As an enthusiastic fan of fantasy/science fiction from an early age, the "many worlds"
(MW) hypothesis appeals to me; how nice, if it were true!
I, too, seem to have been born with the gene for "sci-fi fan" turned on. Unfortunately, as I
continue to learn about physics, I find myself less able to suspend belief than in years past. As
a result, I usually prefer shows that either skip the technobabble completely (such as Firefly and
Battlestar Galactica) or generally get the technobabble (reasonably) correct. Stargate Atlantis is
the only show I can think of that even comes close, and it's only reasonably correct 20% of the
time or so...
With all respect sir, I must frown on your uttering the name of Occam in the same
decade of your life as the phrase "many worlds". I truly cannot think of a more complex
hypothesis! Perhaps the MW theory is no more strange than "collapse", but it's quite a bit more
extravagant. I mean...all those universes!
MW is extravagent, but only in the sense that it implies the universe is larger and stranger than
we thought it was before. That's been happening for millenia- every new paradigm in science
(heliocentricity, relativity, the realization that our sun is just another star, etc) has shown us
that the universe is stranger than we thought it was before.
So most physicists have stopped trying to apply common sense to physics theories. If Einstein had
used common sense to say "Of course everyone experiences time at the same rate!", then we wouldn't
have special relativity today. The only criteria I use are: (1) Does the theory match experiment?
(2) Is the theory mathematicall consistent? and (3) Does the theory have fewer axioms than its
nearest competitors?
In this sense, the MW interpretation wins. It is mathematically consistent, involves one fewer
assumption than the conventional "collapse" interpretation of quantum mechanics, and it describes
experimental results just as well. It's possible that there are other interpretations that work
(such as Cramer's "Transactional Interpretation") but for now I'm leaning towards the MW
interpretation.
I am pleased to learn that there are no epistemic requirements for MW. That is, I
think you're saying that MW does not rely on the activity of observers--that the generation of new
universes occurs whether or not someone is observing quantum events. Do I understand this
correctly? If so, that is an improvement. I can't, however, concur with your claim that MW is
"obvious".
Yes, the "collapse" effect in MW is a purely physical phenomenon. It's difficult to translate the
math into english, which is why I've said strange things like "generates new universes". This is
a clumsy (and probably overly dramatic) way of describing the process, but it's the best I can do.
A more mathematical way of describing the process would be to say that coupling an isolated
quantum system to a much larger system (like a detector) dramatically reduces the off-diagonal
terms of the density matrix describing the original quantum system. Since these off-diagonal
terms describe interference between the various eigenstates of the quantum system (horizontal and
vertical polarization, for example), this process effectively prevents the two eigenstates from
interfering with each other. Because the two eigenstates no longer interact, some physicists
interpret the resulting density matrix as saying that the two outcomes are now in two "separate
universes" which no longer interact.
But, as you can tell it's a lot easier to say it "splits the universe in two".
This sounds as though neither hypothesis is empirically verifiable; both explain
observed phenomena equally well, correct? I suppose that is no reason to reject either theory...
Yes. They're simply interpreting the math of quantum mechanics in different ways, and the mat
I agree that quantum collapse is bizarre, and leads to many paradoxes such as Schrodinger's Cat, Bertelman's Socks, Wigner's Friend, etc. My personal answer is that there is no such thing as collapse. I use the term because it's part of the standard "interpretation" of quantum mechanics, but I actually believe that the many worlds interpretation (that I detailed in my last post) is more likely to be true. I say this because:
Quantum collapse is introduced in the standard interpretation as an arbitrary axiom. Therefore, if any different formulation of quantum mechanics can eliminate this axoim while producing identical predictions about real experiments, we should choose the new formulation based on Occam's razor.
Because quantum collapse is introduced as an axiom, it is not justified in any specific physical manner. In the many worlds interpretation, collapse is simply seen as "the decoherence caused by interacting with a system containing a very large number of particles". This phenomenon, known as einselection, is rigorously described on a fundamental level. It is a purely mechanical process, not a mystical one. It has nothing to do with knowledge. In fact, it emerges as an obvious consequence of letting an individual particle interact with an object composed of a very large number of particles.
Quantum collapses are a fundamentally non-unitary process, as opposed to every other process in quantum mechanics. It's inconsistent with the rest of the theory in that respect.
Abandoning quantum collapse by choosing the Many Worlds Interpretation of Everett and Wheeler (and more recently Deutsch) results in exactly the same experimental predictions as the "standard interpretation".
Now, the many worlds interpretation is weird. It implies that a nearly infinite number of parallel universes exist, each representing the state of the universe if a particle had gone this way or that way, collapsed onto horizontal or vertical, etc. Because we humans are made up of particles, that means that there is a different universe for every possible event in history. There is a universe where the Nazis won WW2, where dinosaurs never became extinct, where Paris Hilton is a college professor, etc. But this weirdness is, in my mind, more than offset by the elegant way that it simplifies quantum theory. Not all physicists agree with me, but the many worlds interpretation is not a fringe view by any stretch of the imagination, and it seems to be growing more accepted with each year...
After thinking about your last point some more, I think my "continuum between particles and waves" explanation isn't really the best answer. It's better to say that the whole particle-wave duality thing isn't really important here. Quantum entanglement can be demonstrated using completely different properties than polarization. For instance, one of the first quantum teleportation experiments (Boschi, et. al.) used "path entanglement". They created a pair of photons, each of which went through two paths (two paths for each particle, for a total of four different paths) at the same time. Even though each particle was actually traveling through two different paths, if you tried to measure one of them and find out which path it "collapsed" onto, the other particle (again, potentially on the other side of the galaxy) would instantly be "collapsed" onto a certain path in the other lab. Thus entanglement doesn't really have anything to do with particle/wave duality; it's simply that the most easily explained example involves polarization.
However, there are also some obviously very intelligent and serious people who talk about this stuff, who devote their lives to studying it, and yet utter what appear to be completely crazy propositions, propositions that should clearly be dismissed out of hand as nonsense.
I agree, as do most physicists. Quantum mechanics is difficult to learn, not only because the math is complicated, but also because it's seemingly nonsensical. If it's any comfort, every quantum physicist since the 1920s has gone through the same stage of incredulity that you find yourself in now. In fact, that very incredulity has caused physicists to test quantum mechanics to a greater degree of precision than any other theory I can think of off the top of my head. In every experiment, designed to disprove every bizarre property of quantum mechanics, quantum theory has prevailed...
Though I'd like to, I can't do that--I can't simply dismiss what appears to be the dominant opinion among the leading scientific luminaries of the day. On the other hand, I can't bring myself to agree with it either, because I don't really understand it. Call me stubborn, but I cannot, in good conscience, agree with anything I don't understand.
It took me a long time to believe in black holes (even after most physicists thought they were conclusively proven to exist) so we agree on this principle.
I must admit to a major handicap that colors my understanding (or lack of it) of this subject: acute dysmathia. Math and I have never gotten along...I can handle logic (deduction, argument, that sort of thing) just fine; I can use words like razors (especially when I'm more awake than I am now).
I've always found math and logic to be extremely similar, if not synonymous. They both start with a small collection of axioms and use deductive (and occasionally inductive) logic to arrive at a conclusion. Have you ever tried to learn symbolic logic? If so it's quite similar to math, and I suspect it would lessen the transition shock because it encodes information into symbols in similar ways.
As you mentioned, one opinion I have taken comfort in is that "well, this quantum wave collapse looks good in their mathematical equations, it makes for an internally consistent mathematical description of what they're trying to explain, but it doesn't have anything to do with the world I live in.
Interestingly, wave function collapse is NOT an internally consistent description of reality. The inconsistency arises because the "collapse" of a quantum state is a completely different process than the normal time evolution of a quantum state; physicists say that it is a "non-unitary" process because it annihilates some of the quantum state (a state which is originally horizontal and vertical collapses onto vertical only, thus annihilating the horizontal part of the state). This is opposed to ordinary "unitary" processes that occur at all other times which don't affect "how much" of the state exists. This paradox was resolved (IMO) by Everett and Wheeler when they reformulated quantum mechanics without the "collapse" axiom- instead of collapsing onto horizontal or vertical, the entire universe splits in two. In one universe, the observer sees the collapse result in a horizontal state, while the other universe sees a vertical state. This is sometimes referred to as the "many worlds interpretation" of quantum mechanics. It involves fewer axioms, has no internal mathematical inconsistencies such as those created by the notion of wave function collapse, and results in the same physical predictions. The only caveat is that it predicts a nearly infinite number of parallel universes, leading some physicists to say that the many worlds interpretation is cheap in terms of axioms, but expensive in terms of universes.
I mention this only because I find it interesting, but it really doesn't change any part of the argume
SirBruce's explanation is dead on, but I spent so many years confused about this exact same issue that I thought I'd try to provide an alternative explanation.
First of all, photons (particles of light) behave as though they're waves. There's a lot of subtlety hidden in this statement, but it's not relevant now: just picture a single particle of light moving into the screen while moving up and down pretty much like a water wave. This is a vertically polarized photon, and it can be easily distinguished from a horizontally polarized photon (a photon traveling into the screen while "waving" left to right instead of up and down). When I say "easily distinguished", I mean that you can place a device in the photon's path that produces a "click" if the photon is horizontally polarized, and a "beep" if the photon is vertically polarized.
