From the Depths of Earth: Seismic Waves May Unlock Gravity’s Secrets

Composition of Earth’s Mantle

Researchers are exploring the possibility of using seismic motions on Earth to test models of gravity different from Einstein’s general theory of relativity. The current understanding of gravity is based on the assumption that dark matter and dark energy, which make up 95% of the universe, are physical entities. However, general relativity is known to be incomplete, leading to proposals for modified gravity theories. By examining how seismic waves travel under modified gravity, scientists can use the Earth’s well-known properties to constrain these theories. Although no deviations from Einstein’s work have been found, developing more tools to probe modified gravity remains essential. Credit: Argonne National Laboratory

Scientists are investigating the use of Earth’s seismic motions to test alternative models of gravity beyond Einstein’s general theory of relativity. By analyzing seismic waves under modified gravity, researchers can constrain these theories and continue the search for a more complete understanding of gravity.

Testing the possibility of models of gravity different from general relativity may be closer to home than we think. A team of researchers has proposed that we might be able to use seismic motions in the Earth itself to test for modified gravity.

We do not understand 95% of the contents of the universe. Collectively known as the dark sector, the unknowns include both dark matter and dark energy. Dark matter appears to be the dominant form of matter in the universe, with each galaxy containing up to 80% of this invisible form of matter. Meanwhile, dark energy is some source of energy that suffuses all of space-time and is responsible for the accelerated expansion of the cosmos.

But the statements that dark matter and dark energy are physical entities rests on the assumption that our understanding of gravity is correct. Currently, our best understanding of gravity comes from Einstein’s general theory of relativity. This theory tells us that gravity is the manifestation of the bending and warping of space-time itself. 

But we know that general relativity is incomplete. We know that it breaks down in the centers of black holes and at the beginning of the universe. So we know we do not yet have the full story of gravity in our hands. Motivated by this, many people over the decades have proposed theories of modified gravity, which constitute a set of extensions and refinements to Einstein’s original model.

However, all these extensions face a series of difficult hurdles. We have tested general relativity in many contexts and in many scales, so it is difficult to construct a theory that is significantly different enough from vanilla general relativity to potentially explain away dark matter and dark energy, and yet satisfies all known observational constraints.

The more ways we can develop to probe modified gravity the better. And so a team of researchers has found that we don’t necessarily need to look to the stars to test various modified theories of gravity. We can instead look down into the Earth. They discovered that under modified gravity, seismic waves travel through the Earth at different rates and in different ways.

Since we know so many properties of the Earth so well, like its mass and its moment of inertia, we can turn this knowledge around to use seismic data to constrain modified gravity theories.

So far the data do not suggest any need for a deviation from Einstein’s original work. But the more tools we develop, and the more ways we can search, the better.

Adapted from an article originally published on Universe Today.

18 Comments on "From the Depths of Earth: Seismic Waves May Unlock Gravity’s Secrets"

  1. Charles G. Shaver | April 16, 2023 at 10:10 am | Reply

    As previously posted on SciTechDaily and elsewhere, with uploaded videos of at-home-low-budget lay demonstrations of gravity intensification in wheels due to rotation beginning in 2012 and currently on my Odysee dot com video channel, in my model of the universe gravity is locally generated, pulsing, angular and radiating out across the universe in roughly spherical fields, in accordance with the inverse square law of attraction/density. Again, the problem is not with Einstein’s general theory it’s with the mistaken finding of a duality of particles/waves based upon misinterpretations of the classic double-slit experiments. The scattering of impacts on the targets is due to pulsing lines of gravity force redirecting the paths of the particles.

    Furthermore, with scientifically observed ‘gravity lensing’ proving even photons are affected by gravity, I postulate they accelerate (blue shift) on widening lines of gravity force when departing their distant sources and decelerate (red shift) on narrowing lines of local gravity force when arriving to earth. In brief summary of my lay findings, neither the age nor size of the universe have been accurately determined yet and neither dark energy nor dark matter exist; rotation, rotation, rotation.

    • Fixed gravity for you. | April 17, 2023 at 1:32 am | Reply

      “Again, the problem is not with Einstein’s general theory …”

      Of course not, that would have everyone quietly complaining about your opinion.
      Do you agree physics would appeal to an audience twice as wide if we could figure out a way to mention Einstein twice as much?

    • Fixed gravity for you. | April 17, 2023 at 1:42 am | Reply

      “photons … accelerate (blue shift) … and decelerate (red shift) on … gravity”

      You’re bending time for that, right? It’s just another way of saying “c” is constant as required to agree with General Relativity, right? I wish the idea of conservation of time existed, but GR forbids it.

    • Fixed gravity for you. | April 17, 2023 at 1:57 am | Reply

      “widening lines of gravity force … narrowing lines of local gravity force”

      Widening and narrowing like lines of different widths painted on a surface?

      Seems you are vaguely referring to “diverging” (weakening) and “converging” (strengthening) gravity “flux lines.” Not sure why I bring this up however, as I have alluded to this nagging issue of mine before and subsequently there appears to be no reason to expect any change on that point other than a more advanced passive resistance combined with a further-developed admirably sociable attitude. Thanks in advance.

