This is news? It’s the first thing I thought of when I first heard about black holes as a loli.
It really feels like crackpottery that got past Phil’s sensor somehow (though it wouldn’t surprise me in the least Slashdot picked it up if it were).
I finished this one a while ago, but I guess I never got around to reviewing it. What is Life? is, of course, a famous work by Erwin Schrödinger, of cat fame.
In it, he argues that chromosomes behave according to physical laws classical physics can’t really approach, since classical physical laws are statistical, and only hold for large numbers of molecules, while a chromosome is in essence just one very large molecule. He speculates that DNA is, in fact, a large aperiodic crystal, and muses about the ways in which it could encode hereditary information.
And yes, it’s all speculation. This was written in 1944, well before the actual structure of DNA became known, and, indeed, long before much of anything was known about genetics. It still speaks about DNA as being the carrier of heredity in the hypothetical, even.
What is Life? was a visionary work, and its influence is undeniable. Even today, it can still inspire people because of the intense sense of curiosity it conveys (Schrödinger was, after all, a theoretical physicist first, but he didn’t let that stop him from delving into this alien field of biology).
As a source of accurate information, though, it’s much more likely to misguide than to educate, at this point, so it really isn’t a book uninformed laypeople should be reading. Still, if you know a bit about genetics and molecular biology, it’s a very interesting read for its historic value.
This edition also contains Mind and Matter, an essay I didn’t bother reading since I figured it would make me angry (especially since Roger Penrose wrote the introduction), and Autobiographical Sketches, in which Schrödinger talks about his life.
This is particularly interesting, since Schrödinger was, after all, a scientist during the World Wars (which is always an interesting topic; just look at Richard Feynman). Moreover, he was Austrian, so he spent much of his time on the side we never really hear first-hand accounts from. It’s nice to hear someone talk about this without the off-hand demonisation we’ve become so used to.
The Elegant Universe, by Brian Greene, is a guide to physics in general and superstring theory in specific.
Greene starts out by explaining, in simple terms, the basic ideas behind the theories of relativity and quantum physics, and how they’re increasingly coming into conflict.
Relativity dealing with massive things moving quickly, and quantum physics dealing with tiny things, the theories have managed to coexist for a while, but the discovery of singularities like black holes, which are both massive and tiny, need something to tie it all together without actually getting infinities anywhere (be it infinitely small sizes, or infinite densities or temperatures, or what).
Clearly, string theory is the solution, and the second half of the book is devoted to explaining why this is the case.
Keeping in mind that string theory hasn’t made any predictions yet that can be tested with current technology other than ones that can be explained by other, older theories as well (which Greene openly acknowledges), he makes a pretty good case.
Without going into the underlying mathematics, he manages to explain how the various particles and forces we observe (including gravity and the as yet undetected graviton) flow naturally from string theory, and how it seems to accomodate supersymmetry, which is just pretty, and how the theory is really too elegant not to be true (which, I’ll grant, isn’t a valid argument on its own).
It’s a very interesting book, both for the physics (even if you dislike string theory, the bit about relativity and quantum physics is good enough in its own right) and for the history lessons. The way string physicists approach mathematics is, of course, obnoxious, but even that isn’t too bothersome.
Definitely worth reading, even—or especially—for those with no background in physics whatsoever.
Richard Feynman once said that all of quantum physics can be derived by carefully thinking about the double-slit experiment. All of relativity can be derived (much more easily) by carefully thinking about a flashlight on a train.
Last time, I said one of the consequences of special relativity was that there is no absolute way of telling which of two events happened first. Let’s look at what I meant by that.
Consider the following set-up: two light sensors, at a fair distance from each other, and a lightbulb in the middle, the same distance from both sensors.
If you switch on the lightbulb, which sensor will go off first? They’ll both go off at the same time, right?
Starting at the bulb, light has to travel the same distance to reach the sensor on the left as it does to reach the one on the right. So yes, they go off at the same time.
Now consider what that scene would look like if it were moving past an observer (or if an observer were moving past it; same thing).
Now the sensor on the left is actually being moved into the light beam, so light starting at a given point in time has to travel less far to reach that sensor than it does to reach the one on the right.
