Category Archives: Science

How to reverse-engineer the universe.

Physics Thought Experiment

My friend Pete (he’s the one who looks like John Tesh) is trained as a physicist, so naturally I thought of him when I couldn’t get this thought experiment out of my head:

Imagine a spaceship, one light-year in length.  Assume it’s built in such a way that it magically has zero ability to compress or flex.  Humans are in the front, and engines are in the back.

If the engines turn on, I know that it takes one year from the perspective of the crew until they could see the light from the engines.  Obviously, the vibrations from the engines would take much much longer.

What I don’t know is when the humans would notice motion.  If the motion was bound by the speed of light, then it would take them one year to notice that they were moving.  But based on my rudimentary physics knowledge, this doesn’t seem to make sense.  I never heard of any physics that made the head of an object move long after the tail was pushed.

Luckily, Pete saved me from a series of sleepless nights in which I half-wondered if I’d derived some form of really clunky FTL communication technology.  His response was so thorough and informative that I wanted to share it with the world.  Well, the subset of the world who reads my blog.

The speed of light is not just a limit for light transmission, but for all interactions. From a particle viewpoint, interactions are mediated by particles. In the case of electromagnetism, this particle is the photon, which moves of course at the speed of light. The mediator particles for other types of interactions are also limited by the speed of light. Generally, massless particles travel at the speed of light, and all others are limited by it (but can never reach it.)

The macroscopic effects of what you described, aside from any resulting motion, might be called material stress or a material shock wave.

With regard to the humans in the front, not only is there no instant notification of what’s happening in the back, there can be no effect at all for 1 year. That is, no stresses, no motion, no nothing.

So what you’re thinking right now is, well then how can I conserve momentum? If the engines are spewing things out backwards, the center of mass of the spaceship taken as a whole must be moving the other way to balance that. In fact, there is momentum produced in the other direction (as there must be), and if you found a way to calculate precisely the center of mass motion of the spaceship as a whole you’d find it to be moving, but it is in the form of either material deformation in the rear, or microscopic dynamics that on a macroscopic level could be described by a type of wave in the material which can be associated with an overall macroscopic momentum.

In this context, an analogy between the spaceship material and fluid medium might be useful. If you’re in the middle of the lake and row your boat, the boat goes one way, and the momentum is balance by the motion within the water. The water at the edge of the lake doesn’t know anything about it until the waves you’re making reach there. If you were to calculate the momentum of all the water molecules at once and add them all together, you’d find that it cancels out the momentum of your boat. You can think of the momentum of your engine exhaust being balanced by the momentum associated with the shock wave traveling forward through the material of your spaceship.

You might not believe that the effects of the engines could be absorbed entirely by material waves with no macroscopic motion. This is because the scale of your spaceship is rather extreme. If you made the spaceship too rigid and not large enough width-wise, and the engines were too powerful, then the rear of your spaceship would just bust apart. If you imaged that the spaceship was a borglike cube of solid iron 1 light year per side, then you can start to believe that the engine thrust could be “absorbed” by wave disturbances within the material.

The apparent paradox in your thought experiment is due to the false assumption that you can make something that’s completely rigid. This is not physically possible. On a logical level, your thought experiment itself, combined with the speed of light restriction, proves this. On a microscopic level, you can make arguments regarding microscopic interactions as I did above for why 100% rigidity is not possible.

This reminds me of a special relativity problem I used to give my students that is related in one respect, but otherwise different:

Imagine a garage that’s 20 ft long, and a pole vaulter with a 30 ft pole that can run really fast into the garage.  As you may know, things that are moving get contracted in length. This is not because they are being compressed or anything like that – it is a result of the nature of space time.

Suppose the vaulter runs so fast that in the rest frame of the garage the pole is only 20 ft long. (He would have to run really really fast to get that kind of effect.) Then he would be able to fit the pole inside the garage, and you could close the door quickly and the entire pole would be contained in the garage undamaged for a split second until everything hits the back wall with massive destruction ensuing.

So that’s all well and good, but what about the rest frame of the vaulter? In that frame, the pole is still 30 ft. To make matters worse, the garage, which is in this frame speeding towards the vaulter, is contracted to only 10 ft. So in that frame when the front of the pole hits the back wall, there’s still 20 ft of pole outside the garage.

