Dark Matter: Crash Course Astronomy #41
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Date: 2022-04-04
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Comments and reviews: 10
Richard
Would you please stop using rubber sheets and flexible membranes to represent gravity. It is three dimensional. More like a gas with density, pressure, momentum, energy. vorticity, magnetic moment, charge, concentrations of things. All that is required is a simple 3D visualization like a point cloud. Please! a rubber sheet and bowling ball might have been good enough three decades ago, but we certainly can do much better than that now. If it will help you, then think of the gravitational potential itself, and its associated gradient, the gravitational accelerations. The physical vacuum is not a bad way to remember. Change the reflectivity, transparency for every voxel according to some reasonable visualization.
We don't any Internet wide standard for 3D videos. We should. Then you could change your viewpoint while the 3D video to let you see things from different places, and at different time rates (change over a vast range of frame rates to see details invisible to humans. If you integrate the gravitational energy density, that value can be calculated for every point in space. Is it exact or verified? Not yet. But it is one place to start. Even simple things like electron densities, axion densities and their respective flows, vorticities and temperature can have complex and beautiful periodic and chaotic structures. You are representing a complex beautiful field with a cheap visualization.
So this old method is a lot misleading. At least use the gravitational potential and then color it some way humans can see. We false color radio telescope pictures and a vast number fields and signals that humans cannot directly see. There are excellent models for the global gravitational and magnetic fields of the earth at the surface and into space. They are in spherical harmonic forms, and real time measurement. It takes a bit of looking to find a decent calculator, then a 3D visualizer. But not impossible. Maybe your friendly geophysicist or astrophysicist friends can do it for you.
Most people are not familiar with the gravitational energy density. I only happened on it back in the 1970's after I met Joe Weber. He told me to look at his student, Robert Forward's, work. It is g-2/(8 pi G) in SI units, where g is in (meters/second-2, and G is 6. 6743E-11 (meters/second-2) per (kilogram/meter-2. At the surface of the earth the gravitational energy density is the same as a magnetic field of about 380 Tesla, a laser of 1. 7E19 Watts/m-2 or a black body at 2. 95 million Kelvin (not sure if this to within a factor 2 based on different model assumptions. My point is that space is not empty by any means. Even if you do not fill it with gravitons and axions, the gravitational potential itself is extremely stable and well understood. At least color that in 3D so people can see it. And you will see that the earth's gravitational potential is dwarfed by the sun.
The gravitational potential changes constantly because of changes in the atmosphere, oceans, and earth on the earth, and changes on the sun and moon and more distant sources of gravitational potential change. So if you really want to get fancy show how that is changing constantly. The time dilation equation used for GPS time corrections can be used to show how that changes with time. And it is well defined everywhere in space, so you could plot the rate of clocks, or the vacuum index of refraction, anywhere on earth or in space or on the sun or on the moon - as a function of time. Many many experiments on earth and in space are now sensitive enough to measure these changes in the potential. And many more can measure the gradient of the gravitational potential, the gravitational acceleration. Any 3D video would be fine.
Thank you for listening. Please don't use that rubber sheet any more. Gravity is not a rubber sheet!
I have to deal with the gravitational potential every day. My own view is that it is filled with gravitons, axions, quarks, gluons and neutrinos in different concentrations. These vary in mass and number density, velocity and cross section. It might be wrong, but that simple step greatly simplified things for me. And gave me a more concrete thing to -see- with my human mind when I try to visualize the action of the gravitational potential field at atomic, subnuclear and global scales. I guess I am more a chemist. I like to count moles of gravitons, and not leave them invisible and transparent, even if my human eyes cannot see them.