For “normal” objects this wouldn’t make a difference, since to the motionless observer, the objects on the left (that is, fired in the opposite direction to the movement of the system) would appear to move more slowly than the objects on the right (which would be moving at a speed equal to that of the system plus the speed at which the object appears to be fired to the person on the train with it), but light doesn’t work that way (neither do objects, but the difference is too small to be really noticeable at low speeds). Light always appears to be going equally fast to all observers.
So what does this mean? To the motionless observer, light moving to the left sensor has less distance to travel than light moving to the one on the right, but it still moves at the same speed.
The result is that to that observer, the sensor on the left will appear to be triggered before the one on the right!
Furthermore, if there were another observer, moving in the same direction as the train but faster than it, he would see the sensor on the right going off first!
We’ve already seen that all reference frames are equally valid (except accelerated ones, but really they are if you include gravity and work according to general relativity, but that’s not a concern here), so it follows that there is no absolute way of telling which sensor went off first.
It doesn’t take much imagination to see that this doesn’t just apply to this situation, but to every situation imaginable.
Relativity is really quite interesting, and it makes sense once you get used to it. The hard part is getting used to it. Human beings are generally just too slow to notice its effects, like they’re too big to notice most quantum effects and too light to get a good feel of Newtonian physics.
Nature is a great deal more fascinating than it appears at first glance.
(If you’re interested in a similar thought experiment which also makes use of the fact that objects contract along their direction of motion, the ladder paradox is pretty neat.)
Special relativity is the theory introduced by Einstein in 1905 which overthrew our understanding of classical physics. It’s a special case of general relativity, which he would come up with later on.
The central ideas of special relativity are so easy to explain that I’m not sure why it isn’t taught in high schools. Well, not in ours, anyway.
There are two important ones:
If you aren’t accelerating, you can’t tell if you’re moving, except if you take some other object as a reference point, in which case all you can say is that you’re moving in reference to it. If you’re floating in space and you see someone else float by, it’s meaningless to ask if you’re stationary and they’re moving past you, or if they’re stationary and you’re moving past them, or if you’re both moving past each other.
If you’re in a space shuttle with no windows, there’s no experiment you can do to tell if you’re moving or not; there’s no absolute frame of reference, so the question is meaningless.
This isn’t true for accelerated motion or rotation, but special relativity doesn’t deal with that. That’s general relativity’s area.
If you’re moving at 30 kilometers per hour (from the point of view of a second observer), and you throw a ball ahead of you at 60 kilometers per hour (from your point of view), it will be moving at 90 kilometers per hour (according to that observer), yes?
So, if you’re moving at 30 kilometers per hour, and you know the speed of light is 299,792,458 meters per second, and you shine a flashlight ahead of you, how fast will that second observer say the light is going?
Exactly 299,792,458 meters per second, turns out. And that’s also the speed you’ll measure from your own frame of reference.
To make this easier to think about, let’s consider a very simple clock.
Take two mirrors, and bounce a single photon back and forth between them. Every time it hits a mirror, there’s a soft tick. If the mirrors are slightly less than thirty centimeters apart, a billion ticks will equal one second.
Now, imagine that clock is moving past you at a uniform velocity, on a tiny train, perhaps. How will that photon appear to move?
(Leaving aside the issue of how you’d see a single photon bouncing between mirrors.)
The photon appears to be travelling a greater distance than the thirty centimeters it appears to be travelling to the person on the train with the clock.
But light being what it is, it will appear to still be moving at 299,792,458 meters per second to both of you, which means that a billion ticks will actually take longer from the point of view of the person watching it go past (you) than to the person in the train with the clock, so time is actually moving more slowly on the train!
Even more interestingly, imagine what would happen if you had a second clock, which you kept with you as you were watching the train go by.
In exactly the same way, your photon would appear to be travelling more than the thirty centimeters as well to the person on the train, so to him, you would be moving more slowly too. Both of you perceive the other as moving more slowly!
How can this be?
Suppose you were both wearing wristwatches (or whatever; something to tell how much time has passed, rather than how quickly time is passing, which is all the photon clock is capable of). If after a bit, you and the guy on the train came together to compare watches, you should be able to tell which one of you was really moving more slowly, right?
