Lets say I have a super small space ship.
I have read before that you could actually fly through the asteroid belt and never really know you did because of the space between asteroids.
Would it be the same on a micro scale?
Could I fly through a wall and never know it?
Sure, neutrinos do it all the time.
Good luck fitting in a neutrino, though.
I’m pretty sure that if you could miraculously turn off the electromagnetic force you could put your hand (or spaceship) through the wall.
You’re assuming the planetary model of the atom, with the nucleus as the sun and the electrons as atoms. That’s a long out-of-date model:
ETA: Ninja’d by Wendell Wagner …
It seems the OP has an unstated assumption that atoms are like a very small solar system with a central sun/nucleus and orbiting planets/electrons. That’s certainly what junior high school science texts would have you believe.
But it has almost no connection to reality.
Atoms are mostly empty space in the sense there’s not a lot of matter there. But there’s a huge amount of energy filling all the space inside and near every atom. The reason you can’t stick your hand through a wall is not because the hand atoms bump into the wall atoms. It’s because the energy cloud in and around the hand atoms collides with the energy cloud in and around the wall atoms.
As such, there’s no energy-free empty space to drive your atom-scale spaceship through. Unless it’s made of something pretty magical which doesn’t feel the energy of ordinary matter. Such as neutrinos.
The above is still a massive simplification, but at least it’s qualitatively valid, unlike the idea of little lumpy protons & electrons.
This clip may go some way towards suggesting a layman’s answer.
It’s also true that photons can go right through walls if they are at certain wavelengths. Think radio waves. Photons are not matter, in the usual sense, yet they are quite interactive, unlike neutrinos.
And the complete answer to the OP’s question “Could I fly through a wall and never know it?” would have to include the infinitesimally small but finite chance that his atoms might quantum tunnel through the wall and appear on the other side.
The place to start, though, is with the Electromagnetic Field since all modern physics is essentially field theory. The “energy cloud” LSLGuy mentions is the electromagnetic field.
Yes, if your tiny space ship has no electric charge, like a neutron.
Neutrons typically slam into atoms, as opposed to passing between them.
Yes of course you could. Even ordinary subatomic particles mostly do. The typical cross section for neutron absorption is something like 100 million times less than the cross sectional area of the atom, so very crudely you can say almost always a neutron just blasts right through the atom. You might also look up the famous Geiger-Marsden experiment, which demonstrated the nuclear model of the atom by the fact that almost all alpha particles (helium nuclei) passed straight through a sheet of gold atoms without noticing.
Now it’s certainly true if you try to slowly move an electron, say, into the same space already occupied by an atom, you will have a hard time. But this proceeds from a different reason – because electrons are fermions, you can’t have them in the same space in the same energy state (with minor exceptions that don’t matter here). So if you try to push them into the same stationary state, you’ll have to promote one to a higher energy state, and since electronic energy states are far apart, you will need a LOT of force. This is in fact the origin of the unwillingness of matter to penetrate other matter, it has squat to do with electromagnetic forces.
But this is only true if you are trying to put the electrons in the same stationary state, meaning you move them very slowly (“slowly” on an electron’s time scale, that is, which means femtoseconds). But if you are just firing an electron through, that’s no real problem. You can interpret that a few different ways. One is to say that on the speedy time scale you’ve got, the electrons aren’t likely to collide (meaning come very close to each other – it’s hard to precisely define the collision of point particles). Perhaps a more reasonable approach is just to say at those energies and given the tiny thickness of an atom, it’s no problem for the speeding electron to just tunnel through the stationary electrons. It’s actually possible to tune the wavelength of the incoming electron to minimize or maximize it’s chances of absoprtion – this is used in electron microscopy work.
Anyway, I assume by your miniature spaceship you meant something more like a neutron than an electron – it would be peculiar to drive around in a spaceship with the kind of staggeringly enormous charge to mass ratio of an electron.
The thing is that the model is explaining why an alpha particle can shoot through at high speed…there’s empty space for it to get through… its not going to suffer due to high G’s due to the various fields (electric,magnetic,gravity and the strong,weak nucleus ones…)… it feels no pain.
The concept that is that if you were merely shrunk, you’d be experiencing the same forces. Of course if you were shrunk and made of something immune to the force fields, plenty of space to get through… in fact, if you immune to force fields, then you go through solid walls without being shrunk…
It has everything to do with electromagnetic forces. If you’re trying to push an electron into that space, and something’s resisting your push, that something is a force. And the Pauli Exclusion Principle is not a force. It might seem like it ought to be, since it keeps things out of the same state… but now ask yourself, just what defines those states? The states themselves are defined by the electromagnetic interactions of all of the particles in the system… including the new one that you’re pushing in. Push hard enough, and you’ll create new states that your new particle can occupy, and it will in fact be able to pass through.
I think what the OP really wants is something more visually intuitive. Let’s say I could shrink my flying car down to the size of a neutrino and went cruising around inside a block of iron. If every atom in the block were scaled to the size of a golf ball (meaning that the outer boundaries of the golf ball are the point at which the probability of finding an electron drops to what the average person considers zero), how far apart would the golf balls be?
Look at this video, it may help you envision what you would see.
Also, how big would I be relative to the golf balls? I once read a children’s book that said that if an atom were the size of an aircraft carrier, a neutrino would like an apple sitting on the deck. Is that really true?
It is instructive to read this: New Page 2. Rutherford sent helium nuclei through ultra-thin gold foil. Nearly all of them were scattered by less a degree, but one in 20,000 by more than 90 degrees. He said it was like shooting bullets through tissue paper and having an occasional one come back and hit you. And remember the helium nucleus (emitted from Uranium decay) is charged. So I think the answer to the OP is yes.
A neutrino hardly ever reacts. I think I once read that it takes a light-year thickness of lead to have a 50-50 chance of capturing a neutrino.
If you don’t have that much lead, you can use 100,000 gallons of dry cleaning fluid (perchlorotehylene) nearly a mile underground to record a few solar neutrinos.
How big is your block of iron? If it’s the size of a golf ball to begin with, then the distance between the atoms would be, to scale, about 2.9 Ångstroms. In a metal, the electrons can be at any distance in the same continuous piece of metal.
If, instead, we take a lump of some non-conductive solid, then the distance between the atoms would be of the same order of magnitude as but smaller than the distance of the furthest electrons from an atom’s nucleus. As in, the electron clouds of the atoms are overlapping.
Indeed. In another thread a few months back, we established that cats can do this.
I don’t recall exactly when and where I heard the Pauli Exclusion Principle explanation for the resistance of matter combining, but I definitely heard it somewhere outside some random person on a message board; that is, it was from someone who definitely was in a position to say that he knew what he was talking about because it was his job to explain these sorts of things.
I’m somewhat ambivalent, because as you said, the PEP isn’t a force. I think in essence both explanations are correct to some extent; were it not for the PEP, you’d be able to move your hand through other matter, but the force that you feel resisting your movement is the Coulomb force that arises as the electrons come near each other but are forced to not live in the same state.
But I’m just a dilettante in matters of physics; nothing I say should really be thought of as coming from any sort of authority.