I came up with another simplified explanation that likely doesn’t stand up to new physics in detail, nbut might help those of us less educationally endowed (like me) with an understanding of how this works:
Imagine a net made of fine but strong threads, say monofilimant. It has wide holes (say 1" x 1") which makes it composed of mostly space. It is streched across a frame, giving it some rigidity. Let this represent your desk.
Now, another net, perhaps with larger holes but the same filiments, rolled up into the shape of a hand. (The filiments can represent the forces holding the atoms together.)
Try to toss the hand-shaped net through the desk-shaped net. Though they are both mostly empty space, they will not pass through.
Go to a party supply store. Get a gross of round latex balloons. (The mylar ones won’t work for our purpose.) Mix and match colors, logos, whatever, as long as they’re all more or less the same size. If it’s near Valentine’s Day, get red, pink, and white ones, so you can surprise your sweetie who you’ll convince you’ve done this all for her. While you’re there, get a keg of good beer, unless your friends are used to cheap beer, in which case you should get a keg of Milwaukee’s Best. (If your friends are real mutants, get Blatz.)
Call up your friends and tell them about the keg, but not about the balloons. If you don’t have friends, call up the local chapter of Sigma Nu, who’ll be willing to do anything for beer. When they show up (and this is key), offer up the beer only after they have blown up the balloons. If you let them drink before, some damn fool is likely to suck instead of blow, and then you’ll spend the rest of the evening in the ER while interns are performing open chest surgery to remove the balloon from your friend’s lung.
So, the next day, after you’ve cleaned up the inevitable broken glass, cigarette butts, guacamole droppings, and mysterious stains on the couch, take out the now inflated balloons. You should have a gross of balloons, minus the ones your friends popped to see how high they can make each other jump, and the one that someone peed in on a dare to see how full they could get it. (Now you see the importance of having the balloons inflated and put away before the drinking starts.)
Rub some of them on your head to give them a static charge and toss them among the others on the floor. They should clump together due to the charge. Take three or four from the edge and hold them in your hand.
Now, visualize the balloons on the floor as being atoms in a desktop. The surface of the balloon is the electrically negative field-of-effect of the electrons. The actual electrons are somewhere inside, and the nucleus is near the center of the balloon. The static charge you’ve applied to the balloons are the molecular bonds (ionic or covalent) that hold molecules together and to each other. The balloons in your hand are part of your virtual hand, and are held together by similar forces.
Now, try pushing the balloons in your hand (which we’ll just call your “hand” for the rest of the example) through the balloons on the floor, which we’ll call flooroons, partially to distinguish them from the ones in your hands, but mostly because it looks funny. If you just lay your “hand” gently on the flooroons, they’ll rest there in equilibrium. Even though there is space between and inside the flooroons, the gaps aren’t wide enough for your “hand” to fit through, and the space inside of the flooroons is bounded by the balloon skin. If you try to pull them away, they’ll stick a little bit (if they’ve a static charge) and one or two might stay if you don’t hold them tight enough. If you push them harder, they’ll push the flooroons apart and go in between, breaking the bonds between the flooroons.
If you keep the flooroons contained, say by dragging some of your still-passed out friends and using them to make a barricade around the flooroons, and then force your “hand” into the flooroons, the balloons (both in your hand or on the floor) will start to deform. The harder you push, the more they deform, until one of them gives way and pops, which will no doubt wake up your friends, who are wondering why they are sleeping on the floor, what in the heck they are doing surrounded by balloons, and why you are standing above them with an illuminated look on your face.
It is vitally important at this point that you not explain what you are doing. However companionable or accomodating your friends might be under normal circumstances, they are unlikely, in their current state, to be impressed by the demonstration you have performed or your explaination of it. Instead, you should promise in oblique terms never to talk about what happened the previous night and promise to keep all photographic evidence to yourself if they help you clean up the mess.
You will now have demonstrated why objects can’t pass through one another, and your friends will think that you throw really wild parties. Yet another triumphant victory for science.
Not when I was in school. They were the most party-hardy of the bunch (and in Rolla, where there was nothing else to do but drink or hack around on the VMS mainframe, that was saying quite a bit.) Have they all been converted to Southern Baptists while I wasn’t looking?
Simple answer: Because light is a wave, and visible light can’t fit between the atoms in your hand unless it gets really lucky. (X-rays can, however.) Some of the waves are absorbed and others reflect in a dispersed pattern, depending on the composition of the waves and the pigment in your hands.