Well, no. Bringing the watches together requires motion as well, and for the other guy to change his direction (or for you to start moving) so you two can meet requires acceleration (even if only briefly), which actually doesn’t work according to special relativity.
The acceleration breaks the reference frames and makes the guy doing the accelerating experience time lag in a way that neatly cancels out the apparent paradox and will make him the slow one.
Bringing the watches together might seem like a simple matter of logistics, but it’s not actually exempt from the laws of physics.
This is rather more complicated to explain properly, though, so I’m not going to bother.
An interesting consequence of this, though, is that for any two events, you can never say in an absolute sense which occured first, which is quite interesting.
This book took far longer to finish than it should have. This is in large part due to the silly conclusion Penrose tries to reach, which just makes my brain bleed.
The thesis of the book is simply this:
It starts promisingly enough, with an explanation of Turing machines, computability, and the Turing test. Having explained these concepts, Penrose then tries to argue that the brain is, in fact, not a deterministic Turing machine.
Central to this claim seem to be the Chinese Room experiment and similar thought experiments (which I’ll grant can be difficult to grasp properly), and various minor things like “flashes of insight” (which clearly can’t be explained deterministically!) and whatnot.
Fortunately, he quickly abandons this line of reasoning and starts talking about mathematics and quantum physics for a few hundred pages. I’m not sure why he does this, since neither has any relevance to the subject at hand, but I’m not complaining.
He tries to return to the brain in the final chapters, but he just makes an ass of himself in the process.
Penrose doesn’t understand psychology, physiology, fetal development, evolution or natural selection (at some points coming perilously close to endorsing ID), the (often counter-intuitive) capabilities of actual computers, or cognitive science, but he tries to venture into each of these fields to make his point and fails spectacularly.
His whole point is essentially a giant, infuriatingly dense argument from incredulity and personal pride (the human brain can’t be a deterministic Turing machine, that would make it too common!), and his attempts to involve quantum physics are more reminiscent of Deepak fucking Chopra than of a theoretical physicist of Penrose’s stature.
Now, does this make The Emperor’s New Mind a bad book? Well, yes. Let me rephrase.
Does this mean The Emperor’s New Mind isn’t worth reading? Absolutely not.
Like I said, most of the book is just seemingly irrelevant stuff about mathematics and quantum physics, and it really is quite interesting. It’s worth keeping in mind that Penrose isn’t just some random woo artist, but an accomplished mathematician and actually a rather competent theoretical physicist.
He talks about Turing, fractals (including the Mandelbrot set), Penrose tilings, the history of physics, and plenty of fascinating concepts in theoretical physics ranging from well-known to rather obscure. If you’re willing to gloss over his forays into cognitive science and AI, and maybe skip the last chapter entirely, it’s actually a very good read.
As far as philosophy of the mind goes, though, I’d just leave that to people like Daniel Dennett.
The explanation I’ve been given says that due to vacuum fluctuations, a particle-antiparticle is created near the event horizon of a black hole, and one of these particles is drawn into the black hole, while the other escapes, thereby giving the appearance of the black hole emitting a particle.
Now, the only way I can see a black hole losing mass (and heating up, which it apparently does as well) through this is if the particle drawn into it happens to be the antimatter particle.
However, on average, as many matter particles would be drawn in as antimatter particles, cancelling out the effect (and, incidentally, the radiation).
Either I’m missing something profound about Hawking radiation itself or (more likely) about virtual particles, or this is an example of lies-to-children oversimplifications confusing more than they educate. Or both.
I will keep looking~
I just finished Six Not-So-Easy Pieces. Together with Six Easy Pieces, it’s a much abridged version of the Feynman Lectures on Physics, by, of course, Richard Feynman.
I finished Six Easy Pieces weeks ago, but since it and the sequel add up to less than a third of a typical book, size-wise (about 140 pages each), I decided to review them together. I just got side-tracked for a bit.
Six Easy Pieces is actually the exact same book as The Character of Physical Law (which I reviewed earlier), just with the chapters moved around a bit and some bits reworded.
It’s much more recent than Character, but I thought it was a bit less coherent. Still, quite good.
Six Not-So-Easy Pieces takes most of the concepts introduced in Six Easy Pieces a step further, and introduces some relevant equations.