I was actually aware of the pole-vaulter example, but I hadn’t considered how it applied to my own thought experiment.  Physics is filled with such awesome stuff like this.  Thanks, Pete!

The Awesome Task of Recoating a Telescope Mirror

If you enjoy pretty pictures of the universe, you owe it to yourself to learn how a common bit of maintenance is done on ESO’s VLT, or Very Large Telescope.

At some point, the reflector used in the VLT is beyond recovery, and they need to strip it of its mirror finish and recoat it.  This seems like it would be straightforward, but some of the most impressive robotics, machinery, engineering, and minds are applied to this task.  If anyone involved in the process is having a bad day, and they break the ceramic mirror base, the telescope would be out of commission for years until a replacement mirror is built.

I’ve worked on multiple critical systems in my career, but I’ve never seen anything quite like this.

Genetic Domestication

At one point, I was hoping to develop this idea into something patentable, but I lack the proper background.  So here it is for you and the rest of the internet to find and use.  I’d rather see the idea work than hold onto it.  First, some background. Those of you who watched Dogs That Changed the World will find some familiar information here, but my crazy proposal goes beyond it.

Wolves are a canid species, as are dogs.  Dogs are basically domesticated wolves, although there’s apparently no consensus on whether the selection was done by humans or by the wolves themselves, but we do know that there is a path from wolf to dog.  Wolf DNA and dog DNA are close enough that they can consistently breed and produce fertile wolfdog offspring, despite the fact that most dog breeds look very unlike wolves, and no dog breed behaves much like a wolf (at least in ways that determine their suitability as pets).  You also won’t find an adult wolf with traits such as floppy ears, “patchy” fur, blue eyes, or anything else we consider cute and doglike.

Another wild canid species is the fox.  Long ago, the animal portion of the Russian fur trade involved feeding and generally looking after lots of caged foxes prior to them being harvested for fur.  The problem was that foxes don’t like people very much, especially when the foxes are trapped in tiny cages, so they’d bite the workers any time they could.  The people in charge got the bright idea that they’d interbreed the foxes that attacked humans less so that the next generation of fur foxes would be easier to handle.  This process of breeding our aggression went very well and improved productivity, but then they hit a snag.  Several generations in, their fur foxes changed from a solid color to a black and white mix, which was simply no good for fur.  Many of them even ended up with floppy ears and blue eyes.  (Sound familiar?)  For more details, check out this video clip and these before and after pictures.

The foxes seemed to be domestication-ready just like wolves were.  Geneticists learned that in canids, genes that regulate certain appearance-related characteristics are associated with genes that regulate adrenal response.  Roughly speaking, this means that when one set of genes changes, it tends to drag another set of changed genes along with it.  This is why canids that look “cute” also tend to be docile because the genes that were selected for reduced adrenal response not only reduce the animal’s fear and aggression, but they’re tied to the “cute” genes.  This is why you tend to get docility along with “cuteness.”  Why we happen to think domesticated animals are cute is another question entirely, but it’s certainly useful that we associate a dog’s cuteness with docility.

It seems reasonable to conclude that the genetic basis of domestication in canids is either well established or could be, given a little effort.  I suspect it’d be possible to get a handle on a specific set of genetic changes that could turn any wild canid into a domesticated canid in a single generation, if gene therapy were used.  For canids, this might not be cost-effective, since it seems to be pretty easy to breed them into domestication in a few generations.  But maybe the process of genetically domesticating canids could be generalized to other animal families.  Like bears, lions, or tigers.

Pretend I’m not wearing my crazy man hat and hear me out.  There are species of bears and big cats that are threatened or endangered.  While we can try to save their habitats, a multi-pronged strategy seems to be less dangerous to me.  What if we could genetically domesticate bears and big cats?  People already attempt to keep big cats as pets, so there’s a demand for it.  Anyone who’s ever seen a baby polar bear could be persuaded to adopt one as a pet.  So why not create a pet breed for each endangered animal, encouraging people to adopt them as pets and get their numbers to grow?  When the time comes to introduce wild versions of them into their ancestral habitats, the genetic alteration could be reversed again in one generation.

