What if we dug a tunnel through the center of the earth connecting the two ends (like two poles). Suppose we have these condition in our tunnel.  1:There is no heat at all.  2:The tunnel be vacuumed (there is no air resistance in it).  Questions 1:What if we jump through this tunnel what would happen then?  2:Can we reach the other end of the earth?  3:If yes, How long it would take to reach the other end point?  4:Can we survive through the journey (if the above conditions are applied)?  5:If there is air at the center what would be the pressure at center?
11591
...And you jumped in.  What would happen when you got to the middle of the Earth? Would you gradually slow down, until you got to the middle and once you were in middle would every direction feel like it was up?
83028
First, I consider the following as given: All the galaxies, solar systems and planets in the universe travel on a different route at a different velocity through space, mostly moving away from each other.  Now, imagine we would be able to create a wormhole from planet x in solar system y in galaxy z to planet a in solar system b in galaxy c. Since both planets are moving in different directions, I see 2 options how it could work.  1) The wormholes would travel with the planets, constantly changing the spacetime-wrapping.  2) The wormholes would stay at the position they were initially created, which means the planets would move away from them, after they were created. But the spacetime-wrapping would stay the same.  I know most people (me included) think that option 1 is the case. But the following question really made me think, and led me to the question I'm now asking:  If option 1 was the case, what would happen if someone entered the wormhole? Would he keep the velocity of the planet where he entered at the planet he came out, which means he would move away from the target planet? Or would he adopt the velocity of the target-planet? If the latter was the case, would this person notice the slow-down/speed-up/direction-change? Could the person even die?  I'm not a physicist, so I may assume totally wrong concepts. I'm sorry about that.
47567
I don't understand the fact that let's say hypothetically I was pushing a block on a frictionless surface, and I kept applying the same force on the object how it would keep accelerating! Wouldn't there have to be a certain velocity where it would stop getting faster? If not then what is actually acting on the object to cause it to accelerate infinitely?
77064
Isn't G a continuous function and although you leave the immediate vicinity of the earth with an escape velocity won't it always exert a force, however small it may be. Won't that force eventually pull the object back to the earth (assuming the absence of other objects)
105727
If yes, why don't they fill up with water, and can you breathe the air there? Like, it's not exactly atmosphere there, but an underwater cave with higher ceiling.  P.S. Possible that it has a different name than air pocket, but due to my limited knowledge of English, I have no idea.  Thanks in advance!
115376
If we had an airtight container that was large enough, say extended out to the Karman line, would there still be a pressure gradient? If we assume that the pressure at the bottom was $1\ \mathrm{atm}$, would it have the same exact pressure gradient at 6 miles up on the outside? This is assuming that the gravity is still $9.8\ \mathrm{m/s^2}$.
35568
If you could travel to the center of the Earth (or any planet), would you be weightless there?
94969
I was thinking about why the poles are colder and I came out with three possible explanations.  1. The atmosphere blocks light beams coming to poles    The Sun is seen only slightly over the horizon at the poles, so the light beams have longer way to the poles. If only this case were true, then the total difference between the poles and the equator would be the same as the energy that was absorbed by the atmosphere.  2. Sun is only slightly over the horizon at the poles.    Poles are often in shadow of the parts of the Earth which are closer to the equator.  3. Poles are farther from the Sun    The longer is the way to Sun the lower is the chance to catch a light from the Sun.  Please, correct me wherever I'm wrong. I'd like to know   Which of these three is most correct?  How significant are the described effects of the other explanations?
111374
There are 2 balls in a vacuum, next to each other but not touch. They are on the edge of a surface they will both leave the table at exactly the same time. One gets pushed harder than the other. The earth is completely flat. Apparently both balls will hit the floor at exactly the same time and even further be at the same vertical height from the floor at any point in time. How is this possible?  If you push the one ball much much much harder than the first so that it is going at a considerable speed 100m/s compared to 1m/s say. The balls can't possible hit the floor at the same time, right?  Now the earth is round. You hit the one ball so hard it goes into orbit the other ball just falls of the table straight down like before. As the one ball has gone into orbit it will never reach the ground. However the slow ball will reach the ground much faster. How can a rule be different? If it doesn't work at the extreme then it shouldnt work at all.
54888
I'm having trouble understanding why the earth is a viable fault path for electricity brought into my home. Isn't there really high resistance? I mean, it's dirt?   Also, let's say I connect the hot wire coming into my house directly to the ground wire. What is the path that the electricity takes to get back and "complete the circuit?"
47451
The  has microgravity and is thought to be solid and almost 6000 degrees hot. What is the pressure like there? The confusing thing, for the common man I suppose, is that there's no gravity there, but lots of matter around it which does gravitate towards the center. How does that add up? Is the center just a gas cloud or is it highly compressed?  And I could add the aside question about what it is like in the microgravity center of a  or a black hole, but I don't expect anyone to know about that.
5603
The idea that as you move through the earth you get a symmetric cancelling of gravitational acceleration which approaches zero acceleration due to gravity at the center of the earth makes a lot of sense I think. I also think that is a pretty easy idea to understand physically.  On the other hand, I am just beginning to study and understand the general relativistic explanation for gravity and I'm wondering how this same idea is explained using general relativity. That is, what is the explanation for why gravitational acceleration decreases (linearly if I'm not mistaken) as you approach the center of the earth using general relativity? Specifically, I would like to understand what is going on with the curvature of spacetime in this scenario? Is it becoming less curved? Some math would be appreciated in answers!
104123
Assuming that a place in Europe is exactly on the opposite side of the earth than Sydney. Now I want to take a plane to travel there. Does it matter if the plan flies with the rotation of the earth or counter the rotation of the earth? i.e. Does it matter if the plane flies westbound or eastbound?  Intuitively I would say it does matter, because if I fly against the earth rotation the goal, in this case Sydney is coming nearer. On the other hand, maybe the plane is still in the atmosphere and therefore part of the earth rotation.
121027
What would happen if the earth would stop spinning? How much heavier would we be? I mean absolutely stop spinning. How much does the centrifugal force affect us?  If you give technical answers (please do), please explain them in laymen's terms, thanks.  Edit: I am asking what would be different if the earth were not spinning. Nevermind the part about it stopping.
100151
Hypothetically, if you were to travel say, 6 months into the past with no spatial displacement, you would end up floating in space because the Earth would be on the opposite side of the sun.  I know when it comes to sci-fi, they can't account for everything and I don't expect them to. So I'm not nit-picking or anything, I'm just wondering if this is something that has been addressed to any detail, as it seems like it would have to be a major component of any time travel.
16014
It's said the earth is approaching the sun. Can we push it away little by little?  Although we can emit rocket towards the sun, but it's too expensive to make a rocket:    So I think maybe we can recycle the rocket, at first, the rocket is send out with a very fast speed, so give back a big force to the earth. And then, we let the rocket slowly comes back to the earth, and re-send it again:    Well, this solution sounds a little inefficient. Still I don't know if it works. Better ideas?  EDIT  Umm.. It seems the earth is leaving the sun. That's ok. Then, the question is how can we push the earth towards the sun, i.e., correct the orbit by human force? Even if the sun turns into a red giant someday, we may finally find a way to put the earth at a safe position far enough from heat.
84533
I have been researching for a while looking for what to include more than just deriving the equation of Newton’s law of cooling and a website gave me inspiration by stating what if the temperature of the environment is changing (± C). In conclusion, I wasn’t sure if that person carried out the mathematical process in the right way and the only place I could ask for accurate information is here so please let me know what you think about the mathematical process he went for and if it is right or wrong. Thanks a lot. Website: