Mike Smith Cosmos Posted February 26, 2016 Posted February 26, 2016 (edited) . Mike Smith Cosmos, on 26 Feb 2016 - 7:20 PM, said:in Science News ( Gravity waves ) . I thought there was possibly some form of Fermion grid that pervaded space , and only responding to fermion style matter ( particles ) , and so propagating ' gravity waves ' ? I am comfortable with Electric Fields , and magnetic fields being set up , one way of another by some form set of components ( coil, plates etc ) into a space . These can be probed , measured , and with a little bit of electronics , an Electro magnetic oscillating field to be set up and a EM wave is produced Which races away at the speed of light . I believe these are derived from ' Bosons ' and produce ' Photons ' that travel at 'c' . Now what is the equivalent with ' Gravitational waves ' are they produced by ' Fermions ' : - how can one probe them , and send them off at 'c' ? Mike Edited February 26, 2016 by Mike Smith Cosmos
Mike Smith Cosmos Posted February 26, 2016 Author Posted February 26, 2016 (edited) No.But I can probe the force , or rubber sheet , because if I step out of my window , onto a sloping plank , I feel pulled down the plank . Something in my neighbourhood is distorting the 'rubber sheet ' . The earth I presume . Trillions upon Trillions of Fermionic matter particles . And I am a ball of many many fermions . If I had stepped onto a sloping plank out in space somewhere a long way a way . Far away from any suns , galaxies, planets etc . I would be able to go out of my window , stand on the sloping plank , and " I would NOT be pulled down the slope ! ( at least only very very minutely , by some far distant dark attractor ) I probed and felt a force ( Gravitational ) . Now how do I make a gravitational wave ? jump up and down ? No, I am serious . How do I make a gravitational wave . Do I need a supply of fermions. Or do I shake the Fermions I have . Do I stand on a vibrating platform . Or perhaps I find something else something massive many many fermions , that is oscillating ? Mike Edited February 26, 2016 by Mike Smith Cosmos
swansont Posted February 27, 2016 Posted February 27, 2016 how can one probe them Look at how masses move when they interact with the waves. Similar to how an antenna is looking at how electrons move when they interact with an EM wave. How do I make a gravitational wave . Do I need a supply of fermions. Or do I shake the Fermions I have . Do I stand on a vibrating platform . Or perhaps I find something else something massive many many fermions , that is oscillating ? It has nothing to do with fermions, other than fermions having mass. But composite bosons do, too. You get gravitational waves when masses accelerate in a way that isn't spherically symmetric. They are exceedingly weak.
Mike Smith Cosmos Posted February 27, 2016 Author Posted February 27, 2016 You get gravitational waves when masses accelerate in a way that isn't spherically symmetric. They are exceedingly weak..Can you go into a bit more detail , and could you keep the explanation , in simple terms . If that is possible . Thanks . Mike
Strange Posted February 27, 2016 Posted February 27, 2016 Can you go into a bit more detail , and could you keep the explanation , in simple terms . If that is possible . Thanks . Any object with masses gravity. That gravity doesn't change over time. Even if the object revolves (like the Earth) the gravity is constant. But if the object is not symmetrical (like a pair of orbiting black holes) then there will be variations in the gravity they causes as they move; you would feel changes in the force of gravity as first one black hole went past and then the other. These variations in gravity spread out from the rotating objects at the speed of light, getting fainter as they go.