The first chapter introduces vectors as if it’s some super-advanced new concept (which it may well have been at the time, though I would hope that anyone who’s gone through highschool now would know what they are), and talks about how they apply to Newton.
The second returns to the various symmetries in physical laws, and delves deeper into what they mean. It also talks more in-depth about the various laws of conservation (momentum, energy, angular momentum, charge, baryons, and leptons).
The final four chapters are about special relativity and what it means, exactly. He gets a few jabs at philosophers in on the side, because he wouldn’t be Feynman if he didn’t.
While it does require some background in mathematics, it’s actually pretty easy to follow. It may be a bit too advanced for the casual reader, but anyone with an interest in physics should be able to pick it up quite readily.
At various points he hints at the limitations of the various theories and areas where our knowledge is still very much on shaky ground, or missing altogether. Given that these lectures were given in the 1960s, I’d be very interested in seeing another book, perhaps, that revisits the not-so-easy pieces and tells us what progress has been made.
Either way, they’re very interesting, and make for a surprisingly light read, given the subject matter. As a layperson, it’s kind of hard to know which bits, if any, are completely outdated, and the mathematics can be hard to follow, but it’s still very much worth reading. I certainly learned a few things.
(I never really understood the equivalence principle as well as I wanted to. Now I do.)
I managed to finish a book before buying new ones!
The Infinite Book, by John D. Barrow, tries to explain the concept of infinity in several fields, and talks about how it has historically been regarded.
The first half of the book deals with infinity in mathematics. It starts with the obvious — Zeno’s paradoxes — and works its way through the history of mathematics all the way up to Georg Cantor and his infinite sets (א is a neat symbol), taking care to introduce complicated concepts in a way anyone could understand.
The second half deals with infinity in physics: infinite density, temperature, &c. in singularities, the infinity of space and time, and the infinity of the multiverse. It touches on things like the Big Bang (obviously), whether or not the universe will continue to expand forever, time travel, &c.
All of it is at least moderately interesting, though it does get repetitive.
The final chapter tries to philosophise a bit about what life would be like if we could live forever, in a stoner stream-of-consciousness kind of way. Barrow may be a good mathematician and theoretical physicist (though if he is, the scope of this book didn’t exactly allow him to show it off), but he’s no great philosopher.
But other than that, it was a pretty decent book. It made for easy reading, but it doesn’t treat readers like idiots, which is a hard balance to find. I certainly learned a few things.
One thing that did bother me, though: he touches on theology rather more than I thought was needed (though some mention is obviously going to be necessary, given the subject matter and the historical context), and he seemed to be extremely careful not to comment on its inanities.
Dunno. Maybe I’m more sensitive to that sort of thing than most. Still, since Barrow apparently won the Templeton Prize in 2006, I don’t think it’s just in my head.
One thing that did amuse me, though: at one point, he points out how advances in science and a deeper understanding of the world around us meant that the concept of God retreated further and further over the course of history, being confined to things science could not yet explain, time and time again.
The punchline? John D. Barrow is a deist.
Anyway. If you’re willing to ignore all that, it really isn’t a bad book. I’ll probably buy more of his books at some point, at least.
I just finished A Briefer History of Time, by Stephen Hawking and Leonard Mlodinow. It’s a 2005 revisit of the famous A Brief History of Time. In it, Hawking briefly explains things like black holes, quantum physics, string theory, and the origin of the universe, in terms anyone could understand. And I do mean anyone.
I can understand how a book written in 1988 could need an update, but I’m not entirely sure why it needed to be made more accessible. Over 9 million people bought the first book, so clearly the public thought it was accessible enough.
I never read the original (I’ve been meaning to forever, but I just never got around to it); as such, I’m not sure exactly how simplistic it presented things, but I really hope it wasn’t nearly as bad as this one. I’ve never been a big fan of the lie-to-children approach to education past middle school, and that’s exactly the approach the book takes.
Yes, relativity and quantum physics are difficult subjects, and small steps are required to explain them to laypersons, but ye gods, there is such a thing as too much.
Having said that, it’s a great introductory book to physics for children in 7th or 8th grade, but I was really disappointed by the fact that Hawking doesn’t even hint at some of the controversies that made him infamous, such as the black hole information paradox.