Long answer: Go to the closest university with a physics program. Sign up for Introduction To Modern Physics. Prepare to spend every Friday and Saturday night pouring over the Dirac equation, figuring out Fourier transformations, and worrying about Schrodinger’s Cat. Finish final exam still feeling like you know less than when you started the class.
Sometimes it’s better not to know what you don’t know. :dubious:
I didn’t read through all the responses but this one is easy using common sense. I am not certain on the % of nothingness stated, but I am going to pretend it’s accurate.
While your hand and the desk are 99% nothingess, the 1% something is moving so fast that when the borders of the 1% movement merge they are repelled because the speed at which they collide isn’t faster than the speed at which the 1% moves within it’s border.
make sense? take a pen and whirl it around as fast as you can and visually you see a circle. It might be hard but at this speed you can get a finger through the circle without being hit, right? Imagine if you sped that up a billion times there is no way you could successfully weave your finger through the circle.
While this isn’t any more wrong than any other attempt to render quantum mechanics by the light of our experience in the natural world, I think it may offer a somewhat misleading impression of what the atoms and photons are actually doing. If you imagine the electrons shooting back and forth fast enough to nail any passing electron and then start running numbers on exactly how fast a particle of the diameter of electron would have to go in order to cover the “area” of its shell, you realize that it would be moving at huge multiples of the speed of light, and therefore should sell itself out to the Yankees as a shortstop. This is obviously not the case, and that is because there is nothing obvious about QM. Trying to make “common sense” of QM is impossible for the simple reason that nothing about QM really makes any kind of sense in the observable, causal world.
Let’s try this conceptualization:
Imagine that the photons (light particles) are a sort of “wavy particle”[sup]1[/sup]. For additional fun, think of it as a helix, or more familiar to the dipsomaniacs among us, a corkscrew. Now, this corkscrew has a central axis (though the middle of the corkscrew), a diameter (the outside to outside distance about the axis), and a pitch (the distance, measured along the axis, that it takes for the wire to go all the way around the axis) that is related to the diameter. For our purposes, the wire of the corkscrew is big enough for us to see but too small to measure or worry about.
For the moment, consider your hand to be a wall with a bunch of holes in it. Now, you are going to throw the corkscrew at the wall, axis forward, giving it a spin, as you would a football. If you are far more athletically adept than I am, you’ll be able to throw the football so that a) the corkscrew doesn’t precess or tumble end-over-end in flight, and b) the spin you impart is exactly equal to the pitch of the corkscrew, so that it appears to be corkscrewing through the air.
What happens when it gets to the wall depends on a couple of things; namely, the size of the holes and the frequency of their distribution. If the holes are sparse, its very likely that the corkscrew will completely fail to hit a hole and fall off in a dejected manner. If the holes are very small, the corkscrew might get the tip in the hole but then get jammed because it doesn’t have enough room to make its helical path without hitting the interior of the hole. But if the hole is large enough and the corkscrew comes in just so, it’ll screw its way right through the wall. If the holes are really large (much bigger than the diameter of the corkscrew) and frequent, it’ll probably pass right through without interference and go on to play havoc with some other atom’s electron, which fortunately is somebody else’s problem to deal with.
Of course, as has been previously noted, “solid” materials are anything but solid. They are, like the photon, composed of “wavy particles”[sup]2[/sup]. So instead of a solid wall, consider a wall made of corkscrews that are stacked on each other, their axes pointed out of the wall. Now you have a “wall” that is mostly open space but through which a straight[sup]3[/sup] path is infrequent. Now when you throw your corkscrew, it’ll go through if it happens to find a gap between screws or match up with one of the corkscrews in the wall. Otherwise, it bounces off or knocks one of the wall corkscrews out of place.
Photons interact with solid (and liquid and gaseous) materials the same way; most solids are, by dint of their density, opaque to visual light, save for some amenable ceramics, water ice, and according to Star Trek fans, transparent aluminum[sup]4[/sup]. Liquids are somewhat less so, and gases even less, to the point that many gases, like hydrogen or oxygen are “colorless”, or nearly completely transparent. Other wavelengths of “light” travel readily through solids (like x-rays) with little interference ‘cause they’re so small, some are almost completely absorbed (infrared or what most people think of when you say “heat”), and some just go right around a lot of materials, like big ol’ radio-frequency waves[sup]5[/sup].