If you still think I’m a crazy man, here are some data points that may convince you of the idea’s viability:

  • There are already more tigers in the US than there are in the wild, and not all of them are in zoos.
  • Only recently, a species of fox that lived on a Californian island dwindled down to 15 members.  There was a mad scramble to save them and breed them in captivity, which they ultimately did, but it was very expensive.
  • People try to own wild animals as pets anyway, so why not use their interest as a way of genetically banking wild animal DNA?  Just check YouTube for videos of pet foxes, pet anteaters, pet cougars, pet squirrels, pet monkeys, and so on.

Conferring Immortality?


Authors, philosophers, and scientists have explored these concepts in detail, and it’s my hope to introduce them to you, not to claim them as my own.

Feasible Immortality

There is a recent notion that some people alive today may achieve biological or technological immortality.  Biological immortality focuses on things like prevention and repair of cellular damage, immortality of cell lines, replacing aged organs with newly-grown ones, and removal of what I can best call “crud” that accumulates in your body as you age.  Technological immortality involves replacing failing biological components with artificial ones, replication of your personality, in essence porting it from wetware to hardware or software.  We do much of this now under the umbrella of general medicine, achieving longer and healthier lives.

What I want to explore is the philosophical question of whether or not immortality can be conferred on an individual, or if the conversion to immortality conceptually kills the original and produces an immortal copy.

Biological Immortality

While our structure remains relatively constant over time, the atoms that comprise us change regularly as cells replace themselves.  On average, you are made from completely different atoms every seven years.  If you define yourself based on the atoms that are in your body, or specifically your brain, then you’ve already been replaced Y/7 times if you’re Y years old.  Any memory you have from eight years ago was stored in cells that have died and left copies.  You can still access those old memories because cell replacement doesn’t change structure, assuming everything goes well.

If medicine did allow us to extend our cell lines indefinitely, avoid replication errors, fix or prevent inherited genetic diseases, and remove accumulated “crud,” we could live forever if we avoid the same things that can kill us prematurely now.  We’d still be ourselves – at least as much as we are ourselves now, with our atoms changing every seven years.

Technological Immortality

An immortality solution that emphasizes technology could eventually replace each part of your biological body with a piece of technology.  To jump ahead slightly, let’s assume every organ, including the brain, can be replaced with a modular piece of technology that performs like the original.

What if your biological brain were put in a technological body?  Simply doing this would significantly extend life, since a lot of things that damage the brain are caused by the rest of the body.  In conjunction with biological brain immortality, it could confer full immortality.

Would your real brain in a technological body still be you?  If you think of our brains as piloting our bodies anyway, then you’d probably say yes.  To me, this seems reasonable.

What if, instead of using your biological brain, some process scans your biological brain and produces an exact copy of it in hardware and/or software?  Does that confer immortality to you, or does it merely copy you?  What if the scanning process is destructive, resulting in some time when the pattern in your brain that is you isn’t complete?  Would that murder you and create a copy?  To me, I’d consider it murder for a scanner to tear my brain to bits as it studied the structure.

Those are the edge cases.  It gets trickier when you think of the middle ground.

What if there were a way to slowly replace the biological structures in your brain with technological ones?  Your brain already replaces cells on its own, and we don’t generally think of this as killing us, so how is it different for a technological process to take over?  One by one, neurons, axons, dendrites, would be replaced by functionally-equivalent nanotechnological components.  If we set the timescale for the conversion to be seven years, then we ensure that it happens no faster than nature.  Are you still you when one of your neurons is technological?  What about 100?  What about 10 billion (roughly 10%)?  One thing is assured: by the end of the seven-year process, your biological brain will be gone.

Wait, it gets creepier.

Let’s say you’ve made the switch to a nanotech brain, as above.  Assuming you still think you’re you, and not the murderer of your identical twin, what would happen if you converted your nanotech hardware brain into a software brain?  Is there a difference between two things if they behave the same?  As before, the conversion could be done gradually, over a seven-year period, slowly deactivating pieces of the hardware brain and activating equivalent software representations in a computer brain.  Would you still be you?  If the answer is yes, then what exactly are you now?  Are you the structure that the software represents?