    • Fixed gravity for you. | April 17, 2023 at 3:02 am | Reply

      I must apologize for the multiple responses, I know we have discussed these issues to a lesser extent before, and so the idea of trying to deconstruct your gravity perspective continues to pique my interest.

      I suppose if you have flux lines linking two equal flux sources (sharing an otherwise empty universe) then the sources share an equal number of flux lines. Since the source strength determines the flux intensity, only the flux density at the two surfaces is needed to describe flux effects between the two sources.

      Looks like you prefer to have your flux lines bending to accomplish such couplings, since you prefer bent space-time.

      What do you suppose would be the biggest hurdle to making sense out of the picture if the vector-evocative lines of gravity flow were never bent, as if there was no light to show the way for gravity?

      I think about things like that when I have the spare time. It’s an energy balance issue, it implies objects could radiate away all their energy through gravity unless some mechanism is possible such as an emerging tendency toward gravity energy conservation by focusing on local sources as temperatures drop.

      Seems the dynamics of three mutually intersecting valence quark orbitals would merely need to independently flatten out with cooling for an interesting property to emerge. Translations and jostling may be replaced with simple kinetic spin around one of the three disk axes concentrating most of the nucleon energy on a single retroreflective-aligned spinning disk. Seems reasonable to expect nearby cold nucleons to end up facing each other and retro-reflectively concentrating twisting gravity energy streams between them.

      A plausible triaxial mechanism for re-orienting a nucleon surface to face a new dominant nearby gravity source seems possible. Bearing in mind I am also referring to a situation like the open space between cooled hydrogen ions, at cosmological scales this effect could emerge between spinning galaxies as strong axial DM filaments. A simultaneous secondary focus mode plane perpendicular to the cold spin axis seems possible. At cosmological scales this effect could emerge between galaxies as weaker radial DM filaments.

      • Charles G. Shaver | April 17, 2023 at 8:37 am | Reply

        No apology needed, ‘Fixed,’ and thank you for your rather thorough critique of my personal lay perspectives on flawed cosmology, physics and dark matter. Mostly ignoring everything I see and hear about what I believe (based in large part on multiple actual at-home experiments with rotating wheels) to be imaginary, I viewed the dark matter filament video at the link provided below. The video began much in agreement with my model of the universe but rapidly transgressed into what I find to be the standard misinterpretation of red shift based distances, and failures to factor-in the gravity intensifying rotation of all of included objects: https://www.universetoday.com/98022/hubble-studies-dark-matter-filament-in-3-d/

        More specifically, I find your labels of “diverging” and “converging” not quite right, either. And, too, ‘expanding’ and ‘contracting’ don’t quite fit. It almost boggles the mind to try to visualize a single line of pulsing coherent attractive force coiling and spiraling from the effective center of all individual objects in one locality radiating out to the extremes of the universe in a field of declining density but that’s what I see. And, that’s what my rotating wheel experiments confirm (with ‘feeling’ when hand held) for me.

        If the lines (curves and coils) weren’t angular at the ambient, local level would a change in the direction of rotation of a wheel result in a change of behavior? And, I doubt a three pound tireless bicycle wheel would lift itself up to a temporarily stable horizontal aspect from an externally imposed vertical spin if gravity were just a manifestation of so-called “space-time.” Three of my low-budget videos are available for viewing on my non-monetary Odysee dot com/@charlesgshaver video channel, or directly from me as video files. First, though, having a curious, open and objective mind is probably essential.

        • Fixed gravity for you. | April 17, 2023 at 10:09 am | Reply

          “It almost boggles the mind to try to visualize a single line of pulsing coherent attractive force coiling and spiraling from the effective center of all individual objects in one locality radiating out to the extremes of the universe in a field of declining density but that’s what I see.”

          “pulsing coherent attractive force coiling and spiraling from the effective center of all individual objects”

          So something is causing the gravity to bend around, it seems. Is it conserving something, because it seems to be mysteriously changing momentum constantly. Maybe some of these things are hard to visualise because they can’t be seen anywhere? I can’t even comprehend exactly what you when you compound “coiling” with “spiraling” unless it resembles a spiral cut ham.

          • Fixed gravity for you. | April 17, 2023 at 10:15 am |

            “I can’t even comprehend exactly what you (mean) when you compound “coiling” with “spiraling” unless it resembles a spiral cut ham.”

            Honestly, I don’t like ham (bacon is great, however), but the rippling in the spiral cut version was the only thing I could come up with. It’s funny but more and more often it seems to be the case that dark matter resembles a processed pork product to me.

        • Fixed gravity for you. | April 17, 2023 at 10:45 am | Reply

          Thank you for you reply, in any case.

