the visible spectrum) are non-zero.  And I don’t know about you, but I have a very heavy preference against extra spectral colors.

Now, admittedly, white (RGB = [255,255,255]) is about as extra spectral as you can get.  Does white annoy me?  Not really; but as a color, it’s also pretty dull.  Does anyone paint their bedroom pure white on purpose?  Does anyone really want an entirely white car?

But the other extra spectral colors I mentioned earlier are a who’s who of mediocrity.  Does anyone older than 16 actually like pink?  Has anyone in the history of the world every uttered the sentence, “Gray is my favorite color”?  And beige—ugh.  Just, ugh.

Standard pink has an RGB code of [255, 192, 203].  Surprisingly, there are combinations that are much, much worse.  Hot pink [255, 105, 180] disturbs me.  Champagne pink [241, 221, 207] bothers me.  Congo pink [248, 131, 121] doesn’t actually make your eyes bleed, but I had to check a mirror to verify this for myself.

Beiges are less offensive, but that’s like saying cauliflower tastes better than broccoli.   Of particular note are “mode beige” [150, 113, 23] which used to be called “drab” but was re-branded in Orwellian fashion, and feldgrau [77, 93, 83] which was used in World War II by the German army, in an apparent attempt to win the war by losing the fashion battle.

This is speculation, but I’ve often wondered if these colors bother me because they are stimulating all three kinds of cones in my retina.  Maybe in some deep part of the reptilian complex portion of my brain, I know (on an intuitive level) that these colors don’t correspond to any particular wavelength.  These colors don’t appear in the rainbow.  You can’t make a laser pointer with one of these colors.  You can’t have a magenta, or a beige, or a gray photon.  And somehow, my aesthetic sense knows this.  So when I see the color “dust storm” [229, 204, 201] my limbic system tells me to wince, and I’m saved from even having to know why.

Anyway, I’d be interested in seeing which color(s) bother you the most.  I’m going to guess the color(s) are extra spectral.

[Note: my book Why Is There Anything? is now available for download on the Kindle!]

Read Full Post »


Very slightly more green than blue, “Tropical Rain Forest” can be thought of as a dark cyan.

My wife called me the other day and asked what my favorite color was.

“Hold on one second,” I said.  “I have it written down.”

She explained that she just needed a color in the most general terms, because she was buying me a case for my new iPhone.  So I said “blue.”  But I was disappointed that I didn’t get to be more specific.

You see, my actual favorite color is (currently) Tropical Rain Forest, formulated by Crayola in 1993.  Its RGB color code is (0, 117, 94).  If you want to read about the color, it’s the first variation on jungle green in the Wikipedia article of the same name.

But what’s an RGB color code?  Anyone familiar with computer graphics will recognize RGB as standing for Red/Green/Blue, which are taken to be the three primaries.  And therein lies a tale: for didn’t we all learn in kindergarten that red, blue, and yellow (not green) were the primary colors?  What’s going on?

Light comes in different wavelengths, or more commonly, combinations of multiple wavelengths.  Color is a purely biological phenomenon having to do with what we perceive with our eyes.  So when a kindergarten teacher says that “mixing red and blue make purple”, there’s really a whole lot of physics and biology that’s being glossed over.

In our retinas, we (generally) have three kinds of cones that react to incoming light.  These cones can detect many wavelengths of light, but each peaks in a different part of the spectrum.  Very simplistically, we can say that one peaks in the “red” part of the visible spectrum, one peaks in the “green” part of the spectrum, and one peaks in the “blue”.

Now, the “red” cones don’t just react to red light—it’s just that they react most strongly to red light.  But light in the “green” part of the spectrum might also stimulate a “red” cone to some degree.  The colors that we see depend on how our brains interpret three signals: how much each of the three kinds of cones is stimulated by incoming wavelengths of light.  For example, if a “red” cone and a “green” cone were stimulated about equally, your brain would interpret this as seeing yellow.  If all three cones were stimulated strongly, you’d “see” white.  (It’s weird to note that different combinations of wavelengths can actually cause the same sensation in your brain: there’s not necessarily a unique combination of wavelengths for any given color perceived.)

Here’s a chart to help you out (note that this is very simplistic and glosses over many issues which I will address later):

Kind(s) of cone stimulated            What you perceive

“Red”                                                                Red

“Green”                                                            Green

“Blue”                                                               Blue

Red & Green                                                    Yellow

Red & Blue                                                       Magenta

Green & Blue                                                   Cyan

Looking at this chart makes the notion of an “additive” primary easy to understand.  We declare red, green, and blue (RGB) to be the additive primary colors.  We can then build (most) other colors by adding these colors together.  This corresponds to multiple wavelengths of light stimulating one or more cones in the retina to varying degrees.  If you want an applet to play around with this kind of additive color mixing, try this.  Input (0, 117, 94) if you want to see Tropical Rain Forest.