Mike Smith Cosmos Posted February 27, 2016 Author Posted February 27, 2016 (edited) Any object with masses gravity. That gravity doesn't change over time. Even if the object revolves (like the Earth) the gravity is constant. But if the object is not symmetrical (like a pair of orbiting black holes) then there will be variations in the gravity they causes as they move; you would feel changes in the force of gravity as first one black hole went past and then the other. These variations in gravity spread out from the rotating objects at the speed of light, getting fainter as they go. O.k.Thanks . I get that specific example ! Is that the only way you get gravity waves . How about things like imploding stars going to neutron stars. Or things going to black holes? Exploding stars going supernova. First generation stars going supernova . The Big Bang itself ? All these are changing their 'gravitational density ' ( if that is a correct statement ) . Will these too emanate ' gravity waves ' ? It all sounds a bit like a flywheel which was rotating perfectly smoothly . But now it's 'big end' bearing , has gone worn or bust , and the whole flywheel is out of balance . Thus vibrating , giving a vibration to anyone sitting in the car , or on their motor bike ! ( ooh my Big End has gone ! A statement from Biker days ) . I still find it hard to see how these waves are travelling across space . Unless space is some form of distributed fermionic grid , full of fields and fermionic mass of some sort or another , even if the distribution is ' fine ', or not very dense ? ( I am using the word Fermion here to indicate something with mass as opposed to something Boson like , without mass , but with associated fields like electric charge and magnetism, etc . If I have got things right ? ) ( but maybe I have not got things right ?) ( unless of course, unless gravity waves are some new set of orthogonal fields , at right angles to each other in the way that radio waves, electro magnetic waves , are orthogonal , at right angles to each other , magnetic and electric . If that is the case ' what are the two orthogonal fields ? ' for gravity waves , mass field and movement field ? Or what ? ) Mike Edited February 27, 2016 by Mike Smith Cosmos
ajb Posted February 27, 2016 Posted February 27, 2016 Now what is the equivalent with ' Gravitational waves ' are they produced by ' Fermions ' : - how can one probe them , and send them off at 'c' ? I am not quite sure what you are asking for... but maybe gravitational waves in supergravity? Some solutions to particular types of supergravity and types of waves are known. I am far from an expert in this. ( I am using the word Fermion here to indicate something with mass as opposed to something Boson like , without mass , but with associated fields like electric charge and magnetism, etc . If I have got things right ? ) ( but maybe I have not got things right ?) Being a fermion or a boson does not depend on mass. It is to do with spin. Fermions have half integer spin and bosons integer (including zero) spin. Maybe my post above is not really what you were asking about
Mike Smith Cosmos Posted February 27, 2016 Author Posted February 27, 2016 (edited) I am not quite sure what you are asking for... but maybe gravitational waves in supergravity? Some solutions to particular types of supergravity and types of waves are known. I am far from an expert in this.Being a fermion or a boson does not depend on mass. It is to do with spin. Fermions have half integer spin and bosons integer (including zero) spin.Maybe my post above is not really what you were asking about . I thought fermions were things like protons and electrons which have mass . And I thought bosons were things like photons and other interaction particles which did not have mass. But did have fields ( like electric and magnetic fields ) Is it the difference in spin , that gives it mass or is that just coincidence ? I can't say I know anything about super gravity and gravity waves for that matter , maybe I should look it up ! In some respects , I thought this is what all this experiment LIGO is all about . Are there gravitational waves ? And thus what are they like ? Yes there are , apparently. ! And what they are like I hope somebody will tell us ! Mike Edited February 27, 2016 by Mike Smith Cosmos
ajb Posted February 27, 2016 Posted February 27, 2016 I thought fermions were things like protons and electrons which have mass Fundamental particles of matter are fermions. But we also have composites which are bosons as the spin is additive. For example we have mesons. I thought bosons were things like photons and other interaction particles which did not have mass. The W and Z bosons have mass. But did have fields ( like electric and magnetic fields ) You are describing the difference between fundamental forces and fundamental matter. Basically forces = fundamental bosons and fermions = fundamental matter. But this is for fundamental matter and not composites, which can be either bosons or fermions (but as far as we know one or the other). Is it the difference in spin , that gives it mass or is that just coincidence ? Spin is the important thing.
michel123456 Posted February 27, 2016 Posted February 27, 2016 Any object with masses gravity. That gravity doesn't change over time. Even if the object revolves (like the Earth) the gravity is constant. But if the object is not symmetrical (like a pair of orbiting black holes) then there will be variations in the gravity they causes as they move; you would feel changes in the force of gravity as first one black hole went past and then the other. These variations in gravity spread out from the rotating objects at the speed of light, getting fainter as they go. What are the laws that govern their movements in the first place? I mean, their movement is also governed by gravity. Or are there other forces that play a role in their movement and thus provoke gravitational waves?