Now, according to the math of quantum mechanics, it's possible for a photon to be in a "superposition state" of horizontally and vertically polarized. This is sometimes described by saying that the photon is traveling into the screen while "waving" at, say, a 45 degree angle- somewhere in between horizontal and vertical. This isn't wrong, strictly speaking, but it's very misleading unless you've taken a lot of physics. Instead, I'll say that the math literally implies that the photon is in two states (horizontal and vertical) at once- but when you measure it the photon randomly "collapses" onto one of those states. The important point is that quantum mechanics says that the photon was in two states at once before the measurement, and that it's impossible- even in principle- to say which state the photon was in before the measurement took place. Theories which attempt to describe the state of the particle before the measurement (in contradiction to quantum mechanics) are known as "hidden variable theories". No physicist that I've met considers these theories plausible, despite their intuitive appeal.
As SirBruce said, this "superposition then random collapse" is a bizarre property of quantum theory. But it becomes even more bizarre when you create two entangled photons- two photons that are each in their own superpositions, but created such that if one photon is horizontal, the other is vertical. Now, a measurement performed on one particle doesn't just collapse its polarization down to vertical or horizontal, it also collapses the other particle into the opposite polarization.
Again, calling this phenomenon "spooky" depends on you believing me when I say that the photons are in a literally unknowable state before they are measured. Before the 1980s, it was plausible to believe that the whole concept of a "superposition" was mere fiction: the misguided result of equations that produced good answers for some problems, but implied a nonsensical property like entanglement in other cases. This is certainly the opinion Einstein held, so you're in good company.
The problem is that in the 1980s, Aspect et. al. performed a series of experiments that have (nearly) conclusively proven that quantum mechanics is correct: particles do not have precisely determined states before they are measured. The details of these experiments are simply horrendous (I don't understand the nitty gritty of them myself, to be honest).
So we don't really have any option but to abandon the picture that each particle is like a pair of particles which are produced by a machine in pairs of "blue and white". Each particle is literally blue AND white, and there is no way for anyone- no matter how advanced their technology- to be able to tell which is which before they're measured. It's not a matter of our inability to describe the situation fully, it's because the particles are literally in both states at once. Seem a little more spooky now?
You're absolutely right, there might be some effect on large scales that screws up entanglement. I only used that example to drive home the fact that current theory says that there is no distance limitation at all, but it hasn't been tested. On the other hand, I would be very surprised to find that distance matters, because the math is (relatively) simple and clear, and it seems like distance dependence in this case would imply many other things about quantum theory are wrong (which seems unlikely- it's the most aggressively tested theory in science IMHO).
Unfortunately, it's not easy to demonstrate that FTL communication implies backwards-in-time communication without using spacetime diagrams. I've done a little googling, and the best website I could find on this subject is here.
The gist of the argument is that special relativity divides the universe into three regions of spacetime: the timelike future (which is the set of all points where you COULD be in the future if you could travel at any speed up to and including the speed of light), the timelike past (which is where all events that could POSSIBLY have an affect on you at the present reside) and "elsewhere", which is comprised of all other events. An example of an "elsewhere" event is the state of the Mars rovers RIGHT NOW. I can't possibly know that at the moment because there's about a 30 minute light travel time delay. It's important to realize that FTL communication connects you to an event in "elsewhere" in a causal manner.
If you draw a spacetime diagram for two people, one of whom is moving very fast (at a conventional sublight speed) relative to the other, you'll find that the "elsewhere" of one observer intersects the past of the other. So using FTL communication and sublight engines to send a message to the past would work like this:
1. Bob gets in his fancy spaceship and travels directly away from earth at 90% the speed of light. He travels for 1 year (the time and speed aren't really important, they just allow the message to be sent farther into the past).
2. Alice, on earth, sends Bob an instantaneous message using her FTL communication device. It travels to Bob along what Alice considers to be her "line of simultaneous events" - the line in her spacetime diagram that goes through her present position and on through "elsewhere", to define the "present". It's not necessary for Alice's communication to be instantaneous, but it makes the argument (a little) clearer and doesn't really matter because going 1.0000001x the speed of light is just as impossible as going infinitely fast (as an instantaneous communication device would have to do).
3. Bob receives the message at the exact instant (in Alice's timeframe) as when she sent it. He then sends the message back to Alice using the same FTL device. The difference is that Bob is travelling at 90% of the speed of light, so his "line of simultaneous events" is completely different- it actually intersects Alice's "timelike past".
All of this makes a lot more sense once you get the hang of drawing spacetime diagrams, but it confused me for many years. You might want to google for tutorials on spacetime diagrams or "pole and barn" paradoxes to see some examples of spacetime diagrams...
IAAP, and yes, you're reading it wrong. The no-cloning theorem says that you can't take state "A" (which you can't measure or know anything about) and send it through a copying machine which gives you "A" and "Copy of A". Actually, you can build a machine like this, but only for state "A". You couldn't use the same copying machine for another unknown state "B". Which makes it kind of useless as a copying machine; it would be like requiring a different xerox machine for each book or magazine article you wanted to copy.
Now, that doesn't mean that you can't create multiple copies of the same known state. In fact physicists do this all the time to run experiments enough time to obtain statistically reliable results.
But it's also not the same thing as entangled particles. Entangled particles are not identical, in fact most of the time they've got different qualities like polarization. I've got another post in this topic that I believe sums the issue up fairly concisely.
Actually, quantum teleportation destroys the original state in the act of teleporting it. This is required by the no-cloning theorem of quantum information.
On the other hand, the rest of your post makes very little sense to me. As long as the teleportation process is carried out at sufficient resolution to capture all the relevant details of my consciousness, and I emerge on the receiver pad with all my memories and personality, I don't understand how it could be anything but successful. If you're referring to the psychological strain of instantly seeing a new room... maybe all teleporter rooms can look exactly the same, down to the smallest perceptible detail.
I am a physicist, and I don't understand the connection between the no-cloning theorem and using entanglement for FTL communication.
Think of entanglement this way: you've got two particles, each of them in a superposition of two states (horizontal and vertical polarization, for example). The "spookiness" of entanglement lies in the fact that the particles are created in a state where (for example) they have to have opposite polarizations. Thus even though each particle is in a (literally unknowable) superposition of horizontal and vertical, when you measure the first particle and find that it's horizontally polarized, that automatically means that a measurement on the second particle will show that it's vertically polarized. This occurs even if the second measurement is made a millisecond after the first measurement, and the two particles are on opposite sides of the galaxy.
At first glance, this is remarkable. At second glance, it's just conservation of momentum: say the two particles are created from another particle with angular momentum=0. Then the sum of the two angular momentums needs to be 0, so their polarizations must be opposite. The "spookiness" Einstein referred to lies in the fact that quantum mechanics says that both particles are literally horizontally AND vertically polarized, up until the point where the first one is "collapsed" onto horizontal (or vertical). Then all of a sudden the states of both particles are well defined, which occurs even if both particles are separated by a great distance. Einstein took this spookiness to mean that quantum mechanics must be incomplete (namely, that each particle DID have a well defined state that quantum mechanics simply can't describe), but 30 years later a physicist named Bell found a way to experimentally test the issue using "Bell inequalities". Quantum mechanics predicted the outcome of these experiments (google Aspect experiments in the 1980s) up to very high sigma values.
The problem with using these correlations for superluminal correlations is that each measurement just gives you a random horizontal or vertical outcome. The only interesting facet of these measurements is that, when you meet up with the guy who has the other entangled particles (at sublight speed), you find that your answers correlate perfectly. This isn't useful for communication! The only way that it could be used for communication is if quantum mechanics has small nonlinear terms which would allow one party to "bias" his collapse preferentially onto horizontal or vertical. Unfortunately, decades of testing have shown that any nonlinearities in the Schrodinger or Dirac equations underlying quantum mechanics are very, VERY small.
Bummer. On the other hand, FTL communication automatically implies backwards-in-time communication (and thus travel) so at least we don't have to worry so much about being killed by our own grandchildren.
Actually, I recently wrote a paper on quantum teleportation, and I was surprised to find that teleporting a human being with current telecom equipment would take longer than the age of the universe.
There are lots of other problems, though. First of all, they can't even teleport single photons yet. All they can do is teleport a single degree of freedom of a single photon, such as polarization or transverse spatial state. Secondly, scaling the teleportation process up to macroscopic objects would require isolating the object to be teleported from its environment in order to preserve quantum coherence. I imagine vacuum exposure would make this procedure uncomfortable for... you know... living things.
It should be noted that quantum teleportation is not able to transfer matter or energy from transmitter to receiver. All the protocol can do is transfer the quantum state of a particle (or, in the future, groups of particles) from transmitter to receiver. That doesn't mean that humans can't be teleported, though; the receiver would simply keep a stock of raw materials such as carbon, hydrogen, calcium and oxygen atoms out of which to reconstruct the person.
For the moment, quantum teleportation bears little resemblance to its sci-fi namesake. It's still useful for sending secure messages because of one bizarre property of teleportation: a teleported state can be sent between points A and B without ever existing between those points. It's also the best way to network quantum computers.
Sorry for the delay. I tried to install Kubuntu on a software RAID array and it completely nuked
my MBR- I had to reinstall Windows from scratch. Fun fun fun.
