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Summer Reading:

One of the books I've been spending some time with, the past week or so (on a recommendation from my daughter - thanks, Sarah!), is Brian Greene's truly magnificent "The Fabric of the Cosmos: Space, Time, and the Texture of Reality." It's a kind of summary snapshot of the state of modern physics, very much intended for the non-specialist, and it's been, for me, something of a revelatory experience. I've never read anything that does nearly as good a job explaining the truly extraordinary and bizarre rules that, apparently, govern our universe. Greene does a spectacular job explaining, using really well-chosen and well-thought out (and incredibly simple) examples, the fundamental ideas underlying special and general relativity, the profound differences between the Einsteinian view of the universe and the quantum mechanical view of the universe, the reason why "string theory" might actually better explain the nature of things, and the like. And he's appropriately awe-struck at how un-real reality seems to be. I had thought I understood (at least in a non-technical way) the idea behind Heisenberg's Uncertainty Principle: that you could not simultaneously measure both a particle's velocity and its position, that measuring one of them necessarily meant you could not obtain information about the other. Pretty weird, but not nearly as weird as the actual version of the Principle, which I now, thanks to Greene, have a glimpse of: that particles don't have any "position" or "velocity" until you attempt to measure the one or the other. That, friends, is a very strange universe to live in.
In any event, if you're interested in any of this stuff and don't feel you really have a grasp of what the physicists are all arguing about, I can't recommend Greene's book highly enough.

Mhoram:
I assume you have read Greene's "The Elegant Universe"?
7.17.2008 10:12am
Observer:
The Uncertainty Principle as it relates to the U.S. Supreme Court: You cannot at the same time know what the Constitution says and what the left wing of the Court will say the Constitution say (or else you go crazy).
7.17.2008 10:16am
CK:
Even cooler is the idea that one particle (electron, proton, quark, etc) can be described by a wave equation. But when you add a second particle to the mix, you now don't have two wave equations. Instead, they add and you get one bigger wave equation. Keep going and you find out that every particle in the universe can be described by the same one big complicated equation. As a result, in quantum mechanics, everything in existence is tied together and can affect each other.
7.17.2008 10:36am
GMUSL '07 Alum (mail):
David, if you're interested in the multi-billion dollar debacle that is string theory (which is not even science at this point, let alone physics, but instead mere mathematical masturbation), check out Lee Smolin's The Trouble with Physics and Peter Woit's Not Even Wrong.
7.17.2008 10:54am
GU (mail):
I will second Prof. Post's recommendation. This is about as good of an explanation you'll get without any math. Excellent book.
7.17.2008 11:29am
bornyesterday (mail) (www):
Greene is definitely one of the better writers of non-technical physics books. The stuff is even more bizarre when you get down to the mathematical side of it, as CK mentions. I'll never regret having gotten a degree in physics, even if I never do use it.
7.17.2008 11:30am
Eric Muller (www):
I had thought I understood Heisenberg's Uncertainty Principle, but now I am uncertain, which I guess proves the principle.
7.17.2008 11:30am
Eric Muller (www):
Incidentally, my wife and daughter tell me that Lisa Randall's "Warped Passages" is pretty good in this same domain.
7.17.2008 11:33am
Fredrik Nyman XXX (mail):
Any meaningful difference between the hardcover and the paperback editions?
7.17.2008 11:36am
Nameless coward (mail):
I have not read this one, but Prof. Post's prior recommendation (The Betrothed) was a spectactular success so this one goes to the top of my list.
7.17.2008 11:49am
bornyesterday (mail) (www):

I had thought I understood Heisenberg's Uncertainty Principle, but now I am uncertain, which I guess proves the principle.


The confusion arises from the fact that particles are usually described as probability wave functions, not as individual units. Until it is observed, there is a range of velocities/energies/positions/momentums which the particle could potentially exist in. Until it is observed, it exists in a superposition of these states - it exists simultaneously in all and none of them. When it is observed, the wave function collapses (don't ask how), allowing you to determine either its position or velocity and either its energy or its momentum.
7.17.2008 11:49am
Michael F. Martin (mail) (www):
String theory is a relatively autistic field -- it is undernourished by actual experimental data. There's nothing wrong with it physically. It just doesn't mesh with reality (at least not yet).

And note that there are alternative theories. Smolin and this newcomer Garrett Lisi have a theory that doesn't require more than 4 dimensions. I like minimalist theories, personally.
7.17.2008 12:22pm
CJColucci:
particles don't have any "position" or "velocity" until you attempt to measure the one or the other

Reminds me of the umpire who said about calling balls and strikes, "They ain't nothin' 'til I calls 'em." [Insert Supreme Court analogy or joke here.]
7.17.2008 12:33pm
Realist Liberal:
I'll put this at the top of my list to read in two weeks and a day (in other words, when the Bar is over) and I want to get as far away from anything law related as possible. Thanks for the recommendation.
7.17.2008 12:49pm
Curt Fischer:

There's nothing wrong with it physically. It just doesn't mesh with reality (at least not yet).


