# Quantum World

1. Jun 18, 2012

### azizlwl

I watch a series on quantum world.
The host said particles can pass through each others.
And then he pushed a wall and said if he keep on pushing for billion of years, there will be possibilities he will pass through the wall.

We have more than 7 billions people in this world. I never heard that somebody fingers ever pass through any object.
I think the possibility is nil

2. Jun 18, 2012

### 256bits

One person pushing on a wall for 7 billion years is not the same as 7 billion people pushing on a wall for 1 year.
If though you did hear of one person's fingers passing through a wall, it would not be believable, and would be considered a magic trick.
The host, or progam, was trying to expand the audiences' mind about quantum physics, albeit in a non-verifiable fashion. I suspect he gave no explanation for why billions of years was chosen over millions or trillions of years.

If you consider that a mole of substance is 6.02214179(30)×10^23 elementary particles and your hand weighs about 500 grams then you are looking at 10^25 particles in your hand that would have to 'pass through' a corresponding number of particles in the wall, all at the same time ( in unison).

so yeah, nil.

3. Jun 18, 2012

### Karimspencer

Well , if particles can pass through each other, then how come when an anti-matter and matter collide , they annihilate and won't pass through each other.

4. Jun 18, 2012

### ZapperZ

Staff Emeritus
You are comparing apples and oranges. Tunneling means that a particle went through a POTENTIAL BARRIER. It does not mean that it went through another particle!

Zz.

5. Jun 18, 2012

### Karimspencer

Oh well , i guess i misunderstood.

6. Jun 18, 2012

### Staff: Mentor

The key is to understand that there is a possibility of him passing through the wall. It is kind of like playing the lottery, but with odds so far against you that you have practically no hope of ever winning. The probability of a person quantum tunneling through a wall and appearing on the other side fully intact is so small that I don't think I have enough room to put all the zeroes in this post. (A rough estimate, but you get my point I hope) So while it is unbelievably small, it is not exactly zero.

7. Jun 18, 2012

### Staff: Mentor

The term "collide" isn't very useful at the quantum scale. Things are described much differently in quantum mechanics than they are in classical physics.

8. Jun 18, 2012

### azizlwl

Thanks. It is unbelievably small.