5 ms·

Just like sea waves which are permanently changing(shaping) the structure of rocks they are hitting[0]. [0] https://en.wikipedia.org/wiki/Wave_pounding https:/

Just like sea waves which are permanently changing(shaping) the structure of rocks they are hitting[0]. [0] https://en.wikipedia.org/wiki/Wave_pounding https://en.wikipedia.org/wiki/Wave_pounding

LegitShady 5y ago
I’m not sure that’s a good analogy. Spacetime isn’t necessarily pounding anything - it could be Spacetime itself that is distorted and curved by such a phenomonon. If spacetime is the medium of the waves, why are these waves hitting anything, and what?
- mrkramer 5y ago
  >If spacetime is the medium of the waves, why are these waves hitting anything, and what? "Gravitational waves are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light." [0] They are hitting everything what is on their way just like sea waves are. [0] https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave
  - LegitShady 5y ago
    It depends what “everything” is though. We exist in spacetime, so we are as much the medium of the wave as everything else is. What are the ‘rocks’ in the analogy? What’s ‘wearing’ like the rocks? We don’t know enough about the spacetime or what’s out of spacetime to say.
    - mrkramer 5y ago
      I'm not a physicist but it doesn't seem hard to understand: "Water waves, sound waves, and electromagnetic waves are able to carry energy, momentum, and angular momentum and by doing so they carry those away from the source. Gravitational waves perform the same function[0]." So as water wave is hitting rock or any other object(mass/energy) on its way gravitational waves should hit also everything and anything on their way until they lose energy and collapse. "Gravitational waves are constantly passing Earth; however, even the strongest have a minuscule effect and their sources are generally at a great distance. For example, the waves given off by the cataclysmic final merger of GW150914 reached Earth after travelling over a billion light-years, as a ripple in spacetime that changed the length of a 4 km LIGO* arm by a thousandth of the width of a proton, proportionally equivalent to changing the distance to the nearest star outside the Solar System by one hair's width[0]." Gravitational waves are all around us but they have minimal impact whatsoever unless I suppose some large event(source) propagates strong gravitational waves near us. *Laser Interferometer Gravitational-Wave Observatory [0] https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave
      - pomian 5y ago
        "I'm not a physicist but"... You should be. That was a nice postulation.
      - galaxyLogic 5y ago
        When we have a sound-wave it means air-pressure changes along the peaks and troughs of the wave. When we have a gravitational wave what measurable quantity changes?
        mrkramer 5y ago
        Ask a physicist but as far as I understood gravitational waves are dents in spacetime[0] and as they travel their energy, momentum, and angular momentum change over time because of interaction and collision with other "stuff" in space. Idk how you can measure any of that. [0]https://www.esa.int/Science_Exploration/Space_Science/Gravitational_waves_dents_in_spacetime https://www.esa.int/Science_Exploration/Space_Science/Gravit...
        galaxyLogic 5y ago
        Is there a simple way to explain what a "dent in spacetime" means? How can it be measured. I don't doubt that science and you all are right, I'm only asking questions in the hope that there is a simple explanation that would make a light-bulb go off in my head.
        jjk166 5y ago
        Gravitational waves change the definition of length and time. If you have some baseline pressure in a room, a pressure wave causes a small region to be briefly higher or lower pressure. If you have a meterstick and a stopwatch, a gravitational wave causes the meter to grow bigger or smaller and the stopwatch to run fast or slow. It's as if you are briefly closer to some immense object like a black hole which causes time dilation - indeed that's exactly what it is. No matter how ridiculously far away they are, as two celestial objects orbit each other they are continually moving closer and then further away from you, and while gravity drops off with distance it never goes to zero. You are feeling the gravitational pull of that celestial object on the other side of the universe getting infinitesimally stronger and weaker as the distance between you and it shrinks and grows, or more accurately as the distance between you and where it was all those millions of years ago when the waves were first emitted shrinks and grows.
    - goldenkey 5y ago
      Correct, it's all just spacetime. This is what Einstein was after in the last years of his life - a unified geometric theory, where mass was not separate from the sheet, but rather, part of it - a deformation of it. [1] https://www.arxiv.org/pdf/0706.0190v2 https://www.arxiv.org/pdf/0706.0190v2 Water waves can crash into eachother. There's no reason that spacetime waves cannot either. You can get some hint of this if you look at the oscillations that comprise the Higgs field. The negative curvature of gravitation should be cancelled out by the positive curvature of matter and energy. https://en.wikipedia.org/wiki/Zero-energy_universe https://en.wikipedia.org/wiki/Zero-energy_universe
    - jjk166 5y ago
      We, and everything else, are stuff floating in the sea of spacetime. Just as a ship would bob up and down as an ocean wave passed along but is not itself part of the wave, so too are we affected by gravitational waves as the pass through spacetime. The difference is instead of up and down motion, the distance between two points in space and time expands and contracts.
      - mrkramer 5y ago
        >We, and everything else, are stuff floating in the sea of spacetime. Just as a ship would bob up and down as an ocean wave passed along but is not itself part of the wave, so too are we affected by gravitational waves as the pass through spacetime. Exactly it's called Frame-dragging[0]: "Frame-dragging is an effect on spacetime, predicted by Albert Einstein's general theory of relativity, that is due to non-static stationary distributions of mass–energy. A stationary field is one that is in a steady state, but the masses causing that field may be non-static -rotating, for instance." [0] https://en.wikipedia.org/wiki/Frame-dragging https://en.wikipedia.org/wiki/Frame-dragging
    - akomtu 5y ago
      I'll make a guess that matter is like bubbles in spacetime. For some reason the bubbles remain stable and due to cleverness of equations governing spacetime, it allows to form stable complex structures around those bubbles. This is even a verifyable hypothesis: check what happens with GR equations in topologies with tiny spherical holes.
      - drran 5y ago
        Bubbles + thermal noise. Noise causes vibration, vibration makes bubbles stable. Vibration also causes bubbles to stick together due to Casimir effect.
      - LegitShady 5y ago
        I guess the question is what is spacetime made of, which is the big problem in physics right now. Whether it's loop quantum gravity, string theory, or one of the many other theories that exist, the question of what is spacetime is what people are trying to solve to figure out quantum gravity. What is spacetime made of? Nobody knows yet.
andrewflnr 5y ago
More like the sea itself doesn't go completely flat after the wave passes. If the water is space, a rock is more like a break in space.