... evolution is a particularly hard case. It's a very malleable theory in the broad,
and entertains some diverse possibilities.... it can be hard to find data that contradicts a
theory -- or even find enough data to make people consider that the evidence might actually
contradict the theory -- but new theories only have to adjust the story to fit that new data....
Bits of evolution are modestly hard -- where it has hard data like genes, for instance. Bits of
evolution are really soft -- fossils are soft data that aren't very amenable to experiment, and are
more or less compatible with a lot of explanations.
Based on these statements, and links you provided in another post, it's clear that you think
evolution produces no predictions and is not falsifiable. I don't agree, because as far as I know
there are many potential falsifications
(click on parts 1,2,3,4,5 for long lists of potential falsifications) for evolution and lots of verifiedpredictions.
I especially like this quote from Origin of Species: "If it could be proved that any part of the
structure of any one species had been formed for the exclusive good of another species, it would
annihilate my theory, for such could not have been produced through natural selection."
What predictions can creationism offer, and how can we falsify it? As far as I can tell, the
answers are "none" and "it's not falsifiable". Creationism is compatible with every conceivable
discovery. For instance, it's strange that all life we find uses the same DNA bases (which is
a specific requirement of common descent). But it's also compatible with creationism because, even
though God could have created every species with different bases of DNA (or something even wilder)
to provide obvious proof that common descent is false, He obviously chose not to, presumably
because His Ways Are Mysterious. It's strange that the fossil record shows a general progression
from simpler, less diverse organisms in the distant past to more diverse and complex organisms in
the "recent" past (which is a specific prediction of evolution), but this is ALSO compatible with
creationism because God (or Satan?) could be playing games with our heads.
I noticed your link to "Message Theory", but I'm surprised that you would consider this to be a
valid example of a prediction. As far as I can tell from the book synopsis and this review, the author is basically saying
"the prediction of intelligent design is that intelligent design is obviously correct and no other
interpretation is possible." Isn't that tautological? It's like saying "evolution predicts that
evolution is correct and no other interpretation is possible". Notice that none of the predictions
or potential falsifications I have mentioned or linked to follow this pattern...
Incidentally, did you ever read the novel Contact (NOT the movie)? At the end of the book,
Sagan's heroine discovers an obvious, indisputable message encoded in the digits of pi. This is
what I would consider to be definitive proof of God's existence, and a true example of the
discovery of a message from an intelligent designer.
I sense a problem in that many evolutionists complain that creationists don't have
theories of their own, but just pick on the theories of others. That shouldn't be perceived as a
problem -- it should be perceived as modern science in action....
Thanks for a much more thoughtful reply than average
for this thread.
Right back at ya.
Sadly I can't give your reply all the time it
deserves, because I've chosen to reply to quite a few already, as
well as having my original post modded up to Interesting+4 and
then back down to hell by angry mods.
For what it's worth, I'd have modded you +1 interesting had I not
posted.
Well, that's part of the problem with attempting to
falsify evolution. What was once a valid objection becomes
invalid because the target moves.
Evolution in particular, or science in general?
Before we knew how much dust was actually on the
moon, for example, long-age theory made "lots" the obvious
prediction. Now that we know how much dust there is on the moon,
we have a post hoc explanation for it in terms of long ages.
First of all, I'm not sure that obvious prediction was "lots".
After reading these twopages,
it looks like there was just one guy (Pettersson) providing data
that implied a large amount of dust. He did so by making a
number of bad assumptions, such as the assumption that any nickel
in the air must be coming from meteors.
Secondly, your "post hoc explanation" sound bite gives the
impression that scientists looked at the amount of dust on the
moon and fudged the numbers to make it fit. The actual process
involved measuring meteorite impact rates using satellites above
earth's atmosphere to avoid earthly contamination, which resulted
in an estimate 1000x less than Pettersson's. This estimate was
then subjected to an independent cross-check by comparing them to
average amounts of meteorite dust found in sedimentary rock, and
they agreed.
If you want anti-evolutionists to keep up with all
the latest developments, give them funding specifically to find
flaws in the latest pro-evolutionary findings.
What's special about the field of evolution that makes the usual
scientific process break down? Every other field of science
follows the same basic process: researchers present evidence
which is then checked for accuracy by their peers. What is it,
specifically, about evolution that requires tacking a separate
step onto the process of peer review? Why not give that
(limited) funding to people who have problems with modern medicine or plasma physics or
heliocentricity? Before you
answer, note that I don't really see a qualitative difference
between most creationists and the arguments presented at these
sites (especially the heliocentricity site). Is there a
difference, other than the fact that you believe one rather than
the other? (I'm crossing my fingers hoping you're not a
geocentrist.)
This objection irks me. It seems that the people who
accuse Behe of arguing from ignorance provide refutations in the
form of arguments from credulity. Behe points out complex systems
and says "remove any one piece and the system breaks." His
opponents respond, "so it happened some other way." Where does
the onus lie?
...
His opponents are already persuaded that "naturally" is the only
way anything forms, so they give a just-so story about how it
might possibly have happened, and consider the case
closed.
Behe is making an extraordinary claim, namely that the evolution
of a specific structure (take your pick from his examples) will
never, repeat NEVER, be explained in full detail.
Furthermore, he's arguing that this (predicted) failure isn't
evidence for our collective stupidity. No, instead he jumps to
the conclusion that this (again, predicted) fai
In your first paragraph (of point #3) you point
out a strong correlation between belief in intelligent design
and certain religious views. You are appealing to the
prevailing Slashdot bias against organised religion when you
do this: the correlation says absolutely nothing in and of
itself as to whether the idea is true or false. C. S. Lewis
described that form of argument as "Bulverism": dismiss the
argument on the basis that the person raising it has
particular motives for doing so. "You just say that because
you hold religious view X." I can't argue against this,
because it isn't an argument.
Note that I wasn't attempting to use this correlation to argue
that intelligent design is false. I was arguing that
intelligent design is a religious idea, not a scientific idea.
I believe that the fact that evolution is not well correlated
with religion, whereas intelligent design IS well correlated
with religion, is evidence that intelligent design is related
to religion in some manner. Of course, as I point out at the
end of that paragraph, there are ways to argue around this
point so I don't consider it particularly strong evidence.
I will point out, however, that Intelligent Design
and Creationism are not the exclusive property of theists. Sir
Fred Hoyle and the "panspermia" proposal are an example of a
prominent scientific atheist and a naturalistic intelligent
design theory (limited to chemical evolution in scope). His
ideas were not accepted, of course, and I wonder whether his
audacity in questioning such sacred cows (and providing
quotable material to the infidel creationists) didn't cost him
Nobel Prize recognition in the end. Still, he started a meme
that may yet bloom and grow: "seeds of life".
That's interesting. I didn't know that Fred Hoyle identified
as an atheist. I wonder if he continued to self-identify as
an atheist after espousing these ideas...
I'm not sure that panspermia is at odds with evolution. As
far as I understand the idea, panspermia simply expands the
"biosphere" from planet Earth to the whole galaxy or even
beyond. Natural selection still acts, species still evolve to
fill available ecological niches, etc. If true, it completely
changes the answer to the question of the origin of life on
earth (ordinarily called abiogenesis, but that term doesn't
seem appropriate in this context). Depending on the rate at
which microbes survive re-entry into earth's atmosphere, it
might also contribute somewhat to genetic diversity on
geological timescales. But it seems compatible with evolution
unless I'm misunderstanding something.
As far as his often-quoted "tornado assembling a 747 from a
junkyard" remarks, I don't think I'm qualified to deal with
this issue in detail because I'm not a molecular biologist. I
do have two things to say, though. First, he seems to be
arguing that abiogenesis (rather than evolution) is
statistically unlikely. From what I can tell he's not arguing
that natural selection is incapable of producing the diversity
we see around us, provided we assume the existence of just one
living cell. He's simply arguing against abiogenesis by
saying that the first cell is so improbable that it can't have
formed by chance.
Secondly, abiogenesis is arguably the most mysterious question
in biology because of the fact that it happened so long ago
and left no trace of how it happened. It will probably remain
mysterious until we find other biospheres (crossing my fingers
for Mars, Europa and Titan) or find a way to successfully
simulate abiogenesis in the lab. I haven't read his
explanation of how he arrived at his claim that "the cell has
one chance in 10^(40,000) of forming". And, again, I'm way
out of my depth here, but I'd like to go out on a limb and
suggest a possible flaw in his analysis. As far as I can
tell, he seems to be examining the simplest cell he can find,
and calculating the probability of
For the sake of argument, I believe you could place an lower bound on the number of animals on the ark by estimating an upper bound on speciation rates for the species which would have been on the ark (land animals primarily, I would assume). In other words, if all the species alive today came from a very small number of species, the small initial population of each species would have had to speciate at a high rate in order to produce the diversity observed today.
Maybe the best answer is to say that it's actually a fact and a theory. It's a fact that objects fall to the earth when we release them, and several theories (Newtonian gravity, Einstein's General Theory of Relativity) have been proposed to fit these facts into a coherent whole. It's a fact that species evolve, and several theories (gradualism, punctuated equilibrium) have been proposed to fit these facts into a coherent whole.
Physics is probably my weakest area of science but I thoroughly enjoy reading layman-level explanations of some of the strange stuff out there. Naturally, String Theory has been a pretty hot topic of late (indeed a friend of mine rather amusingly proclaims it to be scientific evidence for the principles of Buddhism!) but I cannot help but wonder how it attained the "theory" designator. Isn't it more of a hypothesis or set of hypotheses, especially since neither it nor its predictions seem to be particularly testable?
