The more I learn about the universe, the more stunned and amazed I am that we can know anything at all about the way it works down at its roots. That our primitive math and even more primitive observations have come up with results that peer into the heart of existence is more improbable than anything Douglas Adams ever played with.
The universe’s language is math. Scientists try to express things in words for us slow illiterates, but the translation is always going to be farcically inadequate.
As for it making sense, I blame the education system. Science is always presented as a series of explanations, a neat and neato collection of answers to “Why?” This works pretty well for our everyday lives, but nobody wants to admit that once we get beyond the everyday, we have no answers to “Why” and that even “How” is mostly incomprehensible. “Here’s the way it is: take it or leave it” doesn’t satisfy anyone, and the metaphysics of it all can start brawls at any university.
There are wonders out there, and at our fingertips, and within. And we, by which I mean people who devote their lives to the subject, and grappling with wonders the way knights once grappled with dragons. All those of us back at the castle get are the secondhand stories. They may be great stories, but they can’t translate the feel of the real battle.
A paragraph on the Internet is never enough to convey to understanding of subjects that require a lifetime’s worth of context and learning. Sorry if I sound impatient at times when shortcuts are asked for, but I’m glad you’re asking.
I feel the same way: awe and wonder. Particularly when I think about how little I know when compared to other mortals. It’s the same feeling I get when I look at images from the Hubble.
You’re right: I’d be a fool to think that a paragraph on the internet would allow me to understand a complex subject. In this, perhaps you overestimate me: I’m still struggling to just understand the paragraph itself. And if there are shortcuts, well, I need all the help I can get. The description of this experiment is a shortcut itself: I remember hearing about it in high school and grasped the basic nature of problems it presented even then. How difficult would it be to just arrive at even that basic understanding without such a simple backdrop to make it as plain as possible? In fact, it’s a stretch to even call the experiment simple: it’s not like I have the foggiest idea about how one would build a gun that fired single electrons. I don’t know how you’d even get your hands on an electron in the first place (really small tweezers?) or how you’d know it if you did.
Saying that it doesn’t make sense doesn’t even express it, though. Like you said before, radio waves don’t make sense, either. They seem like magic if you don’t know how they work, and there’s still something magical about them even if you do.
I guess the difference is, with a concept like radio waves, it might not make sense, but you can make sense of it. Or at the very least, you can follow the road to understanding it without having your basic assumptions about matter, energy, and the universe we live in challenged in such a dramatic way, you know? And with harder problems, even if you can’t know the “how” or the “why,” you can know that others do and, I suppose, take some measure of comfort in that. Particularly since we can’t all expect to understand everything; we all stand on the shoulders of those who came before. So maybe you’d never have a hope of knowing what it takes to vanquish the dragon, but you’d take some small respite in the fact that you know someone who does.
But you’re right about how it’s often presented in a neat little package. And the amount of material which one can find that is premised on quantum behavior suggests (at least to me) an understanding of its hows and whys. You just don’t see disclaimers like “we have no idea why this is the way this works, by the way. We think it’s pretty funky, too. Anyway, moving on…”
And it’s to science’s credit that it didn’t get stopped in its tracks by that. Because of the problems you point out, science often gets a bad rap for being narrow-minded. For instance, there’s a Cecil column on the home page about Uri Geller. Now if you told me Uri had a 100% success rate under the most controlled conditions and that, to the best of our scientific knowledge, he actually can melt spoons via telekinesis…I would still find quantum behavior much, much harder to believe. I think it’s much more interesting than something as mundane as scientifically verifiable psychic power. That, to me, is proof that those who think science simply turns up its nose at things like psychic phenonmena without consideration are wrong: here’s something much more improbable that’s much harder to square with our understanding of nature, and yet, after many experiments produced the same results, scientists eventually came to accept it, canonize it, and kept moving forward.
The first question that I have about this experiment is this: when the electron passes thru a field whose fluctuations indicate its presence to an observer, is it the presence of the field which the electron pass thru, or the detection of a fluctuation, that “causes” the electron to behave more like a partical than a wave. Can we not turn off half the machine? If it is the presence of the field alone is sufficient to cause the electron to behave like a partical, then we have an entirely different sort of problem from that of the detection/Observer problem. Indeed, even if the simple presence of a field doesnt affect the nature of the electron, then we should inquire into the physical nature of the (inter?)reaction of the sensor and the electron, before we hazzard the notion that it is mind’s observation of the electrons position that “causes” it to act like a partical.
Thus my second question: are we exploring the mind-body issue, or does it only appear so? (Appearences are often deceptive.)
You can, indeed, collapse a wavefunction without anything that we would think of as an “observation” by a human or other thinking thing. The point is that there is no possible way to make an observation without collapsing a wavefunction.
A better illustration for some of these concepts can be found in the spin of a single electron. An electron has an inherent angular momentum, called spin, which can, in principle, point in any direction (in the usual pseudovector sense in which we talk about any angular momentum having a direction). Now, I can pick any axis I want to measure the spin of an electron. No matter what axis I pick, there are two possible outcomes: Either I’ll measure that it has an angular momentum of +[del]h[/del]/2 in that direction, or it’ll have -[del]h[/del]/2 in that direction. So if I measure it on a vertical axis, I’ll either get spin up or spin down, and if I measure on an East-West axis, I’ll get spin-East or spin-West, and so on.