So, conceptually at least, the reason your hand appears solid is because the electrons in your hand interfere with the “wavy particles”[sup]6[/sup] that are the photons shining on it. Most reflect off, some are absorbed (and converted, in a multistep-process, into heat), and a few actually make it through, which you can see when you press a bright flashlight into your palm at night.
Now, how do you file a successful claim on your house insurance polity for foundation cracking? I got no idea. Some things are beyond the bounds of science.
Stranger
Yes, I know “wavy particle” is an oxymoron, but so is “public servant” and people still use that term with a straight face.
Just shut up and listen, will you?
And by straight we mean strictly helical, which is not at all straight, but…look, if you want to argue semantics, don’t mess with quantum mechanics.
Yes, I know about this. Now please go back to the Spike TV Star Trek marathon, will ya?
Though radio waves interact with, and can be easily blocked by, conductive metals. Let’s just not go there right now, 'kay?
Again, the percentage of nothingness is 0%. The space is not empty; it’s full of fields. If you’re going to count the fields as “nothing”, then everything is 100% nothing. It’s not just that the spaces between the particles are full of fields; the particles themselves are 100% field.
Actually it is possible for matter to pass through each other…sort of. I expect people are thinking of Quantum Teleportation when talking about passing their hand through a desk. Indeed it has been experimentally verified (see below). Admittedly it is one thing to do this with one atom and a fantastically tougher thing to do with a macro object like, say, a whole person, I believe it is theoretically possible for a person to pass through solid objects…it’ll just take a staggering long time (read life of the Universe long or longer) to ever see someone do it.
Perhaps it is wrong to say an object passes “through” another object per your post and they are rather blinking out of one place and reappearing in another. I honestly do not know and wonder as that implies travel through other dimensions or hyperspace or something even more magical (blink out of existance and back into existance somewhere else with nothing actually happening in between).
I am not suggesting the details of what happens in the middle is not important or interesting but it is worth noting that objects can seem to pass through each other where common sense tells us it should not be possible.
[quote]
In 1993 an international group of six scientists, including IBM Fellow Charles H. Bennett, confirmed the intuitions of the majority of science fiction writers by showing that perfect teleportation is indeed possible in principle, but only if the original is destroyed. In subsequent years, other scientists have demonstrated teleportation experimentally in a variety of systems, including single photons, coherent light fields, nuclear spins, and trapped ions. Teleportation promises to be quite useful as an information processing primitive, facilitating long range quantum communication (perhaps unltimately leading to a “quantum internet”), and making it much easier to build a working quantum computer. But science fiction fans will be disappointed to learn that no one expects to be able to teleport people or other macroscopic objects in the foreseeable future, for a variety of engineering reasons, even though it would not violate any fundamental law to do so.
This underscores the problem with talking about subatomic particles as being “both a wave and a particle”. They aren’t any kind of particle, in the sense that we normally think of “small bits of stuff”. They aren’t a planet, or a baseball shrunk down to scale. The are wave packets of energy with quantum (specific levels) properties, like charge and spin. Even their “mass” isn’t something you can weigh on a balance scale or with an inertial potentiometer, but a function of the energy level. Only with taken together with big groups and examined with our notoriously nearsighted eyes do we think of them as being solid. But really, they’re all just massive systems of interfering waves. You, everything you see and feel, including the desk you’re sitting at, the chair you’re perched on, the keyboard in front of you, and the enormous tangle of fibres and cables that attaches you to the SDMB, including all the data travelling down it, is nothing more than a collection of information that could, as far as we know, experience a sudden and gratuitous total existence failure[sup]1[/sup] for no reason whatsoever.
Freaky, huh?
So, next time someone tells you to do The Wave, tell them “I already am, and so are you.”
That’ll make you popular at all the best parties. Take it from me.
Stranger
See The Hitchhiker’s Guide To The Galaxy, notes on the Starship Titanic. Yes, I do get all my information about physics, evolutionary theory, and economics from a five-part trilogy of fiction novels. Why do you ask?
Well, this doesn’t really have so much to do with passing solids through one another, or indeed, moving anything at all, as it does with transfering information instantaneously between one particle and another, and using that information to build another particle exactly like the first. The gist of it is that when two particles share a complementary state (like two electrons in the same atomic shell) they are forever “entangled”; their destinies are woven together, like that couple in that romantic comedy; you know, the one with Tom Hanks and that blond chick who’s always in romantic comedies with Tom Hanks, where they hook up in the end because, well, because they have to hook up in the end, else it’s not a romantic comedy.