Just like sea waves which are permanently changing(shaping) the structure of rocks they are hitting[0]. [0] https://en.wikipedia.org/wiki/Wave_pounding https://en.wikipedia.org/wiki/Wave_pounding

LegitShady 5y ago

I’m not sure that’s a good analogy. Spacetime isn’t necessarily pounding anything - it could be Spacetime itself that is distorted and curved by such a phenomonon. If spacetime is the medium of the waves, why are these waves hitting anything, and what?

mrkramer 5y ago
>If spacetime is the medium of the waves, why are these waves hitting anything, and what? "Gravitational waves are disturbances in the curvature of spacetime, generated by accelerated masses, that propagate as waves outward from their source at the speed of light." [0] They are hitting everything what is on their way just like sea waves are. [0] https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave
- LegitShady 5y ago
  It depends what “everything” is though. We exist in spacetime, so we are as much the medium of the wave as everything else is. What are the ‘rocks’ in the analogy? What’s ‘wearing’ like the rocks? We don’t know enough about the spacetime or what’s out of spacetime to say.
  - mrkramer 5y ago
    I'm not a physicist but it doesn't seem hard to understand: "Water waves, sound waves, and electromagnetic waves are able to carry energy, momentum, and angular momentum and by doing so they carry those away from the source. Gravitational waves perform the same function[0]." So as water wave is hitting rock or any other object(mass/energy) on its way gravitational waves should hit also everything and anything on their way until they lose energy and collapse. "Gravitational waves are constantly passing Earth; however, even the strongest have a minuscule effect and their sources are generally at a great distance. For example, the waves given off by the cataclysmic final merger of GW150914 reached Earth after travelling over a billion light-years, as a ripple in spacetime that changed the length of a 4 km LIGO* arm by a thousandth of the width of a proton, proportionally equivalent to changing the distance to the nearest star outside the Solar System by one hair's width[0]." Gravitational waves are all around us but they have minimal impact whatsoever unless I suppose some large event(source) propagates strong gravitational waves near us. *Laser Interferometer Gravitational-Wave Observatory [0] https://en.wikipedia.org/wiki/Gravitational_wave https://en.wikipedia.org/wiki/Gravitational_wave
    - pomian 5y ago
      "I'm not a physicist but"... You should be. That was a nice postulation.
    - galaxyLogic 5y ago
      When we have a sound-wave it means air-pressure changes along the peaks and troughs of the wave. When we have a gravitational wave what measurable quantity changes?
      - mrkramer 5y ago
        Ask a physicist but as far as I understood gravitational waves are dents in spacetime[0] and as they travel their energy, momentum, and angular momentum change over time because of interaction and collision with other "stuff" in space. Idk how you can measure any of that. [0]https://www.esa.int/Science_Exploration/Space_Science/Gravitational_waves_dents_in_spacetime https://www.esa.int/Science_Exploration/Space_Science/Gravit...
        galaxyLogic 5y ago
        Is there a simple way to explain what a "dent in spacetime" means? How can it be measured. I don't doubt that science and you all are right, I'm only asking questions in the hope that there is a simple explanation that would make a light-bulb go off in my head.
      - jjk166 5y ago
