Asked in Solid State Physics
Can a human walk through a solid wall?
February 16, 2010 11:25PM
When looking at the structure of the atom, we know that it is about 99.99(some number of 9's)999% empty space (meaning not filled by subatomic particles). This means that everything and all matter is mostly empty space. If you took all the empty space out of all the atoms in the earth, the earth would fit in your hand, but still weigh around 5.9 * 1024 kg.
Without taking quantum physics into account, some people will make the assumption that all of this empty space in atoms can make it possible for objects to pass through other objects. Although this is not taking electrons into account. Electrons are tiny even when comparing it to a proton, but it packs a strong negative charge. In addition, these electrons are moving around the circumference of the atom around the speed of light. So when an atom comes into contact with another atom, the electrons that are constantly circling the atoms will repel each other. In fact, this repelling charge is enough that you haven't actually touched anything in your life! If you stand up, the electrons in your shoes repel the electrons in the floor and you're levitating about a millionth of a centimeter above the floor. Getting back to the walking through walls question, the electrons in the atoms in your body will always repel the electrons in the atoms of the wall. No phasing though a barrier there.
But we have another option we can look to. In the beginning I said that you needn't take quantum physics into account. For this solution, we will have to bring it back.
One of the most central ideas of quantum physics is the theme of uncertainty. Quantum mechanics says that the location of anything is always uncertain. If you are looking at a book on a bookshelf, you can't say with 100% certainty that the book is on the bookshelf. Nor can you say that the book is still on the bookshelf when you leave the room. In general, we can say that the electrons in an atom have a lot more uncertainty when talking about it's position. The position of an electron on an atom is called an orbital, although an orbital really means the most likely position an electron will be.
Taking all of that uncertainty into account, the effect of "quantum tunneling" comes into play. Quantum tunneling is when particles will jump from point A to point B without passing though the space inbetween. This is an actual observed effect that has some applications in technology today. It is believed that atoms will sometimes do this to combine and form heavier elements. Back to the main point, singular atoms may do this, but humans are made up of a lot more atoms. This means if quantum tunneling were to take effect, all the atoms in your body would move from one side of the wall to the other without passing through the wall itself.
If you would like to try this, go ahead, just walk into any wall....... about a couple of trillion times. One of those trillion times, your atoms are likely to tunnel right through the wall. Unfortunately, the time it would take you to run into a wall that many times would take you billions of years. Anyway, you would be dead after a certain number of intentful hits to the head.
Or you could save yourself the time and just use the door!