Richard Collins, The Internet Foundation
reply
Would you please stop using rubber sheets and flexible membranes to represent gravity. It is three dimensional. More like a gas with density, pressure, momentum, energy. vorticity, magnetic moment, charge, concentrations of things. All that is required is a simple 3D visualization like a point cloud. Please! a rubber sheet and bowling ball might have been good enough three decades ago, but we certainly can do much better than that now. If it will help you, then think of the gravitational potential itself, and its associated gradient, the gravitational accelerations. The physical vacuum is not a bad way to remember. Change the reflectivity, transparency for every voxel according to some reasonable visualization.
We don't any Internet wide standard for 3D videos. We should. Then you could change your viewpoint while the 3D video to let you see things from different places, and at different time rates (change over a vast range of frame rates to see details invisible to humans. If you integrate the gravitational energy density, that value can be calculated for every point in space. Is it exact or verified? Not yet. But it is one place to start. Even simple things like electron densities, axion densities and their respective flows, vorticities and temperature can have complex and beautiful periodic and chaotic structures. You are representing a complex beautiful field with a cheap visualization.
So this old method is a lot misleading. At least use the gravitational potential and then color it some way humans can see. We false color radio telescope pictures and a vast number fields and signals that humans cannot directly see. There are excellent models for the global gravitational and magnetic fields of the earth at the surface and into space. They are in spherical harmonic forms, and real time measurement. It takes a bit of looking to find a decent calculator, then a 3D visualizer. But not impossible. Maybe your friendly geophysicist or astrophysicist friends can do it for you.
Most people are not familiar with the gravitational energy density. I only happened on it back in the 1970's after I met Joe Weber. He told me to look at his student, Robert Forward's, work. It is g-2/(8 pi G) in SI units, where g is in (meters/second-2, and G is 6. 6743E-11 (meters/second-2) per (kilogram/meter-2. At the surface of the earth the gravitational energy density is the same as a magnetic field of about 380 Tesla, a laser of 1. 7E19 Watts/m-2 or a black body at 2. 95 million Kelvin (not sure if this to within a factor 2 based on different model assumptions. My point is that space is not empty by any means. Even if you do not fill it with gravitons and axions, the gravitational potential itself is extremely stable and well understood. At least color that in 3D so people can see it. And you will see that the earth's gravitational potential is dwarfed by the sun.
The gravitational potential changes constantly because of changes in the atmosphere, oceans, and earth on the earth, and changes on the sun and moon and more distant sources of gravitational potential change. So if you really want to get fancy show how that is changing constantly. The time dilation equation used for GPS time corrections can be used to show how that changes with time. And it is well defined everywhere in space, so you could plot the rate of clocks, or the vacuum index of refraction, anywhere on earth or in space or on the sun or on the moon - as a function of time. Many many experiments on earth and in space are now sensitive enough to measure these changes in the potential. And many more can measure the gradient of the gravitational potential, the gravitational acceleration. Any 3D video would be fine.
Thank you for listening. Please don't use that rubber sheet any more. Gravity is not a rubber sheet!
I have to deal with the gravitational potential every day. My own view is that it is filled with gravitons, axions, quarks, gluons and neutrinos in different concentrations. These vary in mass and number density, velocity and cross section. It might be wrong, but that simple step greatly simplified things for me. And gave me a more concrete thing to -see- with my human mind when I try to visualize the action of the gravitational potential field at atomic, subnuclear and global scales. I guess I am more a chemist. I like to count moles of gravitons, and not leave them invisible and transparent, even if my human eyes cannot see them.
Richard Collins, The Internet Foundation
reply
Alvan
This will be fun. The theoretical Alcubierre warp drive can move faster than 'C'. Because physics does not limit the speed of any individual piece of spacetime compared to any other piece. I want to offer a seed of thought. - Gravity moves faster than 'C'. - The old mental experiment. If the sun just vanished. We would see the sunlight for 8(+) minutes. It has been put forward that the Earth would continue to move around where the sun was at for that same 8(+) minutes because the gravity from the sun would also last that long. Because of the speed of 'C'. But if gravity. The warping of spacetime, moves faster than 'C'. The Earth would fling out of orbit faster than the visible light from the sun would vanish. - A gravity wave (or ripple in spacetime) is in effect an Alcubierre-style warp, with no laws of physics limiting it's speed. - I have some possible consequences to this thought. - Let's follow the birth and evolution of a particular gravity wave. I'll call him Gerard. Gerard is formed by the orbits of two massive objects and radiates outward. He behaves as we have learned that he behaves. But at the point where we think that he has expanded (or dissipated) to being ineffective to the matter that he encounters. The actuality of his existence is something different. He joins a vast 'flow' of every bit of gravity ever birthed. And contributes to this flow. Amplifying the other gravity waves. As he is also amplified. This flow has eddies and back-washes where matter accumulates. And becomes (among other things) galaxies. The matter that grows in these eddies of gravity 'flow' can be seen to move too fast for its own gravity and we think it should be spinning itself apart. But actually, the gravity that keeps the galaxies together is from the outside 'flow' - Not the inside mass, or more accurately - both. - Dark matter does not exist. When we map the areas where we see more gravity. and call it dark matter. What we are seeing is the 'flow' of all the gravity that was ever birthed. If we want to move to other parts of this galaxy - And even to other galaxies. We need to harness this 'flow'. And surf. :)
reply
This will be fun. The theoretical Alcubierre warp drive can move faster than 'C'. Because physics does not limit the speed of any individual piece of spacetime compared to any other piece. I want to offer a seed of thought. - Gravity moves faster than 'C'. - The old mental experiment. If the sun just vanished. We would see the sunlight for 8(+) minutes. It has been put forward that the Earth would continue to move around where the sun was at for that same 8(+) minutes because the gravity from the sun would also last that long. Because of the speed of 'C'. But if gravity. The warping of spacetime, moves faster than 'C'. The Earth would fling out of orbit faster than the visible light from the sun would vanish. - A gravity wave (or ripple in spacetime) is in effect an Alcubierre-style warp, with no laws of physics limiting it's speed. - I have some possible consequences to this thought. - Let's follow the birth and evolution of a particular gravity wave. I'll call him Gerard. Gerard is formed by the orbits of two massive objects and radiates outward. He behaves as we have learned that he behaves. But at the point where we think that he has expanded (or dissipated) to being ineffective to the matter that he encounters. The actuality of his existence is something different. He joins a vast 'flow' of every bit of gravity ever birthed. And contributes to this flow. Amplifying the other gravity waves. As he is also amplified. This flow has eddies and back-washes where matter accumulates. And becomes (among other things) galaxies. The matter that grows in these eddies of gravity 'flow' can be seen to move too fast for its own gravity and we think it should be spinning itself apart. But actually, the gravity that keeps the galaxies together is from the outside 'flow' - Not the inside mass, or more accurately - both. - Dark matter does not exist. When we map the areas where we see more gravity. and call it dark matter. What we are seeing is the 'flow' of all the gravity that was ever birthed. If we want to move to other parts of this galaxy - And even to other galaxies. We need to harness this 'flow'. And surf. :)
reply
Ian
I thought I was alive until I woke up to death which was my existence until I lived again. And again. The again that I can't remember until I died and died again and again. And then I remembered for a moment the sweet bitterness of life, I think. And yet the yearning for death continues while I reach desperately for life. So much to live for yet so tired. Confusion. Did I live? Am I dead? Did I die? Will I die? Will I live? Am I alive? Maybe. I think yes. For ever? But, does it matter. Here or there? Am I happily wrong or will I despair and disappear happily into the blissful darkness of death and life. Life will never leave me alone
reply
I thought I was alive until I woke up to death which was my existence until I lived again. And again. The again that I can't remember until I died and died again and again. And then I remembered for a moment the sweet bitterness of life, I think. And yet the yearning for death continues while I reach desperately for life. So much to live for yet so tired. Confusion. Did I live? Am I dead? Did I die? Will I die? Will I live? Am I alive? Maybe. I think yes. For ever? But, does it matter. Here or there? Am I happily wrong or will I despair and disappear happily into the blissful darkness of death and life. Life will never leave me alone
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Roger
A simple observation of plasma behaviour around two microwave magnets proves that red shift has been misinterpreted, that the theoretical models themselves have introduced mysteries where there shouldn't be and tries to fix the theories with bizarre, unobservable entities borne of faulty theory and maths alone. Kirchhoff is the father of multiple errors further fostered by Planck, Einstein and Hawking, etc. too numerous to mention. It's a theory swamp, miring progress.