Additive color mixing

One caveat: the RGB scheme arbitrarily chooses three exact wavelengths of light to be “the” additive primaries, but this represents a judgment call on our part.  The degree to which different wavelengths of light stimulate the three kinds of cones is messy; the graphs of intensity (of cone response) vs. wavelength are not perfect bell curves, and have bumps and ridges.  Furthermore, it has long been known that if you try to limit yourself to only three “primary” additive colors then you cannot reproduce every possible color that humans can perceive.  We would say that the gamut of possible colors you can make with an RGB scheme does not encompass all possible perceived colors.  (For example, true violet as seen in the rainbow cannot be reproduced with RGB—it can only be approximated.  You can’t see true violet on a computer monitor!)

Now, tell a 6-year-old that Red + Green = Yellow, and they will look at you like you’ve grown a second head.  That’s because most experience we have with “color mixing” doesn’t involve mixing different kinds of light; it involves mixing different kinds of pigments.  And that’s a totally different ball of (crayon?) wax.

Suppose I have a flashlight that shines red light.  I have another flashlight that shines green light.  If I shine both flashlights into your eyes, you will see yellow, as we just discussed.  With two flashlights (two colors), more light has reached your eyes than would have with just one flashlight.

Pigments (such as crayons or paint) work in the opposite way.  “Red” paint is paint that takes white light (a combination of R,G, and B) and subtracts some of the light away, so that only the R reaches your eyes.  Green paint takes RGB light and lets only the G reach your eyes.  In other words, red paint “blocks” G and B, whereas green paint “blocks” R and B.

Can you guess what happens if we mix red and green paint?

The 6-year-old knows you get black.  That’s because two successive blockers have filtered out all the light, and nothing reaches your eyes at all.  And when no cones are stimulated, we perceive that as black.

When a teacher says that the “primary” colors are red, blue, and yellow, they are referring to so-called subtractive primaries.  By mixing those three kinds of pigments, you can make many of the colors we can see.  But not all the colors.  Try mixing red, blue, and yellow to make pink.  It cannot be done.  Like the additive primaries, the gamut of the subtractive primaries is limited.  And, like the choice of RGB as additive primaries, the choice of red, blue, and yellow as the subtractive primaries is arbitrary.  Arbitrary, and inferior.  It turns out that using yellow, magenta, and cyan as the subtractive primaries expands the gamut and increases the number of colors you can make by subtraction.

Why yellow, magenta, and cyan?  Well, those choices make sense if you’ve already picked RGB as your additive primaries.  Consider the chart above.  It’s clear that a paint that looks magenta must be blocking green, since you’re seeing an (additive) combination of red and blue.  Similarly, yellow paint blocks blue, and cyan paint blocks red.  So what happens if we mix, say, yellow and cyan?  Well, the mixture will block blue, and then block red, so what is left is green.  You can try this here.

Anyway, I spent some time at this site trying to determine exactly my favorite color.  I finally chose Tropical Rain Forest, RGB=(0, 117, 94).  I think it’s peaceful and organic.  I also enjoy Tyrian purple, RGB = (102, 2, 60).  Let me know which colors you favor.

Coming soon: some thoughts about the extra-spectral colors!

Read Full Post »

An Oulipo story

A friend of mine recently made the following challenge: can you start a story with one sentence, and logically end with another sentence?  The sentences were:

(1)   The washing machine repairman grunted.

(2)   The archbishop vowed never to eat figs again.

In the spirit of Oulipo (Ouvroir de littérature potentielle) I present my efforts here.  Don’t forget : if you’re a many-worlds adherent, then this is a true story.


The 1938 Bendix washing machine

The Foundation that Saves

The washing machine repairman grunted.  “I don’t know as you remember as much of the Bible as you think, your Excellency.”  He wiped his hands on his boilersuit.

“You may be right.  But still—can the Bendix be saved?”

“Well sir, that’s what I was referrin’ to.  Saving.  This here contraption, it wobbles a great bit, drifts, if you will.  So if’n you need it to stop walkin’ across the floor, well sir, it needs a foundation, like.”  His eyes glittered.

Lang nodded.  “I get your reference now.  You said the machine couldn’t be shaken by the steam if it were founded upon a rock.  That’s what, Luke Chapter 6?”

“Just so, your Excellency.  When the steam from the intake beats vehemently, well sir, the pantry here gets a might flooded, with all your Canterbury particulars and vestments getting wet and so forth.  ‘less of course we was to bolt the ol’ Bendix to the floor so as it didn’t walk.  And so I thought of my Sunday canon, sir, and heard my ol’ rector saying clear as a bell: ‘He is like a man which built an house, and digged deep, and laid the foundation on a rock: and when the flood arose, the stream beat vehemently upon that house, and could not shake it: for it was founded upon a rock’.”

“I am impressed.”

“As long as you ain’t impressed by no rock, sir, then we’re good, sir, if you get my meaning.”

