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1Devilsadvocate
Posts: 1,518
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3/7/2013 2:10:54 AM
Posted: 3 years ago
I'm having trouble understanding how this is correct:

"Ron Maimon, theoretical biologist, physicist:
A physicist I met once told me he asked his 6 year old son to imagine standing on top of a big ball in outer space. Then, he told his son, he looks over the edge, and there is a person on the other side of the ball, upside down, with feet on the bottom of the ball. He asked his son: will that upside-down person fall off the ball? His son thought about it, and said "If the other person looks at me, he sees my feet, and I'm upside down to him. I'm not falling off, so he doesn't fall off"."

I saw it here: http://www.quora.com...
I cannot write in English, because of the treacherous spelling. When I am reading, I only hear it and am unable to remember what the written word looks like."
"Albert Einstein

http://www.twainquotes.com... , http://thewritecorner.wordpress.com... , http://www.onlinecollegecourses.com...
slo1
Posts: 4,313
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3/7/2013 5:59:17 AM
Posted: 3 years ago
At 3/7/2013 2:10:54 AM, 1Devilsadvocate wrote:
I'm having trouble understanding how this is correct:

"Ron Maimon, theoretical biologist, physicist:
A physicist I met once told me he asked his 6 year old son to imagine standing on top of a big ball in outer space. Then, he told his son, he looks over the edge, and there is a person on the other side of the ball, upside down, with feet on the bottom of the ball. He asked his son: will that upside-down person fall off the ball? His son thought about it, and said "If the other person looks at me, he sees my feet, and I'm upside down to him. I'm not falling off, so he doesn't fall off"."

I saw it here: http://www.quora.com...

I don't think you are having any trouble at all. If they booth jumped at the same time, they would learn a ball that you can see another on the other side is not large enough to have enough gravity from keeping them float off into space. However it does have gravity as anything with mass does.

When the mass is distributed equally as in a ball, the gravitational attraction is equal and extends in all directions from the ball. It is just like why people in china don't fall off the earth despite them being oriented the opposite of what we are.

I think they just ignored the first point that the ball is not really big enough to have a large enough gravitational force to keep them on the ball. I would imagine the force of solar winds would be much much larger than the gravitational force the ball puts out and they would even blow right off the ball.
chui
Posts: 507
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3/7/2013 6:04:07 AM
Posted: 3 years ago
So A,who is not falling off, looks at B.
If B looked at A, what B sees is much the same as what A saw when he looked at B. The situation is symmetrical. So what happens to A should happen to B.

This is the basic principle of relativity. The laws of physics work the same way every where.
Sidewalker
Posts: 3,713
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3/7/2013 3:11:43 PM
Posted: 3 years ago
At 3/7/2013 5:59:17 AM, slo1 wrote:
At 3/7/2013 2:10:54 AM, 1Devilsadvocate wrote:
I'm having trouble understanding how this is correct:

"Ron Maimon, theoretical biologist, physicist:
A physicist I met once told me he asked his 6 year old son to imagine standing on top of a big ball in outer space. Then, he told his son, he looks over the edge, and there is a person on the other side of the ball, upside down, with feet on the bottom of the ball. He asked his son: will that upside-down person fall off the ball? His son thought about it, and said "If the other person looks at me, he sees my feet, and I'm upside down to him. I'm not falling off, so he doesn't fall off"."

I saw it here: http://www.quora.com...

I don't think you are having any trouble at all. If they booth jumped at the same time, they would learn a ball that you can see another on the other side is not large enough to have enough gravity from keeping them float off into space. However it does have gravity as anything with mass does.

When the mass is distributed equally as in a ball, the gravitational attraction is equal and extends in all directions from the ball. It is just like why people in china don't fall off the earth despite them being oriented the opposite of what we are.

I think they just ignored the first point that the ball is not really big enough to have a large enough gravitational force to keep them on the ball. I would imagine the force of solar winds would be much much larger than the gravitational force the ball puts out and they would even blow right off the ball.

As the ladies say, size doesn't matter...as far as gravity is concerned, it's density that matters, a black hole can be the size of a basketball. If the ball these guys are standing on is dense enough then it doesn't matter how big it is.
"It is one of the commonest of mistakes to consider that the limit of our power of perception is also the limit of all there is to perceive." " C. W. Leadbeater
slo1
Posts: 4,313
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3/7/2013 8:41:19 PM
Posted: 3 years ago
At 3/7/2013 3:11:43 PM, Sidewalker wrote:
At 3/7/2013 5:59:17 AM, slo1 wrote:
At 3/7/2013 2:10:54 AM, 1Devilsadvocate wrote:
I'm having trouble understanding how this is correct:

"Ron Maimon, theoretical biologist, physicist:
A physicist I met once told me he asked his 6 year old son to imagine standing on top of a big ball in outer space. Then, he told his son, he looks over the edge, and there is a person on the other side of the ball, upside down, with feet on the bottom of the ball. He asked his son: will that upside-down person fall off the ball? His son thought about it, and said "If the other person looks at me, he sees my feet, and I'm upside down to him. I'm not falling off, so he doesn't fall off"."

I saw it here: http://www.quora.com...

I don't think you are having any trouble at all. If they booth jumped at the same time, they would learn a ball that you can see another on the other side is not large enough to have enough gravity from keeping them float off into space. However it does have gravity as anything with mass does.

When the mass is distributed equally as in a ball, the gravitational attraction is equal and extends in all directions from the ball. It is just like why people in china don't fall off the earth despite them being oriented the opposite of what we are.

I think they just ignored the first point that the ball is not really big enough to have a large enough gravitational force to keep them on the ball. I would imagine the force of solar winds would be much much larger than the gravitational force the ball puts out and they would even blow right off the ball.

As the ladies say, size doesn't matter...as far as gravity is concerned, it's density that matters, a black hole can be the size of a basketball. If the ball these guys are standing on is dense enough then it doesn't matter how big it is.

Good point. While I said mass, which is independent of size, I made the assumption that "Ball" is something with the mass and density of a ball one would use to play with.
malcolmxy
Posts: 2,855
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3/26/2013 5:18:44 AM
Posted: 3 years ago
At 3/7/2013 8:41:19 PM, slo1 wrote:
At 3/7/2013 3:11:43 PM, Sidewalker wrote:

As the ladies say, size doesn't matter...as far as gravity is concerned, it's density that matters, a black hole can be the size of a basketball. If the ball these guys are standing on is dense enough then it doesn't matter how big it is.

Good point. While I said mass, which is independent of size, I made the assumption that "Ball" is something with the mass and density of a ball one would use to play with.

awesome.
War is over, if you want it.

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rainbowmunkeyz2
Posts: 11
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4/8/2013 11:38:02 PM
Posted: 3 years ago
Well, first of all there is no absolute or discernible direction in space, agreed? Say you are on one side of the earth. You will not fall because of earths gravity. Someone on the opposite side of the earth will also not fall off. If you could see that person they would not be upside down or right side up (just as one persons left is your right and their right your left), not relative to the earths magnetic poles. Now I know you understand all this, but I think he is making something very simple into something quite confusing. Do you understand? Lets say there is absolutely no gravity in a given amount of space. You see someone as upside relative to your position in 3-D space, because of the opposition of his/her location he/she will also see you as upside down. If you understand this (I'm sure you do it's a very simple concept) don't just take my word for it, I'm only 14 although I'm not one that should be underestimated. My brain's wired differently than most...People.