Still, even as an adult, if it’s been a few decades since you’ve had Physics, and you’ve forgotten all about Einstein, and you want to relearn but aren’t willing to think at all, it should be a pretty good read. I’d still recommend the original, though.
I’ve touched on this before, but I didn’t give it as much attention as it deserved the last time. The fine-tuned universe argument states, simply, that there are a number of cosmological constants which are fine-tuned to allow for life to develop; if they were anything else, life wouldn’t be possible at all, and the odds of them having the values they have are extremely small. Therefore, God exists.
(Well, or some form of creator, anyway.)
There are several assumptions implicit in this. Let’s spell them out.
Whether or not the cosmological constants involved could be a different value is open to debate, but it seems pretty likely they could be. Whether they could be any other value is a different matter entirely, and the range in which they could vary might not be as wide as all that. Still, we’ll give them this point.
The second assumption, though, should be obviously preposterous to anyone who stops to think about it. Let’s break it into two further parts: first, the claim that our universe is suited to develop life, and secondly, the claim that, that life having come into existence, it’s a hospitable place for that life to continue to exist.
It’s true that there are some physical constants that are pretty vital to life as we know it. Most of them have no bearing on life one way or the other, but that, of course, is just a minor detail. Apparently.
Either way, life as we know it requires a star, a planet close enough to it to have liquid water but far enough not to fry in its radiation, and perhaps another large body nearby to catch most stray asteroids in the neighborhood (in our case, Jupiter, and our moon). If they get as far as this, usually defenders of the fine-tuned universe point out how wonderfully fortuitous our set-up in our solar system is, and that even that cannot be the product of chance, conveniently failing to point out that not having the asteroids in the first place would be a much better set-up, and perhaps a little less radiation would be nice as well. Either way.
There’s nothing to suggest Earth is unique, or even particularly rare, so perhaps there is other life in our universe (Fermi paradox aside). Perhaps it really is supremely suited to developing life.
It sure seems to suck at keeping it alive once it gets going, though. An obvious point is the fact that the vast majority of the locations in the universe just cannot support our kind of life at all. Freezing cold almost everywhere, scorching heat almost everywhere else, killer radiation throughout (even the cosmic background radiation is enough to kill you in hours), complete lack of breatheable air, &c.
Sticking to planets, then? There seems to be a shortage of habitable planets as well. In our solar system, we have one, and we can only live on the vulnerable surface. Mars might be an option, given some creative terraforming, but out of the box, it doesn’t work.
Staying on a single planet isn’t really an option, from a survival-of-the-species standpoint. Asteroids are an obvious concern. Jupiter helps, and so does the moon, but there have been several close calls already (some not-very-close-but-still uncomfortable ones in recent history, a much closer one a while ago (though there’s an obvious explanation), and a lot of frighteningly destructive ones even further back). And of course, there are things like wandering black holes and the threat of nearby stars going supernova, among many other things. And don’t forget that eventually, our own sun will become a red giant, swallowing up the Earth in the process.
If a creator wanted life to develop in this environment, he must have been a sadist.
I’ve been careful to say “our kind of life” rather than just “life”. This leads us to the next assumption, which, incidentally, is also the reason the fine-tuned universe is often called an argument from lack of imagination: there is no reason whatsoever to believe that our kind of carbon-and-water-based life is the only life possible.
Even within the constraints of our physical constants, that doesn’t seem to be the case; why would you assume that if you vary those constants, any other system couldn’t possibly contain life, if perhaps in a rather different form than we’re used to?
It’s this part of the claim that led to the Douglas Adams quote I used last time:
[I]magine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’
This is a form of the weak anthropic principle, which (roughly) states that conditions observed in the universe must be such as to allow the observer to exist. On its own, this may seem like circular reasoning, but it leads us neatly into the next bit.
Is there only one universe?
String theory, of course, disagrees. It (along with some other hypotheses) predicts a large number of parallel universes (that is, a multiverse), each of which could have its own set of physical constants. In this case, a fine-tuned universe wouldn’t just not be evidence of a creator, but it’d be completely inevitable.
And of course, there’s that other theory that says black holes a universe’s way of reproducing, which would essentially subject whole universes to Darwinian selection, but I don’t know enough about that to talk about its validity, I’m afraid.
