So I was in the shower today...

[Agamemnus]

Not at all. The pressure at the center of the earth is incredibly high because there's a planet on top of it, the fluid is forced to become a solid.

Pressure is "the force applied to a unit area of surface". If there is little gravity in the center of the Earth, there would be little pressure, since that is the only force in play there. Unless you want to tell me about some other force..?

Just because "there is a planet on top of it" does not increase the pressure. "Top" is not an absolute term, and your statement implies that the force of gravity is very high there, and it isn't... or are you going to side with Aetherfox's ridiculous argument?

The same idea is taken advantage when a valve is physically placed at a lower elevation to eliminate flashing and cavitation -- the lower elevation increases the pressure head, which lowers the temperature at which the liquid moving through the pipe turns to gas, eliminating cavitation.

I'm not quite following you. Whatever the lower elevation does, at that elevation there is a high amount of gravity. In the center of the earth, the amount of gravity would be very small.

In my example with the drill, the gravitational pull increases indefinately as you approach the COM of Earth.

In this scenario, you don't just simply "plug in" the numbers into the formula. You have to take the limit as the radius approaches by zero. As a result, I am right.

No, as a result, you are wrong. You are plugging in the numbers for one equation: the particle and the earth, when it should be the particle and all the other particles.

And Aga: to disprove your example to disprove me:
If something were in the center of your hollow sphere (it would have to get there somehow, it wouldn't come to rest there naturally unless some serious lucky throwing happened), it would sit there. The attraction from all sides would be equal. If this is -not- what you meant, let me know.

Well, now you are simply contradicting yourself. You admit that gravity moves any object not at the exact center towards the crust, which means that you do not count the mass of the super-sized object as one entity. (Otherwise everything would fall towards the center.) But you also forget that there is no way that you can ever have 0 gravity. There is always some imbalance, unless the universe is and acts perfectly symmetrical from the point of that particle. So, it would always fall towards the crust from the center.

Also, Aga: Your technique for travelling faster than light is not new. Yours is a basic example of what people thought would be the first way to do it. In practice it is impossible, because we have no way to move black holes, and we aren't even imaginably close to creating an electromagnetic force generator strong enough to rip through space-time once, let alone three times.

Practice makes perfect.

I should further add that according to relativity, infinite energy is possible. As a mass approaches the speed of light, it's (sic) relative mass increases, approaching infinity. e=mc^2...

Of course, mass never approaches the speed of light, hence why the speed limit of mass is thought to be slightly less than the speed of light, and why infinite energy doesn't exist...

[Radical Raccoon]

It's no mystery. There earth's core is solid. Solid objects don't need pressure on them to keep them solid. The liquid outer core circles the inner core because of gravitaional attraction. There's pressure on the inner core because the outer core, mantle, and crust are all being pulled towards the center. Why are they being pulled by the center? Actually, they aren't being pulled by the center, but to the center. Every bit of matter on the earth is actually being pulled by all of the other matter. The average of all these forces added up create the center of gravity, the geometric point where all the matter "appears" to be attracted to. It doesn't move towards that point because it's the center, but because all of the other forces point it that direction. Imaging 2 huges planets of equal size in space. They will have a gravitaional attraction to each other, right? So they will move closer to each other. Now, if you are residing in the center of gravity between those 2 objects, you won't be pulled either way by them because the one's gravitational pull cancels the other's out. But this does not stop the planet's from moving towards you! Gravity is still in play with those 2 planets and you will be crushed once they collide. This same concept applies with the earth. Even though you wouldn't feel any of the earth's gravitational force in the center, there is still a massive amount of matter being pulling towards the center, thus creating pressure.

[Zack]

This is a bit off-topic, but consider for a second that a massive object, bigger than Earth, passed really close to Earth, within a few kilometres. Wouldn't all loose objects, including people, be pulled towards that object? And if it wasn't directly above you, you could "fall" sideways.
Earth would be pulled too, albeit more slowly.

[thegrogen]

This is a bit off-topic, but consider for a second that a massive object, bigger than Earth, passed really close to Earth, within a few kilometres. Wouldn't all loose objects, including people, be pulled towards that object? And if it wasn't directly above you, you could "fall" sideways.
Earth would be pulled too, albeit more slowly.