swansont Posted February 27, 2016 Posted February 27, 2016 O.k. Thanks . I get that specific example ! Is that the only way you get gravity waves . How about things like imploding stars going to neutron stars. Or things going to black holes? Exploding stars going supernova. First generation stars going supernova . The Big Bang itself ? All these are changing their 'gravitational density ' ( if that is a correct statement ) . Supernova or imploding stars, if they are spherically symmetric, will not emit gravitational waves. Only to the extent that they are not will they do so.
Strange Posted February 27, 2016 Posted February 27, 2016 I still find it hard to see how these waves are travelling across space . Unless space is some form of distributed fermionic grid , full of fields It is better to think of them as waves of space (more accurately space-time) rather than travelling independently of space. Electromagnetic waves are ripples in the electromagnetic field and, by analogy, space-time is the field that gravitational waves travel rhrough. unless of course, unless gravity waves are some new set of orthogonal fields , at right angles to each other in the way that radio waves, electro magnetic waves , are orthogonal , at right angles to each other , magnetic and electric . If that is the case ' what are the two orthogonal fields ? ' for gravity waves , mass field and movement field ? Or what ? ) Juts because electromagnetic waves can be modelled in terms of two components doesn't mean that all waves have to be. Sound waves are not, for example. What are the laws that govern their movements in the first place? I mean, their movement is also governed by gravity. Or are there other forces that play a role in their movement and thus provoke gravitational waves? It is gravity all the way down.
michel123456 Posted February 27, 2016 Posted February 27, 2016 (edited) It is better to think of them as waves of space (more accurately space-time) rather than travelling independently of space. Electromagnetic waves are ripples in the electromagnetic field and, by analogy, space-time is the field that gravitational waves travel rhrough. Juts because electromagnetic waves can be modelled in terms of two components doesn't mean that all waves have to be. Sound waves are not, for example. It is gravity all the way down. If it is gravity all the way down then it is hard for me to understand the asymmetry. A pair of orbiting black holes would be like any other orbital system with a center of mass somewhere between them. where would the gravitational wave come from? Edited February 27, 2016 by michel123456
Mike Smith Cosmos Posted February 27, 2016 Author Posted February 27, 2016 (edited) It is better to think of them as waves of space (more accurately space-time) rather than travelling independently of space. Electromagnetic waves are ripples in the electromagnetic field and, by analogy, space-time is the field that gravitational waves travel rhrough. Juts because electromagnetic waves can be modelled in terms of two components doesn't mean that all waves have to be. Sound waves are not, for example. It is gravity all the way down. O.k. All over the universe there is this ' Glupe' called 'space time ' its quiescent state is sort of settled with all the matter throughout the universe rearranged into its pits and peaks where concentrations of spinning matter , like stars , black holes , or whatever exert a gravitational distortion in this ' space time ' sort of transparent ' glupe' . Not many ripples to speak ok . Then a couple of black holes decide to crash in on one another in a dance of death , and as they near amalgamation the fun starts and large disturbances in the ' Glupe ' radiate out in all directions , presumably by some inverse square rule or ( inverse r to the 3 rule ) . And by the time the waves have reached us it's pretty small. My lingering , nagging , desire is to get my mental handle on the ' disturbed Glupe ' . I know. It's called ' space time ' but for it to be stirred up by these twirling black holes , like thin consume soup , it must 'BE ' something? Does/ is Fermionic Mass , in any way , present in this ' space time Glupe ? Mike Edited February 27, 2016 by Mike Smith Cosmos
Strange Posted February 27, 2016 Posted February 27, 2016 O.k. All over the universe there is this ' Glupe' called 'space time ' It isn't a separate thing. It is just distances and time. large disturbances in the ' Glupe ' radiate out in all directions , presumably by some inverse square rule or ( inverse r to the 3 rule ) . It is actually 1/r. My lingering , nagging , desire is to get my mental handle on the ' disturbed Glupe ' . You have a ruler? That measures the "space" part. You have a clock? That measures the "time" part. Put them together (distances in three dimensions plus time) and you have space time. We naturally tend to think of the distances and times between events as fixed and linear, because that is the way it appears to us. But it turns out that if you measure very accurately (or at very high speeds or energies) that they are not constant nor linear. I know. It's called ' space time ' but for it to be stirred up by these twirling black holes , like thin consume soup , it must 'BE ' something? What would you expect distance to be made of? Does/ is Fermionic Mass , in any way , present in this ' space time Glupe ? Neither distance not time have any mass, so no. If it is gravity all the way down then it is hard for me to understand the asymmetry. A pair of orbiting black holes would be like any other orbital system with a center of mass somewhere between them. where would the gravitational wave come from? A sphere rotating in water will generate almost no ripples. An asymmetrical object (e.g. a stick) will generate significant ripples.