The last claim is, of course, the most important one: God did it.
As always with these kinds of cop-outs, this raises more questions than it answers. The most obvious one, of course, is “Where did this God come from?”
There can be no coherent answer to this that has anything even resembling evidence to back it up.
It’s just another retreat of the God of the Gaps, and in light of “new” developments in quantum physics, it’s looking like he won’t be able to hide there for much longer.
I said I was going to do this, so I am.
The double-slit experiment is a classic experiment, first done in 1801 by the English Thomas Young, who was looking to solve the issue of whether light is particles or waves once and for all. Originally it was done with light, but it can be done with electrons or protons or neutrons or whatever as well.
First, let’s look at our set-up. It’s a box.
If we’re dealing with light, it’s a simple box out of which no light can escape. If we’re dealing with electrons, it’s a conductive plate over which the electrons can travel.
The important part is that O is the source of light or electricity or whatever we’re dealing with, and S1 and S2 are slits or openings in a central wall through which lights or electrons can travel. The back (green, here) is a detector type plate, which registers when light or electrons hit it.
Let’s think about what behavior we should expect, here.
If we’re dealing with particles, we can expect that O would fire a particle in a random direction, and if it happens to be aimed at a slit, it will perhaps bounce off the slit and hit the detector plate behind it. There will always be just one impact on the detector plate at a time.
You can see the area we’d expect the most particles to land in that picture there.
If we count the number of particles that hit a certain position and plot it on a graph, we get something similar to the one on the right. P1 would be the particles that went through S1, and P2 would be the ones that went through S2.
Of course, we can’t really know, when we look at a place where an electron hit, which slit it went through, so the actual graph will be the sum of those graphs, with two obvious peaks.
(I stole the graph picture from a scan of a Physics textbook someone put online, since I don’t really have the software to plot this sort of thing. This explains why it’s shoddy-looking.)
Now, what if it’s a wave? Well, it’d look a bit more complicated.
As you can see, a new wave would be started at each slit simultaneously, and this leads to a complicated-looking interference pattern, with light hitting the detector plate continuously.
The result looks something like the graph on the right. P12 is the sum of two wave patterns. In some places the waves cancel each other out, in others they amplify each other, as you’ve no doubt seen in highschool Physics or Mathematics.
It’s a beautiful interference pattern.
It’s quite meaningless to talk about which slit every thing that was detected came through, since we aren’t dealing with discrete chunks.
Now, if we actually perform the double-slit experiment, the pattern we get on the detector looks something like this:
Obviously a wave interference pattern. Problem solved, then, right? Light is a wave!
But those impacts are obviously impacts of particles, and we already know light exists as particles, since we know about photons through things like the photoelectric effect. And electrons make the same pattern, and we know those are particles too. So why does it do this?
Another experiment we could try is to do this with electrons, but this time, we’re going to keep track of which hole each electron went through. We could do this by, for example, shining a really bright light in the first chamber, and looking at the slits from the other side. If the light in one slit dims for a bit, we know an electron has passed through, since it blocked out the light when it passed.
Someone did an experiment similar to this, and found something very interesting: when we watch the electrons like this, they generate a pattern like in graph 1.
If we keep track of which slit the electrons pass through, they behave like particles. If we don’t, they behave like waves.
And this isn’t just true when we use this particular set-up, in case you’re concerned that since light is so unusual itself, it may have done something weird to the electrons. If we observe the path of the electron in any way, it stops behaving like a wave, and acts like a normal particle.
So why does it do this?
I’m not actually sure.
The Copenhagen interpretation (remember Heisenberg and Bohr?) posits the existence of probability waves, essentially meaning that until the position of a particle is determined, it essentially exists in all places at once, just with a higher probability in some areas.
So unless someone actually determines which slit the particle goes through, it essentially goes through both slits at once, which creates this wave-like interference pattern.
It’s all very interesting, but unfortunately it also means Physics is incredibly counter-intuitive and hard to approach without explicitly using mathematics, which makes the whole field a bit inaccessible to the common man.
I finished The Character of Physical Law by Richard Feynman the other night. It’s pretty short (about 170 pages), being just a collection of seven lectures by Feynman on (surprisingly) the character of physical law.