Now, suppose I take a random electron, and measure it vertically. Suppose I get the result spin-up. That electron is now definitely spin-up. If I measure it vertically ten thousand times in a row, I’ll always get spin-up. But what’s its component of spin on the east-west axis? Until I measure it, I can’t say. If I do measure it, I can’t find that it’s 0, since that’s not a possible measurement of an electron’s spin. I have to get spin-east or spin-west. And since there’s nothing to favor one or the other, I have a 50% chance of finding either. Let’s say I do the measurement, and find it’s spin-west. Now that I’ve done the experiment, that electron is now definitely absolutely spin-west. If I measure the east-west component ten thousand times in a row, it’ll always point west.
And now suppose that we take this same electron, and measure it on a vertical axis again. Does it remember that it’s supposed to be up, since this electron was definitely up before? No. Now that we’ve measured its east-west component of spin, it’s now one of those two, and no longer up or down. The first vertical measurement we make will have a 50-50 chance of being up or down.
To me it says that the “spin” we are measuring is a function of the measurement, not of the electron. We are measuring “something” which we choose to call spin, that has these properties, which is a combination of the electron and the measurement. If I understand any QM, which I don’t, QM describes the science of measuring very small things. It isn’t a description of the very small things themselves, but of the measurement of same. Useful, perhaps the only thing we can do, but not a description of the universe in the absence of measurement. This electron description is an very good example.
Another variation on the 2 slit experiment I’ve read about. Instead of immediately having the detector report that the electron passed through a slit, it records it and reports it later. The, when you do the experiment, have it erase the data after the electron passes the slot(s), but before it hits the target. Result ? The electron acts as if was never detected in the first place, like it’s detection has been erased from history.
A theory I’ve heard explain this blames it on reversability. One of the distinctions between quantum level behavior and larger scale behavior is there isn’t much of a “time’s arrow”; quantum interactions look much the same projected forward or backward in time. Large scale interactions OTOH have an obvious times error; run a film of an eggs falling and being smashed, and you can easily tell if it’s projected backwards; eggs don’t unsmash themselves. The idea being that until some irreversable measurement ( or other interaction ) occurs, the position of a particle is uncertain in both space and time, that it has multiple possible pasts as well as multiple possble futures.
OK, I’m going by a vague memory of a Scientific American article I only dimly understood at the time, but I believe there is a way. There’s a quantum mechanics based scanning technique, designed specifically to detect things without collapsing their wave function; rather than actually interacting with the target, it works by detecting the possibility of interaction. Somehow. Sorry I don’t remember the name or the details, it’s been years, and I’m just an interested layman.
My take is that the universe has no language at all (i.e. is non- or better yet trans-
algorthimic), but mathematical structures are what we see when we examine
it. It is likely this kind of quantum weirdness (and other anomalous stuff) is what
we see when our mathematical models hit up against their own limits once we’ve
pushed them a bit too far. It’s all shadows on the wall, the map is not the territory,
etc. etc.
Is there a way to see beyond the shadows? Will science 500 years from now be
a mixture of Western dualism and Eastern monism? Note I do not necessarily
ascribe to the “physics equates to mysticism” school like Fred Alan Wolf. In most
cases the likes of him are equally guilty of building air castle theories as are those
who fall into the string theories (if not more so). A good book just came out which
dissects string theory BTW-“Not Even Wrong” by Peter Woit.
This may be true, if you could genuinely erase the information, but I don’t think quantum mechanics allows for the possibility of sufficiently-thorough erasure. The best I can think of would be to throw the measuring equipment into a black hole (which is outside the bounds of what can be described by our current quantum theories), but even that might not be thorough enough.
< shrugs > IIRC it’s already been done. I tried googling “quantum erasure” and found stuff that sounds like a variation on what I’m talking about, but I can’t be sure. Here’s an ( warning; PDF ! ) article I found.
If you want to understand QM, you have to start with the idea that physics is science, and ‘description’ from a science view is all about making verifiable predictions, and about nothing else. Now what kind of verifiable predictions can you make without any measurements? None. So from a physics point of view, your distinction doesn’t make any sense.
If that seems too narrow-minded, you might also want to ask yourself, what, exactly, do you mean by‘describing’ an object separate from anything that can be measured?
Let me give an example of why I don’t think it’s true. Suppose you have that setup, and the information about which slit the electron went down gets beamed into a laboratory situated in the middle of a black hole. Meanwhile, the actual electrons get sent over to Mrs. MacLeod’s third grade elementary class, delta quadrant of the Andromeda galaxy. The scientists then erase the data about some of the electrons but not others. If “later on”, the students check to see whether the electrons in a given segment of time show a wave pattern or a gaussian pattern, you now have a method for something inside a black hole to send information to the outside world.
This isn’t how a quantum eraser experiment works. There’s no confusing causality issue because the erasure process requires that the measurement device (or whatever quantum states were originally entangled with the electron’s state) and the electron be in causal contact. In your black-hole example, since the states within the black hole can’t be brought back out to the classroom, the erasure can’t be performed (at least not outside of the black hole; the students could send their states in to the black hole, but that won’t help transmit information back out).
Basically, the idea of a quantum eraser experiment is that the “measurement process” can be thought of as a process that creates entanglement between the measuring device and quantum system. (Eventually this may cause the wavefunction to collapse, but imagine that the measuring device is small enough and isolated well enough that this doesn’t happen.) This entanglement-creation process is, at least for some measuring devices, a reversible process, so you can undo it if you’re careful. After this “erasure” the system is no longer entangled with the measuring device, and the measuring device has no information about the state of the system.