        Gravitational waves change the definition of length and time. If you have some baseline pressure in a room, a pressure wave causes a small region to be briefly higher or lower pressure. If you have a meterstick and a stopwatch, a gravitational wave causes the meter to grow bigger or smaller and the stopwatch to run fast or slow. It's as if you are briefly closer to some immense object like a black hole which causes time dilation - indeed that's exactly what it is. No matter how ridiculously far away they are, as two celestial objects orbit each other they are continually moving closer and then further away from you, and while gravity drops off with distance it never goes to zero. You are feeling the gravitational pull of that celestial object on the other side of the universe getting infinitesimally stronger and weaker as the distance between you and it shrinks and grows, or more accurately as the distance between you and where it was all those millions of years ago when the waves were first emitted shrinks and grows.
  - goldenkey 5y ago
    Correct, it's all just spacetime. This is what Einstein was after in the last years of his life - a unified geometric theory, where mass was not separate from the sheet, but rather, part of it - a deformation of it. [1] https://www.arxiv.org/pdf/0706.0190v2 https://www.arxiv.org/pdf/0706.0190v2 Water waves can crash into eachother. There's no reason that spacetime waves cannot either. You can get some hint of this if you look at the oscillations that comprise the Higgs field. The negative curvature of gravitation should be cancelled out by the positive curvature of matter and energy. https://en.wikipedia.org/wiki/Zero-energy_universe https://en.wikipedia.org/wiki/Zero-energy_universe
  - jjk166 5y ago
    We, and everything else, are stuff floating in the sea of spacetime. Just as a ship would bob up and down as an ocean wave passed along but is not itself part of the wave, so too are we affected by gravitational waves as the pass through spacetime. The difference is instead of up and down motion, the distance between two points in space and time expands and contracts.
    - mrkramer 5y ago
      >We, and everything else, are stuff floating in the sea of spacetime. Just as a ship would bob up and down as an ocean wave passed along but is not itself part of the wave, so too are we affected by gravitational waves as the pass through spacetime. Exactly it's called Frame-dragging[0]: "Frame-dragging is an effect on spacetime, predicted by Albert Einstein's general theory of relativity, that is due to non-static stationary distributions of mass–energy. A stationary field is one that is in a steady state, but the masses causing that field may be non-static -rotating, for instance." [0] https://en.wikipedia.org/wiki/Frame-dragging https://en.wikipedia.org/wiki/Frame-dragging
  - akomtu 5y ago
    I'll make a guess that matter is like bubbles in spacetime. For some reason the bubbles remain stable and due to cleverness of equations governing spacetime, it allows to form stable complex structures around those bubbles. This is even a verifyable hypothesis: check what happens with GR equations in topologies with tiny spherical holes.
    - drran 5y ago
      Bubbles + thermal noise. Noise causes vibration, vibration makes bubbles stable. Vibration also causes bubbles to stick together due to Casimir effect.
    - LegitShady 5y ago
      I guess the question is what is spacetime made of, which is the big problem in physics right now. Whether it's loop quantum gravity, string theory, or one of the many other theories that exist, the question of what is spacetime is what people are trying to solve to figure out quantum gravity. What is spacetime made of? Nobody knows yet.

andrewflnr 5y ago

More like the sea itself doesn't go completely flat after the wave passes. If the water is space, a rock is more like a break in space.