Where was I? Oh, so anyway, once two particles share this bond, whatever influences one influences the other, instantly, no matter how far apart they are. While this might seem like a good premise for a long distance commercial, the fact is physics undergraduates, space exporation advocates, and CEOs of small Palo Alto start-ups get all weak-kneed and wide-eyed about this, because it means that you can transfer information faster than light and therefore lodge your bet with the bookie before the doggedly slow electromatically-transmitted information meanders its way to him and tells him he’s screwed. Sort of like The Sting, but done with science instead of grift, and without the ragtime music (though I’m always in favor of including some music apprecitation into the curriculum.)
Cool, no? Want to invest? How much equity to you have in that condo, anyway? This’ll be worth billions once we get it off the ground! We’re going to call our company, um, Wiggle!!**. Or maybe **Oodles&$!.
Reality time: the problem with this is, as with reading a message transmitted in code, you both have to be using the same code book. If someone is transmitting a message from Point A, and someone has a complementary entagled particle at Point B, the guy[sup]1[/sup] at point B needs to know what’s going on with the particle at Point A, so he rings up Point A, and waits for the scientist at Point A to finish responding to a SDMB thread, by which time the information received by the particle at Point B is moot. You might as well have just sent it by post for all the good you’ve done, and look at the mess you’ve made in the lab to boot.
There are a lot of people trying to figure out some kind of loophole around this sort of thing, which if you were an omnipotent god who created the universe and put specific limits on the speed of things for a reason, damnit, would probably piss you off, and some hypotheses about this have been made that are, quite frankly, beyond my knowledge of the topic, but there are still significant uncertainties as to whether we’ll ever be able to practially transmit information faster than light can travel the direct path from A to B. Also, it would totally fuck with our understanding of the universe as a system of cause and effect (though that ideal comes apart on the quantum level like a Gremlin at 90 mph, anyway.)
But if it leads to some way we can stick it to the bastards at the phone company, I say good on ya, mate!
Stranger
Well, it could be a girl, but there just aren’t nearly enough women who are willing to give up their social lives and the possibility of having sex to spend 18 hours a day in a subbasement laboratory with buzzing fluorescent lights and fire-code-hazard wiring decorating every wall and floor surface. Pity, that.
This is not the case. The concept of “instantly” has no validity with respect to two points separated by a space-like distance. Put simply, if you can build a machine that can influence particles at a distance in such a fashion, you will have built a time machine.
The property of entangled particles is only that you gain knowledge of the distant particle’s state once you look at the local particle’s state, but any modification of either of those particles’ state breaks their entanglement.
Yes, and that highlights the trouble with trying to talk about the topic in plain English (or High German, for that matter.) The point is, there are fundamental problems with using entanglement as a means of communication. I know that a lot of clever blokes (and a few ingenious shelias, as well) are trying to figure out some way out of this logical corrundurm so that you can order a pizza after it’s been delivered and thereby avoid all the tedious confusion over which toppings to order, but I don’t really understand how they are approaching the topic, and I suspect it is something that makes no sense in any jargon spoken by more than a few dozen people.
Certainly, it’s beyond my modest two semesters of modern physics.
Ack…my bad. I was thinking of Quantum Tunneling where a particle that one would think had no chance of crossing a barrier actually may do so. The more mass the less likelihood of this happening but as close to zero as the answer may be the possibility is not zero (actually has a pretty good chance for the very, very small…for a human to do the same the odds are vanishingly small albeit not zero).
So, you have a box with a wall in the middle and a perfect (for the sake of the thought experiment) vacuum on both sides and drop an electron into one side of the box. You have made your box such that you “know” the electron has nowhere near the energy to penetrate the wall to the other side of the box. Imagine your surprise when you go to look in the box at some later time and see that the electron has somehow moved to the other side anyway (it doesn’t have to of course but the point is it can despite your best efforts to seal off the other side).
IIRC the particle actually does pass through the barrier and does not disintegrate on one side and reintegrate on the other (although I could well be wrong about that but diagrams in the link below seem to suggest as much…how this jibes with the electrons in the barrier getting out of the way as talked about earlier I have no clue).