swansont Posted February 27, 2016 Posted February 27, 2016 If it is gravity all the way down then it is hard for me to understand the asymmetry. A pair of orbiting black holes would be like any other orbital system with a center of mass somewhere between them. where would the gravitational wave come from? That's not spherically symmetric. It looks different on-axis vs in the plane of the orbit. You have a dipole configuration, but it's changing over time — it's rotating and the orbit is decaying. http://www.tapir.caltech.edu/~teviet/Waves/gwave.html O.k. All over the universe there is this ' Glupe' called 'space time ' its quiescent state is sort of settled with all the matter throughout the universe rearranged into its pits and peaks where concentrations of spinning matter , like stars , black holes , or whatever exert a gravitational distortion in this ' space time ' sort of transparent ' glupe' . Not many ripples to speak ok . Then a couple of black holes decide to crash in on one another in a dance of death , and as they near amalgamation the fun starts and large disturbances in the ' Glupe ' radiate out in all directions , presumably by some inverse square rule or ( inverse r to the 3 rule ) . And by the time the waves have reached us it's pretty small. My lingering , nagging , desire is to get my mental handle on the ' disturbed Glupe ' . I know. It's called ' space time ' but for it to be stirred up by these twirling black holes , like thin consume soup , it must 'BE ' something? Does/ is Fermionic Mass , in any way , present in this ' space time Glupe ? Mike Thinking of spacetime as a substance is probably not going to help. When you think of length, do you consider it as a substance? Because it is a version of your "Glupe".
Mike Smith Cosmos Posted February 27, 2016 Author Posted February 27, 2016 (edited) http://www.tapir.caltech.edu/~teviet/Waves/gwave.html Thinking of spacetime as a substance is probably not going to help. When you think of length, do you consider it as a substance? Because it is a version of your "Glupe". But it must be something of substance ! Vibrations and shock waves and mechanical disturbances , do not go through a vacuum , or empty space ...Surely ? . . So radio waves ( electromagnetism as waves ) seems to go through empty vacuum . But sound, vibrations , disturbances , as far as I know , do not go through space. Especially from 1.3 billion years of travel. If they did we could hear the sun ! The mechanical noise, vibrations and distortions that must be going on , on the surface of the sun . I am out in a park at the moment . I can not hear a ' dicky bird ' let alone a deafening cacophony from the surface of the sun. So what is the " Glupe " . Is it a mixture of low density matter , both Fermionic as Bosonic , virtual particles , quantum particles, neutrinos , dark matter, what is it ? Mike Edited February 27, 2016 by Mike Smith Cosmos
Strange Posted February 27, 2016 Posted February 27, 2016 But it must be something of substance ! Why? What is 1 foot made from? Is it the same thing 1 second or 1 metre is made of? Vibrations and shock waves and mechanical disturbances , do not go through a vacuum , or empty space ...Surely ? . So what? That logic is what led people to assume there must be some material "aether" that light was transmitted through. It turned out later that there is no such substance. This is one of many cases where "common sense" is useless. So what is the " Glupe " . Is it a mixture of low density matter , both Fermionic as Bosonic , virtual particles , quantum particles, neutrinos , dark matter, what is it ? It is the geometry of distances and time (aka space-time).
