更新1:
Are those super packed planets on which nothing moves anymore the famous "black holes"?
Is the expansion of the universe a misconception of ourselves shrinking?
2012-02-01 7:29 am
In a perfectly ball shaped planet the only place of balance of gravitation forces (or negative and positive vectors) is in the very center. In all places unequal to the center an object is attracted by the masses between the object and the center and the masses on the other side of the center. If an object is inside the ball it becomes lighter the closer it is to the center because it is attracted outwards by the masses between the object and the surface and inwards by the masses mentioned above.In the very middle of the ball shaped planet is zero gravity then. That would mean that gas planets with time would develop hot liquid cores by the pressure from the external mass being attracted inwards and the density with time continously increases until all mass is packed as close as possible towards the middle. That would mean: we shrink and is the reason for my question above (I am not a scientist of physics so please be kind and give me an answer being understood easily).
回答 (3)
2012-02-01 8:34 am
✔ 最佳答案
You would be weightless in the centre of a planet if a suitable space could be provided because as you suggest, the pull would be outwards in all directions. The pull of gravity is greatest on the surface where the whole planet's mass provides the force. Then the pull of gravity reduces again as you move further away into space.Looking at your question, you seem to be suggesting that a universe which is static, and in which everything is shrinking; could look exactly the same as the conventional view of a universe which is expanding and everything in it remains the same size. The problem as I see it would be the speed of light would have to be shrinking at the same rate as the universe, because that is our scale for distance measurements of stars and galaxies in units of light years. Also, particle accelerators seem to confirm the history of the universe as beginning with a big bang, whereas a static universe in which everything is shrinking would require a different theoretical origin.
A planet or star is not a black hole. Every mass has a Schwartzschild radius into which, if you could squeeze that mass, gravity would overcome all other forces and it would collapse inward to form a black hole. Any astronomical body described otherwise is not a black hole.
2012-02-01 7:37 am
When astronomers (particularly Hubble) looked out at the galaxies and measured their velocity (using the Doppler shift) they found that the farther the galaxy was away, the faster (on average) it was moving away from us. These speeds can be very, very fast.
A contracting Earth would give a uniform speed shift for everything in the sky, and it would be very, very small.
I like your enthusiasm, but its hard enough to get a good picture of what might be out there with all the things we know (or think we know). But this is where we start.
A contracting Earth would give a uniform speed shift for everything in the sky, and it would be very, very small.
I like your enthusiasm, but its hard enough to get a good picture of what might be out there with all the things we know (or think we know). But this is where we start.
2012-02-04 3:51 pm
I'd say the expansion of the universe is a misconception for a different reason. It is based on the assumption that galactic redshifts are a doppler effect when it is quite possible that they are instead a scattering effect. Light may simply be losing energy to matter in the intergalactic medium and the galaxies are not actually moving away from each other at all. I recommend you watch this documentary...
http://www.youtube.com/watch?v=1yTfRy0LTD0&playnext=1&list=PL35A32C6E877FEAC3
http://www.youtube.com/watch?v=1yTfRy0LTD0&playnext=1&list=PL35A32C6E877FEAC3
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