The only other thing I’ve read by Feynman was The Meaning of It All, which is also a collection of lectures. I wonder if he wrote “proper” books.
Either way, it’s a very interesting read. These lectures took place in 1965, and no doubt some fundamental advances have been made since then (if you want to call string theory an advance, all of that only started in the late ’60s), but it’s general enough that it’s still a relevant and fascinating work.
Feynman talks about a number of things, starting, in the first lecture, with the law of gravitation as an example, going over Kepler, Brahe, Newton, and eventually Einstein, to demonstrate how the law was derived and refined further and further.
In the second lecture, he talks about the relationship between mathematics and physics, noting that physics is a very mathematical field, but that there are some important difference between doing physics and doing mathematics. In mathematics, you derive tons of conclusions from a fixed set of axioms, and in physics, we have a vast amount of conclusions, but nothing to unify it to come up with the central model from which they flow. In Feynman’s own words, we’re doing physics in the way the Babylonians did mathematics, rather than in the way the Greeks did it.
The next few lectures describe some interesting properties which seem to hold across the various laws of physics, including various principles of conservation, various types of symmetry (which, as he explains, is vital to being to derive new laws, through inconsistencies in known ones), and the principle of causality and the arrow of time.
In the sixth lecture, he gets into the basics of quantum mechanics. Probability and uncertainty, the way light (and electrons) behaves variously like particles or like waves (he goes into some detail regarding the double-slit experiment, which I think I’ll go into in a future post; every single popular science work on physics written in the past seventy or so years has explained it, but it’s an interesting and important experiment), &c.
And in the final lecture, he explains how physicists usually go about finding new laws, and more importantly, how he himself does it. It’s worth remembering that Feynman was perhaps the most influential physicist of the second half of the 20th century (and by second half, I mean part of the first half as well).
To sum up, The Character of Physical Law is a fascinating read, even if it shouldn’t really tell you anything new. If anyone but Feynman had written it, it would’ve sucked, but he makes it work.
Also, he spelled “connection” “connexion”, which made me happy.
Next up is Six Easy Pieces, also by Feynman. Apparently it’s supposed to cover much of the same ground, and it certainly seems to have the same preface by Paul Davies, but it looks a bit more advanced.
Ready for another 50-minute video?
This one is an interview with Richard Feynman, the American physicist. (This is the Feynman of the Feynman gate, among many other things.)
He talks about science and the pleasure of finding things out. There’s also a bit about developing nuclear weapons. The interview starts with a longer version of the quote in our random quotes thing, which is a quote I’ve always liked.
I should really read more of his stuff. All I have is a tiny book with three of his lectures, called The Meaning of It All.
It’s a pity he died. He was a pretty awesome guy.
He doesn’t have a cute British accent, but he has a New Yorkian one~
Religious people often raise the point that the natural world is rather dull, and adding the supernatural adds a dimension of splendor. I really believe these people wouldn’t feel this way if they understood the natural world at all.
The actual history of the universe is so much grander than any Bronze Age mythologer could possibly have imagined. Let me sum it up for you.
The story of the universe starts 13.7 billion years ago, at the Big Bang, with the great expansion and the crystallisation of the physical laws. Very quickly, hadrons, including the building blocks of our modern elements, are created, and some three hundred thousand years later, the early elements form; vast clouds of hydrogen and helium and lithium.
Eventually, gravity makes these clouds comes together and processes of nuclear fusion eventually create the early stars. The same gravitational forces pull stars together in galaxies, galaxies together in clusters, and clusters together in superclusters.
In these early stars, heavier elements, including our own carbon and oxygen, are formed.
Our own solar system was formed by similar processes, about 4.6 billion years ago, when a huge nebula collapsed under its own gravity. As it collapsed, it heated up (because of the conversion of gravitational potential energy to kinetic energy of the atoms), its spin increased (because of the preservation of angular momentum), and it flattened out into a protoplanetary disk.
Eventually accretion formed, among other things, the planets, all revolving on roughly the same plane and in the same direction (with two fascinating exceptions), and their moons (again, with a few very interesting exceptions, including, perhaps, our own moon).
At the center, of course, was the largest ball of mass of all; so large, in fact, that under the force of its own gravity, the process of nuclear fusion was initiated, and the ball of gas became a bright star—the Sun.