I can't for the life of me read the second sentence as anything but a complete contradiction of the first.
7.17.2008 12:59pm
bornyesterday (mail) (www):
He probably meant that there is nothing wrong with it mathematically/conceptually. String theory seems to accurately describe non-Planck length events, but only in such complex math that it's pretty much useless otherwise. And so far, nothing that it predicts has been testable.
7.17.2008 1:10pm
cp277:
Odd. I just started reading this book this morning. I'd also recommend "Big Bang" by Simon Singh.
7.17.2008 1:12pm
PersonFromPorlock:
Still, I can't help but wonder if all those extra dimensions aren't just big enough to dump awkward data into, and if the matter in 'dark matter' isn't really fudge.
7.17.2008 1:20pm
Richard Nieporent (mail):
There is currently a nasty war going on among theoretical physicists. Lee Smolin is considered persona non grata by many string theorists. However, not being able to tie string theory to Global Warming they have not been able to bring him up on charges of crimes against humanity like Hanson would like to do to Global Warming skeptics. Although string theory has been around at least as long as Global Warming, string theorists, unlike the climate scientists, have not been able to shut up critics by appealing to a consensus of physicists. Where is Al Gore when you need him?
7.17.2008 1:39pm
A. Zarkov (mail):
" ... check out Lee Smolin's The Trouble with Physics and Peter Woit's Not Even Wrong."

A string theorist, Motl, reviews The Trouble with Physics here. As one might expect, Motl has a pretty low opinion of Smolin's book, but not Smolin. He has an even lower opinion of Woit's book, and Woit himself. I read the The Trouble with Physics, but I can't judge what either Mothl or Smolin says about string theory. It would take a too much effort to learn enough to have an informed opinion. Although I'm uncomfortable with a theory that can't be tested. Actually string theory is zillions of theories. Another discomforting aspect.
7.17.2008 1:47pm
Nathan:
It's good to ask oneself why concepts like the Uncertainty Principle seem weird. If you study physics, do lots of experiments, and work on designing new semiconductor materials and devices, then all of these principles and behaviors come to seem very normal. The only reason they don't seem normal to start with is because we extrapolate our experience in the large scale down to the small scale. It really shouldn't be a shock that our brain's first untested conjecture about something we have no experience with turns out to be false.
7.17.2008 2:37pm
Katl L (mail):
The heiddeberger principle is wrong explained . the hitachi experiment showed that the particle is in many palces at the same time. The new edition of PenroseĀ“s New emperors mind explains it.
7.17.2008 2:48pm
TruePath (mail) (www):
No, the particle is not many places at the same time, nor does it satisfy any of the other spooky descriptions people like to through around because there isn't any particle there in the first place. What is there is a wave function and we just get into trouble because we pretend it is a classical particle.

Now a classical wave is nothing like a wavefunction but consider how things would seem if we tried to describe ocean waves as a particle. If ocean waves were very tiny we might first think of them as particles since either the wave detector goes off or it doesn't. But then further experiments would reveal that opening two slits in a wall could affect whether or not we observed that particle at the other end. Moreover, as our instruments got better we would discover that waves don't really have a position (they are spread out in space). Of course the truth is that waves aren't very bizarre at all but if we tried to think of them as particles we would end up thinking waves were weird particles that could be in two places at once, didn't have a position and so forth.

Don't get me wrong there are real mysterys in QM, for instance how does a totally linear evolution give rise to the (apparently non-linear) reality we observe. Is this because there is a real process called collapse? But when does it happen and what causes it? Or maybe it's really best described by a many minds theory.

However, the whole not having a position and being in two places crap is just that, crap. The physicists understand what it means mathematically and like the funding/attention this use of language means (and sometimes get a bit drawn in by it too) but really if we just said: "It turns out we were wrong, electrons aren't particles at all. Just like everything else they are really wave functions and wave functions are distributed entities that aren't characterized by a classical position and velocity that act like such and such." Sure, wave functions will always be unfamiliar to us since they don't resemble the behavior of any macroscopic objects but that's all.
7.17.2008 3:43pm
DJR:
An excellent layman's description of how strange quantum phsyics teaches us the universe is can be found in A.C. Weisbecker's "Quantum Banditos." You can finish it in a couple of hours but you will never forget it.
7.17.2008 4:14pm
Kevin Lynch (mail):
I'm in complete agreement with TruePath here.

As a practicing physicist, I'm particularly disappointed in popularizations that push these silly interpretations of physical theory. It makes my job that much harder, as the general public sees such "weird" and fundamentally "unreal" stuff as completed disconnected from their lives, and not worthy of their support or interest. This, despite the fact that modern physical theory is absolutely fundamental to our everyday lives: computers, cell phones, LCD and plasma televisions, DVD and Blue Ray players, high speed internet, medical imaging, laser and radiation therapy, nuclear power, and GPS; all examples of relatively recent societal advances that depend intimately on what's been inaccurately presented as "weird" and "unreal". It deeply wounds the field when we have intelligent and engaging popularizers making a deep hash of concepts that are really quite easy to understand when stripped of historical popularization baggage.

Don't take this as a comment on the quality of this particular book; I've not read it. Nor, unfortunately, do I have a read to suggest. I don't read popularizations ... I've usually had enough of physics by the end of a day of actually doing it. :-)
7.17.2008 4:40pm
Michael F. Martin (mail) (www):
TruePath and Kevin:

Energy and Time are not quite non-commutative observables, although they do obey something like Heisenberg's uncertainty principle. I say not quite because isn't it the consequence of Schrodinger's equation being first-order in time that gives rise to their uncertainty relation?

Now here's why I ask: What if economic equilibriums were unstable in time because of dissipation (through cross-elasticity) into other markets?
7.17.2008 6:39pm
Splunge:
Pretty weird, but not nearly as weird as the actual version of the Principle, which I now, thanks to Greene, have a glimpse of: that particles don't have any "position" or "velocity" until you attempt to measure the one or the other.

Goodness, this is complete garbage, and knowing that Greene is a decent physicist, I have to hope it results from your gross misreading of his book.

No modern theory of physics presumes to tell you what a particle is doing when you aren't looking. They only tell you what you may and may not see when you do look. Asserting what a particle is "really" doing -- what its position and momentum "really" are -- when you have not measured them is an act of theology, not physics.
7.17.2008 8:49pm