Well, first of all I'm a geophysicist, so string theory is above my head too. I have some friends working on high energy colliders, and that's about as close as I get to the field of string theory. But I have had several professors argue very strongly that it doesn't deserve the label of "theory". At this point, I'd say that it seems more like mathematics that may or may not have a connection to the real world. Maybe in the future we'll find a way to test string "theory" but for now I agree that it is, at best, a hypothesis.
The real problem is that these terms, "theory" and "hypothesis" are used interchangeably by almost everyone; even scientists sometimes fall into the trap of saying "I have a theory" when they actually mean "I have a hypothesis". I'd imagine that's what's going on here- it's simply unwieldy to say "string hypothesis", whereas "string theory" has a nice ring to it. Probably the best approach to take here is not to worry too much about semantics like the labels we put on ideas. That was basically the gist of what I was trying to say to creationists in my above post: "debate evolution if you like, but don't waste my time arguing about labels like 'theory' ".
I've not really considered that before, but I'm not really sure I'd want to give a lecture like this in public. From what I've seen, public debates on evolution are usually failures for rationalists. There are several reasons:
(1) Most scientists are accustomed to honest, civilized debate. Scientific conferences are full of disagreements and arguments, make no mistake about that. But (almost) all the participants are aiming to understand the universe better, to examine their assumptions and use experimental evidence and logic to figure out whether or not they need to change their assumptions or ideas. They might attack a speaker's ideas if they believe that a mistake is being made, but there's nothing very personal at stake. So once proven wrong, they admit it (usually politely if you're lucky). Most creationists, on the other hand, are defending the One True Religion. They already know The Truth, and simply pick and choose arguments from creationist websites to attempt to defend that Truth. This kind of backwards reasoning (arrive at conclusion first, find supporting facts later) is so alien to scientists that they simply can't handle it. I'm not sure I could, for that matter.
(2) Creationists often make statements like "Evolution can't produce new information in a genome" or "We don't know how old the earth is because carbon dating isn't useful on large timescales and we don't know the initial amounts of isotopes and polonium halos disprove old ages anyway". Answering each one of these statements would require hours of boring, dry lecturing- something that simply isn't going to happen. And the problem is that creationists don't just make one of these statements, they make DOZENS of them. Answering this kind of deluge of mis-information in such a way that it can be intelligible to the average person would take an unbelievably long amount of time. As such, even answering questions from the crowd can be a tricky business. How do you explain isochronology and radioactive dating methods in 2 minutes to a young earth creationist? I can barely explain it to a fellow scientist in less than 15 minutes. Now imagine someone standing up and asking two or three of these questions in rapid fire mode, and ridiculing you for not having a snappy answer. This kind of public failure would not look good.
(3) Creationists are usually much better at the fine art of crowd manipulation, whether they're participating in a debate or simply asking an "impromptu" question from the audience. I'm finishing up my PhD now, and I've taught some pretty big classes, but never had to worry about anything like this. I'd probably be slaughtered if I tried...
I'm not completely knocking the idea, it's just that I can easily see it becoming ugly.
I've noticed that many slashdot articles about evolution seem to attract a sizeable number of creationists. Because of this, I've decided to address the serious (i.e. non-trolling) creationists that frequent slashdot in the hope that I can prevent you from making the same easily avoided mistakes that make so many of your brethren sound like ignorant cretins. Here are some common arguments that creationists use, and why I think that you shouldn't use them... unless of course you want to be ridiculed. Note: this is by no means a comprehensive list.
(1) "Evolution is just a THEORY"
This is the most common (and the most disappointing) creationist argument I hear on a regular basis. While it's true that evolution is a theory, this statement is made in an attempt to cast doubt on evolution by implying that evolution is akin to a wild guess that scientists came up with after a night of heavy drinking. Newsflash: it's not going to work. Most educated people understand that you're confusing the word "theory" (which means an explanation or model that is capable of predicting future events) with the word "hypothesis" (which means an educated guess). Calling evolution a "theory" isn't an insult. For the millionth time, I will repeat this: gravity is also "just" a theory (for example, google the "General Theory of Relativity"). I might even add that most scientists would consider evolution to be a better-supported theory than gravity, because of the fact that gravity cannot (currently) be quantized, despite decades of attempts. If you want to debate evolution, fine- but don't play these childish word games.
(2) "But evolution has never been observed!"
Most creationists, faced with the mind-numbingly obvious fact that viruses and other creatures (like those famous moths) evolve right in front of our eyes, make a distinction between micro-evolution and macro-evolution. Micro-evolution is "proven", they say, because it only represents a change in allele frequency within a species. Macro-evolution, defined as change from one species to another (aka "speciation"), is more of a problem for creationists. They often insist that speciation has never been observed outside of laboratory experiments. This is blatantly false. Many examples of speciation have been observed in the wild- for example check out this large list of peer-reviewed journal articles here and also here.
The next step that creationists take in response to this rebuttal is to claim that speciation proves nothing- only a change from one kind of organism to another will prove evolution. What's a "kind", you might ask? No one knows. Creationists will give vague examples, such as saying that a dog is a different kind of animal than a whale, but a rigid definition has never (to my knowledge) been offered or universally accepted by the major creationist organizations. It's just a convenient goal post which keeps getting pushed back every time new evidence is found. The fact is, speciation is rather easy to observe in organisms which breed relatively quickly. Observing the creation of, say, a new phylum or order could take many millennia. Unfortunately, human civilization hasn't been around that long. Plus, standard biological nomenclature isn't based on evolutionary criteria, so it isn't clear to me that equating a "kind" with a phylum or order is meaningful in this context.
(3) "But Intelligent Design is different than Biblical Creationism! It's a purely scientific alternative theory."
Don't try to pretend that "Intelligent Design" is somehow different than creationism. Especially don't try to pretend that it's a scientific theory. Seriously. No one's buying it. "Intelligent Design" is a disguise- a secular-sounding term thrown over religious creationism to try to smuggle it into a state-funded science class
I've pretty much agreed with you until I got to this. Something had to be done to the Taliban because they are Taliban not because they refused to hand over bin Laden, which they did not do. In fact the Taliban asked to see any evidence bin Laden had anything to do with 911, which is the correct thing to do.
I agree that the Taliban was oppressive, and long before 2001 I remember reading reports of the horribly misogynistic nature of their rule and hoping something would be done about it. But after the Iraq debacle I'm not so sure that it's a good idea to invade a country unless it poses a tangible, imminent threat to our own national security. Protecting other people from their own governments seems hopeless, because it requires a lengthy occupation during which matters often seem to get worse, and furthermore the new carnage is now associated with us rather than the previous thug, which turns global public opinion even more solidly against us. Pursuing a policy like that would also be a huge, never-ending task. We'd have to overthrow North Korea, Cuba, China (arguably), Saudi Arabia, Iran, etc. It's just not possible.
As far as the Taliban not turning over Bin Laden, I have mixed feelings about this issue. On the one hand, it does seem reasonable to ask for evidence, but given the disreputable source I'd say it wasn't a careful, honest attention to legal detail as much as it was an attempt to stall us to allow Bin Laden to flee the country. Not to mention that even they must have realized that openly and brazenly defending Bin Laden would have only quickened their deaths because it would have turned the entire civilized world against them.
The thing is is Bush actually supported the Taliban at one tyme, he gave them more than $40,000,000 of US taxpayer money. By the logic above, either hand over a suspect without seeing any evidence or being invaded then Venezuela should be able to invade the USA, because the USA is shielding suspected Cuban terrorists Orlando Bosch and Luis Posada Carilles who are accused blowing up Cubana Flight 455.
That's a very interesting point. I don't know much about these men, and am under considerable time constraints with the end of semester approaching, so I'm afraid I won't be able to research it and give you a well thought out answer.
1. After 9/11, Gore would have made some big talk in front of the U.N. about terrorist groups. But the U.N. would have done exactly what it did do: nothing. The terrorists would have seen us as unwilling to defend ourselves and would have made subsequent attacks on us. This cues more rhetoric from Gore and eventually he and the U.N. would try to negotiate a truce with the terrorists, which would have given them "legitimate" status and guaranteed more attacks in the future.
I can't confidently say what Gore would have done after 9/11; I'm not even sure that Gore could, frankly. I can say that you seem to be displaying a "black and white" mentality very common with right wingers nowadays. You're either with us or against us. You either support the President or you're spitting on the troops like some kind of treasonous bastard. The false dichotomy I see in this point is "the president is either willing to start wars at the drop of a hat, or he's a cowardly eunuch who doesn't understand the basic principle of "don't give in to terrorism."
But, provisionally, let's say your black and white view of the situation is right. Let's say that Gore is a fucking pussy, and that he wouldn't have invaded Afghanistan in response to 9/11. I think that's very unlikely, but for the sake of argument I'll run with it. (For the record I fully supported the invasion of Afghanistan even though its later execution was botched, largely because of resource diversion due to Iraq as far as I can tell). What would have happened on a global scale after such a non-reaction? Would it have been a disaster of subsequent attacks as you say? I don't think so, and my reasons for saying so are based on my current understanding of how terrorism works. If I've made any mistakes in my analysis, please point them out so I can improve my understanding of the current geopolitical situation.