Our own Earth is, of course, one of those planets that orbits our sun. It’s about 4.5 billion years old, and it’s the largest of our solar system’s four terrestrial planets (the other four are gas giants; Ceres is a terrestrial dwarf planet, and Pluto is composed mostly of ice; we aren’t sure what Eris is yet, but it’s smaller than we are, in any event).
The early Earth was very hot, obviously, but it cooled down quickly, and its surface solidified into tectonic plates. Light elements, including the various gases that would make up the early atmosphere, floated to the top, while heavier ones, including most of the planet’s iron, sunk to the center.
Comets brought a fair amount of a water to our planet, creating the early hydrosphere (which has since become a lot complexer), and the relative stability of the planet allowed for the formation of small organic molecules.
There is some debate as to how exactly life itself got started. An interesting theory as to what kind of mechanism could start it was laid out by Graham Cairns-Smith in his clay theory. I’ll write a longer post about abiogenesis at some point.
Whatever the cause, eventually life got underway; first with simple replicators, like naked RNA (that is, RNA which isn’t protected by a cell, like modern viruses). These reproduced for hundred of thousands of years. Natural selection favored the ones who cooperated (unconsciously, mind) by living in groups, and who could form their own protective soap-bubble-like skins. This eventually led to the simplest single-celled life, the prokaryotes.
Life on Earth spent a lot of time in this single-celled form (though the individual cells got quite complex), but eventually, about a billion years ago, these cells discovered that they could work together in symbiotic colonies, and multi-cellular life was formed.
Early on, of course, these were just tiny and simple organisms living in the water, but eventually they became quite complex indeed.
Some of these eventually became plants. Others became simple sessile polyps. Eventually these polyps developed simple gills to aid them in feeding, and some became mobile during the larval stage, but still sessile as adults. Some of those retained their larval mobility throughout their lifespan.
These free-swimming polyps eventually developed something like a backbone, and came to look more like very simple fish. Jawless, filter-feeding fish, somewhat similar, perhaps, to modern lampreys.
Gradually, these early fish developed eyes and jaws. This enabled them to eat one another, which added another dimension to natural selection.
Since they could now use their jaws to eat with, they didn’t need their gills anymore, and they were repurposed to breathe the oxygen in the water. This is the way modern fish eventually arose.
Now, these fish didn’t necessarily live in the ocean. Some of them lived in lakes and puddles which dried up during the summer. As such, some fish developed a primitive lung to tide them over until the rainy season.
If the rainy season didn’t come, it helped to be able to pull yourself along to the next puddle, perhaps, so there was an advantage to developing simple limbs rather than just fins. This was, of course, a very important adaptation. The first amphibians were born.
Now, like fish, amphibians laid their eggs in water, where they were an easy target to be eaten. As such, some of them began laying (hard-shelled) eggs on land, which was still low on predators. Reptiles and turtles would be the eventual result.
Many of these reptiles never returned to the waters, and some became the dinosaurs (and eventually some of these dinosaurs would develop feathers for flight, and become birds). Some of the ones that didn’t become dinosaurs started carrying their young inside themselves rather than lay eggs, and these became the marsupials and the mammals.
These young were very immature at birth, and had to be taught how to survive. This was important, because it meant the brain would need to be larger and more developed.
The earliest mammal was something like a shrew.
One line of mammals took to the trees. This required a greater dexterity and depth perception, and, of course, the larger brain to go with it. These became primates, including lemurs, tarsiers, monkeys, and, of course, apes.
Some of these apes walked upright, freeing their hands to poke at their surroundings. They learned how to use tools, and got smarter.
Eventually they learned how to talk, and developed culture.
These walking apes are still incredibly curious about their surroundings, and have learned so much more than any other species on the planet. This has enabled them to build vast cathedrals, to explore distant continents, and even to leave the planet they were born on.
The human species is a marvellous thing, and the world it grew in a fascinating place.
Why does this garden need fairies at the bottom of it? It’s rich enough in its own right.
If you want to understand your origins, this is where you’ll find them. If you want a sense of awe at the world, this is where it is. To say “goddidit” for no reason really just subtracts from it.
The creation story is pathetically unimaginative in comparison.