Lang smiled.  “You have a deep knowledge of scripture, for—”

“You can say it, Excellency.  For a handyman.  My mum raised me proper, in the ecclesia anglicana if you will, sir.”

“And you were saying, I don’t remember as much of the Bible as I might think I do.”

Mr. Suttles stood up, cracking his knuckles and turning to face Archbishop Cosmo Lang.  “Well, you was talkin’ about the Lady’s feast upstairs, the bounty, how it was ‘a land of wheat, and barley, and vines, and fig trees, and pomegranates; a land of olive oil, and honey’.”

“Deuteronomy 8:8.”

“But our Lord Jesus didn’t go in for any figs, you understand, despite what the Old Testament might say.”

The archbishop smiled.  “You refer to Mark Chapter 11.  When our Lord comes across the fig tree, and finds it barren—”

“Yes, sir.  With all respect, Excellency, Jesus forbade us to eat figs ever again, and I for one don’t want to disobey.”

“Well, it was a parable, son.  The point was that—”

“Plus, them figs that grow on Dr. Speelman’s farm, well sir, they’re infested.  Wasps, you know.  They lay their eggs in the figs, and them larvae hatch inside, and eat up the seeds, sir, and get right fat and happy.  You ever bite into a fig, sir, and feel that crunchy, gritty texture?  Like them little globules that get stuck in your teeth, kinda soft yet kinda firm at the same time?  They as get stuck like that, are wasp eggs.  I kid you not, Excellency.  Jesus knew what he was talking about.  He didn’t want to eat no wasp eggs, and didn’t want his disciples eating no wasp eggs, neither.  That’s one foundation I can get behind.  So forget about no land of bounty with wheat and honey and figs.  Stay away from those larvae.”

The archbishop vowed never to eat figs again.

Read Full Post »

2012 in review

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

The new Boeing 787 Dreamliner can carry about 250 passengers. This blog was viewed about 1,700 times in 2012. If it were a Dreamliner, it would take about 7 trips to carry that many people.

Click here to see the complete report.

Read Full Post »


A recent Toyota commercial begins, “In space, the shuttle Endeavor is practically weightless.”

Do we really have to go over this again?

The fact that the word “practically” is in there indicates that the copy writers don’t have a clue about physics at all.

If they had just said that Endeavor is weightless, I’d be more forgiving.  Such a statement could mean that Endeavor was millions of miles from the solar system, in deep space, and therefore (almost) weightless.  Or it could (more plausibly) mean that Endeavor was in orbit, and that its apparent weight was zero, and they were just confusing weight with apparent weight (like most non-physicists do).

But the Madison Avenue geniuses said Endeavor was “practically weightless.”


This implies, of course, that in space you have weight, but it has been reduced—by being in space, apparently.  The acceleration due to gravity, g, does decrease as you leave the Earth, but as I’ve already discussed, it doesn’t go down enough to approach zero—not unless you go ridiculously far from any other massive object.

Now, a commercial with stupid physics wouldn’t normally get me to reblog about a topic I’ve already covered.  But it gets worse: the Toyota people double-down on their ignorance, and pile BS onto their BS.  The whole point of the commercial is that their truck can pull the space shuttle.

Gee, really?  Well guess what—a mini-Cooper could have pulled the space shuttle, too, given enough time.  So could I.  So could Mr. Burns.  You see, Newton’s 2nd Law says that a net force causes an acceleration, so any net force will cause (some) acceleration.  Sure, it might be small, but in the absence of friction it will eventually get the job done.


…and so, ad infinitum.

I once saw a video of a flea pulling a hockey puck along the ice, even though the puck (around 160 g) had a mass over 700,000 times bigger than the flea (around 220 μg).  It took some time, but the puck eventually moved noticeably.  (Sorry, I couldn’t find the video on the internet.)

Well, what about friction?  Maybe there’s some horizontal friction between the shuttle and the ground, and a Toyota Tundra is forceful enough to “overcome” that friction whereas a mini-Cooper is not.  This is a valid point, but the writers of the commercial were definitely not thinking of this.  How do I know they were not thinking of this?  Well, because they say (as if it is important), “that bad boy weighed 292,000 pounds.”  If that’s all the information we are to be given, then we can’t conclude anything about the merits of their truck: if friction is zero, then the feat is less than impressive.  If instead the coefficient of friction is tremendous, and the normal force between the shuttle and the ground is truly 292,000 pounds, then the feat is amazing, in particular because I would wonder why the truck doesn’t subsequently pull itself back towards the shuttle à la Newton’s 3rd law.  But they don’t mention friction, and therefore they don’t get to play that card.  Occam’s razor suggests that the copy writers just don’t know squat about physics.

Anyway, I have nothing to say about the merits of the Toyota Tundra.  Maybe it’s a good truck, maybe it’s not.  But as for Toyota Truck commercials…please turn the channel.  You’d do better to watch a roadrunner cartoon.  The physics isn’t any better, but at least it’s entertaining.

Read Full Post »