I think that Islamist terrorists are comprised of two basic groups. There's a very small group of fanatics who are fundamentally evil, and want to kill as many innocent people as possible in order to further whatever their agenda might be. This includes things like (1) Establishing a global Islamic state, (2) Destroying Israel, (3) Removing US bases from the Middle East, (4) Getting revenge for actions the US has taken like overthrowing the Shah of Iran, imposing trade sanctions on Iraq and supporting Israel for decades. I've probably missed a few, but that's okay because new reasons crop up every day because of US actions in Iraq and Guantanamo Bay and the CIA's secret prisons in Europe, etc.
Now, this very small group of people may be crazy and evil, but they're not (as a rule) stupid. They know that they can't win a real war because modern warfare requires large armies and high technology (neither of which they have), so their only option is to use desperate tactics like suicide bombers. But they can't suicide bomb places themselves (because otherwise the movement would end very quickly), so they have to recruit dupes to do that for them. I think that the vast majority of suicide bombers and "Al Qaeda fighters" we hear about so often fall into this second category. They're impressionable young men who may not be fundamentally evil or psychotic, but they're morons who have grown up in a world steeped in hatred, and probably nurse anger towards the US and our allies because, say, a US bomb fell on their house and killed their family. Or any number of different tragedies, really, not all of them related to the US.
What this means, as far as I can see, is that terrorism depends crucially on the discontent of the populace in the country where they're operating and recruiting. If society sees them as saviors against a Great Satan, then their only real resource- idiotic, violent, gullible young males filled with bitter hatred- is plentiful. People want to shelter them, to further their efforts as "freedom fighters". If society sees them as a bunch of bloodthirsty killers of women and ch
This is a fascinating idea, but I wonder if the cell phones could actually be located accurately enough. My understanding of cell phones is that each phone is "located" in the sense that the tower that it's communicating with is reported to 911 operators. Perhaps different cell phone towers could compare the time delay of the phone signals and perform triangulation? If so, this would seem to require nanosecond timing accuracy (1 foot at lightspeed takes 1 ns) and I'm not sure that's feasible across the country. Someone mentioned GPS receivers, but those are only accurate to within 10s of meters unless they're very expensive fixed geological stations as far as I know.
There's one thing I don't understand about black holes. I've read that a black hole is so massive that space itself is warped around it. This warping means that a straight line that starts at the center will return to the center. It returns even though in its local context it is straight.
More precisely, a black hole warps space in the sense that if you had a flashlight right on the event horizon and pointed it parallel to the event horizon, the light would travel in a great circle on the event horizon. Inside the event horizon, things are way different. It's more accurate to say that space and time swap identities. The spatial direction towards the singularity becomes the "future" and the direction away from the singularity becomes the "past". So the reason you are doomed when you cross the event horizon is because the singularity literally lies in your future.
But don't gravitons move like light? So how does the force of gravity escape? No light or other signal can escape... And yet gravity can! Weird.
(1) Gravitons are the mediating particle of the force of gravity in a theory that has yet to be discovered called "Quantum Gravity". This is analagous to quantum electrodynamics, where the force of electromagnetism is mediated by a particle called the photon (yes, as in light photons). It's reasonable to assume that because electromagnetism and gravity have similar inverse square laws, that their mediating "particles" would be similar at least in terms of long range interactions. But I simply don't know for sure- no one does.
(2) Black holes can hold an electric charge, and they exert a coulomb force on nearby charges. So, really, gravitons and photons exhibit the same strange, seemingly contradictory behavior- they seem to be able to cross the event horizon.
(3) I believe the easiest way to resolve this apparent paradox is to regard the mass and electric charge of the black hole to be caused by the mass and charge just before it passed through the event horizon. The matter and charge disappears behind the event horizon, but the electric field lines and gravitational effects remain because of the time dilation- matter seems to take an infinitely long time to pass through the horizon. I'm not sure about this, though. It seems like you could test this (in principle) by adding a significant amount of mass to a non-spinning black hole in one specific location and testing the gravity field of the black hole later for any deviations from a central field. In other words, if the gravity and electric field really does continue to emanate from the place where the mass was right before it hit the event horizon, that would mean that its gravity would be drawing you towards one spot on the event horizon, not towards the singularity. Now that I think this through, it would seem to violate the "no-hair theorem" by Hawking, who's a shitload smarter and more experienced than I'll ever be.
Anyway, take this with a grain of salt. This isn't my specialty...
You bought the right to sell up to 1 CD when you buy 1 CD from a music store.
I just wanted to mention that, even though this is true for CDs, I'm not sure that it's possible for most forms of legally downloaded music (i.e. music with DRM). Does anyone know?
I worry that, in the future, this basic "right of resale" won't still be around because it will be impossible to implement without excessively harsh technological restrictions. And, yes, I know that "excessively harsh" is a subjective judgment on my part...
Slashdot Mirror
I, too, seem to have been born with the gene for "sci-fi fan" turned on. Unfortunately, as I continue to learn about physics, I find myself less able to suspend belief than in years past. As a result, I usually prefer shows that either skip the technobabble completely (such as Firefly and Battlestar Galactica) or generally get the technobabble (reasonably) correct. Stargate Atlantis is the only show I can think of that even comes close, and it's only reasonably correct 20% of the time or so...
MW is extravagent, but only in the sense that it implies the universe is larger and stranger than we thought it was before. That's been happening for millenia- every new paradigm in science (heliocentricity, relativity, the realization that our sun is just another star, etc) has shown us that the universe is stranger than we thought it was before.
So most physicists have stopped trying to apply common sense to physics theories. If Einstein had used common sense to say "Of course everyone experiences time at the same rate!", then we wouldn't have special relativity today. The only criteria I use are: (1) Does the theory match experiment? (2) Is the theory mathematicall consistent? and (3) Does the theory have fewer axioms than its nearest competitors?
In this sense, the MW interpretation wins. It is mathematically consistent, involves one fewer assumption than the conventional "collapse" interpretation of quantum mechanics, and it describes experimental results just as well. It's possible that there are other interpretations that work (such as Cramer's "Transactional Interpretation") but for now I'm leaning towards the MW interpretation.
Yes, the "collapse" effect in MW is a purely physical phenomenon. It's difficult to translate the math into english, which is why I've said strange things like "generates new universes". This is a clumsy (and probably overly dramatic) way of describing the process, but it's the best I can do. A more mathematical way of describing the process would be to say that coupling an isolated quantum system to a much larger system (like a detector) dramatically reduces the off-diagonal terms of the density matrix describing the original quantum system. Since these off-diagonal terms describe interference between the various eigenstates of the quantum system (horizontal and vertical polarization, for example), this process effectively prevents the two eigenstates from interfering with each other. Because the two eigenstates no longer interact, some physicists interpret the resulting density matrix as saying that the two outcomes are now in two "separate universes" which no longer interact.
But, as you can tell it's a lot easier to say it "splits the universe in two".
Yes. They're simply interpreting the math of quantum mechanics in different ways, and the mat
- Quantum collapse is introduced in the standard interpretation as an arbitrary axiom. Therefore, if any different formulation of quantum mechanics can eliminate this axoim while producing identical predictions about real experiments, we should choose the new formulation based on Occam's razor.
- Because quantum collapse is introduced as an axiom, it is not justified in any specific physical manner. In the many worlds interpretation, collapse is simply seen as "the decoherence caused by interacting with a system containing a very large number of particles". This phenomenon, known as einselection, is rigorously described on a fundamental level. It is a purely mechanical process, not a mystical one. It has nothing to do with knowledge. In fact, it emerges as an obvious consequence of letting an individual particle interact with an object composed of a very large number of particles.
- Quantum collapses are a fundamentally non-unitary process, as opposed to every other process in quantum mechanics. It's inconsistent with the rest of the theory in that respect.
- Abandoning quantum collapse by choosing the Many Worlds Interpretation of Everett and Wheeler (and more recently Deutsch) results in exactly the same experimental predictions as the "standard interpretation".
Now, the many worlds interpretation is weird. It implies that a nearly infinite number of parallel universes exist, each representing the state of the universe if a particle had gone this way or that way, collapsed onto horizontal or vertical, etc. Because we humans are made up of particles, that means that there is a different universe for every possible event in history. There is a universe where the Nazis won WW2, where dinosaurs never became extinct, where Paris Hilton is a college professor, etc. But this weirdness is, in my mind, more than offset by the elegant way that it simplifies quantum theory. Not all physicists agree with me, but the many worlds interpretation is not a fringe view by any stretch of the imagination, and it seems to be growing more accepted with each year...After thinking about your last point some more, I think my "continuum between particles and waves" explanation isn't really the best answer. It's better to say that the whole particle-wave duality thing isn't really important here. Quantum entanglement can be demonstrated using completely different properties than polarization. For instance, one of the first quantum teleportation experiments (Boschi, et. al.) used "path entanglement". They created a pair of photons, each of which went through two paths (two paths for each particle, for a total of four different paths) at the same time. Even though each particle was actually traveling through two different paths, if you tried to measure one of them and find out which path it "collapsed" onto, the other particle (again, potentially on the other side of the galaxy) would instantly be "collapsed" onto a certain path in the other lab. Thus entanglement doesn't really have anything to do with particle/wave duality; it's simply that the most easily explained example involves polarization.
