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Author Topic: Is dark energy pushing or pulling or what?  (Read 1002 times)

Offline diverjohn

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Is dark energy pushing or pulling or what?
« on: 07/10/2013 11:12:44 »
The other day I thought of how a ground-based explosion causes debris to fly upward, slow, then fall back to the ground. As the explosive force increases, the debris moves higher and takes longer time to fall back to the ground, as described from Newton's famous calculations. However, if the force were very large, the debris would leave the Earth's atmosphere and may pass a point where the sun's gravity overcomes that of the Earth, and that ejected mass then accelerates away from the Earth and towards the solar disk instead of falling back to the ground.
Now scale this idea up to cosmic proportions, substitute the big bang for the ground-based explosion, and stars for debris, then we'd observe the stars accelerating away from the original force instead of slowing and collapsing. Because this matches what astronomers are observing in our skies, I wonder if one explanation could be there is a mass surrounding the universe that is pulling the stars and galaxies towards it. In other words, instead of a "dark energy" pushing space apart, is it likely our universe is within a massive container whose gravity is pulling space apart?
Taking it further, when will our world crash into the walls of this enormous box?
I'm sure this has been talked of before but I've never come across it before.


 

Offline webplodder

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Re: Is dark energy pushing or pulling or what?
« Reply #1 on: 07/10/2013 11:29:27 »
I don't think anyone really knows. Due to the study of supernovea in distant galaxies it has been found the the universe is expanding at a greater rate that was thought and this 'force' is called dark energy, although it is not currently known what it is.
 

Offline Pmb

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Re: Is dark energy pushing or pulling or what?
« Reply #2 on: 07/10/2013 18:53:11 »
Quote from: diverjohn
The other day I thought of how a ground-based explosion causes debris to fly upward, slow, then fall back to the ground. As the explosive force increases, the debris moves higher and takes longer time to fall back to the ground, as described from Newton's famous calculations. However, if the force were very large, the debris would leave the Earth's atmosphere and may pass a point where the sun's gravity overcomes that of the Earth, and that ejected mass then accelerates away from the Earth and towards the solar disk instead of falling back to the ground.
What you're referring to is known as escape velocity. Are you familiar with this term?

Quote from: diverjohn
Now scale this idea up to cosmic proportions, substitute the big bang for the ground-based explosion, and stars for debris, then we'd observe the stars accelerating away from the original force instead of slowing and collapsing.
This isn’t necessarily true. The stars would only accelerate away if there were a repulsive force at work. However, that said, this is how our particular universe works. There is matter which we’ve called “dark energy” which is causing the accelerated expansion. My point is that without dark energy the stars won’t accelerate away from each other but towards each other. I just wanted to make sure that you understood this. Think of dark energy as causing anti-gravity, i.e. gravitational repulsion.

Quote from: diverjohn
Because this matches what astronomers are observing in our skies, I wonder if one explanation could be there is a mass surrounding the universe that is pulling the stars and galaxies towards it. In other words, instead of a "dark energy" pushing space apart, is it likely our universe is within a massive container whose gravity is pulling space apart?
No. That’s not the way it works nor can it be described in that way.

Quote from: diverjohn
Taking it further, when will our world crash into the walls of this enormous box?
I'm sure this has been talked of before but I've never come across it before.
Nope.
 

Offline Pmb

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Re: Is dark energy pushing or pulling or what?
« Reply #3 on: 07/10/2013 18:54:57 »
Quote from: webplodder
Due to the study of supernovea in distant galaxies it has been found the the universe is expanding at a greater rate that was thought and this 'force' is called dark energy, although it is not currently known what it is.
To be precise it’s the matter causing the accelerating expansion that is referred to as
”dark energy.” Dark energy is not the name given to the force. The force is merely called the gravitational force.
 

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Re: Is dark energy pushing or pulling or what?
« Reply #3 on: 07/10/2013 18:54:57 »

 

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