# Passage principle

1. Nov 24, 2009

### Jon_C

I'm interested in learning the physic's principle to the following query. It's not homework. Just wanting to learn what I'm presuming is a fundamental in physics.

If two natures exist seperated by a barrier and an entity or element from one nature (first) uses a gateway to enter into the other nature (second), then, presumably, an entity or element from the second nature could, likewise, use the same gateway to enter the first nature.

Thanks for any feedback or insights,

Jon_C

2. Nov 24, 2009

### Danger

Although I don't know the precise nature of your scenario, your conclusion is incorrect. There are plenty of examples to the contrary. Turnstiles, check valves, the biological sodium pump, etc..

3. Nov 25, 2009

### Jon_C

I apologize if I was being too vague in my query.

The examples you provided are good, however, I trust that they are examples of manufactured containment or control of the passageway.

The principle I'm seeking is regarding if a passage is established that allows for one nature to pass through a barrier, which had seperated two different natures, allowing the first nature to enter into the second, then, presumably, the second nature would be capable to access the same passage to enter into the first.

For example;
A needle pierces through the skin and injects a solution into the body. As the needle is removed from the skin, the puncture continues to exist (the opening or passage) and allows for blood to exit from the body.

Here's a different type of example;
Pilgrims get on a boat and travel across the ocean from one continent to a second continent. After the pilgrims enter into the second continent the natives of the second continent use the boat to travel back across the ocean and enter into the first continent.

And, another;
An astronaut flies a spacecraft onto a distant planet. He enters onto the planet. A microorganism from the planet enters into the spacecraft and returns to the astronaut's home planet.

So, essentially, once a barrier, seperating two natures, is opened, then, regardless of which nature enters first, theorhetically, the second nature has an equal opportunity to access the passage and enter into the first.

4. Nov 25, 2009

### James Leighe

EDIT: Let me just preface this by saying that 'barriers' connecting 'natures' is to vague for a meaningful answer as your question ultimately depends on the properties of the 'natures' and the 'barriers'.

EDIT 2: Don't call your idea a 'principal', people will be (slightly) less likely to take you seriously.

Allot of stuff both natural and unnatural is one way or favors one way like Danger has said... even in the natural subatomic particles themselves. The process of time itself. We can give counter-examples all day but lets try something else...

Your trying to draw a conclusion that if you went from one 'nature' to another 'nature' then someone from the other 'nature' should be able to cross over to your 'nature' as easily as you went into theirs... I don't see any reason this should be.