reply
A simple observation of plasma behaviour around two microwave magnets proves that red shift has been misinterpreted, that the theoretical models themselves have introduced mysteries where there shouldn't be and tries to fix the theories with bizarre, unobservable entities borne of faulty theory and maths alone. Kirchhoff is the father of multiple errors further fostered by Planck, Einstein and Hawking, etc. too numerous to mention. It's a theory swamp, miring progress.
reply
Christopher
So why does dark matter seemingly only affect galaxies and not stars/planets? In other words, why does it only seem necessary to include dark matter for galactic observations? Wouldn-t there be dark matter in our solar system, affecting the movement and orbits of the sun snd planets?
Is it too spread out to have a meaningful impact on something as small as our solar system? Is it only concentrated at the edges of galaxies?
reply
So why does dark matter seemingly only affect galaxies and not stars/planets? In other words, why does it only seem necessary to include dark matter for galactic observations? Wouldn-t there be dark matter in our solar system, affecting the movement and orbits of the sun snd planets?
Is it too spread out to have a meaningful impact on something as small as our solar system? Is it only concentrated at the edges of galaxies?
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MICHAEL
The observer shines the fundamental light around itself lighting up the dark matter. The information within the dark matter is then observed as physical matter. The entire cosmos is made of dark matter it is the soul foundation that is within all matter. The 0. 1% light we see is only a reflection of the observers light that shines onto the dark matter-
reply
The observer shines the fundamental light around itself lighting up the dark matter. The information within the dark matter is then observed as physical matter. The entire cosmos is made of dark matter it is the soul foundation that is within all matter. The 0. 1% light we see is only a reflection of the observers light that shines onto the dark matter-
reply
TheInvshika
What if the expansion of spacetime itself is what's causing material further out from a galaxy's core to move quicker? If spacetime expansion is uniform, it would make sense that less dense material further out from the core would move faster, since it has less gravity from other mass acting on it.
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What if the expansion of spacetime itself is what's causing material further out from a galaxy's core to move quicker? If spacetime expansion is uniform, it would make sense that less dense material further out from the core would move faster, since it has less gravity from other mass acting on it.
reply
Daniel
One concept I struggle with when dealing with dark matter is trying to understand at what scale dark matter predominates over local movements such as Andromeda galaxy moving towards us does it need to be a lot larger scale for black dark matter to be effective?
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One concept I struggle with when dealing with dark matter is trying to understand at what scale dark matter predominates over local movements such as Andromeda galaxy moving towards us does it need to be a lot larger scale for black dark matter to be effective?
reply
BalleRina
Ok let me get this straight. Dark matter is a substance in space that if supposedly invisible unless it gives oof light and where ever there isn't a star or some sort of space object in an area of space, it has dark matter, we just don't see it?
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Ok let me get this straight. Dark matter is a substance in space that if supposedly invisible unless it gives oof light and where ever there isn't a star or some sort of space object in an area of space, it has dark matter, we just don't see it?
reply
Internet
In the bullet cluster, gravity is where you'd expect it to be - around the stars. The gas in the middle can't possibly be heavier than all those stars. So the idea that most of the mass is the gas, is just idiotic.
reply
In the bullet cluster, gravity is where you'd expect it to be - around the stars. The gas in the middle can't possibly be heavier than all those stars. So the idea that most of the mass is the gas, is just idiotic.
reply
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