I agree, as do most physicists. Quantum mechanics is difficult to learn, not only because the math is complicated, but also because it's seemingly nonsensical. If it's any comfort, every quantum physicist since the 1920s has gone through the same stage of incredulity that you find yourself in now. In fact, that very incredulity has caused physicists to test quantum mechanics to a greater degree of precision than any other theory I can think of off the top of my head. In every experiment, designed to disprove every bizarre property of quantum mechanics, quantum theory has prevailed...
It took me a long time to believe in black holes (even after most physicists thought they were conclusively proven to exist) so we agree on this principle.
I've always found math and logic to be extremely similar, if not synonymous. They both start with a small collection of axioms and use deductive (and occasionally inductive) logic to arrive at a conclusion. Have you ever tried to learn symbolic logic? If so it's quite similar to math, and I suspect it would lessen the transition shock because it encodes information into symbols in similar ways.
Interestingly, wave function collapse is NOT an internally consistent description of reality. The inconsistency arises because the "collapse" of a quantum state is a completely different process than the normal time evolution of a quantum state; physicists say that it is a "non-unitary" process because it annihilates some of the quantum state (a state which is originally horizontal and vertical collapses onto vertical only, thus annihilating the horizontal part of the state). This is opposed to ordinary "unitary" processes that occur at all other times which don't affect "how much" of the state exists. This paradox was resolved (IMO) by Everett and Wheeler when they reformulated quantum mechanics without the "collapse" axiom- instead of collapsing onto horizontal or vertical, the entire universe splits in two. In one universe, the observer sees the collapse result in a horizontal state, while the other universe sees a vertical state. This is sometimes referred to as the "many worlds interpretation" of quantum mechanics. It involves fewer axioms, has no internal mathematical inconsistencies such as those created by the notion of wave function collapse, and results in the same physical predictions. The only caveat is that it predicts a nearly infinite number of parallel universes, leading some physicists to say that the many worlds interpretation is cheap in terms of axioms, but expensive in terms of universes.
I mention this only because I find it interesting, but it really doesn't change any part of the argume
First of all, photons (particles of light) behave as though they're waves. There's a lot of subtlety hidden in this statement, but it's not relevant now: just picture a single particle of light moving into the screen while moving up and down pretty much like a water wave. This is a vertically polarized photon, and it can be easily distinguished from a horizontally polarized photon (a photon traveling into the screen while "waving" left to right instead of up and down). When I say "easily distinguished", I mean that you can place a device in the photon's path that produces a "click" if the photon is horizontally polarized, and a "beep" if the photon is vertically polarized.
Now, according to the math of quantum mechanics, it's possible for a photon to be in a "superposition state" of horizontally and vertically polarized. This is sometimes described by saying that the photon is traveling into the screen while "waving" at, say, a 45 degree angle- somewhere in between horizontal and vertical. This isn't wrong, strictly speaking, but it's very misleading unless you've taken a lot of physics. Instead, I'll say that the math literally implies that the photon is in two states (horizontal and vertical) at once- but when you measure it the photon randomly "collapses" onto one of those states. The important point is that quantum mechanics says that the photon was in two states at once before the measurement, and that it's impossible- even in principle- to say which state the photon was in before the measurement took place. Theories which attempt to describe the state of the particle before the measurement (in contradiction to quantum mechanics) are known as "hidden variable theories". No physicist that I've met considers these theories plausible, despite their intuitive appeal.
As SirBruce said, this "superposition then random collapse" is a bizarre property of quantum theory. But it becomes even more bizarre when you create two entangled photons- two photons that are each in their own superpositions, but created such that if one photon is horizontal, the other is vertical. Now, a measurement performed on one particle doesn't just collapse its polarization down to vertical or horizontal, it also collapses the other particle into the opposite polarization.
Again, calling this phenomenon "spooky" depends on you believing me when I say that the photons are in a literally unknowable state before they are measured. Before the 1980s, it was plausible to believe that the whole concept of a "superposition" was mere fiction: the misguided result of equations that produced good answers for some problems, but implied a nonsensical property like entanglement in other cases. This is certainly the opinion Einstein held, so you're in good company.
The problem is that in the 1980s, Aspect et. al. performed a series of experiments that have (nearly) conclusively proven that quantum mechanics is correct: particles do not have precisely determined states before they are measured. The details of these experiments are simply horrendous (I don't understand the nitty gritty of them myself, to be honest).
So we don't really have any option but to abandon the picture that each particle is like a pair of particles which are produced by a machine in pairs of "blue and white". Each particle is literally blue AND white, and there is no way for anyone- no matter how advanced their technology- to be able to tell which is which before they're measured. It's not a matter of our inability to describe the situation fully, it's because the particles are literally in both states at once. Seem a little more spooky now?
You're absolutely right, there might be some effect on large scales that screws up entanglement. I only used that example to drive home the fact that current theory says that there is no distance limitation at all, but it hasn't been tested. On the other hand, I would be very surprised to find that distance matters, because the math is (relatively) simple and clear, and it seems like distance dependence in this case would imply many other things about quantum theory are wrong (which seems unlikely- it's the most aggressively tested theory in science IMHO).
The gist of the argument is that special relativity divides the universe into three regions of spacetime: the timelike future (which is the set of all points where you COULD be in the future if you could travel at any speed up to and including the speed of light), the timelike past (which is where all events that could POSSIBLY have an affect on you at the present reside) and "elsewhere", which is comprised of all other events. An example of an "elsewhere" event is the state of the Mars rovers RIGHT NOW. I can't possibly know that at the moment because there's about a 30 minute light travel time delay. It's important to realize that FTL communication connects you to an event in "elsewhere" in a causal manner.
If you draw a spacetime diagram for two people, one of whom is moving very fast (at a conventional sublight speed) relative to the other, you'll find that the "elsewhere" of one observer intersects the past of the other. So using FTL communication and sublight engines to send a message to the past would work like this:
1. Bob gets in his fancy spaceship and travels directly away from earth at 90% the speed of light. He travels for 1 year (the time and speed aren't really important, they just allow the message to be sent farther into the past).
2. Alice, on earth, sends Bob an instantaneous message using her FTL communication device. It travels to Bob along what Alice considers to be her "line of simultaneous events" - the line in her spacetime diagram that goes through her present position and on through "elsewhere", to define the "present". It's not necessary for Alice's communication to be instantaneous, but it makes the argument (a little) clearer and doesn't really matter because going 1.0000001x the speed of light is just as impossible as going infinitely fast (as an instantaneous communication device would have to do).
3. Bob receives the message at the exact instant (in Alice's timeframe) as when she sent it. He then sends the message back to Alice using the same FTL device. The difference is that Bob is travelling at 90% of the speed of light, so his "line of simultaneous events" is completely different- it actually intersects Alice's "timelike past".
All of this makes a lot more sense once you get the hang of drawing spacetime diagrams, but it confused me for many years. You might want to google for tutorials on spacetime diagrams or "pole and barn" paradoxes to see some examples of spacetime diagrams...
Now, that doesn't mean that you can't create multiple copies of the same known state. In fact physicists do this all the time to run experiments enough time to obtain statistically reliable results.
But it's also not the same thing as entangled particles. Entangled particles are not identical, in fact most of the time they've got different qualities like polarization. I've got another post in this topic that I believe sums the issue up fairly concisely.
On the other hand, the rest of your post makes very little sense to me. As long as the teleportation process is carried out at sufficient resolution to capture all the relevant details of my consciousness, and I emerge on the receiver pad with all my memories and personality, I don't understand how it could be anything but successful. If you're referring to the psychological strain of instantly seeing a new room... maybe all teleporter rooms can look exactly the same, down to the smallest perceptible detail.
Think of entanglement this way: you've got two particles, each of them in a superposition of two states (horizontal and vertical polarization, for example). The "spookiness" of entanglement lies in the fact that the particles are created in a state where (for example) they have to have opposite polarizations. Thus even though each particle is in a (literally unknowable) superposition of horizontal and vertical, when you measure the first particle and find that it's horizontally polarized, that automatically means that a measurement on the second particle will show that it's vertically polarized. This occurs even if the second measurement is made a millisecond after the first measurement, and the two particles are on opposite sides of the galaxy.
At first glance, this is remarkable. At second glance, it's just conservation of momentum: say the two particles are created from another particle with angular momentum=0. Then the sum of the two angular momentums needs to be 0, so their polarizations must be opposite. The "spookiness" Einstein referred to lies in the fact that quantum mechanics says that both particles are literally horizontally AND vertically polarized, up until the point where the first one is "collapsed" onto horizontal (or vertical). Then all of a sudden the states of both particles are well defined, which occurs even if both particles are separated by a great distance. Einstein took this spookiness to mean that quantum mechanics must be incomplete (namely, that each particle DID have a well defined state that quantum mechanics simply can't describe), but 30 years later a physicist named Bell found a way to experimentally test the issue using "Bell inequalities". Quantum mechanics predicted the outcome of these experiments (google Aspect experiments in the 1980s) up to very high sigma values.
The problem with using these correlations for superluminal correlations is that each measurement just gives you a random horizontal or vertical outcome. The only interesting facet of these measurements is that, when you meet up with the guy who has the other entangled particles (at sublight speed), you find that your answers correlate perfectly. This isn't useful for communication! The only way that it could be used for communication is if quantum mechanics has small nonlinear terms which would allow one party to "bias" his collapse preferentially onto horizontal or vertical. Unfortunately, decades of testing have shown that any nonlinearities in the Schrodinger or Dirac equations underlying quantum mechanics are very, VERY small.