          Seems possible that properties of light waves (curving under gravity and field vectors effectively spiraling around as circular polarized light waves advance through a point in space, seemingly dilating or contracting with corresponding changes in wavelength) are becoming sublimated into your (gravity information flow?) “lines.” This implies to me that you have a sort of “electric universe” unification of gravity and electromagnetism in mind, which appears to be the logical consequence of adhering to GR quantized as simply as possible. I’ve tried to indicate in various ways that it’s too lockstep sterile of a concept to keep my interest for long.

          • Charles G. Shaver | April 17, 2023 at 12:24 pm |

            Yes, I can’t explain it yet but the lines of gravity force do appear to propagate at a particular angle, resulting in the field loosing density and strength as it grows, in accordance with the inverse-square law. Have you ever seen the filament of an incandescent lamp close up, similar but straighter with limited length and layers.

            I’m not in lockstep, at all. The most popular theories are space-time, accelerating expansion, warped space, quantum mechanics, string-theory and dark matter and energy. I see a continuity of a single explanation from electrons orbiting the nuclei of atoms to galaxies spiraling around black holes. But, the idea of photons accelerating from their sources and decelerating arriving to earth does have me questioning the Big Bang some.

            Commenting on medical matters is of a higher priority for me because I’m living the life and to convince others I’m credible could almost immediately positively impact millions of other lives. To be credible about gravity mostly just means to share that interstellar/intergalactic travel is probably impossible. Regardless, for the time being we’re all stuck within our solar/planetary/satellite field of gravity and real proof of any one theory of everything is also probably impossible.

          • Fixed gravity for you. | April 18, 2023 at 12:30 am |

            “I can’t explain it yet but the lines of gravity force do appear to propagate at a particular angle, resulting in the field loosing density and strength as it grows, in accordance with the inverse-square law.”

            Ahh. Seems plausible you are subconsciously creating an endlessly amusing “having it both ways” parody based on describing Euclidean geometry without directly admitting it.

            Only test I can think of for that situation is to ask if the mysterious angle is related to the speed of light and the size and spin rate of the source.

          • Md. Bulbul Kabir | April 30, 2023 at 10:45 am |

            I want to go to USA and researching astronomy and Astrophysics. I may give fully concept on Universal unknown theory. Please help me to processing my ambitions to get a scholarship in physics related subject in YOUR University as international students.

        • Fixed gravity for you. | April 18, 2023 at 12:48 am | Reply

          “I find your labels of “diverging” and “converging” not quite right, either. And, too, ‘expanding’ and ‘contracting’ don’t quite fit. It almost boggles the mind …”

          That seems to be the ultimate goal and yet also an endlessly rewarding and self-affirming mental journey in itself. I’m just going to avoid taking it personally and suppose Euclid is the target.

  2. Fixed gravity for you. | April 18, 2023 at 2:05 am | Reply

    I’m thinking about the spiral pattern that some rocket boosters are creating lately. It’s just a cylindrical object spinning and leaking from both ends, apparently. It’s way up there and impressive but of course it lacks a commonly seen spiral bar evident with galaxies, one might note.

    If you asked me to explain barred spirals, I’d say a barred region would be a consequence of quantum gravity in action and it’s not too hard to imagine simulating it by a vector field incorporating conserved longitudinal pitch in its effects, though not in its radiated path unless it is gravity relayed by surrounding matter and some extra rotational effect relaying may generate, to depart from always pulling inward, somewhat similar to a cycloidal effect. Also with a galaxy the flow on the galactic plane is presumably net inward not outward like an exhaust pattern, so exhaust is relatively time-reversed compared to a possible galactic evolution from its center.

    Time-flips between models like that give vague suggestions that gravity does things easily taken to be counter-entropic. A degree of uncanny focus seems evident in either case, one might say. With galaxies there are also hints of expansion along a rotation axis that carries matter which eventually cools and drops back into the rotation plane.

    • Charles G. Shaver | April 18, 2023 at 8:18 am | Reply

      ‘Fixed,’ to close this conversation out for me, first, the only real gravity secret I find is why is it so hard for scientists to ignore the dogma and try to see/test it from my perspective? Then, about the only secret left is what higher force is inducing those angular lines of attractive force to radiate in the first place, like a magnetic field around a wire with a current flowing through it; electromagnetic? Stimulating, thanks.

  3. Fixed gravity for you. | April 20, 2023 at 2:10 am | Reply

    A logical point is easily replaced by a higher-dimensional logical donut loop, it just takes a loss of focus.

    For instance, take any universally impressive property that has been mapped in dark matter (based exclusively on using general relativity to create the map, of course) but critically it must be a property that has never over-analyzed before. Then use the new dark matter map to demonstrate how dark matter provides short-term memory proof of the predictive power of general relativity. Global amusement results. A teachable “Look … a squirrel!” moment.

  4. Md. Bulbul Kabir | April 30, 2023 at 10:31 am | Reply

    It is very interesting but assumption that reality sky contains 7 layers, each layer is comparison just a coin in a Stadium.

  5. Md. Bulbul Kabir | April 30, 2023 at 10:49 am | Reply

    How can I get a opportunity to MIT / any others University / research sections?

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