It gets stranger, too.

One of the authors I’ve read suggests that if you’re ok with neurons being replaced by functional equivalents, then the physical geometry of these neurons in relation to the others doesn’t matter much.  Instead of direct physical connections, why not go wireless?  You could store parts of your brain in your house and keep just a small portion of it in your body for tasks like reflexes where latency is an issue.

Closing Thoughts

To me, the edge cases seem clear: I’ve had biological immortality conferred upon me if my brain is able to maintain its normal biological process indefinitely;  I’ve had an immortal copy made if someone reads and copies my brain in a single step, and I’m murdered if the read was destructive.  What bothers me is that I don’t know how I feel about something that slowly destructively copies my brain in place.  The continuity seems to be what throws me, because it would offer the same continuity as biological brain immortality, but the end result is that my biological brain will have slowly been destroyed.  Of course, if continuity problems bother me, I should stop sleeping.

Bad QA Can Kill People

Let’s say you’re in the business of buying food raw materials.  How do you know you’re buying a protein powder and not, say, talcum powder?  Tasting it may not be your first idea, just in case a shipment got mixed up, and it doesn’t scale well, so you’d probably want some way to test the powder to make sure it’s what you ordered.  You could probably perform a really specific test that would be costly and/or time consuming but would definitively tell you that you had protein powder with a given protein content and zero contaminants.

But why would you do that?  People are basically honest, right?  All you need to do is look for something associated with protein to check up on your supplier now and then and compare what they’re sending you to what their rivals could provide at the same or better cost. Well, there’s plenty of nitrogen in protein, so a test for nitrogen would be a pretty good test for protein…  Or fertilizer.  Or melamine.

You’ve heard of melamine in the news, and QA is the reason why.  Two tests are generally used to measure protein content in milk, one called the Kjeldahl test, the other called the Dumas test, both of which provide similar results.  It is tempting to call it the Dumbass test instead, though that would be unfair to the test itself, which does a good job of detecting nitrogen levels.  No, the dumbasses are the people who use these test results to determine protein levels, when what they actually do is determine nitrogen content.  That’s how it ended up in baby formula and other food products, because the test results showed a high nitrogen content, which the testers falsely concluded to mean a high protein content – and not a high protein + industrial chemical content.

Put in other terms, this is like taking the knowledge that English documents are about 6.5% N’s and trying to determine if an author sent you a 40,000-word novel by counting the N’s and deriving how many total letters there must be, and by extension how many words.  Much like with the protein test, it works fine as long as the test subject is honest.  When the author who knows your QA process sends you a document containing nothing but N’s, you are in for a surprise of the worst kind.

What is most frustrating is that there do appear to be accurate alternatives to the foolable tests, though they are surely not cheaper.  As with so many things in life, cheaper wins until cheaper fails so badly that cheaper ends up in the headlines and in shiny new laws.

How Did I Not Know This?

While reading a list of strange scientific phenomena, I saw a throwaway comment about a natural nuclear reactor underneath the surface of the Earth at “what is now Oklo in Gabon.”  It had to be a joke.  Surely I had stumbled across some obscure viral marketing for the next horrible scifi movie, and when I researched Oklo, I’d find some website talking about it that looked old but had no archival record prior to 2007, with speculation from prominent UFOlogists suggesting it was from a crashed spaceship.

Except my search quickly brought me to a sub-site of the US Department of Energy talking about how it happened, how they know it happened, and what it means for disposal of radioactive materials.  Huh.  Now, I don’t expect to have learned everything there is just yet, but damn it if this isn’t the most awesome thing nobody seems to talk about. Our planet spontaneously made its own nuclear reactor millions of years before any mind ever considered the possibility.

It ranks up there with the moment I learned that in 1975, the USSR landed probes on the surface of Venus, withstanding the crushing pressures and lead-melting temperatures long enough to take pictures and gather some environmental data and transmit it back to Earth.  6 years later, they repeated their success and returned color picturesBadass.  If you check out their timeline, you’ll see that they failed for 14 years until they got it right, which is possibly very inspirational, but I can’t escape the mental imagery of a special Siberian gulag just for disgraced Venus mission leaders.