Bummer. On the other hand, FTL communication automatically implies backwards-in-time communication (and thus travel) so at least we don't have to worry so much about being killed by our own grandchildren.
There are lots of other problems, though. First of all, they can't even teleport single photons yet. All they can do is teleport a single degree of freedom of a single photon, such as polarization or transverse spatial state. Secondly, scaling the teleportation process up to macroscopic objects would require isolating the object to be teleported from its environment in order to preserve quantum coherence. I imagine vacuum exposure would make this procedure uncomfortable for... you know... living things.
It should be noted that quantum teleportation is not able to transfer matter or energy from transmitter to receiver. All the protocol can do is transfer the quantum state of a particle (or, in the future, groups of particles) from transmitter to receiver. That doesn't mean that humans can't be teleported, though; the receiver would simply keep a stock of raw materials such as carbon, hydrogen, calcium and oxygen atoms out of which to reconstruct the person.
For the moment, quantum teleportation bears little resemblance to its sci-fi namesake. It's still useful for sending secure messages because of one bizarre property of teleportation: a teleported state can be sent between points A and B without ever existing between those points. It's also the best way to network quantum computers.
Based on these statements, and links you provided in another post, it's clear that you think evolution produces no predictions and is not falsifiable. I don't agree, because as far as I know there are many potential falsifications (click on parts 1,2,3,4,5 for long lists of potential falsifications) for evolution and lots of verified predictions. I especially like this quote from Origin of Species: "If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection."
What predictions can creationism offer, and how can we falsify it? As far as I can tell, the answers are "none" and "it's not falsifiable". Creationism is compatible with every conceivable discovery. For instance, it's strange that all life we find uses the same DNA bases (which is a specific requirement of common descent). But it's also compatible with creationism because, even though God could have created every species with different bases of DNA (or something even wilder) to provide obvious proof that common descent is false, He obviously chose not to, presumably because His Ways Are Mysterious. It's strange that the fossil record shows a general progression from simpler, less diverse organisms in the distant past to more diverse and complex organisms in the "recent" past (which is a specific prediction of evolution), but this is ALSO compatible with creationism because God (or Satan?) could be playing games with our heads.
I noticed your link to "Message Theory", but I'm surprised that you would consider this to be a valid example of a prediction. As far as I can tell from the book synopsis and this review, the author is basically saying "the prediction of intelligent design is that intelligent design is obviously correct and no other interpretation is possible." Isn't that tautological? It's like saying "evolution predicts that evolution is correct and no other interpretation is possible". Notice that none of the predictions or potential falsifications I have mentioned or linked to follow this pattern...
Incidentally, did you ever read the novel Contact (NOT the movie)? At the end of the book, Sagan's heroine discovers an obvious, indisputable message encoded in the digits of pi. This is what I would consider to be definitive proof of God's existence, and a true example of the discovery of a message from an intelligent designer.
I completely agree with you
Right back at ya.
For what it's worth, I'd have modded you +1 interesting had I not posted.
Evolution in particular, or science in general?
First of all, I'm not sure that obvious prediction was "lots". After reading these two pages, it looks like there was just one guy (Pettersson) providing data that implied a large amount of dust. He did so by making a number of bad assumptions, such as the assumption that any nickel in the air must be coming from meteors.
Secondly, your "post hoc explanation" sound bite gives the impression that scientists looked at the amount of dust on the moon and fudged the numbers to make it fit. The actual process involved measuring meteorite impact rates using satellites above earth's atmosphere to avoid earthly contamination, which resulted in an estimate 1000x less than Pettersson's. This estimate was then subjected to an independent cross-check by comparing them to average amounts of meteorite dust found in sedimentary rock, and they agreed.
What's special about the field of evolution that makes the usual scientific process break down? Every other field of science follows the same basic process: researchers present evidence which is then checked for accuracy by their peers. What is it, specifically, about evolution that requires tacking a separate step onto the process of peer review? Why not give that (limited) funding to people who have problems with modern medicine or plasma physics or heliocentricity? Before you answer, note that I don't really see a qualitative difference between most creationists and the arguments presented at these sites (especially the heliocentricity site). Is there a difference, other than the fact that you believe one rather than the other? (I'm crossing my fingers hoping you're not a geocentrist.)
Behe is making an extraordinary claim, namely that the evolution of a specific structure (take your pick from his examples) will never, repeat NEVER, be explained in full detail. Furthermore, he's arguing that this (predicted) failure isn't evidence for our collective stupidity. No, instead he jumps to the conclusion that this (again, predicted) fai
Note that I wasn't attempting to use this correlation to argue that intelligent design is false. I was arguing that intelligent design is a religious idea, not a scientific idea. I believe that the fact that evolution is not well correlated with religion, whereas intelligent design IS well correlated with religion, is evidence that intelligent design is related to religion in some manner. Of course, as I point out at the end of that paragraph, there are ways to argue around this point so I don't consider it particularly strong evidence.
That's interesting. I didn't know that Fred Hoyle identified as an atheist. I wonder if he continued to self-identify as an atheist after espousing these ideas...
I'm not sure that panspermia is at odds with evolution. As far as I understand the idea, panspermia simply expands the "biosphere" from planet Earth to the whole galaxy or even beyond. Natural selection still acts, species still evolve to fill available ecological niches, etc. If true, it completely changes the answer to the question of the origin of life on earth (ordinarily called abiogenesis, but that term doesn't seem appropriate in this context). Depending on the rate at which microbes survive re-entry into earth's atmosphere, it might also contribute somewhat to genetic diversity on geological timescales. But it seems compatible with evolution unless I'm misunderstanding something.
As far as his often-quoted "tornado assembling a 747 from a junkyard" remarks, I don't think I'm qualified to deal with this issue in detail because I'm not a molecular biologist. I do have two things to say, though. First, he seems to be arguing that abiogenesis (rather than evolution) is statistically unlikely. From what I can tell he's not arguing that natural selection is incapable of producing the diversity we see around us, provided we assume the existence of just one living cell. He's simply arguing against abiogenesis by saying that the first cell is so improbable that it can't have formed by chance.
Secondly, abiogenesis is arguably the most mysterious question in biology because of the fact that it happened so long ago and left no trace of how it happened. It will probably remain mysterious until we find other biospheres (crossing my fingers for Mars, Europa and Titan) or find a way to successfully simulate abiogenesis in the lab. I haven't read his explanation of how he arrived at his claim that "the cell has one chance in 10^(40,000) of forming". And, again, I'm way out of my depth here, but I'd like to go out on a limb and suggest a possible flaw in his analysis. As far as I can tell, he seems to be examining the simplest cell he can find, and calculating the probability of
For the sake of argument, I believe you could place an lower bound on the number of animals on the ark by estimating an upper bound on speciation rates for the species which would have been on the ark (land animals primarily, I would assume). In other words, if all the species alive today came from a very small number of species, the small initial population of each species would have had to speciate at a high rate in order to produce the diversity observed today.
Maybe the best answer is to say that it's actually a fact and a theory. It's a fact that objects fall to the earth when we release them, and several theories (Newtonian gravity, Einstein's General Theory of Relativity) have been proposed to fit these facts into a coherent whole. It's a fact that species evolve, and several theories (gradualism, punctuated equilibrium) have been proposed to fit these facts into a coherent whole.
Well, first of all I'm a geophysicist, so string theory is above my head too. I have some friends working on high energy colliders, and that's about as close as I get to the field of string theory. But I have had several professors argue very strongly that it doesn't deserve the label of "theory". At this point, I'd say that it seems more like mathematics that may or may not have a connection to the real world. Maybe in the future we'll find a way to test string "theory" but for now I agree that it is, at best, a hypothesis.
The real problem is that these terms, "theory" and "hypothesis" are used interchangeably by almost everyone; even scientists sometimes fall into the trap of saying "I have a theory" when they actually mean "I have a hypothesis". I'd imagine that's what's going on here- it's simply unwieldy to say "string hypothesis", whereas "string theory" has a nice ring to it. Probably the best approach to take here is not to worry too much about semantics like the labels we put on ideas. That was basically the gist of what I was trying to say to creationists in my above post: "debate evolution if you like, but don't waste my time arguing about labels like 'theory' ".
(1) Most scientists are accustomed to honest, civilized debate. Scientific conferences are full of disagreements and arguments, make no mistake about that. But (almost) all the participants are aiming to understand the universe better, to examine their assumptions and use experimental evidence and logic to figure out whether or not they need to change their assumptions or ideas. They might attack a speaker's ideas if they believe that a mistake is being made, but there's nothing very personal at stake. So once proven wrong, they admit it (usually politely if you're lucky). Most creationists, on the other hand, are defending the One True Religion. They already know The Truth, and simply pick and choose arguments from creationist websites to attempt to defend that Truth. This kind of backwards reasoning (arrive at conclusion first, find supporting facts later) is so alien to scientists that they simply can't handle it. I'm not sure I could, for that matter.