If it really passed that close, maybe. But in reality, an object that close would rub atmospheres with us and the two worlds would be sucked into each other, making a gigantic peanut world with an even higher gravity.

Farther away, that wouldn't really happen because since you are closer to the Earth, the Earth's gravitational pull is stronger on you than the other one. The other object will still pull on you, of course. It'll cause tides and whatnot, just like the moon does. The tides would be stronger, that's all, and you might even feel them tugging at you.

Also, we know that the Earth's core is solid because earthquakes can't pass through it very easily, because it is so dense. We have found that earthquakes on one side can't be felt directly opposite the earth from the epicenter, so therefore there must be something dense in it that the waves cannot pass through.

[aetherfox]

Zack - We'd be sucked into the planet's gravitational pull long before a few kilometers.

Aga - you're becoming increasingly arrogant, much like you used to a few years ago when I visited this forum more regularly, and it's starting to piss me off. I'm enjoying talking about this, but stop being a child.

There -is- pressure, because the rest of the Earth is being pulled towards the center, all your "particles", and they are putting pressure on the core of the Earth. You are arguing against known and explained science, not something that I have come up with.

For the record, Newton's Law Of Gravitation (http://en.wikipedia.org/wiki/Newton%27s_...ravitation) is clearly written with r being the distance between the centers of mass of the objects. According to the formula, I believe I am correct. Your argument disproving my limit made no sense to me at all.

And if you read, I said that infinite mass is possible. For you to say that is does no exist is narrow-minded - our advancement in astrophysics has been over such a small period of time, relatively speaking, that we barely know what is going on. Don't throw down ideas because they don't agree with what you want.

[Zack]

Aeth, you would be correct IF DIVISION BY ZERO YIELDED AN INFINITE RESULT. But it doesn't. You cannot divide by zero, and it not produce an infinite result.

Is it really possible for a the distance between two objects to be zero? Take two neutrons, for example. r in the law of gravitation is the distance between the centres of two masses, and even miniscule particles like neutrons cannot have zero distance between their two centres, otherwise they would have to inhabit the same space.

[TheAdventMaster]

So some 15-year-old comes and says that he knows better than all tried, tested and unbroken laws of physics?

Sure, why not?

The energy in a particle, I'm assuming you mean released by nuclear fusion, is greater than that required to make the particle create more energy from another mass? Man, you aren't making any sense. Moving a particle to another mass...doesn't create energy.

Moving a particle to another mass such as a nuetron can cause a reaction though.

.Sorry, you have to be more clear.

I'm doing my best.

And as soon as a particle's energy is released, it is no longer available in the same form to be moved.

Uhmmmm.... Kay.

[Radical Raccoon]

Aeth, you would be correct IF DIVISION BY ZERO YIELDED AN INFINITE RESULT. But it doesn't. You cannot divide by zero, and it not produce an infinite result.

Theoretically speaking, the closer you get to zero (when dividing by it) the more closer you approach infinity. So yes, dividing by zero would give you infinity (positive or negative depending on the sign of the numerator). The reason the schools teach you that you can't divide by zero is because they don't want to get into theoritical number jumbo. That, or because you cannot apply infinity with most formulae.

[Zack]

Nope. It's an asymptote. Graph y=1/x, and notice that there is no value for x=0. x=.00001 is big, x=.000000000000000001 is even bigger, but x=0 is undefined. It's a mathematical rule, that division by zero is undefined.

AdventMaster: So? I still don't see your logic. How do you come to the conclusion that there is such a thing as infinite energy?

Infinite anything is unlikely (except time, and even that is questionable).

[thegrogen]

And as soon as a particle's energy is released, it is no longer available in the same form to be moved.

Uhmmmm.... Kay.

He's right, in a sense. Since matter is just dense energy, if a particle releases ALL it's energy, it no longer exists because it was changed into energy. That's why when you have an antimatter annhilation there's a tremendous burst of energy and the two particlees you annihilated disappear; the energy is the energy that was once the matter making up the two particles, but because they touched each other and canceled out, they turned back into their pure energy form (which proceeded to spew itself all over the place).