swansont Posted February 27, 2016 Posted February 27, 2016 But it must be something of substance ! Vibrations and shock waves and mechanical disturbances , do not go through a vacuum , or empty space ...Surely ? . . So radio waves ( electromagnetism as waves ) seems to go through empty vacuum . But sound, vibrations , disturbances , as far as I know , do not go through space. Especially from 1.3 billion years of travel. If they did we could hear the sun ! The mechanical noise, vibrations and distortions that must be going on , on the surface of the sun . I am out in a park at the moment . I can not hear a ' dicky bird ' let alone a deafening cacophony from the surface of the sun. So what is the " Glupe " . Is it a mixture of low density matter , both Fermionic as Bosonic , virtual particles , quantum particles, neutrinos , dark matter, what is it ? Mike But we're not talking about mechanical vibrations and shock waves, we're talking about gravitational waves. "Glupe" is comprised of the same substance that length is. So what is length made of?
michel123456 Posted February 27, 2016 Posted February 27, 2016 (edited) That's not spherically symmetric. It looks different on-axis vs in the plane of the orbit. You have a dipole configuration, but it's changing over time — it's rotating and the orbit is decaying. http://www.tapir.caltech.edu/~teviet/Waves/gwave.html "It looks different on-axis vs in the plane of the orbit.". OK that I can understand. Many galaxies are like this. Sorry for being obtuse but: - from your link- When the gravitational tidal field of a source changes with time (...) When does that happen? I don't understand. How can a gravitational tidal field change over time? By a rotating source? That doesn't make sense to me. In your link, it is shown as if only one of the red dots was emitting the wave, while in fact the second dot plays also a role. In such a system, I thought that what is important is the center of mass, not especially the one or the other dot. And the center of mass does not go back and forth between the dots. Or am I completely wrong? Please split from the main thread if you want to. Edited February 27, 2016 by michel123456
swansont Posted February 27, 2016 Posted February 27, 2016 "It looks different on-axis vs in the plane of the orbit.". OK that I can understand. Many galaxies are like this. Sorry for being obtuse but: - from your link- When does that happen? I don't understand. How can a gravitational tidal field change over time? By a rotating source? That doesn't make sense to me. It's not that it's a rotating source; here you have two masses revolving. The source of gravity is accelerating, since it's moving in a circle. In your link, it is shown as if only one of the red dots was emitting the wave, while in fact the second dot plays also a role. In such a system, I thought that what is important is the center of mass, not especially the one or the other dot. And the center of mass does not go back and forth between the dots. Or am I completely wrong? You're reading too much into the diagram. The field has an amplitude, so the wave has to be offset from the center for it to make any sense. Otherwise it's just a straight line. The waves are associated with the system. Gravity only looks like it emanates from the center of mass if you have spherical symmetry.
michel123456 Posted February 27, 2016 Posted February 27, 2016 It's not that it's a rotating source; here you have two masses revolving. The source of gravity is accelerating, since it's moving in a circle. OK let's say it is the Sun and Jupiter. For an external observer gravity comes from the center of mass which is not in the center of the Sun. Isn't that correct? Gravity only looks like it emanates from the center of mass if you have spherical symmetry. Why? I don't understand that. See above.
swansont Posted February 27, 2016 Posted February 27, 2016 OK let's say it is the Sun and Jupiter. For an external observer gravity comes from the center of mass which is not in the center of the Sun. Isn't that correct? If that were true, then there would be no moons around any planet. They don't see the gravity as emanating only from the sun, or from the center of mass. They see two distinct sources of gravity.
michel123456 Posted February 27, 2016 Posted February 27, 2016 If that were true, then there would be no moons around any planet. They don't see the gravity as emanating only from the sun, or from the center of mass. They see two distinct sources of gravity. You are correct. Which makes me think I don't understand how gravity works.
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