(2) Creationists often make statements like "Evolution can't produce new information in a genome" or "We don't know how old the earth is because carbon dating isn't useful on large timescales and we don't know the initial amounts of isotopes and polonium halos disprove old ages anyway". Answering each one of these statements would require hours of boring, dry lecturing- something that simply isn't going to happen. And the problem is that creationists don't just make one of these statements, they make DOZENS of them. Answering this kind of deluge of mis-information in such a way that it can be intelligible to the average person would take an unbelievably long amount of time. As such, even answering questions from the crowd can be a tricky business. How do you explain isochronology and radioactive dating methods in 2 minutes to a young earth creationist? I can barely explain it to a fellow scientist in less than 15 minutes. Now imagine someone standing up and asking two or three of these questions in rapid fire mode, and ridiculing you for not having a snappy answer. This kind of public failure would not look good.
(3) Creationists are usually much better at the fine art of crowd manipulation, whether they're participating in a debate or simply asking an "impromptu" question from the audience. I'm finishing up my PhD now, and I've taught some pretty big classes, but never had to worry about anything like this. I'd probably be slaughtered if I tried...
I'm not completely knocking the idea, it's just that I can easily see it becoming ugly.
Either that or you've blown a sarcasm gasket.
(1) "Evolution is just a THEORY"
This is the most common (and the most disappointing) creationist argument I hear on a regular basis. While it's true that evolution is a theory, this statement is made in an attempt to cast doubt on evolution by implying that evolution is akin to a wild guess that scientists came up with after a night of heavy drinking. Newsflash: it's not going to work. Most educated people understand that you're confusing the word "theory" (which means an explanation or model that is capable of predicting future events) with the word "hypothesis" (which means an educated guess). Calling evolution a "theory" isn't an insult. For the millionth time, I will repeat this: gravity is also "just" a theory (for example, google the "General Theory of Relativity"). I might even add that most scientists would consider evolution to be a better-supported theory than gravity, because of the fact that gravity cannot (currently) be quantized, despite decades of attempts. If you want to debate evolution, fine- but don't play these childish word games.
(2) "But evolution has never been observed!"
Most creationists, faced with the mind-numbingly obvious fact that viruses and other creatures (like those famous moths) evolve right in front of our eyes, make a distinction between micro-evolution and macro-evolution. Micro-evolution is "proven", they say, because it only represents a change in allele frequency within a species. Macro-evolution, defined as change from one species to another (aka "speciation"), is more of a problem for creationists. They often insist that speciation has never been observed outside of laboratory experiments. This is blatantly false. Many examples of speciation have been observed in the wild- for example check out this large list of peer-reviewed journal articles here and also here.
The next step that creationists take in response to this rebuttal is to claim that speciation proves nothing- only a change from one kind of organism to another will prove evolution. What's a "kind", you might ask? No one knows. Creationists will give vague examples, such as saying that a dog is a different kind of animal than a whale, but a rigid definition has never (to my knowledge) been offered or universally accepted by the major creationist organizations. It's just a convenient goal post which keeps getting pushed back every time new evidence is found. The fact is, speciation is rather easy to observe in organisms which breed relatively quickly. Observing the creation of, say, a new phylum or order could take many millennia. Unfortunately, human civilization hasn't been around that long. Plus, standard biological nomenclature isn't based on evolutionary criteria, so it isn't clear to me that equating a "kind" with a phylum or order is meaningful in this context.
(3) "But Intelligent Design is different than Biblical Creationism! It's a purely scientific alternative theory."
Don't try to pretend that "Intelligent Design" is somehow different than creationism. Especially don't try to pretend that it's a scientific theory. Seriously. No one's buying it. "Intelligent Design" is a disguise- a secular-sounding term thrown over religious creationism to try to smuggle it into a state-funded science class
As far as the Taliban not turning over Bin Laden, I have mixed feelings about this issue. On the one hand, it does seem reasonable to ask for evidence, but given the disreputable source I'd say it wasn't a careful, honest attention to legal detail as much as it was an attempt to stall us to allow Bin Laden to flee the country. Not to mention that even they must have realized that openly and brazenly defending Bin Laden would have only quickened their deaths because it would have turned the entire civilized world against them.
That's a very interesting point. I don't know much about these men, and am under considerable time constraints with the end of semester approaching, so I'm afraid I won't be able to research it and give you a well thought out answer.I can't confidently say what Gore would have done after 9/11; I'm not even sure that Gore could, frankly. I can say that you seem to be displaying a "black and white" mentality very common with right wingers nowadays. You're either with us or against us. You either support the President or you're spitting on the troops like some kind of treasonous bastard. The false dichotomy I see in this point is "the president is either willing to start wars at the drop of a hat, or he's a cowardly eunuch who doesn't understand the basic principle of "don't give in to terrorism."
But, provisionally, let's say your black and white view of the situation is right. Let's say that Gore is a fucking pussy, and that he wouldn't have invaded Afghanistan in response to 9/11. I think that's very unlikely, but for the sake of argument I'll run with it. (For the record I fully supported the invasion of Afghanistan even though its later execution was botched, largely because of resource diversion due to Iraq as far as I can tell). What would have happened on a global scale after such a non-reaction? Would it have been a disaster of subsequent attacks as you say? I don't think so, and my reasons for saying so are based on my current understanding of how terrorism works. If I've made any mistakes in my analysis, please point them out so I can improve my understanding of the current geopolitical situation.
I think that Islamist terrorists are comprised of two basic groups. There's a very small group of fanatics who are fundamentally evil, and want to kill as many innocent people as possible in order to further whatever their agenda might be. This includes things like (1) Establishing a global Islamic state, (2) Destroying Israel, (3) Removing US bases from the Middle East, (4) Getting revenge for actions the US has taken like overthrowing the Shah of Iran, imposing trade sanctions on Iraq and supporting Israel for decades. I've probably missed a few, but that's okay because new reasons crop up every day because of US actions in Iraq and Guantanamo Bay and the CIA's secret prisons in Europe, etc.
Now, this very small group of people may be crazy and evil, but they're not (as a rule) stupid. They know that they can't win a real war because modern warfare requires large armies and high technology (neither of which they have), so their only option is to use desperate tactics like suicide bombers. But they can't suicide bomb places themselves (because otherwise the movement would end very quickly), so they have to recruit dupes to do that for them. I think that the vast majority of suicide bombers and "Al Qaeda fighters" we hear about so often fall into this second category. They're impressionable young men who may not be fundamentally evil or psychotic, but they're morons who have grown up in a world steeped in hatred, and probably nurse anger towards the US and our allies because, say, a US bomb fell on their house and killed their family. Or any number of different tragedies, really, not all of them related to the US.
What this means, as far as I can see, is that terrorism depends crucially on the discontent of the populace in the country where they're operating and recruiting. If society sees them as saviors against a Great Satan, then their only real resource- idiotic, violent, gullible young males filled with bitter hatred- is plentiful. People want to shelter them, to further their efforts as "freedom fighters". If society sees them as a bunch of bloodthirsty killers of women and ch
This is a fascinating idea, but I wonder if the cell phones could actually be located accurately enough. My understanding of cell phones is that each phone is "located" in the sense that the tower that it's communicating with is reported to 911 operators. Perhaps different cell phone towers could compare the time delay of the phone signals and perform triangulation? If so, this would seem to require nanosecond timing accuracy (1 foot at lightspeed takes 1 ns) and I'm not sure that's feasible across the country. Someone mentioned GPS receivers, but those are only accurate to within 10s of meters unless they're very expensive fixed geological stations as far as I know.
More precisely, a black hole warps space in the sense that if you had a flashlight right on the event horizon and pointed it parallel to the event horizon, the light would travel in a great circle on the event horizon. Inside the event horizon, things are way different. It's more accurate to say that space and time swap identities. The spatial direction towards the singularity becomes the "future" and the direction away from the singularity becomes the "past". So the reason you are doomed when you cross the event horizon is because the singularity literally lies in your future.
(1) Gravitons are the mediating particle of the force of gravity in a theory that has yet to be discovered called "Quantum Gravity". This is analagous to quantum electrodynamics, where the force of electromagnetism is mediated by a particle called the photon (yes, as in light photons). It's reasonable to assume that because electromagnetism and gravity have similar inverse square laws, that their mediating "particles" would be similar at least in terms of long range interactions. But I simply don't know for sure- no one does.
(2) Black holes can hold an electric charge, and they exert a coulomb force on nearby charges. So, really, gravitons and photons exhibit the same strange, seemingly contradictory behavior- they seem to be able to cross the event horizon.
(3) I believe the easiest way to resolve this apparent paradox is to regard the mass and electric charge of the black hole to be caused by the mass and charge just before it passed through the event horizon. The matter and charge disappears behind the event horizon, but the electric field lines and gravitational effects remain because of the time dilation- matter seems to take an infinitely long time to pass through the horizon. I'm not sure about this, though. It seems like you could test this (in principle) by adding a significant amount of mass to a non-spinning black hole in one specific location and testing the gravity field of the black hole later for any deviations from a central field. In other words, if the gravity and electric field really does continue to emanate from the place where the mass was right before it hit the event horizon, that would mean that its gravity would be drawing you towards one spot on the event horizon, not towards the singularity. Now that I think this through, it would seem to violate the "no-hair theorem" by Hawking, who's a shitload smarter and more experienced than I'll ever be.
Anyway, take this with a grain of salt. This isn't my specialty...
I worry that, in the future, this basic "right of resale" won't still be around because it will be impossible to implement without excessively harsh technological restrictions. And, yes, I know that "excessively harsh" is a subjective judgment on my part...